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Publisher: Elsevier   (Total: 3155 journals)

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Showing 1 - 200 of 3155 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 9)
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 34, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 23, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 96, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 27, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 38, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 5)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 7)
Acta Astronautica     Hybrid Journal   (Followers: 411, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 27, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 2)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 10, SJR: 0.18, CiteScore: 1)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.128, CiteScore: 0)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 259, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 28, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 6, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 6)
Acute Pain     Full-text available via subscription   (Followers: 14, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 17, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 8, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 10, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 154, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 14, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 28, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 10, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 11, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 14, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 33, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 4)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 27, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 14)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 12)
Advances in Digestive Medicine     Open Access   (Followers: 9)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 28, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 46, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 58, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Genetics     Full-text available via subscription   (Followers: 16, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 8, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 23, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 35, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 18, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 11, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 12)
Advances in Pharmacology     Full-text available via subscription   (Followers: 16, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 64)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 399, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 11, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 34, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 46, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 346, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 11, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 456, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 17, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 41, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 57, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 6, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 10)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 9, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 51, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 50, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 54, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 45, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 10)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 34, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 35, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 47)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 215, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 28, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 28, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 38, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 63, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 18, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 5, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 42, SJR: 1.512, CiteScore: 5)
Analytical Biochemistry     Hybrid Journal   (Followers: 181, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 12, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 23, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 202, SJR: 1.58, CiteScore: 3)

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Journal Cover
Advances in Space Research
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 2
Number of Followers: 399  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0273-1177
Published by Elsevier Homepage  [3155 journals]
  • Ionospheric and geomagnetic Pc5 oscillations as observed by the ionosonde
           and magnetometer at Sodankylä
    • Abstract: Publication date: Available online 14 December 2018Source: Advances in Space ResearchAuthor(s): O. Kozyreva, A. Kozlovsky, V. Pilipenko, N. Yagova The study is based on the data of the rapid-run ionosonde at the Sodankylä Geophysical Observatory at auroral latitude (L = 5.25) which routinely performs one-minute sounding since 2007. This dataset allows a unique opportunity for investigating possible effects of ultra-low frequency (ULF, 1-7 mHz) waves in the auroral ionosphere. Suitable observations were made during moderately disturbed geomagnetic conditions typically at recovery of the geomagnetic storms caused by solar wind high-speed streams, in the daytime between 9 and 16 MLT. The ionospheric oscillations corresponding to Pc5 geomagnetic pulsations were found in variations of the virtual height of the F layer and the power of ionosonde reflections from E and F layers. The later are most probably caused by modulation of electron precipitation, which is also manifested in weak (about 0.01 – 0.06 dB) variations of cosmic noise absorption. The most important and novel result is that the pulsations of power of reflection from E and F layers typically has a spectral maximum at nearly half the periodicity of the Pc5 geomagnetic pulsations, whereas such spectral peak is negligible in the geomagnetic pulsations.
       
  • Using consecutive point clouds for pose and motion estimation of tumbling
           non-cooperative target
    • Abstract: Publication date: Available online 10 December 2018Source: Advances in Space ResearchAuthor(s): Yipeng Li, Yunpeng Wang, Yongchun Xie This paper proposes a consecutive point clouds-based estimation scheme to resolve the state estimation problem for tumbling non-cooperative space target during the rendezvous phase without a prior knowledge about its structure. First, a consistent pose estimation algorithm is realized by maintaining a global structure of the target that is reconstructed upon the pose graph optimization. Then an extend Kalman filter on Lie group is adopted to estimate the motion and inertia parameters of the target using the pose measurements of the point clouds. A semi-physical experimental study is carried out to evaluate the performance of the proposed estimation scheme. The result shows that the structure, motion and the inertia parameters can be estimated, and the total computation time is approximately linear with the number of point clouds.
       
  • Regolith-Derived Ferrosilicon as a Potential Feedstock Material for
           Wire-Based Additive Manufacturing
    • Abstract: Publication date: Available online 9 December 2018Source: Advances in Space ResearchAuthor(s): Kevin D. Grossman, Tamil S. Sakthivel, Laurent Sibille, James G. Mantovani, Sudipta Seal Ferrosilicon is a primary metallic alloy produced during the reduction of metal oxides contained in lunar and Martian regolith by a variety of techniques. This study examines the usefulness of ferrosilicon as a candidate feedstock material for wire-based 3D printers designed for in-space manufacturing. Alloys of composition ranging from pure iron to 12 wt% Si were synthesized and their electrical and mechanical properties characterized. The melts were cast into rods for mechanical testing to determine ultimate strength and ductility. It was determined that the samples above 3 wt% Si were too brittle to be pulled into wire and ruptured at low strain values. The 3 wt% Si sample and iron had comparable mechanical properties relative to samples of higher silicon content but with differences in ductility and ultimate strength. Microstructure and compositional studies revealed the differences between the ductile and brittle samples as being the complete ferrite phase presence on the iron and low-Si content samples. This study establishes an upper limit on the Si content at 3 wt% in ferrosilicon materials to be used in wire feedstock in additive manufacturing for in-space applications.
       
  • Mars Entry Guidance Using A Semi-Analytical Method
    • Abstract: Publication date: Available online 7 December 2018Source: Advances in Space ResearchAuthor(s): Yiyu Zheng Future Mars missions may require improved landed accuracy to facilitate the landing site selection and finally access a region of complex terrain with high scientific return. This paper is to develop a novel, robust, and precision entry guidance algorithm for Mars entry vehicles with low lift-to-drag ratios. In the presence of large uncertainties, the entry terminal point controller algorithm can encounter severe performance degradation due to: 1) the small perturbation assumption, and 2) theoretically ignoring deviations in the atmospheric-density model, aerodynamic-force model, etc. Based on numerical technologies and the classical variation method (VM), this work develops a semi-analytical (SA) algorithm, in which combined effects of several dynamic uncertainties now can be addressed. The terminal-downrange error is predicted by a numerical predictor such that the dependence on the reference trajectory can be reduced and then the issue caused by the small perturbation assumption can be addressed. Such a predicted terminal-downrange error is finally corrected by an analytical corrector, which is designed by the VM. It is indicative that there can be no numerical iterations in the SA algorithm. Numerical results demonstrate the effectiveness of the SA algorithm.
       
  • Calibration errors in determining slant Total Electron Content (TEC) from
           multi-GNSS data
    • Abstract: Publication date: Available online 5 December 2018Source: Advances in Space ResearchAuthor(s): Wei Li, Guangxing Wang, Jinzhong Mi, Shaocheng Zhang The Global Navigation Satellite Systems (GNSS) is nowadays a powerful tool for sensing the Earth's ionosphere. For this purpose, the ionospheric measurements (IMs), which are by definition slant Total Electron Content (sTEC) biased by satellite and receiver Differential Code Biases (DCBs), need to be firstly extracted from GNSS data, and then used as inputs for further ionospheric representations, such as tomography. Based on the customary phase-to-code leveling procedure, the main scope of this research is to comparatively evaluate calibration errors on experimental IMs obtained from three GNSS, namely the US Global Positioning System (GPS), the Chinese BeiDou Navigation Satellite System (BDS) and the European Galileo. On the basis of ten days' dual-frequency, triple-GNSS observations collected from eight co-located ground receivers that independently form short baselines and zero baselines, the IMs are per receiver determined for all tracked satellites and then per satellite differenced for each baseline to evaluate their calibration errors. As firstly derived from short baseline analysis, the effects of calibration errors on IMs range, in Total Electron Content units (TECu), from 1.58 to 2.16 for GPS, from 0.70 to 1.87 for Galileo and from 1.13 to 1.56 for BDS. Additionally, for short-baseline experiment, it is shown that the code multipath effect accounts for their main budget. Sidereal periodicity is found in single-differenced (SD) IMs for GPS and BDS geostationary satellites, and the correlation of SD IMs over two consecutive days achieve maximum when the time tag around 4 minutes. Moreover, as byproducts of zero baseline analysis, daily between-receiver DCBs for GPS are subject to more significant intra-day variations than that for BDS and for Galileo.
       
  • ° N+and+80 ° N&rft.title=Advances+in+Space+Research&rft.issn=0273-1177&rft.date=&rft.volume=">Seasonal variations in vertical distribution of meteor decay time as
           observed from meteor radars at 8.5 ° N and 80 ° N
    • Abstract: Publication date: Available online 5 December 2018Source: Advances in Space ResearchAuthor(s): B. Premkumar, K. Chenna Reddy, G. Yellaiah, K. Kishore Kumar The decay times of meteor radar echoes have been used for decades to investigate characteristics of the mesosphere and lower thermosphere (MLT) region. As the meteor echo decay time depends on background atmospheric parameters, in the present communication, we examine the seasonal variation of the vertical distributions of underdense meteor echo decay times with respect to echo strength. Observations from two similar radars located at two distinct geographical locations, Thumba (8.5°N, 77°E) and Eureka (80°N, 85.8°W) were used for the present study. Here, the radar received signal power is categorized into strong and weak echoes and vertical profiles of their decay times are constructed. It has been noticed that the monthly mean decay time vertical profile turning altitude (i.e., inflection point) varies in the range of 80 - 87 km of altitude depending on latitude. The turning altitude is observed at relatively lower heights in the winter than in summer at both the latitudes. The present analysis shows that the meteor decay time below the mean turning altitude follows a decreasing trend with decreasing altitude, which is quite distinct to the behaviour of ambipolar diffusion. It is also observed that there is a difference in mean decay time of strong and weak echoes below 90 km of altitude, which is very prominently seen at lower altitudes. This difference shows a seasonal pattern at high latitude, but does not show any seasonal variation at low latitude. The present results are discussed in light of current understanding of the meteor decay time.
       
  • Active Detumbling Technology for Noncooperative Space Target with Energy
           Dissipation
    • Abstract: Publication date: Available online 29 November 2018Source: Advances in Space ResearchAuthor(s): Yuan-Qing Liu, Zhang-Wei Yu, Xiao-Feng Liu, Ju-Bing Chen, Guo-Ping Cai Space debris is generally a kind of tumbling noncooperative space target which poses a serious threat to human space activities. In active debris removal (ADR) missions, capturing a space target directly may cause damage to the space manipulator and chaser satellite, so it is a feasible strategy to reduce the angular velocity of space target to an acceptable range in the pre-capture phase. In this paper, an active detumbling technology for a free-floating tumbling space target with energy dissipation is studied, and an effective detumbling method utilizing intermittent contact impact between the space target and despin mechanism is proposed. First, the dynamic model of the space target is set up by the Jourdain’s velocity variation principle. Then, a contact model between the space target and despin mechanism is established based on the Hertz contact theory and the method of computer graphics. Finally, the detumbling method is validated by numerical simulations. Simulation results show that our method can reduce the angular velocity of the space target effectively without causing large nutation.
       
  • Fringe Fitting and Group Delay Determination for Geodetic VLBI
           Observations of DOR Tones
    • Abstract: Publication date: Available online 28 November 2018Source: Advances in Space ResearchAuthor(s): Songtao Han, Axel Nothnagel, Zhongkai Zhang, Rüdiger Haas, Qiang Zhang Extracting the group and phase delays of interferometric observations produced in the Very Long Baseline Interferometry (VLBI) measurement concept requires a special fringe fitting and delay search algorithm for the recorded bandwidth. While fringe fitting is in use routinely for several megahertz wide channels in geodetic and astrometric VLBI with quasar observations, fringe fitting for artificial tones of very small bandwidth of artificial signals for Differential One-way Ranging (DOR) requires a different way of handling. In a project called Observing the Chang’E-3 Lander with VLBI (OCEL), the DOR tones emitted by the Chang’E-3 lander were observed in a standard geodetic VLBI mode with 8 or 4 MHz wide channels to maintain compatibility with the corresponding quasar observations. For these observations, we modified the existing fringe fitting program of the Haystack Observatory Processing Software (HOPS), fourfit, to properly handle narrow band DOR tones. The main motivations are that through this modification, the data of quasars and artificial radio sources can be processed in the existing geodetic analysis pipeline, and that the algorithm can be used for similar projects as well. In this paper, we describe the algorithm and show that the new algorithm produces much more reliable group delay results than using the standard fourfit algorithm. This is done by a simulation test and in particular by processing of real observations. It is shown that in many cases, systematic deviations of several nanoseconds, which are seen with the standard fourfit algorithm, can be avoided. The ultimate benefit of the new procedure is demonstrated by reducing the errors in delay triangle closures by at least a factor of 3, which, in the OCEL case, is from ∼300 to ∼100 picoseconds.
       
  • Study of the radiation fields in LEO with the Space Application of Timepix
           Radiation Monitor (SATRAM)
    • Abstract: Publication date: Available online 27 November 2018Source: Advances in Space ResearchAuthor(s): Stefan Gohl, Benedikt Bergmann, Hugh Evans, Petteri Nieminen, Alan Owens, Stanislav Posipsil We present the analysis of data taken by the Space Application of Timepix Radiation Monitor (SATRAM). It is centred on a Timepix detector (300 μm thick silicon sensor, pixel pitch 55 μm, 256 x 256 pixels). It was flown on Proba-V, an Earth observing satellite of the European Space Agency (ESA) from an altitude of 820 km on a sun-synchronous orbit, launched on May 7, 2013. A Monte Carlo simulation was conducted to determine the detector response to electrons (0.5 MeV to 7 MeV) and protons (10 MeV to 400 MeV) in an omnidirectional field taking into account the shielding of the detector housing and the satellite. With the help of the simulation, a strategy was developed to separate electrons, protons and ions in the data. The measured dose rate and stopping power distribution are presented as well as SATRAM’s capability to measure some of the stronger events in Earth’s magnetosphere. The stopping power, the cluster height and the shape of the particle tracks in the sensor were used to separate electrons, protons and ions. The results are presented as well. Finally, the pitch angles for a short period of time were extracted from the data and corrected with the angular response determined by the simulation.
       
  • Effect of q-nonextensive hot electrons on bifurcations of nonlinear and
           supernonlinear ion-acoustic periodic waves
    • Abstract: Publication date: Available online 20 November 2018Source: Advances in Space ResearchAuthor(s): Asit Saha, Jharna Tamang Nonlinear and supernonlinear ion-acoustic periodic waves are investigated in a three-component unmagnetized plasma which consists of mobile fluid cold ions, Maxwellian cold electrons and q-nonextensive hot electrons employing phase plane analysis. Using the traveling wave transformation, the plasma system is reduced to a planar autonomous dynamical system. Utilizing phase plane analysis of planar dynamical systems, all possible phase portraits including nonlinear homoclinic orbit, nonlinear periodic orbit, supernonlinear homoclinic orbit and supernonlinear periodic orbit are presented depending on physical parameters q,α,σ and V. Using numerical simulations, nonlinear and supernonlinear ion-acoustic periodic waves are shown for different conditions. It is found that the nonextensive parameter q plays a crucial role in the bifurcations of nonlinear and supernonlinear ion-acoustic periodic waves. Our study may be applicable to understand the nonlinear and supernonlinear periodic features in auroral plasma.
       
  • A Novel Predictive Algorithm for Double Difference Observations of
           Obstructed BeiDou Geostationary Earth Orbit (GEO) Satellites
    • Abstract: Publication date: Available online 20 November 2018Source: Advances in Space ResearchAuthor(s): Yuan Du, Guanwen Huang, Qin Zhang, Rui Tu, Junqiang Han, Xingyuan Yan, Xiaolei Wang Transmission link disturbances and device failure cause global navigation satellite system (GNSS) receivers to miss observations, leading to poor accuracy in real-time kinematic (RTK) positioning. Previously described solutions for this problem are influenced by the length of the prediction period, or are unable to account for changes in receiver state because they use information from previous epochs to make predictions. We propose an algorithm for predicting double difference (DD) observations of obstructed BeiDou navigation system (BDS) GEO satellites. Our approach adopts the first-degree polynomial function for predicting missing observations. We introduce a Douglas-Peucker algorithm to judge the state of the rover receiver to reduce the impact of predictive biases. Static and kinematic experiments were carried out on BDS observations to evaluate the proposed algorithm. The results of our navigation experiment demonstrate that RTK positioning accuracy is improved from meter to decimeter level with fixed ambiguity (horizontal < 2cm, vertical < 18cm). Horizontal accuracy is improved by over 50%, and the vertical accuracies of the results of the static and kinematic experiments are increased by 47% and 27% respectively, compared with the results produced by the classical approach. Though as the baseline becomes longer, the accuracy is weakened, our predictive algorithm is an improvement over existing approaches to overcome the issue of missing data.
       
  • The Adjusted Optical Properties for Galileo/BeiDou-2/QZS-1 Satellites and
           Initial Results on BeiDou-3e and QZS-2 satellites
    • Abstract: Publication date: Available online 20 November 2018Source: Advances in Space ResearchAuthor(s): Bingbing Duan, Urs Hugentobler, Inga Selmke Solar Radiation Pressure (SRP) is the dominant non-gravitational perturbation for GNSS (Global Navigation Satellite System) satellites. In the absence of precise surface models, the Empirical CODE Orbit Models (ECOM, ECOM2) are widely used in GNSS satellite orbit determination. Based on previous studies, the use of an a priori box-wing model enhances the ECOM model, especially if the spacecraft is a stretched body satellite. However, so far not all the GNSS system providers have published their metadata. To ensure a precise use of the a priori box-wing model, we estimate the optical parameters of all the Galileo, BeiDou-2, and QZS-1 (Quasi Zenith Satellite System) satellites based on the physical processes from SRP to acceleration. Validation using orbit prediction proves that the adjusted parameters of Galileo and QZS-1 satellites exhibit almost the same performance as the corresponding published and ”best guess” values. Whereas, the estimated parameters of BeiDou-2 satellites demonstrate an improvement of more than 60% over the initial ”guess” values. The resulting optical parameters of all the satellites are introduced into an a priori box-wing model, which is jointly used with ECOM and ECOM2 model in the orbit determination. Results show that the pure ECOM2 model exhibits better performance than the pure ECOM model for Galileo, BeiDou-2 GEO and QZS-1 orbits. Combined with the a priori box-wing model the ECOM model (ECOM+BW) results in the best Galileo, BeiDou-2 GEO and QZS-1 orbits. The standard deviation (STD) of satellite laser ranging residuals reduce by about 20% and 5% with respect to the pure ECOM2 model for Galileo and BeiDou-2 GEO orbits, while the reductions are about 40% and 60% for QZS-1 orbits in yaw-steering and orbit-normal mode respectively. BeiDou-2 IGSO and MEO satellite orbits do not benefit much from the a priori box-wing model. In summary, we suggest setting up a unified SRP model of ECOM+BW for Galileo, QZS-1, and BeiDou-2 orbits based on the adjusted metadata. In addition, we estimate the optical parameters of BeiDou-3e and QZS-2 satellites using a limited number of tracking stations. Results regarding the unified SRP model indicate the same advantages, the STD of satellite laser ranging residuals reduces by about 30% and 20% for QZS-2 and BeiDou-3e orbits respectively over orbit products without a priori model. The estimation procedure is effective and easy to apply to the new emerging satellites in the future.
       
  • Cumulative Author Index for Volume XX - ISSUE 12 OF EACH VOLUME ONLY
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s):
       
  • Very-low altitude parasitic radar distributed on small satellites
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Salvatore Sarno, Maria Daniela Graziano, Giancarmine Fasano, Marco D'Errico This paper presents an original approach for a radar-based distributed system. The novel mission concept foresees a formation of very low altitude parasitic small satellites capturing the signal transmitted by existing LEO SARs in C and X bands. Both orbital analysis and radar performance estimation are performed. In order to increase the number of potential illuminators and achieve limited lifetimes, the receiver is supposed to be in a very LEO (altitudes between 300 and 350 km), below the transmitters that generally orbit around 500–800 km. The analysis of the orbital elements reveals that the loss of the initial configuration is mostly due to variations of RAAN. A reference scenario is thus considered with COSMO-SkyMed as transmitter and a small satellite as receiver. The latter is the reference unit of the receiving cluster that forms the sparse passive antenna. Simulation results show the initial patterns are lost in a few days unless some design strategies are used to preserve the desired acquisition geometry over long times. Furthermore, the analysis focuses on the piece of relative trajectory with the receiver in the proximity of the transmitter when the signal acquisition becomes possible. The impact of acquisition geometry on imaging performance is evaluated and spatial resolutions of 6 m (along the range) and 14 m (along the azimuth) are estimated as the best achievable values. The coverage potential of the radar is then computed in terms of areas acquired with good imaging capabilities, strongly limited to guarantee a near-rectangular shape of the pixels. Finally, power considerations as a function of receiving antenna area are carried out. Results show that good SNR value are achieved by a total antenna area of 10 m2, which can be usefully split over a ten of platforms.
       
  • Hyper hemispheric lens applications in small and micro satellites
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Claudio Pernechele, Cesare Dionisio, Matteo Munari, Roberto Opromolla, Giancarlo Rufino, Giancarmine Fasano, Michele Grassi, Serena Pastore As well known, micro and nanosatellites are being proposed for a variety of space missions, due to the advantages offered in terms of flexibility, cost and development time-scales. They also allow the development of space missions based on distributed architectures, composed of a number of small platforms in coordinated flight. However, technological advancements are still needed to make micro and nanosatellite competitive with respect to larger platforms. In this paper, we explore the potentiality offered by hyper hemispheric lens for the development of miniaturized and multi-function sensors for use on board of micro satellites. Hyper hemispheric lens belong to the ultra-wide field-of-view optical objectives. Here a novel optics of this category is presented. Its field of view is 360° in azimuth (panoramic capabilities) and 135° for the off-boresight angle (hyper-hemispheric field). With such capabilities the lens may be exploited as a very-large field-of-view optics where moving parts can be avoided. This is of interest to space applications, in which devices with any moving part, representing a possible point of failure, shall be avoided or reduced to the minimum. A hyper hemispheric lens may, then, be adopted for electro optical devices in space satellite subsystems, such as star-, Sun- and Earth-sensors, or for monitoring the environment surrounding the satellite in the case of on-orbit servicing or active debris removal operations. Weight and cost budgets for small and micro satellites are also important parameters to determine their success. Hyper hemispheric lens may be kept quite compact in dimension and the need of a single imaging detector, for a so large field of view, strongly reduces costs. In this paper, we explore possible applications of a multi-purpose space device based on a hyper hemispheric lens on board of micro and nanosatellites.
       
  • Towards an innovative electrical interface standard for PocketQubes and
           CubeSats
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): J. Bouwmeester, S.P. van der Linden, A. Povalac, E.K.A. Gill Developers experience issues with the compatibility, connector size and robustness of electrical interface standards for CubeSats and PocketQubes. There is a need for a lean and robust electrical interface standard for these classes of satellites. The proposed interface standard comprises a linear data bus which is used for housekeeping data, internal commands and small-to-moderate payload data. A community based analytic hierarchy process is used for the trade-off of design options, resulting in the selection of RS-485 as standard data bus, mainly due to its low power consumption and high effective data throughput compared to other candidates. Several switched and protected battery voltage lines are distributed from the central electrical power subsystem unit to the other subsystems to enable a simple and efficient power distribution. The harness comprises a 14 and 9 pin stackable connector for CubeSats and PocketQubes, respectively, occupying very little board space.
       
  • Functional/thermal verification and validation of an S-band radio for the
           nanosatellites
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Yaseen Zaidi, Norman G. Fitz-Coy, Robert van Zyl An S-band radio designed with commercial-grade components for the nanosatellites is functionally and thermally characterized for quiet transmission. The QPSK modulation impairments are minor over −20 °C to +50 °C at 24, 26, 28 and 30 dBm RF levels. The channel response is linear in error vector magnitude, frequency, phase, amplitude and IQ errors. On the average, the stability of amplifier bias and nonlinearity gives −22 dBc maximum upper/lower adjacent channel power and 1.27 MHz occupied channel bandwidth. The acceptable level test results provide good confidence toward robust space-to-earth transmission in variable solar weather at low earth orbital altitudes.
       
  • Direct thrust and plume divergence measurements of the IFM Nano Thruster
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): David Jelem, Alexander Reissner, Bernhard Seifert, Nembo Buldrini, Lissa Wilding, David Krejci The IFM Nano Thruster, which consists of a porous tungsten crown ion-emitter to provide thrust in the range of 10 µN to 1 mN at 2000–5000 s ISP, has been tested on a µN thrust balance that has previously been verified at the ESA Propulsion Laboratories. A comprehensive assessment of the thrust performance has been complemented by measurements of the plume divergence using a novel segmented collector setup that allows to assess the ion current distribution within a 2D-section of the plume in a high time resolution. From the plasma probe measurements, an upper bound of 0.93 for the thrust coefficient has been derived, while direct thrust measurements have shown a thrust coefficient between 0.8 and 0.9 over the entire thrust range. From the test results, a complete thruster performance map could be established linking emitter current and voltage with thrust and Isp.
       
  • Fully magnetic attitude control subsystem for picosat platforms
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Andrea Colagrossi, Michèle Lavagna In this paper, the design of a fully magnetic attitude control subsystem for a picosat platform is discussed. The developed control law is based on a simple and reliable architecture, which can be easily implemented on small spacecrafts for de-tumbling and three-axis stabilization purposes. The subsystem design follows a practical engineering approach, exploiting global optimization methods, which lead to an integral actuation compliant with typical pointing accuracy requirements for picosat missions. Performance of the proposed attitude control subsystem is demonstrated by numerical simulations.
       
  • Robust filter setting in GPS-based relative positioning of small-satellite
           LEO formations
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Flavia Causa, Alfredo Renga, Michele Grassi Formations of small satellites are becoming more and more important to many space applications, since they offer the possibility of distributing the payload functionality among the different elements of the formation, so to improve scientific return, providing at the same time a number of advantages in terms of overall system reliability, flexibility and modularity. However, precise autonomous determination of the relative positions of the formation members is required for formation acquisition and maintenance, and scientific objective achievement. For Low-Earth-Orbit formations, this task can be performed exploiting GPS-based relative positioning techniques. The technique exploited in this paper is designed for on board usage. It processes double differenced pseudo-range and carrier phase observables on two frequencies within a hybrid filtering scheme to get satisfactory precision and high robustness. However, relative positioning by GPS is affected by the capability of correctly estimating differential ionospheric delays, and, then, by the status of ionosphere activity. Hence, the filter includes an ionospheric model capable of reproducing ionosphere horizontal gradients with a minimum number of parameters, which can be estimated on the fly. In addition, a robust tuning approach is developed in the paper to get stable filter performance over long period of times. Specifically, the proposed approach combines an empirical tuning technique with a randomized algorithm to get the best filter tuning. Filter performance and tuning approach effectiveness are successfully verified using freely available GPS flight data of Gravity Recovery and Climate Experiment mission.
       
  • DISCUS – The Deep Interior Scanning CubeSat mission to a rubble pile
           near-Earth asteroid
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Patrick Bambach, Jakob Deller, Esa Vilenius, Sampsa Pursiainen, Mika Takala, Hans Martin Braun, Harald Lentz, Manfred Wittig We have performed an initial stage conceptual design study for the Deep Interior Scanning CubeSat (DISCUS), a tandem 6U CubeSat carrying a bistatic radar as the main payload. DISCUS will be operated either as an independent mission or accompanying a larger one. It is designed to determine the internal macroporosity of a 260–600 m diameter Near Earth Asteroid (NEA) from a few kilometers distance. The main goal will be to achieve a global penetration with a low-frequency signal as well as to analyze the scattering strength for various different penetration depths and measurement positions. Moreover, the measurements will be inverted through a computed radar tomography (CRT) approach. The scientific data provided by DISCUS would bring more knowledge of the internal configuration of rubble pile asteroids and their collisional evolution in the Solar System. It would also advance the design of future asteroid deflection concepts. We aim at a single-unit (1U) radar design equipped with a half-wavelength dipole antenna. The radar will utilize a stepped-frequency modulation technique the baseline of which was developed for ESA’s technology projects GINGER and PIRA. The radar measurements will be used for CRT and shape reconstruction. The CubeSat will also be equipped with an optical camera system and laser altimeter to support navigation and shape reconstruction. We provide the details of the measurement methods to be applied along with the requirements derived from the known characteristics of rubble pile asteroids. Additionally, an initial design study of the platform and targets accessible within 20 lunar distances are presented.
       
  • DustCube, a nanosatellite mission to binary asteroid 65803 Didymos as part
           of the ESA AIM mission
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Franco Perez, Dario Modenini, Antonio Vázquez, Fernando Aguado, Ricardo Tubío, Gergely Dolgos, Paolo Tortora, Alberto Gonzalez, Riccardo Lasagni Manghi, Marco Zannoni, Adeeb Nazeeruddin, Mauro Melozzi, Ian Carnelli Nanosatellites are a promising option for the exploration of the solar system and near-Earth objects, providing an agile, reduced cost and mass solution for interplanetary missions. This paper summarises the efforts done during the Phase A study aimed at assessing the feasibility of a nanosatellite-based mission concept for a 3U CubeSat to the vicinity of the binary asteroid 65803 Didymos. The nanosatellite is meant to be part of the Asteroid Impact Mission (AIM) which is the European element of the NASA-ESA jointly developed Asteroid Impact & Deflection Assessment (AIDA) mission. The inclusion of a scientific optical payload based on a Nephelometer, the selected orbital and navigation strategy, together with the differences found between the Beyond-Earth space environments (radiation, micrometeoroids, ejected material, illumination conditions, communications access) and a typical LEO polar environment, unveils new technical challenges to be faced along interplanetary missions. These challenges have been identified and analysed to be included within the DustCube concept of operations, are described in this manuscript.
       
  • Optical tracking and orbit determination performance of self-illuminated
           small spacecraft: LEDSAT (LED-based SATellite)
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Fabio Santoni, Patrick Seitzer, Tommaso Cardona, Gianmarco Locatelli, Nicola Marmo, Silvia Masillo, Davide Morfei, Fabrizio Piergentili LEDSAT is a 1U CubeSat developed by S5Lab team of Sapienza – University of Rome in collaboration with the Astronomy Department of University of Michigan. The main goal of the mission is to demonstrate that a LED-based active illumination system may be used to achieve orbit and attitude determination. LEDSAT will be placed into a Low Earth Orbit (LEO) and observed by a network of ground-based telescopes. A LED-based system may improve the accuracy in monitoring LEO spacecraft. A simple model is developed to estimate the features of an optical link between a ground station and a self-illumination system. The reliability of orbit determination and the precision of the orbit reconstruction is evaluated.
       
  • Lighthouse: A spacebased mission concept for the surveillance of
           geosynchronous space debris from low earth orbit
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Roberto Lupo, Carlo Albanese, Daniele Bettinelli, Marco Brancati, Giovanni Minei, Claudio Pernechele In this paper, a new mission is proposed for space debris surveillance in geosynchronous orbit (GEO). The mission “Lighthouse”, here proposed as a concept study, describes the use of a small satellite in a low polar orbit, equipped with a Schmidt telescope, constantly observing a belt across the geostationary orbit. In this way, a single instrument can sweep the whole orbit everyday regardless the light and weather conditions. Most of observations are nowadays performed by ground telescopes, which are affected by weather conditions and night time duration. Moreover, a single telescope can observe only a portion of the geostationary orbit. The mission concept arose as space application of an ESA ITI (Innovation Triangle Initiative) project designing a Schmidt telescope purposely conceived for the monitoring of NEO (Near Earth Objects) and space debris. A compact version of the telescope (50 cm diameter and 1.61 m length), particularly suitable for space applications, has been designed too. The size and the mass of the telescope enable the use of a small satellite platform, with the related advantages in term of costs and performance. Lighthouse is proposed as a new asset for Space Surveillance and Tracking sensors, complementary to the ground telescopes network.
       
  • Small launch platforms for micro-satellites
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Chantal Cappelletti, Simone Battistini, Filippo Graziani The number of small satellites launched into orbit has enormously increased in the last twenty years. The introduction of new standards of micro-satellites has multiplied the launch demand around the world. Nevertheless, not all the missions can easily have access to space: not all kinds of micro-satellites have granted a deployer system and, furthermore, once a micro-satellite is able to reach it, it cannot usually choose its final orbit. Recently two new platforms have been introduced for the release of micro-satellites as piggy-backs. These platforms are totally operative spacecrafts that act like motherships, and allow to select some parameters of the final orbit of the piggy-backs. They provide a solution for three different nano-satellites standard, and at the same time they are being developed in order to reach more powerful orbital release capabilities in the future. The design and the mission of these platforms are described in this paper.
       
  • Response surface modeling-based analysis on launch vehicle capability
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s): Sungjun Ann, Namhoon Cho, Youdan Kim, Sangjoon Shin, Jaemyung Ahn This paper proposes a framework to analyze the capacity of a launch vehicle systematically. Important mission requirements and flight parameters that influence the payload capacity of a given launch vehicle configuration are identified. The response surface models (RSM; the “analyzer”) for the launch capacity, coasting/burning arcs, and the velocity increment elements are developed. A series of trajectory optimization results, which are obtained with the “optimizer”, are used to determine the coefficients of the models. The case study to analyze the capacity of a low Earth orbit (LEO) launch vehicle configuration is conducted to demonstrate the validity of the proposed framework.
       
  • List of Referees
    • Abstract: Publication date: 15 December 2018Source: Advances in Space Research, Volume 62, Issue 12Author(s):
       
  • Robust Fault-Tolerant Saturated Control for Spacecraft Proximity
           Operations with Actuator Saturation and Faults
    • Abstract: Publication date: Available online 14 November 2018Source: Advances in Space ResearchAuthor(s): Qi Li, Jianping Yuan, Chong Sun In this paper, the motion control problem of autonomous spacecraft rendezvous and docking with a tumbling target in the presence of unknown model parameters, external disturbances, actuator saturation and faults is investigated. Firstly, a nonlinear six degree-of-freedom dynamics model is established to describe the relative motion of the chaser spacecraft with respect to the tumbling target. Subsequently, a robust fault-tolerant saturated control strategy with no precise knowledge of model parameters and external disturbances is proposed by combining the sliding mode control technique with an adaptive methodology. Then, within the Lyapunov framework, it is proved that the designed robust fault-tolerant controller can guarantee the relative position and attitude errors converge into small regions containing the origin. Finally, numerical simulations are performed to demonstrate the effectiveness and robustness of the proposed control strategy.
       
  • Interaction of magnetoacoustic solitons in electron-positron plasmas
    • Abstract: Publication date: Available online 13 November 2018Source: Advances in Space ResearchAuthor(s): Shahida Parveen, Shahzad Mahmood, Anisa Qamar, Muhammad Adnan The interaction between two, four and six magnetoacoustic solitons in electron-positron plasmas are investigated. The extended Poincaré–Lighthill–Kuo (PLK) perturbation method is employed to derived two KdV equations for magnetoacoustic solitons moving towards each other and studied the head-on collision between them and their phase shifts. The Hirota bilinear method is used to have multi-soliton solutions of already derived two KdV equations for right and left moving solitons. The four and six magnetoacoustic solitons solutions of the two KdV equations are obtained to discuss their interaction and phase shifts. It is found that only compressive magnetoacoustic solitons structures are formed in electron-positron plasma. The present study may be useful to understand the collective phenomena related to head-on and overtaking magnetoacoustic solitons interaction in electron-positron plasmas that may occur in a pulsar magnetosphere.
       
  • Flight safety implications of the extreme solar proton event of 23
           February 1956
    • Abstract: Publication date: Available online 13 November 2018Source: Advances in Space ResearchAuthor(s): Kyle Copeland, William Atwell There is considerable speculation about the effects at aircraft altitudes resulting from extreme solar proton events. The ground level event (GLE) of 23 February 1956 (GLE 5), remains the largest solar proton event of the neutron monitor era in terms of its influence on count rates at monitors near sea level. During this GLE the count rate was increased by as much as 4760% (15-minute average) at the Leeds monitor relative to the count rate from galactic cosmic radiation (GCR). Two modern models of the event cumulative solar proton spectrum for this event, a 6-parameter fit in energy and a 4-parameter Band fit in rigidity, are compared with 1-hour of GCR at solar minimum. While effective doses calculated with CARI-7A for both models at low geomagnetic cutoff rigidities are indeed high when compared with GCR and can exceed recommended exposure limits, both GLE spectra exhibit a much stronger dependence on cutoff rigidity than GCR, and a larger fraction of the dose from neutrons. At locations with cutoff rigidities above 4.2 and 6.4 GV, respectively, the GLE effective doses are smaller than the GCR hourly dose. At locations with cutoff rigidities above about 4 GV, GCR was the dominant source of exposure in 10 hours or less at all altitudes examined. This suggests that if a similar event occurs in the future, low- and mid-latitude flights at modern jet flight altitudes could be well-protected by Earth’s magnetic field.
       
  • Displacement Monitoring Performance of Relative Positioning and Precise
           Point Positioning (PPP) Methods Using Simulation Apparatus
    • Abstract: Publication date: Available online 13 November 2018Source: Advances in Space ResearchAuthor(s): Salih Alcay, Sermet Ogutcu, Ibrahim Kalayci, Cemal Ozer Yigit Besides the classical geodetic methods, GPS (Global Positioning System) based positioning methods are widely used for monitoring crustal, structural, ground etc., deformations in recent years. Currently, two main GPS positioning methods are used: Relative and Precise Point Positioning (PPP) methods. It is crucial to know which amount of displacement can be detected with these two methods in order to inform their usability according to the types of deformation. Therefore, this study conducted to investigate horizontal and vertical displacement monitoring performance and capability of determining the direction of displacements of both methods using a developed displacement simulator apparatus. For this purpose, 20 simulated displacement tests were handled. Besides the 24 h data sets, 12 h, 8 h, 4 h and 2 h subsets were considered to examine the influence of short time spans. Each data sets were processed using GAMIT/GLOBK and GIPSY/OASIS scientific software for relative and PPP applications respectively and derived displacements were compared to the simulated (true) displacements. Then statistical significance test was applied. Results of the experiment show that using 24 h data sets, relative method can determine up to 6.0 mm horizontal displacement and 12.3 mm vertical displacement, while PPP method can detect 8.1 mm and 19.2 mm displacements in horizontal and vertical directions respectively. Minimum detected displacements are found to grow larger as time spans are shortened.
       
  • Determination of the Mean Dynamic Ocean Topography Model Through Combining
           Multi-Source Gravity Data and DTU15 MSS Around China's Coast
    • Abstract: Publication date: Available online 9 November 2018Source: Advances in Space ResearchAuthor(s): Baogui Ke, Liming Zhang, Jun Xu, Chuanyin Zhang, Yamin Dang Mean dynamic ocean topography (or MDT)is closely related to ocean circulation and global climate change. It has important scientific significance and application value for the development and utilization of marine resources in China's coastal areas. Based on the terrain gravity, marine gravity, and SRTM 3s data, an algorithm to reduce the problem of gravity data gaps between land and sea is proposed. A consistent land-sea gravity model is established based on point-mass fusion method . then geoid model,which accuracy was estimated to be 8.5cm through the verification of 348 GNSS/level data from the coastal provinces, of China's coastal areas was calculated through remove-restore technique. Connecting the above geoid model with DTU15 MSS model to establish a MDT model in China's coastal areas using the direct method in space domain. The effect of gravity field model, dominant factors of sea surface topography, and low pass filter are analyzed. Taking Bohai Sea and Yellow Sea as an example, and comparing MDT with the two international models CNES_2013_MDT and DTU15_MDT. The results show that the MDT has the potential to construct a vertical datum of the ocean and carry out related scientific research and application.
       
  • Robust H ∞ Controller Design for Attitude Stabilization of Flexible
           Spacecraft with Input Constraints
    • Abstract: Publication date: Available online 9 November 2018Source: Advances in Space ResearchAuthor(s): Chuang Liu, Keke Shi, Zhaowei Sun This paper addresses the attitude stabilization and vibration suppression problem for flexible spacecraft subject to model parameter uncertainty, controller perturbations, external disturbances and input constraints. The attitude model of flexible spacecraft is described and converted into a state space form in terms of passive and active vibration suppression schemes. A novel state feedback controller is proposed based on the exactly available expectation of a new variable, which is introduced to model a randomly occurring controller gain perturbation. Based on Lyapunov stability theory, sufficient conditions for the existence of the nonfragile H∞ controller considering input constraints are given based on linear matrix inequalities (LMIs) in terms of additive perturbation and multiplicative perturbation. Then, the developed controller subject to required constraints can be obtained, where the nonfragile property is fully considered to improve the tolerance to uncertainties in the controller. Numerical simulations are performed to demonstrate the effectiveness and superiority of the proposed control strategy in attitude stabilization and vibration suppression, where it should be noted that the passive vibration suppression scheme is superior for high natural frequencies while the active vibration suppression scheme is superior for low natural frequencies. Moreover, the low natural frequencies have more influence on the performance of attitude stabilization and vibration suppression.
       
  • List of Referees
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s):
       
  • Polar traveling ionospheric disturbances inferred with the B-spline method
           and associated scintillations in the Southern Hemisphere
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): S. Priyadarshi, Q.H. Zhang, E.G. Thomas, L. Spogli, C. Cesaroni A new method for analyzing travelling ionospheric disturbances (TIDs) is developed by using two B-spline basis functions of degree 4 on the Total Electron Content (TEC) data from the ground-based Global Positioning System (GPS) receivers. This method enhances the spatial resolution to about 0.1° (geographic latitude) × 0.1° (geographic longitude), which is useful in studying all scales (small, medium and large) TIDs. Using this method, we investigated TIDs and their associated scintillation on 18–19 July 2013 at Southern Hemisphere and found phase scintillation is more sensitive than amplitude scintillation to the TIDs at South Pole. To see the full impact of TIDs on scintillation, we have used a proxy phase scintillation index, calculated using geodetic GPS receivers over Antarctica. We have verified the presence of TIDs during these two days by using a Global Navigation Satellite System (GNSS)-TEC single station approach and SuperDARN slant range signals. Our results show the TEC fluctuations are associated with ionospheric scintillation. The shape of TIDs, their elongation and flattening along/across the geographic latitude/longitude, seems to be related to the magnitude and occurrence of ionospheric scintillations. Magnetospheric particle precipitation boost TEC gradients and generate stronger amplitude scintillation, however, large-scale plasma irregularities cause overall enhancement in magnitude of the phase scintillation index. Due to the high turbulence in the polar ionosphere, TIDs change their shapes quite quickly and/or may disappear in the background ionosphere. B-spline TIDs analysis method is very useful in identifying the visible as well as hidden TIDs parts in the polar ionosphere. For the first time, ionospheric scintillation has been investigated in the vicinity of TIDs at high- latitude in the southern hemisphere. Further, the presented B-spline TIDs analysis method is unique and simple in itself as it uses GPS receiver processed TEC data as the primary input. Our results show that at polar latitude it is not necessary that TIDs always appear near the high TEC regions. Usefulness of the B-spline TIDs detection method has been demonstrated in analyzing TIDs at all geographic locations and different solar activity conditions by comparing B-spline TIDs method produced results with the previous case studies.
       
  • Models of solar and lunar motions in the Chinese Chongxiu-Daming
           calendar
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Go-Eun Choi, Ki-Won Lee, Byeong-Hee Mihn The Chongxiu-Damingli (Revised Great Enlightenment Calendar) of the Jin dynasty (A.D. 1115–1234) was developed in 1171 and used until 1280 in China. It had also been used since the reign of King Sejong (A.D. 1418–1450) in Korea to supplement calculations of the eclipse times. In this study, we investigate solar and lunar motions in this calendar. Referring to the Garyeong (Example Supplement for the Calculations of Solar and Lunar Eclipses Occurred in 1447) preserved in Korea, we first investigate sunrise and sunset times by the Chongxiu-Damingli to estimate the observation sites of these times. We then analyze the calculation methods of solar and lunar motions and of the maximum eclipse time using the calendar. We find that a cubic equation was utilized to calculate sunrise and sunset times. Compared with the results of modern calculations, we also find that the sunrise and sunset times are more suitable at Kaifeng (capital of the Northern Song dynasty) than Beijing (capital of the Jin dynasty). This finding confirms the record of the Jinshi (History of the Jin Dynasty) that the Chongxiu-Damingli was made based on the calendar of the Northern Song dynasty. Regarding solar and lunar motions, we find that the mean absolute difference values between the Chongxiu-Damingli and modern calculations are ∼0.005 and ∼0.145 degrees, respectively. Lastly, we find that the difference in the time of maximum solar eclipse that occurred on 1447 September 10 in Seoul (capital of the Joseon dynasty) is approximately 1 min between the calendar and modern calculation. We believe that this study will contribute to understanding the Chongxiu-Damingli and comparing the accuracy with other Chinese calendars such as the Shoushili.
       
  • Suggestion for search of silanone (H2SiO) in interstellar
           medium
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): M.K. Sharma, Monika Sharma, Suresh Chandra Thirteen silicon bearing molecules are detected in the cosmic objects. Carbon (C) and silicon (Si) elements have similar chemical properties and the formaldehyde (H2CO) is identified in a large number of cosmic objects. Hence, there is a possibility of Silanone (H2SiO) being present in the ISM. For each of the ortho and para species of H2SiO, we have calculated energies of 100 lower rotational levels (up to 284 cm−1) and the Einstein coefficients for radiative transitions between the levels. We have solved a set of 100 statistical equilibrium equations coupled with the equations of radiative transfer for each specie where the collisional rate coefficients are taken from a scaling law. For the ortho-H2SiO, five transitions, 110-111, 211-212,312-313,413-414 and 514-515 are found to show the anomalous absorption, and one transition 212-111 is found to show the emission feature. For the para-H2SiO, four transitions, 101-000,202-101,660-514 and 661-542 are found to show the emission feature. These lines may help in the identification of H2SiO in a cosmic object, e.g., in IRC+10216.
       
  • Advanced illumination modeling for data analysis and calibration.
           Application to the Moon
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Erwan Mazarico, Michael K. Barker, Joseph B. Nicholas We present a new illumination modeling tool, called IllumNG, developed at NASA Goddard Space Flight Center (GSFC). We describe its capabilities to enhance the analysis and calibration of science data collected by planetary missions. We highlight these with examples making use of lunar data, particularly the topographic and radiometric measurements collected by the Lunar Orbiter Laser Altimeter (LOLA) instrument, with applications to radiometric measurements from other LRO instruments as well. The unique features of IllumNG are its accuracy and flexibility to handle multiple types of observers and light sources, and its ability to accurately model both singly- and doubly-scattered radiation to an observer.
       
  • Parameters and bifurcations of equilibrium points in the gravitational
           potential of irregular-shaped bodies subjected to a varying external shape
           
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Yu Jiang, Hexi Baoyin In this work, we investigate variations in the positions, eigenvalues, Jacobi integrals, topological cases, as well as the stability of equilibrium points around the asteroid 243 Ida when varying the external shape of the body. First, we employ a polyhedral shape model to calculate the surface height, gravitational force acceleration on the surface, and effective potential on the surface of 243 Ida. We then adopt the homotopy analysis method to generate variations in the external shape of a generic body within a continuum between the modeled external shape of 243 Ida and that of a sphere while maintaining a constant volume. Then, we calculated the positions, eigenvalues, Jacobi integrals, as well as the Hessian matrices of the equilibrium points in the gravitational potential of the generic body. We analyzed the topological cases and stability of the equilibrium points based on the obtained eigenvalues and Hessian matrices. It is concluded that the positions, eigenvalues, and Jacobi integrals change when varying the external shape of the body. For the four external equilibrium points E1–E4, the norm of the position vectors increases; however, the norm of the position vector for the internal equilibrium point E5 decreases. Equilibrium points E2 and E4 are subject to Hopf bifurcation when varying the external shape of the body, and the topological cases and stability of E2 and E4 are correspondingly changed. In contrast, the topological cases and stability of equilibrium points E1, E3, and E5 remain unchanged when varying the external shape of the body.
       
  • An improved augmented X-ray pulsar navigation algorithm based on the norm
           of pulsar direction error
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Qiang Xu, Hong-li Wang, Lei Feng, Wei Jiang, Si-hai You, Yi-yang He Pulsar position error in the Celestial Coordinate System can cause pulsar direction error in the Barycentric Celestial Reference System, which may seriously affect the accuracy of X-ray pulsar navigation. In order to improve the robustness of X-ray pulsar navigation algorithm against the pulsar direction error, an improved augmented X-ray pulsar navigation algorithm is proposed. Different from the previously proposed augmented algorithm, the algorithm introduces the norm of pulsar direction error as the augmented state rather than the systematic bias. At the same time, after the linearization of observation equation, the algorithm uses extended Kalman filter (EKF) as the basic filter, which has faster computation speed and better engineering applicability. The observability of the algorithm is proved by theoretical analysis. Finally, numerical simulations demonstrate that under different error conditions, the improved algorithm not only can effectively reduce the dependence on the state initial value, but also has better real-time performance compared with the previous algorithm.
       
  • Re-entry trajectory optimization using pigeon inspired optimization based
           control profiles
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Gangireddy Sushnigdha, Ashok Joshi In this paper, the entry trajectory optimization problem of lifting type re-entry vehicle with path constraints is solved using Pigeon Inspired Optimization (PIO). Entry trajectory optimization problem involves finding the control profiles, bank angle, and angle of attack to guide the vehicle safely to the destination. The proposed approach parametrizes the bank angle to be a linear function of energy while the angle of attack is considered to be a monotonic function of Mach number. Thus, the problem of finding control profiles is transformed into three parameter search problem. The PIO algorithm is used to find the values of these parameters that minimizes the objective function. The terminal heading angle offset is minimized using traditional bank reversal logic. A new approach is proposed in which the bank angle is modulated to eliminate the oscillations observed in the altitude profile of an entry vehicle with a high lift to drag ratio (L/D). A methodology to satisfy the given load factor constraint is also proposed, as an alternative to traditional penalty factor approach used for incorporating path constraints in PIO algorithm. The proposed approach is further validated by considering sub-cases with different load factor limits and bank angle as the only control variable. The angle of attack profile obtained from the previous case is considered as the nominal profile. The proposed trajectory optimization strategy using PIO algorithm is simulated for Common Aero Vehicle with high L/D ratio (CAV-H) with different load factor constraint limits. The results show that the obtained angle of attack profile minimizes the peak heat rate experienced by the vehicle and bank angle modulation eliminates the oscillations in the altitude profile as well as makes the entry trajectory satisfy the load factor constraint.
       
  • Radiometric microwave field measurements of the complex dielectric
           constant of the water surface
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): V.V. Sterlyadkin The paper describes the new remote method of radiometric in situ measurements of the real and imaginary parts of the dielectric constant (permittivity) of the underlying sea surface, which is an important parameter for remote sensing of the Earth. The method does not require absolute calibration of a radiometer, but uses the black body with the underlying surface temperature, which simplifies the measurement and allows one to measure the effective reflection coefficient at specified polarizations. It is shown that, for a fixed value of the reflection coefficient in sensing to the nadir, R(θ = 0°) = const, the reflection coefficient at the horizontal polarization is almost independent of the of dielectric loss angle. The reflection coefficient at the vertical polarization is most sensitive to the loss angle in the vicinity of the Brewster angle Rv(θ = θBr). The paper presents the results of measurements of the sea surface reflection coefficient using the radiometer operating at frequency of 37.5 GHz. The reflection coefficients at vertical and horizontal polarizations are calculated taking into account the antenna pattern and the distribution of slopes of a weakly roughened sea surface. The paper presents the example of determining the real and imaginary parts of the permittivity based on experimentally measured values of reflection coefficients at incidence angles close to the nadir and the reflection coefficient Rv(θ = θBr) at the Brewster angle. The obtained experimental values correspond to the theory within the limits of diversity of existing models.
       
  • Joint analysis of seasonal oscillations derived from GPS observations and
           hydrological loading for mainland China
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Yunfei Xiang, Jianping Yue, Zhen Li Hydrological loading effects are one of the principal sources of the seasonal oscillations in GPS position time series, and they should be taken into account for improving GPS system accuracy. In this study, the daily vertical position time series of 23 GPS stations derived from the Crustal Movement Observation Network of China (CMONOC) are used to investigate the hydrological loading contributors of seasonal oscillations in GPS observations. The hydrological loading deformations at each GPS station are estimated by the Global Land Surface Discharge Model (LSDM). The result of period analysis suggests that the hydrological loading primarily results in the annual oscillation in GPS observations. Therefore, Multichannel Singular Spectrum Analysis (MSSA) is utilized to derive the annual signal from GPS observations and LSDM-derived deformations simultaneously for each GPS station. Compared with Singular Spectrum Analysis (SSA), the percentage of the variance of the annual signal estimated by MSSA and SSA differs by 6% on average, indicating that MSSA can effectively separate annual signal from other signals and clear noise. Meanwhile, Cross Wavelet Transform (XWT) is performed to measure the correlation and phase relationship between GPS observations and LSDM-derived deformations in the time-frequency space. The result demonstrates that the hydrological loading can only explain the annual oscillation in GPS observations at 5 stations (namely LHAS, LUZH, KMIN, QION, and XIAG) well. For the most GPS stations, other factors (e.g., other geophysical factors, hydrological modeling errors, and systematic errors) and hydrological loading jointly contribute to the annual oscillation in GPS observations. After hydrological loading correction, the Root Mean Square (RMS) values of GPS observations are reduced at 15 stations, especially for the GPS stations located in regions with significant water storage variations (up to 2.46 mm at KMIN). Moreover, the percentage of the variance of the annual signal estimated by MSSA correlates well with the RMS reduction, implying that the RMS reduction may be related to the annual signal derived from hydrological loading deformations.
       
  • Performance assessment of uncombined precise point positioning using
           Multi-GNSS real-time streams: Computational efficiency and RTS
           interruption
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Xinyun Cao, Jiancheng Li, Shoujian Zhang, Lin Pan, Kaifa Kuang The International GNSS Service (IGS) has established the Real-time Services (RTS) that support the real-time precise point positioning (RT-PPP) and related applications. Due to the increasing number of unknown parameters and network instability issues, both the computational efficiency and the RTS stream outage are the key points to realize real-time uncombined GNSS PPP. To improve the computational efficiency of uncombined PPP, the recursive Kalman based on single observation is implemented rather than the standard Kalman filter. The differences between the RTS orbits and the corresponding ultra-rapid predicted orbits reveal that the ultra-rapid predicted orbits can be used as alternatives of the GNSS real-time orbits. During the RTS clock outage period, the linear and sinusoidal terms are determined by the ultra-rapid observed part in advance, while the constant term of clock offsets is determined by the latest available RTS clock corrections. The PPP results have revealed that the proposed prediction method is much more effective than that of directly using the ultra-rapid predicted products. Even when the prediction duration reaches up to 1 h, the 3D positioning accuracy of GNSS RT-PPP is improved by 51.91% compared with the ultra-rapid scheme. Compare to the GPS-only kinematic PPP, the 3D positioning accuracy of GNSS kinematic PPP using CNES (Centre National d’Études Spatiales) RTS products is improved from 8.29 cm to 6.60 cm, and the mean convergence time of achieving 3D position accuracy better than 10 cm is shortened by about 44.99%.
       
  • Analytical hierarchy process (AHP) based landslide susceptibility mapping
           of Lish river basin of eastern Darjeeling Himalaya, India
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Biplab Mandal, Sujit Mandal Landslide is one of the most destructive natural hazards of Darjeeling Himalaya. In the present study, analytical hierarchy process (AHP) has been applied to develop landslide susceptibility map of the Lish river basin of Eastern Darjiling Himalaya based on geospatial tools. A total of 188 landslide location points of very small to large polygon coverage were identified with the help of GPS study, SOI (Survey of India) topo-sheets and Digital Globe Quick Bird image to prepare a landslide inventory map. 70% training data sets of the landslide inventory was applied for training analytical hierarchy process (AHP) model and remaining 30% data sets were used for validation of the landslide susceptibility map. ERDAS IMAGINE, ASTER GDEM image, Arc GIS and PCI Geomatica software, topographical map, Landsat TM and 8 OLI satellite image, google earth image, soil map (NBSS and LUP Regional Centre), geomorphology and lithology (NATMO and GSI) were used and processed to prepare seventeen causative factors i.e. slope angle, slope aspect, slope curvature, altitude, relative relief, geomorphology, geology, distance to lineaments, lineament density, soil, LAND USE & land cover, NDVI, drainage density, distance o drainage, stream power index, topographic wetness index, and rainfall. Factor weights and class weights of all the data layers were derived using AHP and then weighted data layers were integrated to generate the landslide susceptibility map. To validate the result, success rate curve was made with the help of landslide susceptibility and cumulative percentage of landslide occurrence which showed the accuracy level of 89.72%.
       
  • A robust homotopic approach for continuous variable low-thrust trajectory
           optimization
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Mohammadreza Saghamanesh, Hexi Baoyin This paper presents an improved understanding of the interaction of hybrid optimization method with variable low-thrust trajectory optimization requirements. To analyze fuel-optimal bang-bang control problem, a new version of homotopic algorithm, termed robust homotopic method, is investigated with the prospect of improving the efficiency and automation of the homotopic approach to achieve a high-level of robustness, and consequently enlarge its range of application. Such desired characteristics are promoted via a combination of several techniques. As an effective approach, a modified methodology of the switching detection process is presented for the bang-bang optimal-control problem. Moreover, the value of unknown costates and switching functions are mapped to new normalized intervals throughout the computational process. As a result, the optimal solution is rapidly designed to obtain the global robust-convergence to satisfy all constraints without any ambiguity. The fitting process of all iterations robustly find the unknown variables with the percent of converged solutions to maximum, and the penalty terms are quickly satisfied with predetermined high-accuracy, from the energy-optimal to the fuel-optimal solution, especially close to zero point as a critical point. Accordingly, two advanced interplanetary trajectories are optimized using two dynamic modeling approaches for the instantaneous and constant maximal thrust magnitude as a way to analyze and substantiate the robustness of the proposed algorithm. Results and performances are compared with existing solutions of the same mission problem.
       
  • Using only two magnetorquers to de-tumble a 2U CubeSAT
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Matthew Monkell, Carlos Montalvo, Edmund Spencer A CubeSAT is a small satellite on the order of 10 cm along each axis. A 1U satellite is a small cube with 10 cm sides. A 2U CubeSAT has the volume of two single 1U satellites. The size of the satellite is 10 × 10 × 20 cm. These satellites are used for a variety of missions and created by a variety of different organizations. When deployed from a rocket, a CubeSAT may obtain a large angular velocity which must be reduced before most science missions or communications can take place. Maximizing solar energy charging also involves better pointing accuracy. To control the attitude of these small satellites, thrusters, reaction wheels or magnetorquers are used. On a standard CubeSAT, 3 reaction wheels are used as well as 3 magnetorquers. In the initial phase of the CubeSAT mission, the magnetorquers are used to reduce the angular velocity of the satellite down to a manageable level. Once the norm of the angular velocity is low enough, the reaction wheels can spin up reducing the angular velocity to zero. This paper derives a simple control scheme that allows the performance of the de-tumbling maneuver to decline while reducing the number magnetorquers by 1. Thus, the de-tumbling maneuver is completed using 2 magnetorquers rather than 3. This reduces complexity of the satellite, saves weight and reduces energy consumed by the satellite which can be used for other power hungry devices.
       
  • A fast algorithm for the detection of faint orbital debris tracks in
           optical images
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): P. Hickson Moving objects leave extended tracks in optical images acquired with a telescope that is tracking stars or other targets. By searching images for these tracks, one can obtain statistics on populations of space debris in Earth orbit. The algorithm described here combines matched filtering with a Fourier implementation of the discrete Radon transform and can detect long linear tracks with high sensitivity and speed. Monte-Carlo simulations show that such tracks, in a background of Poisson random noise, can be reliably detected even if they are invisible to the eye. On a 2.2 GHz computer the algorithm can process a 4096×4096-pixel image in less than a minute.
       
  • Achievable orbit determination and prediction accuracy using short-arc
           space-based observations of space debris
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Bin Li, Jizhang Sang, Junyu Chen The space-based space surveillance (SBSS) technique is promising in the current and future space surveillance with advantages of global coverage, high covering rate, and strong exploring capacity. This paper focuses on the key problems of this new technique, the accurate orbit determination (OD) and prediction (OP) using short-arc tracking data. 200 debris objects are simulated to be tracked by the satellite in a sun-synchronous orbit. The real-time OD using short-arc space-based optical data of debris from only one pass is performed, and an OP accuracy of 10″ for angles and 100 m for distances over 150 s OP arc is achieved, which is accurate for the pointing guidance of blind space-based lasers operation. The OD/OP performances using multiple passes of short-arc space-based optical data are also assessed. Using at least 2 passes of 120 s short-arc space-based optical data, separated by about 24 h, the determined position accuracy is better than 50 m, and the subsequent 7-day position prediction errors are less than 300 m, which is believed sufficient enough for space applications requiring high accuracy, like the orbit catalogue maintenance, space conjunction analysis for hundreds of thousands of debris.
       
  • Multi-objective optimization of agile satellite orbit design
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Zhiming Song, Xiaoyu Chen, Xin Luo, Maocai Wang, Guangming Dai Satellite orbit design is a fundamental and important task during the mission analysis and the agile satellite design. In this paper we first investigate the design of a more realistic repeating ground track orbit in an accurate geopotential model of Earth. Furthermore, by considering the view field of the resource equipped on an agile satellite, we calculate the variation of the orbital altitude, the tilt angle, and the off-nadir resolution with the desired revisit time. Additionally, we analyze the distribution of all feasible solutions. In considering the spatial resolution and temporal resolution simultaneously, we propose a multi-objective optimization technique for optimal feasible orbits generation. Finally, through various case studies, the application of multi-objective optimization in orbit design of agile satellite is successfully demonstrated. Results also illustrate the validity and effectiveness of the proposed technique.
       
  • Some remarks on geometric dilution of precision (GDOP) at user level in
           multi-GNSS positioning
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Changhai Li, Yunlong Teng, Ronglei Kang The geometric dilution of precision (GDOP) is an important index with positioning, navigation and timing (PNT) applications. In multi-GNSS positioning, the system time offsets between different systems can be determined at user level, namely, calculated by the receiver at the cost of at least one additional satellite from each additional time reference frame. In this paper, we focus on some characteristics of the GDOP at user level (short for GDOPU) in multi-GNSS positioning, including the impact of the number of satellites on the GDOPU, and the calculation of the GDOPU minimum. The theoretical derivations show that the GDOPU decreases with respect to the number of satellites. Moreover, the detailed expression of GDOPU minimum together with the optimal condition leading to the minimum is also given. The experimental results using real data validate these discussions.
       
  • Dynamical uncertainty and demisability occurrence for the atmospheric
           re-entry of SOHO
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Elisa Maria Alessi, Giacomo Tommei, Ian Holbrough, James Beck Re-entry trajectories to the Earth have been recently considered as a valuable end-of-life option also for Sun–Earth Libration Point Orbits (LPO) missions. In this work, we investigate in detail the case corresponding to SOHO. On the one hand, we show how the main uncertainties associated with the problem affect the probability of re-entry and the corresponding point at the interface with the atmosphere. Monte Carlo propagations are applied to different cases of uncertainties. They correspond to the orbit determination, the efficiency of the maneuver required to target the Earth, and the characteristics of the spacecraft determining the solar radiation pressure effect. On the other hand, we provide a comparison between a classical re-entry from a LEO and a hypervelocity re-entry from a LPO, in terms of area affected by the re-entry and demise percentage.
       
  • Orbit, orbital lifetime, and reentry survivability estimation for orbiting
           objects
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Seong-Hyeon Park, Hae-Dong Kim, Gisu Park In this work, an integrated system for the orbit, orbital lifetime, and reentry survivability estimation modules of orbiting objects has been proposed and developed. Each module of the system was compared and validated with results from the well-known existing codes. One practical test model was considered for the orbital lifetime and the reentry survivability. The model was Science and Technology Satellite-3 (STSAT-3). Recently, the STSAT-3 was almost to collide with a space debris. This issue brought a serious alert to the public in Korea regarding collision risks of the orbiting object and a possibility of a consequent threat to the survivability when the object survives and impacts human. For this case study, it was assumed that the satellite consists of 12 parts having different shapes, materials, and sizes. The estimations showed that the calculated orbital lifetime was about 32 years and 7 out of 12 parts survived during the reentry. The effect of true anomaly for the orbiting object on the reentry survivability has been considered in the calculation. The results showed that there is no strong effect on the survivability for different true anomalies in a circular orbit. For an elliptic orbit which is regarded as an extreme case for the near-Earth orbiting object, however, a large difference was observed. Possible reasons are discussed. This work is intended to contribute to the part of the development of the national Space Situational Awareness (SSA) system, for the first time showing an overall procedure for the method of the integrated system.
       
  • Quantum-behaved particle swarm optimization for far-distance rapid
           cooperative rendezvous between two spacecraft
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Kun Yang, Weiming Feng, Gang Liu, Junfeng Zhao, Piaoyi Su Focused on far-distance rapid cooperative rendezvous between two spacecraft under continuous large thrust, this paper presents a series of artificial intelligence algorithms for fuel and time optimization. The process of far-distance rapid cooperative rendezvous was optimized by a type of hybrid algorithm-integrated Quantum-behaved Particle Swarm Optimization (QPSO) and Sequential Quadratic Programming (SQP). The convergent co-state vectors were obtained by QPSO and subsequently set as the initial values of SQP to search for the exact solutions in a smaller area. Applications of non-coplanar cooperative rendezvous are provided to demonstrate that the QPSO-SQP algorithm has better performance than other popular algorithms in less time consumption, faster convergence rate and highly stable solutions.
       
  • Apparent magnitude calculation method for complex shaped space objects
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Yang Wang, Xiaoping Du, Jiguang Zhao, Ruixin Gou The apparent magnitude of a complex shaped space object is difficult to calculate since its visible triangular facets are hard to be determined. The most common-used visible facets determination method is to judge the incident and emergent angle, but this method does not apply to a space object which is a combination of convex bodies or has a concave surface. In this paper, a new quadtree-based hidden vertex removal method is presented, and it is composed of four steps: coordinate transformation, hidden vertex removal, quadtree decompositions and visible triangular facets determination. This method can determine visible triangular facets of a space object of any shapes. Once a space object triangular facet model, the observed direction of a telescope and the incident direction of the sunlight are given, the visible triangular facets of the space object can be obtained. Two experiments are carried out to verify the visible triangular facet determination performance of this method qualitatively and quantitatively. Experiment results show the visible triangular facet calculated by the proposed method is accurate and reasonable.
       
  • Contactless electrostatic detumbling of axi-symmetric GEO objects with
           nominal pushing or pulling
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): Trevor Bennett, Hanspeter Schaub Large asset values of satellites and demand for orbital slots in the Geostationary orbit belt motivates on-orbit servicing and active debris removal strategies. The challenge of on-orbit capture of tumbling serviceable satellites or debris targets is primarily overcome by including a target detumble prior to any mechanical interface. Of the many methods proposed, touchless electrostatic detumbling shows significant advantages in collision avoidance and preservation of the target object. Previous studies demonstrated that the electrostatic interaction is sufficient to touchlessly despin the fixed-axis rotation of a rocket body-sized object within several days. This work focuses on large, generally tumbling axi-symmetric targets in the Geostationary Orbit which form a large component of the GEO debris population. The deep-space controller is augmented for tugging, pushing, and nominal detumbling configurations, providing a complete analysis of the stability and convergence properties. The effectiveness of this detumble control is numerically illustrated by simultaneously detumbling and tugging the target in GEO. The controller reduces the tumbling to the order of the mean motion allowing for mechanical docking methods.
       
  • The influence of several atmospheric variables on cosmic ray muons
           observed by KACST detector
    • Abstract: Publication date: 1 December 2018Source: Advances in Space Research, Volume 62, Issue 11Author(s): A. Maghrabi, M. Almutairi In this study, the effects of atmospheric pressure and temperature on cosmic ray muons have been investigated using data recorded by the KACST detector (Riyadh, Saudi Arabia; Rc = 14.4 GV) for the beginning of the quiet periods of the 24th solar cycle. The muon data were, initially, correlated with the atmospheric pressure, and the desired coefficient was obtained and used to eliminate the pressure effect from the muon measurements. The pressure-corrected data are then analysed to study the effect of the atmospheric temperature on cosmic ray muons, using five methods. Four methods investigate the effect of the ground temperature, the atmospheric temperatures and atmospheric heights at several atmospheric levels, on the measured muon rate. In the fifth method, the muon data were correlated with the atmospheric weighted temperatures integrated up to different atmospheric heights. For all cases, the desired correction coefficients were obtained, and their variations at several atmospheric levels were studied. The obtained coefficients were then used to correct the cosmic ray data. We found that the atmospheric pressure effect shows the greatest differences between the corrected and uncorrected rate (up to 1%). Instead, corrections made to the muon data using the remainder of the considered parameters modify the muon rate by a small amount (less than 0.5%) compared to the uncorrected rate.
       
  • Static and kinematic positioning performance of a low-cost real-time
           kinematic navigation system module
    • Abstract: Publication date: Available online 3 November 2018Source: Advances in Space ResearchAuthor(s): Yun Zhang, Wenhao Yu, Yanling Han, Zhonghua Hong, Siming Shen, Shuhu Yang, Jing Wang To investigate the static and kinematic positioning performance with the low-cost multiple Global Navigation Satellite System (GNSS) receivers is vital for the GNSS community owing to their wide civil applications. In this contribution, we developed the real-time kinematic (RTK) algorithms for low-cost GNSS receiving module to fulfil the task of the integrated RTK positioning with US Global Positioning System (GPS) and the Chinese BeiDou Navigation Satellite System (BDS). The RTK positioning performance of a low-cost module named STA8090 and a state-of-the-art module named Novatel OEM6 was compared. In our study, the virtual reference station (VRS) data stream from QianXun SI was utilized. First, one 12-h static test was performed, achieving the centimeter-level horizontal accuracy with an RMS (Root Mean Square) of less than 1 cm. Afterwards, some kinematic experiments were conducted under four different environmental scenarios, of which positioning accuracy of approximately 20 cm was obtained. The experimental results demonstrated that the RTK positioning performance with low-cost multi-GNSS module can fulfil the current navigation capability well.
       
  • An attempt to inverse the ionospheric sporadic-E layer critical frequency
           based on the COSMIC radio occultation data
    • Abstract: Publication date: Available online 3 November 2018Source: Advances in Space ResearchAuthor(s): Niu Jun, Weng Li-bin, Fang Han-xian Ionospheric sporadic E layer refers to localized thin irregularity with enhanced plasma density appearing in the height range of ionospheric E layer (∼90-130km). The much higher electron density in the sporadic E layer than the background ionosphere would cause sudden TEC enhancement in the occultation TEC profile. A wavelet decomposition and reconstruction method is applied to extract the TEC fluctuation in this paper, and then Smax index is defined to represent the intensity of the sudden TEC enhancement. Smax index is compared with sporadic E critical frequency (foEs) observed by the ionosonde. The results show a well linear correlation between them with mean correlation coefficient about 0.7. Thus, an empirical linear model is established to inverse thefoEs. The monthly/hourly mean values and global distribution of sporadic E intensity and occurrence ratio are calculated using this method based on the COSMIC occultation data from 2007 to 2011. The statistical analysis results indicate that it is feasible to inverse the foEs based on the occultation TEC profile data and the inversion results can be applied to the long-term global variations of sporadic E investigations.
       
  • Compensation of base disturbance using optimal trajectory planning of
           dual-manipulators in a space robot
    • Abstract: Publication date: Available online 3 November 2018Source: Advances in Space ResearchAuthor(s): Xie Yaen, Wu Xiande, Takaya Inamori, Shi Zhen, Sun Xinzhu, Cui Hongtao This paper presents a trajectory planning algorithm for a space robot with dual-manipulators. Here one manipulator of the space robot captures a target, and another manipulator is free. In this case, this study uses one manipulator as the mission manipulator to capture the target, and another as the balance manipulator aiming at the compensation of the pose disturbance. For this method, a novel trajectory planning algorithm applied to the balance manipulator is presented. The trajectory planning problem is transformed into series of problems of the optimal state solution, and then the iterative algorithms for the trajectory planning are designed. In the iterative algorithms, the bias force on the spacecraft base caused by the balance manipulator is used as the compensation force. Then, to calculate the expected compensation force and torque, a pose control law for the spacecraft base is introduced. The expected compensation force and torque provide equality constraints for optimization problems, which implies that the trajectory planning algorithm compensates for not only the disturbance generated by the manipulator’s motion, but also environmental disturbances. This is because the expected compensation force and torque depend on the pose change of the spacecraft base rather than the type of the disturbance. Numerical simulation was carried out to analyze the proposed trajectory planning method. It was observed that the method greatly reduces the disturbance of Manipulator A on the spacecraft base. These results validated the effectiveness of the proposed method for the trajectory planning to make the spacecraft base disturbance up to minimum.
       
  • Near Real-Time BDS GEO Satellite Orbit Determination and Maneuver Analysis
           with Reversed Point Positioning
    • Abstract: Publication date: Available online 3 November 2018Source: Advances in Space ResearchAuthor(s): Peiyuan Zhou, Lan Du, Xiaojie Li, Yang Gao The Geostationary Earth Orbit (GEO) satellite is a crucial part of the BeiDou Navigation Satellite System (BDS) constellation. However, due to various perturbation forces acting on the GEO satellite, it drifts gradually over time. Thus, frequent orbit maneuvers are required to maintain the satellite at its designed position. During the orbit maneuver and recovery periods, the orbit quality of the maneuvered satellite computed with broadcast navigation ephemeris will be significantly degraded. Furthermore, the conventional dynamic Precise Orbit Determination (POD) approach may not work well, because of a lack of publicly available satellite information for modeling the thrust forces. In this paper, a near real-time approach free of thrust forces modeling is proposed for BDS GEO satellite orbit determination and maneuver analysis based on the Reversed Point Positioning (RPP). First, the station coordinates and receiver clock offsets are estimated by GPS/BDS combined Single Point Positioning (SPP) with single-frequency phase-smoothed pseudorange observations. Then, with the fixed station coordinates and receiver clock offsets, the RPP method can be conducted to determine the GEO satellite orbits. When no orbit maneuvers occur, the proposed method can obtain orbit accuracies of 0.92, 2.74, and 8.30 m in the radial, along-track, and cross-track directions, respectively. The average orbit-only Signal-In-Space Range Error (SISRE) is 1.23 m, which is slightly poorer than that of the broadcast navigation ephemeris. Using four days of GEO maneuvered datasets, it is further demonstrated that the derived orbits can be employed to characterize the behaviors of GEO satellite maneuvers, such as the time span of the maneuver as well as the satellite thrusting accelerations. These results prove the efficiency of the proposed method for near real-time GEO satellite orbit determination during maneuvers.
       
  • Evaluation and Improvement of Coastal GNSS Reflectometry Sea Level
           Variations from Existing GNSS Stations in Taiwan
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): Chi–Ming Lee, Chung–Yen Kuo, Jian Sun, Tzu–Pang Tseng, Kwo–Hwa Chen, Wen–Hau Lan, C.K. Shum, Tarig Ali, Kuo–En Ching, Philip Chu, Yuanyuan Jia Global sea level rise due to an increasingly warmer climate has begun to induce hazards, adversely affecting the lives and properties of people residing in low-lying coastal regions and islands. Therefore, monitoring and understanding variations in coastal sea level covering offshore regions are of great importance. Signal-to-noise ratio (SNR) data of Global Navigation Satellite System (GNSS) have successfully used to robustly derive sea level heights (SLHs). In Taiwan, there is a number of continuously operating GNSS stations, not originally installed for sea level monitoring. They were established in harbors or near coastal regions for monitoring land motion. This study utilizes existing SNR data from three GNSS stations (Kaohsiung, Suao, and TaiCOAST) in Taiwan to compute SLHs with two methods, namely, Lomb–Scargle Periodogram (LSP)-only, and LSP aided with tidal harmonic analysis developed in this study. The results of both methods are compared with co-located or nearby tide gauge records. Owing to the poor quality of SNR data, the worst accuracy of SLHs derived from traditional LSP-only method exceeds 1 meter at the TaiCOAST station. With our procedure, the standard deviations (STDs) of difference between GNSS-derived SLHs and tide gauge records in Kaohsiung and Suao stations decreased to 10 cm and the results show excellent agreement with tide gauge derived relative sea level records, with STD of differences of 7 cm and correlation coefficient of 0.96. In addition, the absolute GNSS-R sea level trend in Kaohsiung during 2006–2011 agrees well with that derived from satellite altimetry. We conclude that the coastal GNSS stations in Taiwan have the potential of monitoring absolute coastal sea level change accurately when our proposed methodology is used.
       
  • Vertical and radial metallicity gradients in high latitude galactic fields
           with SDSS
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): Sabiha Tunçel Güçtekin, Selçuk Bilir, Salih Karaali, Olcay Plevne, Serap Ak We used the ugr magnitudes of 1,437,467 F-G type main-sequence stars with metal abundance -2⩽[Fe/H]⩽+0.2 dex and estimated radial and vertical metallicity gradients for high Galactic-latitude fields, 50°
       
  • Early analysis of precise orbit and clock offset determination for the
           satellites of the global BeiDou-3 system
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): Xingyuan Yan, Guanwen Huang, Qin Zhang, Chenchen Liu, Le Wang, Zhiwei Qin Eight new-generation BeiDou satellites (BeiDou-3) have been launched into Medium Earth Orbit (MEO), allowing for global coverage since March 2018, and they are equipped with new hydrogen atomic clocks and updated rubidium clocks. Firstly, we analyzed the signals for the carrier-to-noise-density ratio (C/N0) and pseudorange multipath (MP) by using international GNSS (Global Navigation Satellite System) Monitoring and Assessment System (iGMAS) station data, and found that B1C has a lower C/N0, and B2a has the same level of C/N0 as the B1I and B3I signals. For pseudorange multipath, compared with the BeiDou-2 satellites, the obvious systematic variation of MP scatters related to the elevation angle is greatly improved for the BeiDou-3 and BeiDou-3e satellites signals. For the signals of the BeiDou-3 satellites, the order of the Root Mean Square (RMS) values of multipath and noise is B3I < B1I < B2a < B1C. Then, the comparison of the precise orbit determination and clock offset determination for the BeiDou-2, BeiDou-3, and BeiDou-3 experimental (BeiDou-3e) satellites was done by using 10 stations from iGMAS. The 3D precision of the 24 h orbit overlap is 24.55, 25.61, and 23.35 cm for the BeiDou-3, BeiDou-3e, and BeiDou-2 satellites, respectively. BeiDou-3 satellite has a comparable precision to that of the BeiDou-2 satellite. For the precision of clock offset estimation, the Standard Deviation (STD) of the BeiDou-3 MEO satellite is 0.350 ns, which is an improvement of 0.042 ns over that of the BeiDou-2 MEO satellite. The stabilities of the BeiDou-3 and BeiDou-3e onboard clocks are better than those of BeiDou-2 by factors of 2.84 and 1.61 at an averaging time of 1000 and 10,000 s, respectively.
       
  • Constraining the mass of the black hole GX 339-4 using spectro-temporal
           analysis of multiple outbursts
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): H. Sreehari, Iyer Nirmal, D. Radhika, Nandi Anuj, Mandal Samir We carried out spectro-temporal analysis of the archived data from multiple outbursts spanning over the last two decades from the black hole X-ray binary GX 339-4. In this paper, the mass of the compact object in the X-ray binary system GX 339-4 is constrained based on three indirect methods. The first method uses broadband spectral modelling with a two component flow structure of the accretion around the black hole. The broadband data are obtained from RXTE (Rossi X-ray Timing Explorer) in the range 3.0 to 150.0 keV and from Swift and NuSTAR (Nuclear Spectroscopic Telescope Array) simultaneously in the range 0.5 to 79.0 keV. In the second method, we model the time evolution of Quasi-periodic Oscillation (QPO) frequencies, considering it to be the result of an oscillating shock that radially propagates towards or away from the compact object. The third method is based on scaling a mass dependent parameter from an empirical model of the photon index (Γ) - QPO (ν) correlation. We compare the results at 90 percent confidence from the three methods and summarize the mass estimate of the central object to be in the range 8.28-11.89M⊙.
       
  • Power-law spectra of energetic electrons in solar flares from the maximum
           entropy and dimensional considerations
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): Y.E. Litvinenko The maximum entropy formalism and dimensional analysis are used to derive a power-law spectrum of accelerated electrons in impulsive solar flares, where the particles can contain a significant fraction of the total flare energy. Entropy considerations are used to derive a power-law spectrum for a particle distribution characterised by its order of magnitude of energy. The derivation extends an earlier one-dimensional argument to the case of an isotropic three-dimensional particle distribution. Dimensional arguments employ the idea that the spectrum should reflect a balance between the processes of energy input into the corona and energy dissipation in solar flares. The governing parameters are suggested on theoretical grounds and shown to be consistent with solar flare observations. The flare electron flux, differential in the non-relativistic electron kinetic energy E, is predicted to scale as E-3. This scaling is in agreement with RHESSI measurements of the hard X-ray flux that is generated by deka-keV electrons, accelerated in intense solar flares.
       
  • Finite-time relative orbit-attitude tracking control for multi-spacecraft
           with collision avoidance and changing network topologies
    • Abstract: Publication date: Available online 2 November 2018Source: Advances in Space ResearchAuthor(s): Jianqiao Zhang, Dong Ye, James D. Biggs, Zhaowei Sun This paper addresses the relative position tracking and attitude synchronization control problem for spacecraft formation flying (SFF). Based on the derived relative coupled six-degree-of-freedom dynamics, a robust adaptive finite-time fast terminal sliding mode controller is proposed to achieve the desired formation in the presence of model uncertainties and external disturbances. It is shown that the designed controller is effective for changing information exchange topology making it robust to node failure. Then, the artificial potential function method is employed to generate collision avoidance schemes to modify the controller such that inter-agent collision avoidance can be ensured during the formation maneuver, which is critical for practical missions. The stability of the overall closed-loop system is proved by using Lyapunov theory. Finally, numerical examples for a given SFF scenario are presented to illustrate the performance of the controller.
       
  • GOCE star tracker attitude quaternion calibration and combination
    • Abstract: Publication date: Available online 1 November 2018Source: Advances in Space ResearchAuthor(s): Christian Siemes, Moritz Rexer, Roger Haagmans We analyse the inter-boresight angles (IBA) measured by the star trackers on board the GOCE satellite and find that they exhibit small offsets of 7–9” with respect to the ones calculated from the rotation of the star tracker reference frames to the satellite reference frame. Further, we find small variations in the offsets with a peak-to-peak amplitude of up to 8”, which correlate with variations of the star trackers’ temperatures. Motivated by these findings, we present a method for combining the attitude quaternions measured by two or more star trackers that includes an estimation of relative attitude offsets between star trackers as a linear function of temperature. The method was used to correct and combine the star tracker attitude quaternions within the reprocessing of GOCE data performed in 2018. We demonstrate that the IBA calculated from the corrected star tracker attitude quaternions show no significant offsets with respect to the reference frame information. Finally, we show that neglecting the star tracker attitude offsets in the processing would result in perturbations in the gravity gradients that are visible at frequencies below 2 mHz and have a magnitude of up to 90 mE. The presented method avoids such perturbations to a large extent.
       
  • RS-GIS Based Morphometrical and Geological Multi-Criteria Approach to the
           Landslide Susceptibility Mapping in Gish River Basin, West Bengal, India
    • Abstract: Publication date: Available online 1 November 2018Source: Advances in Space ResearchAuthor(s): Tirthankar Basu, Swades Pal Darjeeling Himalaya is one of the several mountainous areas of India which is often suffered from landslide hazards. In this paper, a multi criteria evaluation is applied using 16 morphometric indicators, geology and lineaments to identify the areas vulnerable in respect to drainage and relief conditions. As both drainage and relief parameters exert strong influences on landslide intensity, both the diversity maps are integrated for final landslide susceptibility mapping. The obtained results show that 20.17 sq. km (7.61%) area within the basin is highly susceptible for landslides, where average drainage density is 3.78 km/sq. km, relative relief is greater than 408 meter and slope is greater than 12°. The validation result shows that very high landslide susceptible zone is associated with very high frequency of landslide occurrence. Beside this, ROC curve also suggests good predicted rate (86.60%) for the model. So, the proposed method can be applied for predicting landslide susceptible zone.
       
  • A fast satellite selection algorithm with floating high cut-off elevation
           angle based on ADOP for instantaneous multi-GNSS single-frequency relative
           positioning
    • Abstract: Publication date: Available online 1 November 2018Source: Advances in Space ResearchAuthor(s): Xin Liu, Shubi Zhang, Qiuzhao Zhang, Nan Ding, Wei Yang With the Global Navigation Satellite System (GNSS) developing, the single-frequency single-epoch multiple GNSSs (multi-GNSS) relative positioning has become feasible. Since a larger number of the observed satellites make the instantaneous (single-epoch) positioning time-consuming, a proper satellite selection is necessary. Among the present methods, the satellite selection with a fixed high cut-off elevation angle (CEA) is least time-consuming. However, there is no criterion how large a fixed high CEA should be to achieve a high success rate and less time consumption. Besides, a fixed high CEA makes the number of visible satellites largely variable, which affects the success rate. Hence, a satellite selection strategy based on ambiguity dilution of precision (ADOP) is proposed. Firstly, the theoretical proof that the ADOP increases the least when removing satellites are all low-elevation-angle satellites is given, which is important to achieve the fast positioning with a high success rate. Then, the threshold β is calculated for a different number of satellites and a given ADOP. The satellites are selected based on their elevation angles from high to low until β of the selected satellites becomes smaller than the corresponding threshold; this method is called the extended floating CEA multi-GNSS (EF-multi-GNSS). The comparison of the single-frequency single-epoch positioning performance of the EF-multi-GNSS with the satellite selections based on a fixed low CEA (L-multi-GNSS) and a fixed high CEA (H-multi-GNSS) via the relative positioning experiments shows that: (1) the EF-multi-GNSS with a minimal number of satellites can achieve the fast positioning and a high success rate close to 100%. It can greatly reduce the time consumption of the L-multi-GNSS, by about 64.0%, by selecting 12.6 satellites of 23.4 satellites; (2) the floating CEA of EF-multi-GNSS eliminates the consideration how large a fixed high CEA should be, and a CEA larger than the fixed high CEA of the H-multi-GNSS makes it more suitable for different conditions.
       
  • Evaluation of a Geiger-mode Imaging Flash Lidar in the Approach Phase for
           Autonomous Safe Landing on the Moon
    • Abstract: Publication date: Available online 29 October 2018Source: Advances in Space ResearchAuthor(s): Hyung-Chul Lim, Daniel Kucharski, Simon Kim, Chul-Sung Choi, Ki-Pyoung Sung, Jong-Uk Park, Mansoo Choi, Eunseo Park, Sung-Yeol Yu, Byoungsoo Kim The imaging flash lidar has been considered as a promising sensor for the future space missions such as autonomous safe landing, spacecraft rendezvous and docking due to its ability to provide a full 3D scene with a single or multiple laser pulses. The linear-mode flash lidar has been developed and demonstrated for an autonomous safe landing on the Moon in order to provide an accurate distance measurement to the landing site and its 3D image. Yet, the Geiger-mode flash lidar has also been recognized as an emerging technology for the space missions because it is highly sensitive even to a single photon and provides the very accurate timing of photon arrival. In this study, the performance of the Geiger-mode flash lidar is simulated in the approach phase and evaluated for the autonomous landing on the Moon. Furthermore, a new statistical signal processing algorithm is proposed to remove the noise counts in order to obtain the 3D image from a sequence of laser pulses in the situation of the fast moving spacecraft. The algorithm is shown to be effective for the autonomous landing due to its ability to remove noise events under the condition of low signal-to-noise ratio and improve ranging accuracy.
       
  • Analytical expression for distant retrograde orbits around a small natural
           satellite
    • Abstract: Publication date: Available online 29 October 2018Source: Advances in Space ResearchAuthor(s): Masaya Kimura, Masanori Kawamura, Katsuhiko Yamada An analytical expression for distant retrograde orbits (DROs) is obtained in this study. Owing to the fact that a planar DRO is a closed orbit and can be expressed as an approximately elliptical orbit, respective geometries and periods of DROs are analytically calculated. A switching point, where various properties of planar DROs change abruptly with an increase in the orbital radius, is determined. The Mars–Deimos system is taken as a case study in this work. The proposed method can be applied to cases where the Hill’s approximation of the restricted three-body problem is valid. Numerical calculations are performed to validate the proposed method.
       
  • On the detection of anomalous seismo-ionospheric behavior in the presence
           of space weather stimuli for large earthquakes
    • Abstract: Publication date: Available online 25 October 2018Source: Advances in Space ResearchAuthor(s): B.J.M. Lim, E.C. Leong Anomalous behavior of ionospheric total electron content (TEC) prior to earthquake has been observed in many studies. Evidence of such seismo-ionospheric coupling effects suggests that it is plausible to rely on TEC signatures for early earthquake warning. However, the detection of pre-earthquake TEC anomalies (PETA) has not been adopted in practice due to two pertinent issues. Firstly, the effects of space weather activity can affect TEC levels and cause anomalous behavior in the TEC. Usually arbitrary thresholds are set for space weather indices to eliminate TEC anomaly due to space weather effects. Secondly, the choice regarding moving time-window length used to characterise background variation of TEC within the statistical envelope approach has an effect on detection of PETA. While the rule-of-thumb in selecting the moving window length is to have a time window capable of capturing background variability and short-term fluctuations, the length of the time window used in the literature varies with little justification. In this study, a critical examination is conducted on the statistical envelope approach and in particular, to eliminate the effect of space weather activity without the use of arbitrary space indices to detect PETA. A two-part PETA identification procedure is proposed, consisting of wavelet analyses isolating non-earthquake TEC contributions, followed by the statistical envelope method using a moving window length standardized based on observed periodicities and statistical implications is suggested. The approach is tested on a database of 30 large earthquakes (M ≥ 7.0). The proposed procedure shows that PETA can be detected prior to earthquakes at higher confidence levels without the need to separately check for space weather activity. More importantly, the procedure was able to detect PETA for studies where it was previously reported that PETA could not be detected or detected convincingly.
       
  • Dispersive shock waves in partially ionised plasmas
    • Abstract: Publication date: Available online 25 October 2018Source: Advances in Space ResearchAuthor(s): I. Ballai, E. Forgács-Dajka, A. Marcu Compressional waves propagating in the partially ionised solar lower atmospheric plasmas can easily steepen into nonlinear waves, including shocks. Here we investigate the effect of weak dispersion generated by Hall currents perpendicular to the ambient magnetic field on the characteristics of shock waves. Our study will also focus on the interplay between weak dispersion and partial ionisation of the plasma. Using a multiple scale technique we derive the governing equation in the form of a Korteweg-de Vries-Burgers equation. The effect of weak dispersion on shock waves is obtained using a perturbation technique. The secular behaviour of second order terms is addressed with the help of a renormalisation technique. Our results show that dispersion modifies the characteristics of shock waves and this change is dependent also on the ionisation degree of the plasma. Dispersion can create short lived oscillations in the shocked plasma. The shock fronts become wider with the increase in the number of neutrals in the plasma.
       
  • Command Filtered Sliding Mode Trajectory Tracking Control for Unmanned
           Airships Based on RBFNN Approximation
    • Abstract: Publication date: Available online 25 October 2018Source: Advances in Space ResearchAuthor(s): Wenjie Lou, Ming Zhu, Xiao Guo, Haoquan Liang This paper presents two sliding mode controllers to address the trajectory tracking problem of unmanned airships in the presence of unknown wind disturbance. The sliding mode controller proposed first is designed by a fast power rate reaching law(FPRRL). The disturbance is compensated by a radial basis function neural network (RBFNN). To avoid the aggressive adaptation, the controller is augmented by a command filter. The controller provides good robustness and tracking performance with no chattering under the hypothesis of ideal wind field. However, serious chattering occurs when simulation is performed under discontinuous wind field. To simulate the wind in practice, the wind field employed in the simulation is generated by the combination of a constant field and white noise. The controller is improved subsequently with an extended model to suppress the chattering induced by the white noise. The enhanced controller manipulates the derivation of system input, thus attenuating the chattering. Stability analysis shows that both controllers drive the tracking error into a controllable small region near zero. Simulations are provided to validate the performance of the proposed controllers under different wind hypothesis.
       
  • Solar Physics with the Square Kilometre Array
    • Abstract: Publication date: Available online 24 October 2018Source: Advances in Space ResearchAuthor(s): A. Nindos, E.P. Kontar, D. Oberoi The Square Kilometre Array (SKA) will be the largest radio telescope ever built, aiming to provide collecting area larger than 1 km2. The SKA will have two independent instruments, SKA-LOW comprising of dipoles organized as aperture arrays in Australia and SKA-MID comprising of dishes in South Africa. Currently the phase-1 of SKA, referred to as SKA1, is in its late design stage and construction is expected to start in 2020. Both SKA1-LOW (frequency range of 50-350 MHz) and SKA1-MID Bands 1, 2, and 5 (frequency ranges of 350-1050, 950-1760, and 4600-15300 MHz, respectively) are important for solar observations. In this paper we present SKA’s unique capabilities in terms of spatial, spectral, and temporal resolution, as well as sensitivity and show that they have the potential to provide major new insights in solar physics topics of capital importance including (i) the structure and evolution of the solar corona, (ii) coronal heating, (iii) solar flare dynamics including particle acceleration and transport, (iv) the dynamics and structure of coronal mass ejections, and (v) the solar aspects of space weather. Observations of the Sun jointly with the new generation of ground-based and space-borne instruments promise unprecedented discoveries.
       
  • Advances in Technologies, Missions and Applications of Small Satellites
    • Abstract: Publication date: Available online 21 October 2018Source: Advances in Space ResearchAuthor(s): Luca Maresi
       
 
 
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