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Showing 1 - 200 of 3042 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 19, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 16, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 81, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 23, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 325, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription  
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 204, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 22, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 5, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 4, SJR: 0.383, h-index: 19)
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Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 3)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 123, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 25, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 21, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 25, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
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: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 8, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 39, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 40, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 45, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 12)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 20, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 24)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 34, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 4)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 5, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 21, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 58)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 2, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 338, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 6, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 29, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 15)
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: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 43, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 307, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 5, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 7, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 422, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 38, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 50, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 10, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 6)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 8, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 5, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 6, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 46, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 47, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 44, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 34, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 15, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 30, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 24, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 44, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 179, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 54, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 2)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 23, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 23, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 33, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 53, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 5)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 160, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Anesthésie & Réanimation     Full-text available via subscription  
Anesthesiology Clinics     Full-text available via subscription   (Followers: 21, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 152, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Acta Astronautica
  [SJR: 0.726]   [H-I: 43]   [325 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0094-5765
   Published by Elsevier Homepage  [3042 journals]
  • A new analytical solution of the hyperbolic Kepler equation using the
           Adomian decomposition method
    • Authors: Abdelhalim Ebaid; Randolph Rach; Essam El-Zahar
      Pages: 1 - 9
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Abdelhalim Ebaid, Randolph Rach, Essam El-Zahar
      In this paper, the Adomian decomposition method (ADM) is proposed to solve the hyperbolic Kepler equation which is often used to describe the eccentric anomaly of a comet of extrasolar origin in its hyperbolic trajectory past the Sun. A convenient method is therefore needed to solve this equation to accurately determine the radial distance and/or the Cartesian coordinates of the comet. It has been shown that Adomian's series using a few terms are sufficient to achieve extremely accurate numerical results even for much higher values of eccentricity than those in the literature. Besides, an exceptionally rapid rate of convergence of the sequence of the obtained approximate solutions has been demonstrated. Such approximate solutions possess the odd property in the mean anomaly which are illustrated through several plots. Moreover, the absolute remainder error, using only three components of Adomian's solution decreases across a specified domain, approaches zero as the eccentric anomaly tends to infinity. Also, the absolute remainder error decreases by increasing the number of components of the Adomian decomposition series. In view of the obtained results, the present method may be the most effective approach to treat the hyperbolic Kepler equation.

      PubDate: 2017-05-25T20:18:08Z
      DOI: 10.1016/j.actaastro.2017.05.006
      Issue No: Vol. 138 (2017)
  • Predictor-corrector entry guidance with waypoint and no-fly zone
    • Authors: Tao Wang; Hongbo Zhang; Guojian Tang
      Pages: 10 - 18
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Tao Wang, Hongbo Zhang, Guojian Tang
      With the requirement of the future entry mission, the guidance method not only needs to be robust, reliable and autonomous, but also needs to have the ability to meet the constraints of no-fly zone and waypoint. The paper proposes a predictor-corrector entry guidance method that satisfies the constraints of no-fly zone and waypoint. The trajectory prediction is realized by numerical integration and the corrector is based on fuzzy logic. No-fly zones and waypoints are transformed to a series of reference points. For each reference point, one bank angle reversal is designed. The attack angle, the magnitude and reversal times of bank angle are cooperatively corrected to meet all constraints. The proposed method can guide longitudinal motion and lateral motion synergistically, so it is more robust and flexible. Only one bank angle reversal is needed for a no-fly zone or waypoint, so the reversal times are few. Moreover, without iteration, only a single trajectory prediction is required in a correction cycle, which is favorable for on-board calculation.

      PubDate: 2017-05-31T03:05:39Z
      DOI: 10.1016/j.actaastro.2017.05.009
      Issue No: Vol. 138 (2017)
  • Concurrent rendezvous control of underactuated spacecraft
    • Authors: Vijay Muralidharan; M. Reza Emami
      Pages: 28 - 42
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Vijay Muralidharan, M. Reza Emami
      The concurrent control of spacecraft equipped with one-axis unilateral thruster and three-axis attitude actuator is considered in this paper. The proposed control law utilizes attitude control channels along with the single thrust force concurrently, for three-dimensional trajectory tracking and rendezvous with a target object. The concurrent controller also achieves orbital transfer to low Earth orbits with long range separation. To demonstrate the orbit transfer capabilities of the concurrent controller, a smooth elliptical orbit transfer trajectory for co-planar circular orbits is designed. The velocity change and energy consumption of the designed orbit transfer trajectory is observed to be equivalent to that of Hohmann transfer.

      PubDate: 2017-05-31T03:05:39Z
      DOI: 10.1016/j.actaastro.2017.05.003
      Issue No: Vol. 138 (2017)
  • Mars Colony in situ resource utilization: An integrated architecture and
           economics model
    • Authors: Robert Shishko; René Fradet; Sydney Do; Serkan Saydam; Carlos Tapia-Cortez; Andrew G. Dempster; Jeff Coulton
      Pages: 53 - 67
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Robert Shishko, René Fradet, Sydney Do, Serkan Saydam, Carlos Tapia-Cortez, Andrew G. Dempster, Jeff Coulton
      This paper reports on our effort to develop an ensemble of specialized models to explore the commercial potential of mining water/ice on Mars in support of a Mars Colony. This ensemble starts with a formal systems architecting framework to describe a Mars Colony and capture its artifacts' parameters and technical attributes. The resulting database is then linked to a variety of “downstream” analytic models. In particular, we integrated an extraction process (i.e., “mining”) model, a simulation of the colony's environmental control and life support infrastructure known as HabNet, and a risk-based economics model. The mining model focuses on the technologies associated with in situ resource extraction, processing, storage and handling, and delivery. This model computes the production rate as a function of the systems' technical parameters and the local Mars environment. HabNet simulates the fundamental sustainability relationships associated with establishing and maintaining the colony's population. The economics model brings together market information, investment and operating costs, along with measures of market uncertainty and Monte Carlo techniques, with the objective of determining the profitability of commercial water/ice in situ mining operations. All told, over 50 market and technical parameters can be varied in order to address “what-if” questions, including colony location.

      PubDate: 2017-05-31T03:05:39Z
      DOI: 10.1016/j.actaastro.2017.05.024
      Issue No: Vol. 138 (2017)
  • Absolute navigation for Mars final approach using relative measurements of
           X-ray pulsars and Mars orbiter
    • Authors: Shuo Wang; Pingyuan Cui; Ai Gao; Zhengshi Yu; Menglong Cao
      Pages: 68 - 78
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Shuo Wang, Pingyuan Cui, Ai Gao, Zhengshi Yu, Menglong Cao
      To achieve a precise Mars landing, the autonomous navigation performance of Mars final approach phase need to be further improved. In this paper, an absolute navigation scheme for Mars finial approach phase using relative measurements of X-ray pulsars and Mars orbiter is proposed. By introducing the difference of time of arrival (DTOA) measurement, the states of approach spacecraft and orbiter are estimated at the same time. Compared to the navigation scheme based on the absolute measurements of pulsars, the error sources such as planetary ephemeris error, pulsar parameter uncertainties, and radio beacon position deviations, are correspondingly reduced or eliminated. Through observability analysis, the method of absolute navigation using relative information is proved observable under the condition of reasonable pulsars selection. The design optimization of beacon configuration based on the Fisher Information Matrix (FIM) is also carried out for achieving a better observability. Two navigation schemes respectively based on the absolute/relative measurements of X-ray pulsars are compared by numerical simulations, and the navigation performance is assessed and the feasibility of the proposed scheme is verified.

      PubDate: 2017-05-31T03:05:39Z
      DOI: 10.1016/j.actaastro.2017.05.017
      Issue No: Vol. 138 (2017)
  • Experimental investigation on laser-induced plasma ignition of hydrocarbon
           fuel in scramjet engine at takeover flight conditions
    • Authors: Xipeng Li; Weidong Liu; Yu Pan; Leichao Yang; Bin An
      Pages: 79 - 84
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Xipeng Li, Weidong Liu, Yu Pan, Leichao Yang, Bin An
      Laser-induced plasma ignition of an ethylene fuelled cavity is successfully conducted in a model scramjet engine combustor with dual cavities. The simulated flight condition corresponds to takeover flight Mach 4, with isolator entrance Mach number of 2.1, the total pressure of 0.65 MPa and stagnation temperature of 947 K. Ethylene is injected 35 mm upstream of cavity flameholder from four orifices with 2-mm-diameter. The 1064 nm laser beam, from a Q-switched Nd:YAG laser source running at 10 Hz and 940 mJ per pulse, is focused into cavity for ignition. High speed photography is used to capture the transient ignition process. The laser-induced gas breakdown, flame kernel generation and propagation are all recorded and ensuing stable supersonic combustion is established in cavity. The highly ionized plasma zone is almost round at starting, and then the surface of the flame kernel is wrinkled severely in 150 μs after the laser pulse due to the strong turbulence flow in cavity. The flame kernel is found rotating anti-clockwise and gradually moves upstream as the entrainment of circulation flow in cavity. The flame is stabilized at the corner of the cavity for about 200 μs, and then spreads from leading edge to trailing edge via the under part of shear layer to fully fill the entire cavity. The corner recirculation zone of cavity is of great importance for flame spreading. Eventually, a cavity shear-layer stabilized combustion is established in the supersonic flow roughly 2.9 ms after the laser pulse. Both the temporal evolution of normalized chemiluminescence intensity and normalized flame area show that the entire ignition process can be divided into four stages, which are referred as turbulent dissipation stage, combustion enhancement stage, reverting stage and combustion stabilization stage. The results show promising potentials of laser induced plasma for ignition in real scramjets.

      PubDate: 2017-06-05T03:08:17Z
      DOI: 10.1016/j.actaastro.2017.05.036
      Issue No: Vol. 138 (2017)
  • Inertial frames and breakthrough propulsion physics
    • Authors: Marc G. Millis
      Pages: 85 - 94
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Marc G. Millis
      The term “Breakthrough Propulsion Physics” comes from the NASA project by that name which examined non-rocket space drives, gravity control, and faster-than-light travel. The focus here is on space drives and the related unsolved physics of inertial frames. A “space drive” is a generic term encompassing any concept for using as-yet undiscovered physics to move a spacecraft instead of existing rockets, sails, or tethers. The collective state of the art spans mostly steps 1–3 of the scientific method: defining the problem, collecting data, and forming hypotheses. The key issues include (1) conservation of momentum, (2) absence of obvious reaction mass, and (3) the net-external thrusting requirement. Relevant open problems in physics include: (1) the sources and mechanisms of inertial frames, (2) coupling of gravitation to the other fundamental forces, and (3) the nature of the quantum vacuum. Rather than following the assumption that inertial frames are an immutable, intrinsic property of space, this paper revisits Mach's Principle, where it is posited that inertia is relative to the distant surrounding matter. This perspective allows conjectures that a space drive could impart reaction forces to that matter, via some as-yet undiscovered interaction with the inertial frame properties of space. Thought experiments are offered to begin a process to derive new hypotheses. It is unknown if this line of inquiry will be fruitful, but it is hoped that, by revisiting unsolved physics from a propulsion point of view, new insights will be gained.

      PubDate: 2017-06-05T03:08:17Z
      DOI: 10.1016/j.actaastro.2017.05.028
      Issue No: Vol. 138 (2017)
  • Extending the coverage of the internet of things with low-cost
           nanosatellite networks
    • Authors: Vicente Almonacid; Laurent Franck
      Pages: 95 - 101
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Vicente Almonacid, Laurent Franck
      Recent technology advances have made CubeSats not only an affordable means of access to space, but also promising platforms to develop a new variety of space applications. In this paper, we explore the idea of using nanosatellites as access points to provide extended coverage to the Internet of Things (IoT) and Machine-to-Machine (M2M) communications. This study is mainly motivated by two facts: on the one hand, it is already obvious that the number of machine-type devices deployed globally will experiment an exponential growth over the forthcoming years. This trend is pushed by the available terrestrial cellular infrastructure, which allows adding support for M2M connectivity at marginal costs. On the other hand, the same growth is not observed in remote areas that must rely on space-based connectivity. In such environments, the demand for M2M communications is potentially large, yet it is challenged by the lack of cost-effective service providers. The traffic characteristics of typical M2M applications translate into the requirement for an extremely low cost per transmitted message. Under these strong economical constraints, we expect that nanosatellites in the low Earth orbit will play a fundamental role in overcoming what we may call the IoT digital divide. The objective of this paper is therefore to provide a general analysis of a nanosatellite-based, global IoT/M2M network. We put emphasis in the engineering challenges faced in designing the Earth-to-Space communication link, where the adoption of an efficient multiple-access scheme is paramount for ensuring connectivity to a large number of terminal nodes. In particular, the trade-offs energy efficiency–access delay and energy efficiency–throughput are discussed, and a novel access approach suitable for delay-tolerant applications is proposed. Thus, by keeping a system-level standpoint, we identify key issues and discuss perspectives towards energy efficient and cost-effective solutions.

      PubDate: 2017-06-05T03:08:17Z
      DOI: 10.1016/j.actaastro.2017.05.030
      Issue No: Vol. 138 (2017)
  • The Lunar Space Tug: A sustainable bridge between low Earth orbits and
           the Cislunar Habitat
    • Authors: M. Mammarella; C.A. Paissoni; N. Viola; A. Denaro; E. Gargioli; F. Massobrio
      Pages: 102 - 117
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): M. Mammarella, C.A. Paissoni, N. Viola, A. Denaro, E. Gargioli, F. Massobrio
      The International Space Station is the first space human outpost and over the last 15 years, it has represented a peculiar environment where science, technology and human innovation converge together in a unique microgravity and space research laboratory. With the International Space Station entering the second part of its life and its operations running steadily at nominal pace, the global space community is starting planning how the human exploration could move further, beyond Low-Earth-Orbit. According to the Global Exploration Roadmap, the Moon represents the next feasible path-way for advances in human exploration towards the nal goal, Mars. Based on the experience of the ISS, one of the most widespread ideas is to develop a Cislunar Station in preparation of long duration missions in a deep space environment. Cislunar space is de ned as the area of deep space under the influence of Earth-Moon system, including a set of special orbits, e.g. Earth-Moon Libration points and Lunar Retrograde Orbit. This habitat represents a suitable environment for demonstrating and testing technologies and capabilities in deep space. In order to achieve this goal, there are several crucial systems and technologies, in particular related to transportation and launch systems. The Orion Multi-Purpose Crew Vehicle is a reusable transportation capsule designed to provide crew transportation in deep space missions, whereas NASA is developing the Space Launch System, the most powerful rocket ever built, which could provide the necessary heavy-lift launch capability to support the same kind of missions. These innovations would allow quite-fast transfers from Earth to the Cislunar Station and vice versa, both for manned and unmanned missions. However, taking into account the whole Concept of Operations for both the growth and sustainability of the Cislunar Space Station, the Lunar Space Tug can be considered as an additional, new and fundamental element for the mission architecture. The Lunar Space Tug represents an alternative to the SLS scenario, especially for what concerns all unmanned or logistic missions (e.g. cargo transfer, on orbit assembly, samples return), from Low Earth Orbit to Cislunar space. The paper focuses on the mission analysis and conceptual design of the Lunar Space Tug to support the growth and sustainment of the Cislunar Station. Particular attention is dedicated to the analysis of the propulsion subsystem effects of the Lunar Space Tug design. Main results are presented and discussed, and main conclusions are drawn.

      PubDate: 2017-06-05T03:08:17Z
      DOI: 10.1016/j.actaastro.2017.05.034
      Issue No: Vol. 138 (2017)
  • Ignition and combustion characteristics of molded amorphous boron under
           different oxygen pressures
    • Authors: Daolun Liang; Jianzhong Liu; Yunan Zhou; Junhu Zhou; Kefa Cen
      Pages: 118 - 128
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Daolun Liang, Jianzhong Liu, Yunan Zhou, Junhu Zhou, Kefa Cen
      Ignition and combustion characteristics of amorphous boron (B) have received much attention from researchers in recent decades. A pressurized concentrated ignition experimental system was designed to evaluate the ignition and combustion characteristics of molded B samples. The ignition experiments were carried out under different oxygen pressures (1–9 atm). The condensed combustion products were then analyzed using a scanning electron microscope, an X-ray energy dispersive spectrometer, and an X-ray diffractometer. Furthermore, the complete oxidation rates of the samples were detected by inductively coupled plasma chromatography. As the oxygen pressure increased, the combustion intensity of the samples steadily increased, and the ignition delay time and combustion time both decreased. Under the oxygen pressure of 9 atm, the average ignition delay time and combustion time were 2640 ms and 2596 ms, respectively, and the highest combustion temperature reached 1561.5 °C. The initial diffusion flame on the sample surface was green and the brightest, which was produced by an intermediate combustion product, BO2 (corresponding molecular emission spectrum wavelength, 547.3 nm). Emission spectra of another intermediate product, BO (431.9 nm) was also detected. Two different types of structures were found in the condensed combustion products of the samples. The first type was the flaky B2O3 structure, and the second type was the flocculent structure of incomplete combustion products. The B2O3 content in the condensed combustion products increased with the oxygen pressure during combustion. The complete oxidation ratio of the samples also increased with the oxygen pressure, and reached the maximum value of 68.71% under 9 atm. Overall, the samples showed better ignition and combustion characteristics under higher oxygen pressure.

      PubDate: 2017-06-05T03:08:17Z
      DOI: 10.1016/j.actaastro.2017.05.019
      Issue No: Vol. 138 (2017)
  • Experimental validation of damping properties and solar pressure effects
           on flexible, high area-to-mass ratio debris model
    • Authors: Sittiporn Channumsin; Matteo Ceriotti; Gianmarco Radice; Ian Watson
      Pages: 129 - 144
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Sittiporn Channumsin, Matteo Ceriotti, Gianmarco Radice, Ian Watson
      Multilayer insulation (MLI) is a recently-discovered type of debris originating from delamination of aging spacecraft; it is mostly detected near the geosynchronous orbit (GEO). Observation data indicates that these objects are characterised by high reflectivity, high area-to-mass ratio (HAMR), fast rotation, high sensitivity to perturbations (especially solar radiation pressure) and change of area-to-mass ratio (AMR) over time. As a result, traditional models (e.g. cannonball) are unsuitable to represent and predict this debris' orbital evolution. Previous work by the authors effectively modelled the flexible debris by means of multibody dynamics to improve the prediction accuracy. The orbit evolution with the flexible model resulted significantly different from using the rigid model. This paper aims to present a methodology to determine the dynamic properties of thin membranes with the purpose to validate the deformation characteristics of the flexible model. A high-vacuum chamber (10−4 mbar) to significantly decrease air friction, inside which a thin membrane is hinged at one end but free at the other provides the experimental setup. A free motion test is used to determine the damping characteristics and natural frequency of the thin membrane via logarithmic decrement and frequency response. The membrane can swing freely in the chamber and the motion is tracked by a static, optical camera, and a Kalman filter technique is implemented in the tracking algorithm to reduce noise and increase the tracking accuracy of the oscillating motion. Then, the effect of solar radiation pressure on the thin membrane is investigated: a high power spotlight (500–2000 W) is used to illuminate the sample and any displacement of the membrane is measured by means of a high-resolution laser sensor. Analytic methods from the natural frequency response and Finite Element Analysis (FEA) including multibody simulations of both experimental setups are used for the validation of the flexible model by comparing the experimental results of amplitude decay, natural frequencies and deformation. The experimental results show good agreement with both analytical results and finite element methods.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.015
      Issue No: Vol. 138 (2017)
  • On the prediction of spray angle of liquid-liquid pintle injectors
    • Authors: Peng Cheng; Qinglian Li; Shun Xu; Zhongtao Kang
      Pages: 145 - 151
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Peng Cheng, Qinglian Li, Shun Xu, Zhongtao Kang
      The pintle injector is famous for its capability of deep throttling and low cost. However, the pintle injector has been seldom investigated. To get a good prediction of the spray angle of liquid-liquid pintle injectors, theoretical analysis, numerical simulations and experiments were conducted. Under the hypothesis of incompressible and inviscid flow, a spray angle formula was deduced from the continuity and momentum equations based on a control volume analysis. The formula was then validated by numerical and experimental data. The results indicates that both geometric and injection parameters affect the total momentum ratio (TMR) and then influence the spray angle formed by liquid-liquid pintle injectors. TMR is the pivotal non-dimensional number that dominates the spray angle. Compared with gas-gas pintle injectors, spray angle formed by liquid-liquid injectors is larger, which benefits from the local high pressure zone near the pintle wall caused by the impingement of radial and axial sheets.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.037
      Issue No: Vol. 138 (2017)
  • Attitude control of towed space debris using only tether
    • Authors: Bingheng Wang; Zhongjie Meng; Panfeng Huang
      Pages: 152 - 167
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Bingheng Wang, Zhongjie Meng, Panfeng Huang
      Tethered towing for Active Debris Removal (ADR) is promising but vulnerable to entanglement and collision due to the debris rotation. This paper proposes a novel way to control the attitude of debris towed with off-centered capture using only tether. For this purpose, a tethered manipulator (TM) on the bottom of gripper is employed to move the tether attachment point. Since the tether cannot yield a torque along itself and the TM motions are constrained, the underactuated problem subject to input saturation arises as a critical control challenge. This is tackled by using backstepping-based hierarchical sliding mode control (HSMC) with anti-windup technique. And a disturbance observer is developed to render the controller robust to the dynamics uncertainty and flexible appendages vibration. To avoid collision, by designing an impedance controller the tether tension is stabilized with a reel mechanism in platform for changing the tether length. Finally, the proposed method is verified numerically by the first impulsive maneuver of Hohmann transfer.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.012
      Issue No: Vol. 138 (2017)
  • Drag and heat flux reduction mechanism of blunted cone with aerodisks
    • Authors: Wei Huang; Lang-quan Li; Li Yan; Tian-tian Zhang
      Pages: 168 - 175
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Wei Huang, Lang-quan Li, Li Yan, Tian-tian Zhang
      The major challenge among a number of design requirements for hypersonic vehicles is the reduction of drag and aerodynamic heating. Of all these techniques of drag and heat flux reduction, application of forward facing aerospike conceived in 1950s is an effective and simpler technique to reduce the drag as well as the heat transfer rate for blunt nosed bodies at hypersonic Mach numbers. In this paper, the flow fields around a blunt cone with and without aerodisk flying at hypersonic Mach numbers are computed numerically, and the numerical simulations are conducted by specifying the freestream velocity, static pressure and static temperatures at the inlet of the computational domain with a three-dimensional, steady, Reynolds-averaged Navier-Stokes equation. An aerodisk is attached to the tip of the rod to reduce the drag and heat flux further. The influences of the length of rod and the diameter of aerodisk on the drag and heat flux reduction mechanism are analyzed comprehensively, and eight configurations are taken into consideration in the current study. The obtained results show that for all aerodisks, the reduction in drag of the blunt body is proportional to the extent of the recirculation dead air region. For long rods, the aerodisk is found not that beneficial in reducing the drag, and an aerodisk is more effective than an aerospike. The spike produces a region of recirculation separated flow that shields the blunt-nosed body from the incoming flow, and the recirculation region is formed around the root of the spike up to the reattachment point of the flow at the shoulder of the blunt body. The dynamic pressure in the recirculation area is highly reduced and thus leads to the decrease in drag and heat load on the surface of the blunt body. Because of the reattachment of the shear layer on the shoulder of the blunt body, the pressure near that point becomes large.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.040
      Issue No: Vol. 138 (2017)
  • Enhanced GPS-based GRACE baseline determination by using a new strategy
           for ambiguity resolution and relative phase center variation corrections
    • Authors: Defeng Gu; Bing Ju; Junhong Liu; Jia Tu
      Pages: 176 - 184
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Defeng Gu, Bing Ju, Junhong Liu, Jia Tu
      Precise relative position determination is a prerequisite for radar interferometry by formation flying satellites. It has been shown that this can be achieved by high-quality, dual-frequency GPS receivers that provide precise carrier-phase observations. The precise baseline determination between satellites flying in formation can significantly improve the accuracy of interferometric products, and has become a research interest. The key technologies of baseline determination using spaceborne dual-frequency GPS for gravity recovery and climate experiment (GRACE) formation are presented, including zero-difference (ZD) reduced dynamic orbit determination, double-difference (DD) reduced dynamic relative orbit determination, integer ambiguity resolution and relative receiver antenna phase center variation (PCV) estimation. We propose an independent baseline determination method based on a new strategy of integer ambiguity resolution and correction of relative receiver antenna PCVs, and implement the method in the NUDTTK software package. The algorithms have been tested using flight data over a period of 120 days from GRACE. With the original strategy of integer ambiguity resolution based on Melbourne-Wübbena (M-W) combinations, the average success rate is 85.6%, and the baseline precision is 1.13 mm. With the new strategy of integer ambiguity resolution based on a priori relative orbit, the average success rate and baseline precision are improved by 5.8% and 0.11 mm respectively. A relative ionosphere-free phase pattern estimation result is given in this study, and with correction of relative receiver antenna PCVs, the baseline precision is further significantly improved by 0.34 mm. For ZD reduced dynamic orbit determination, the orbit precision for each GRACE satellite A or B in three dimensions (3D) is about 2.5 cm compared to Jet Propulsion Laboratory (JPL) post science orbits. For DD reduced dynamic relative orbit determination, the final baseline precision for two GRACE satellites formation is 0.68 mm validated by K-Band Ranging (KBR) observations, and average ambiguity success rate of about 91.4% could be achieved.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.022
      Issue No: Vol. 138 (2017)
  • Velocity-free adaptive backstepping control of underactuated spacecraft
           hovering in circular orbits with input saturation
    • Authors: Xu Huang; Ye Yan; Yang Zhou; Daoliang Hao
      Pages: 185 - 200
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Xu Huang, Ye Yan, Yang Zhou, Daoliang Hao
      This paper investigates the output feedback control problem of underactuated spacecraft hovering in circular orbits subject to unmatched disturbances and input saturation. Two underactuated cases without either the radial or in-track thrust are considered. Besides the unavailability of velocity information, the simultaneous loss of velocity measurements and thrust also gives rise to unknown system parameters, a problem not observed in fully-actuated hovering control. To address the lack of velocity measurements, a filter is designed to generate velocity signals. An augmented system is then proposed to deal with the input saturation. By using the inherent coupling of system states, the adaptive backstepping technique is then adopted to estimate the resulting unknown system parameter and design the velocity-free underactuated controller for either case. A Lyapunov-based approach is utilized to prove the stability of the overall closed-loop system, which indicates that all state errors, parameter and velocity estimation errors are asymptotically convergent in the absence of disturbances; and are uniformly ultimately bounded in the presence of disturbances. Finally, numerical simulations are presented to illustrate the performance of the proposed controllers.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.027
      Issue No: Vol. 138 (2017)
  • Exchange inlet optimization by genetic algorithm for improved RBCC
    • Authors: G. Chorkawy; J. Etele
      Pages: 201 - 213
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): G. Chorkawy, J. Etele
      A genetic algorithm based on real parameter representation using a variable selection pressure and variable probability of mutation is used to optimize an annular air breathing rocket inlet called the Exchange Inlet. A rapid and accurate design method which provides estimates for air breathing, mixing, and isentropic flow performance is used as the engine of the optimization routine. Comparison to detailed numerical simulations show that the design method yields desired exit Mach numbers to within approximately 1% over 75% of the annular exit area and predicts entrained air massflows to between 1% and 9% of numerically simulated values depending on the flight condition. Optimum designs are shown to be obtained within approximately 8000 fitness function evaluations in a search space on the order of 106. The method is also shown to be able to identify beneficial values for particular alleles when they exist while showing the ability to handle cases where physical and aphysical designs co-exist at particular values of a subset of alleles within a gene. For an air breathing engine based on a hydrogen fuelled rocket an exchange inlet is designed which yields a predicted air entrainment ratio within 95% of the theoretical maximum.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.035
      Issue No: Vol. 138 (2017)
  • Numerical simulation of the fluid-solid interaction for CNT reinforced
           functionally graded cylindrical shells in thermal environments
    • Authors: Hamed Asadi
      Pages: 214 - 224
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Hamed Asadi
      Spacecraft and satellite are susceptible to aerothermoelastic flutter instability, which may jeopardize the mission of the spacecraft and satellite. This kind of instability may result from the coupling of the thermal radiation from the sun and the elastic deformations of aeronautical components. As a first endeavor, the aerothermoelastic flutter and buckling instabilities of functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical shell under simultaneous actions of aerodynamic loading and elevated temperature conditions are investigated. The formulations are derived according to the first-order shear deformation theory, Donnell shell theory in conjunction with von Karman geometrical nonlinearity. Thermomechanical properties are assumed to be temperature-dependent and modified rule of mixture is used to determine the equivalent material properties of the FG-CNTRC cylindrical shell. The quasi-steady Krumhaar's modified piston theory by taking into account the effect of panel curvature, is used to determine the aerodynamic pressure. The nonlinear dynamic equations are discretized in the circumferential and longitudinal directions using the trigonometric expression and the harmonic differential quadrature method, respectively. Effects of various influential factors, including CNT volume fraction and distribution, boundary conditions, geometrical parameters, thermal environments, freestream static pressure and Mach number on the aerothermoelastic instabilities of the FG-CNTRC cylindrical shell are studied in details. It is found that temperature rise has a significant effect on the aerothermoelastic flutter characteristics of the FG-CNTRC cylindrical shell. It is revealed that cylindrical shells with intermediate CNT volume fraction have intermediate critical dynamic pressure, while do not have, necessarily, intermediate critical buckling temperature. It is concluded that the critical circumferential mode number ( m C r ) corresponding to the minimum critical dynamic pressure, depends not only on the radius-to-thickness ratio but also on the distribution of the CNTs.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.039
      Issue No: Vol. 138 (2017)
  • Hayabusa 2 extension plan: Asteroid selection and trajectory design
    • Authors: Bruno Victorino Sarli; Yuichi Tsuda
      Pages: 225 - 232
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Bruno Victorino Sarli, Yuichi Tsuda
      The Hayabusa 2 mission is targeted to explore the asteroid (162173) 1999 JU 3 and return surface as well as sub-surface samples through a novel impactor. Upon its return, at the end of 2020, the spacecraft will release the capsule for Earth re-entry and drift away from the planet. Based on the current mission profile, the spacecraft is expected to retain 30 kg of xenon propellant for trajectory maneuvers after the capsule is released. This remaining fuel can be used to extend the mission and improve its scientific return by exploring a new target. Work herein outlines an extension plan for Hayabusa 2, detailing the target selection process and its subsequent trajectory design. Due to final Earth escape trajectory, considering the excess velocity and orbital geometry, the only available extension option is an asteroid flyby. One of the most important trajectory characteristic is to maximize the spacecraft's optical detection capabilities. As a result the asteroid 2001 WR 1 is identified as the most promising target candidate. The resulting trajectory uses all the available xenon with 100% duty cycle. Furthermore, the extension lasts for 932 days and offers 1.57 days of optical navigation time for a flyby on June 27, 2023.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.016
      Issue No: Vol. 138 (2017)
  • Fuzzy attitude control of solar sail via linear matrix inequalities
    • Authors: Joshua Baculi; Mohammad A. Ayoubi
      Pages: 233 - 241
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Joshua Baculi, Mohammad A. Ayoubi
      This study presents a fuzzy tracking controller based on the Takagi-Sugeno (T-S) fuzzy model of the solar sail. First, the T-S fuzzy model is constructed by linearizing the existing nonlinear equations of motion of the solar sail. Then, the T-S fuzzy model is used to derive the state feedback controller gains for the Twin Parallel Distributed Compensation (TPDC) technique. The TPDC tracks and stabilizes the attitude of the solar sail to any desired state in the presence of parameter uncertainties and external disturbances while satisfying actuator constraints. The performance of the TPDC is compared to a PID controller that is tuned using the Ziegler-Nichols method. Numerical simulation shows the TPDC outperforms the PID controller when stabilizing the solar sail to a desired state.

      PubDate: 2017-06-10T03:14:30Z
      DOI: 10.1016/j.actaastro.2017.05.021
      Issue No: Vol. 138 (2017)
  • On-board orbit determination for low thrust LEO-MEO transfer by Consider
           Kalman Filtering and multi-constellation GNSS
    • Authors: Francesco Menzione; Alfredo Renga; Michele Grassi
      Pages: 242 - 254
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Francesco Menzione, Alfredo Renga, Michele Grassi
      In the framework of the novel navigation scenario offered by the next generation satellite low thrust autonomous LEO-to-MEO orbit transfer, this study proposes and tests a GNSS based navigation system aimed at providing on-board precise and robust orbit determination strategy to override rising criticalities. The analysis introduces the challenging design issues to simultaneously deal with the variable orbit regime, the electric thrust control and the high orbit GNSS visibility conditions. The Consider Kalman Filtering approach is here proposed as the filtering scheme to process the GNSS raw data provided by a multi-antenna/multi-constellation receiver in presence of uncertain parameters affecting measurements, actuation and spacecraft physical properties. Filter robustness and achievable navigation accuracy are verified using a high fidelity simulation of the low-thrust rising scenario and performance are compared with the one of a standard Extended Kalman Filtering approach to highlight the advantages of the proposed solution. Performance assessment of the developed navigation solution is accomplished for different transfer phases.

      PubDate: 2017-06-14T20:18:35Z
      DOI: 10.1016/j.actaastro.2017.05.029
      Issue No: Vol. 138 (2017)
  • Operations Data Files, driving force behind International Space Station
    • Authors: Tom Hoppenbrouwers; Lionel Ferra; Michael Markus; Mikael Wolff
      Pages: 255 - 261
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Tom Hoppenbrouwers, Lionel Ferra, Michael Markus, Mikael Wolff
      Almost all tasks performed by the astronauts on-board the International Space Station (ISS) and by ground controllers in Mission Control Centre, from operation and maintenance of station systems to the execution of scientific experiments or high risk visiting vehicles docking manoeuvres, would not be possible without Operations Data Files (ODF). ODFs are the User Manuals of the Space Station and have multiple faces, going from traditional step-by-step procedures, scripts, cue cards, over displays, to software which guides the crew through the execution of certain tasks. Those key operational documents are standardized as they are used on-board the Space Station by an international crew constantly changing every 3 months. Furthermore this harmonization effort is paramount for consistency as the crew moves from one element to another in a matter of seconds, and from one activity to another. On ground, a significant large group of experts from all International Partners drafts, prepares reviews and approves on a daily basis all Operations Data Files, ensuring their timely availability on-board the ISS for all activities. Unavailability of these operational documents will halt the conduct of experiments or cancel milestone events. This paper will give an insight in the ground preparation work for the ODFs (with a focus on ESA ODF processes) and will present an overview on ODF formats and their usage within the ISS environment today and show how vital they are. Furthermore the focus will be on the recently implemented ODF features, which significantly ease the use of this documentation and improve the efficiency of the astronauts performing the tasks. Examples are short video demonstrations, interactive 3D animations, Execute Tailored Procedures (XTP-versions), tablet products, etc.

      PubDate: 2017-06-14T20:18:35Z
      DOI: 10.1016/j.actaastro.2017.06.001
      Issue No: Vol. 138 (2017)
  • A novel nonlinear control for tracking and rendezvous with a rotating
           non-cooperative target with translational maneuver
    • Authors: Dayu Zhang; Jianjun Luo; Dengwei Gao; Weihua Ma; Jianping Yuan
      Pages: 276 - 289
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Dayu Zhang, Jianjun Luo, Dengwei Gao, Weihua Ma, Jianping Yuan
      This paper studies the control of flexible chaser spacecraft to track and rendezvous with a rotating non-cooperative target accompanied by translational maneuver. The problem is formulated that the chaser spacecraft is required to track target position and be synchronized with its attitude precisely. Meanwhile, the elastic vibration, induced by large angular maneuver in the tracking process, needs to be reduced. With respect to this unique movement of target, a novel modified θ − D control method, derived by standard θ − D algorithm and Lyapunov min-max value theorem, is proposed to incorporate position, attitude and flexural motion into one united control frame. The modification term in the proposed control method is dealt with target translational maneuver, which is the primary contribution in this paper. The asymptotically stability of closed-loop system is proved via the Lyapunov theory and Lyapunov min-max value theorem. Numerical results demonstrate an excellent tracking performance of proposed united control frame even under large inertia uncertainties.

      PubDate: 2017-06-19T20:23:55Z
      DOI: 10.1016/j.actaastro.2017.05.026
      Issue No: Vol. 138 (2017)
  • Attitude motion compensation for imager on Fengyun-4 geostationary
           meteorological satellite
    • Authors: Wang Lyu; Shoulun Dai; Yaohai Dong; Yili Shen; Xiaozheng Song; Tianshu Wang
      Pages: 290 - 294
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Wang Lyu, Shoulun Dai, Yaohai Dong, Yili Shen, Xiaozheng Song, Tianshu Wang
      A compensation method is used in Chinese Fengyun-4 satellite to counteracting the line-of-sight influence by attitude motion during imaging. The method is acted on-board by adding the compensation amount to the instrument scanning control circuit. The mathematics simulation and the three-axis air-bearing test results show that the method works effectively.

      PubDate: 2017-06-19T20:23:55Z
      DOI: 10.1016/j.actaastro.2017.05.033
      Issue No: Vol. 138 (2017)
  • Space assets, technology and services in support of energy policy
    • Authors: C.A. Vasko; M. Adriaensen; A. Bretel; I. Duvaux-Bechon; C.G. Giannopapa
      Pages: 295 - 300
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): C.A. Vasko, M. Adriaensen, A. Bretel, I. Duvaux-Bechon, C.G. Giannopapa
      Space can be used as a tool by decision and policy makers in developing, implementing and monitoring various policy areas including resource management, environment, transport, security and energy. This paper focuses on the role of space for the energy policy. Firstly, the paper summarizes the European Union's (EU) main objectives in energy policy enclosed in the Energy Strategy 2020–2030–2050 and demonstrates how space assets can contribute to achieving those objectives. Secondly, the paper addresses how the European Space Agency (ESA) has established multiple initiatives and programs that directly finance the development of space assets, technology and applications that deliver services in support of the EU energy policy and sector. These efforts should be continued and strengthened in order to overcome identified technological challenges. The use of space assets, technology and applications, can help achieve the energy policy objectives for the next decades.

      PubDate: 2017-06-19T20:23:55Z
      DOI: 10.1016/j.actaastro.2017.06.005
      Issue No: Vol. 138 (2017)
  • Backstepping control for attitude tracking of the spacecraft under input
    • Authors: Yong Guo; Jin-hua Guo; Shen-min Song
      Pages: 318 - 325
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Yong Guo, Jin-hua Guo, Shen-min Song
      Finite-time control schemes without the drawback of unwinding are investigated by backstepping method for the spacecraft. The first finite-time controller is robust to external disturbances in which a novel virtual angular velocity is designed to avoid that the trace of the error rotation matrix equals to one. By using adaptive control, the second finite-time controller that can deal with input saturation is also robust to external disturbances. Theoretical analysis and numerical simulations are presented to prove the validity of the designed controllers.

      PubDate: 2017-06-19T20:23:55Z
      DOI: 10.1016/j.actaastro.2017.06.002
      Issue No: Vol. 138 (2017)
  • Karl Poggensee - A widely unknown German rocket pioneer - The early years
           1930–1934 - A chronology
    • Authors: Karlheinz Rohrwild
      Pages: 343 - 355
      Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Karlheinz Rohrwild
      The rediscovered estate of Karl Poggensee allows to reproduce chronologically his rocket tests of the period 1930–1934 almost completely for the first time. Thrilled by the movie “The Woman in the Moon” for the idea of space travel, he started as a student of Hinderburg-Polytechnikum (IAO), Oldenburg, to build his first solid-fuel rocket, producing his own propellant charges. Being a coming electrical engineer his main goal was not set up new record heights, but to provide his rockets with automatic measuring instruments, camera and parachute release systems. The optimization of this sequence was his main focus.

      PubDate: 2017-06-19T20:23:55Z
      DOI: 10.1016/j.actaastro.2017.06.004
      Issue No: Vol. 138 (2017)
  • Green hypergolic combination: Diethylenetriamine-based fuel and hydrogen
    • Authors: Hongjae Kang; Sejin Kwon
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Hongjae Kang, Sejin Kwon
      The present research dealt with the concept of green hypergolic combination to replace the toxic hypergolic combinations. Hydrogen peroxide was selected as a green oxidizer. A novel recipe for the non-toxic hypergolic fuel (Stock 3) was suggested. Sodium borohydride was blended into the mixture of energetic hydrocarbon solvents as an ignition source for hypergolic ignition. The main ingredient of the mixture was diethylenetriamine. By mixing some amount of tetrahydrofuran with diethylenetriamine, the mixture became more flammable and volatile. The mixture of Stock 3 fuel remained stable for four months in the lab scale storability test. Through a simple drop test, the hypergolicity of the green hypergolic combination was verified. Comparing to the toxic hypergolic combination MMH/NTO as the reference, the theoretical performance of the green hypergolic combination would be achieved about 96.7% of the equilibrium specific impulse and about 105.7% of the density specific impulse. The applicability of the green hypergolic combination was successfully confirmed through the static hot-fire tests using 500N scale hypergolic thruster.

      PubDate: 2017-04-16T07:58:03Z
      DOI: 10.1016/j.actaastro.2017.04.009
      Issue No: Vol. 137 (2017)
  • Space-based pseudo-fixed latitude observation mode based on the
           characteristics of geosynchronous orbit belt
    • Authors: Yun-peng Hu; Lei Chen; Jian-yu Huang
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Yun-peng Hu, Lei Chen, Jian-yu Huang
      The US Lincoln Laboratory proved that space-based visible (SBV) observation is efficient to observe space objects, especially Geosynchronous Orbit (GEO) objects. After that, SBV observation plays an important role in the space surveillance. In this paper, a novel space-based observation mode is designed to observe all the GEO objects in a relatively short time. A low earth orbit (LEO) satellite, especially a dawn-dusk sun-synchronous orbit satellite, is useful for space-based observation. Thus, the observation mode for GEO objects is based on a dawn-dusk sun-synchronous orbit satellite. It is found that the Pinch Point (PP) regions proposed by the US Lincoln Laboratory are spreading based on the analysis of the evolution principles of GEO objects. As the PP regions becoming more and more widely in the future, many strategies based on it may not be efficient any more. Hence, the key point of the space-based observation strategy design for GEO objects should be emphasized on the whole GEO belt as far as possible. The pseudo-fixed latitude observation mode is proposed in this paper based on the characteristics of GEO belt. Unlike classical space-based observation modes, pseudo-fixed latitude observation mode makes use of the one-dimensional attitude adjustment of the observation satellite. The pseudo-fixed latitude observation mode is more reliable and simple in engineering, compared with the gazing observation mode which needs to adjust the attitude from the two dimensions. It includes two types of attitude adjustment, i.e. daily and continuous attitude adjustment. Therefore, the pseudo-fixed latitude observation mode has two characteristics. In a day, the latitude of the observation region is fixed and the scanning region is about a rectangle, while the latitude of the observation region centre changes each day in a long term based on a daily strategy. The capabilities of a pseudo-fixed latitude observation instrument with a 98° dawn-dusk sun-synchronous orbit are discussed. It is found that most of GEO objects can be visited every day and almost all the GEO objects can be visited in two days in the whole year using a sensor with 20°×2° field of view (FOV). The seasonal drops, which are caused by the characteristics of GEO belt and the influence of earth shadow at the two equinoxes, have been overcome under the pseudo-fixed observation mode.

      PubDate: 2017-04-16T07:58:03Z
      DOI: 10.1016/j.actaastro.2017.03.031
      Issue No: Vol. 137 (2017)
  • Investigation of transient ignition process in a cavity based scramjet
           combustor using combined ethylene injectors
    • Authors: Xiao Liu; Zun Cai; Yiheng Tong; Hongtao Zheng
      Pages: 1 - 7
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Xiao Liu, Zun Cai, Yiheng Tong, Hongtao Zheng
      Large Eddy Simulation (LES) and experiment were employed to investigate the transient ignition and flame propagation process in a rearwall-expansion cavity scramjet combustor using combined fuel injection schemes. The compressible supersonic solver and three ethylene combustion mechanisms were first validated against experimental data and results show in reasonably good agreement. Fuel injection scheme combining transverse and direct injectors in the cavity provides a benefit mixture distribution and could achieve a successful ignition. Four stages are illustrated in detail from both experiment and LES. After forced ignition in the cavity, initial flame kernel propagates upstream towards the cavity front edge and ignites the mixture, which acts as a continuous pilot flame, and then propagates downstream along the cavity shear layer rapidly to the combustor exit. Cavity shear layer flame stabilization mode can be concluded from the heat release rate and local high temperature distribution during the combustion process.

      PubDate: 2017-04-16T07:58:03Z
      DOI: 10.1016/j.actaastro.2017.04.007
      Issue No: Vol. 137 (2017)
  • Discharge reliability in ablative pulsed plasma thrusters
    • Authors: Zhiwen Wu; Guorui Sun; Shiyue Yuan; Tiankun Huang; Xiangyang Liu; Kan Xie; Ningfei Wang
      Pages: 8 - 14
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Zhiwen Wu, Guorui Sun, Shiyue Yuan, Tiankun Huang, Xiangyang Liu, Kan Xie, Ningfei Wang
      Discharge reliability is typically neglected in low-ignition-cycle ablative pulsed plasma thrusters (APPTs). In this study, the discharge reliability of an APPT is assessed analytically and experimentally. The goals of this study are to better understand the ignition characteristics and to assess the accuracy of the analytical method. For each of six sets of operating conditions, 500 tests of a parallel-plate APPT with a coaxial semiconductor spark plug are conducted. The discharge voltage and current are measured with a high-voltage probe and a Rogowski coil, respectively, to determine whether the discharge is successful. Generally, the discharge success rate increases as the discharge voltage increases, and it decreases as the electrode gap and the number of ignitions increases. The theoretical analysis and the experimental results are reasonably consistent. This approach provides a reference for designing APPTs and improving their stability.

      PubDate: 2017-04-16T07:58:03Z
      DOI: 10.1016/j.actaastro.2017.04.006
      Issue No: Vol. 137 (2017)
  • Robustness analysis method for orbit control
    • Authors: Jingrui Zhang; Keying Yang; Rui Qi; Shuge Zhao; Yanyan Li
      Pages: 15 - 24
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Jingrui Zhang, Keying Yang, Rui Qi, Shuge Zhao, Yanyan Li
      Satellite orbits require periodical maintenance due to the presence of perturbations. However, random errors caused by inaccurate orbit determination and thrust implementation may lead to failure of the orbit control strategy. Therefore, it is necessary to analyze the robustness of the orbit control methods. Feasible strategies which are tolerant to errors of a certain magnitude can be developed to perform reliable orbit control for the satellite. In this paper, first, the orbital dynamic model is formulated by Gauss’ form of the planetary equation using the mean orbit elements; the atmospheric drag and the Earth's non-spherical perturbations are taken into consideration in this model. Second, an impulsive control strategy employing the differential correction algorithm is developed to maintain the satellite trajectory parameters in given ranges. Finally, the robustness of the impulsive control method is analyzed through Monte Carlo simulations while taking orbit determination error and thrust error into account.

      PubDate: 2017-04-16T07:58:03Z
      DOI: 10.1016/j.actaastro.2017.03.034
      Issue No: Vol. 137 (2017)
  • Flow field characteristics analysis and combustion modes classification
           for a strut/cavity dual-mode combustor
    • Authors: Chenlin Zhang; Juntao Chang; Yuanshi Zhang; Youyin Wang; Wen Bao
      Pages: 44 - 51
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Chenlin Zhang, Juntao Chang, Yuanshi Zhang, Youyin Wang, Wen Bao
      Experimental and numerical study of a strut/cavity dual-mode combustor has been conducted in this paper. Under different fuel equivalence ratio and allocation proportion conditions, the pressure distribution and flow field structure of combustor show distinct characteristics. For strut fuel injecting at a low equivalence ratio, the luminosity images show that combustion zone distributes in the shear layer behind the strut. The wall fuel injecting before strut would change the starting point of pressure rising. Based on the flow field structure, the dual-mode combustor operation process is classified into three combustion modes, including scramjet mode, weak ramjet mode and strong ramjet mode. Because of a strong interaction of the shock wave with the boundary layer, weak ramjet mode has a stronger isolator compression effect and higher combustion efficiency than scramjet mode. With heat release increasing, the thermal throat formation is an indication of the strong ramjet mode, which has a subsonic gap in the isolator. Further, by judging the pressure from dominant pressure sensor before the strut, the three different combustion modes could be classified. Comparing the specific impulse of combustor, it has an obvious distinction in the different combustion modes.

      PubDate: 2017-04-23T08:02:41Z
      DOI: 10.1016/j.actaastro.2017.03.023
      Issue No: Vol. 137 (2017)
  • The influence of cavity parameters on the combustion oscillation in a
           single-side expansion scramjet combustor
    • Authors: Hao Ouyang; Weidong Liu; Mingbo Sun
      Pages: 52 - 59
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Hao Ouyang, Weidong Liu, Mingbo Sun
      Cavity has been validated to be efficient flameholders for scramjet combustors, but the influence of its parameters on the combustion oscillation in scramjet combustor has barely been studied. In the present work, a series of experiments focusing on this issue have been carried out. The influence of flameholding cavity position, its length to depth ratio L/D and aft wall angle θ and number on ethylene combustion oscillation characteristics in scramjet combustor has been researched. The obtained experimental results show that, as the premixing distance between ethylene injector and flameholding cavity varies, the ethylene combustion flame will take on two distinct forms, small-amplitude high frequency fluctuation, and large-amplitude low frequency oscillation. The dominant frequency of the large-amplitude combustion oscillation is in inverse proportion to the pre-mixing distance. Moreover, the influence of cavity length to depth ratio and the aft wall angleθexists diversity when the flameholding cavity position is different and can be recognized as unnoticeable compared to the impact of the premixing distance. In addition, we also find that, when the premixing distance is identical and sufficient, increasing the number of tandem flameholding cavities can change the dominant frequency of combustion oscillation hardly, let alone avoid the combustion oscillation. It is believed that the present investigation will provide a useful reference for the design of the scramjet combustor.

      PubDate: 2017-04-23T08:02:41Z
      DOI: 10.1016/j.actaastro.2017.03.018
      Issue No: Vol. 137 (2017)
  • Reentry trajectory optimization with waypoint and no-fly zone constraints
           using multiphase convex programming
    • Authors: Dang-Jun Zhao; Zheng-Yu Song
      Pages: 60 - 69
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Dang-Jun Zhao, Zheng-Yu Song
      This study proposes a multiphase convex programming approach for rapid reentry trajectory generation that satisfies path, waypoint and no-fly zone (NFZ) constraints on Common Aerial Vehicles (CAVs). Because the time when the vehicle reaches the waypoint is unknown, the trajectory of the vehicle is divided into several phases according to the prescribed waypoints, rendering a multiphase optimization problem with free final time. Due to the requirement of rapidity, the minimum flight time of each phase index is preferred over other indices in this research. The sequential linearization is used to approximate the nonlinear dynamics of the vehicle as well as the nonlinear concave path constraints on the heat rate, dynamic pressure, and normal load; meanwhile, the convexification techniques are proposed to relax the concave constraints on control variables. Next, the original multiphase optimization problem is reformulated as a standard second-order convex programming problem. Theoretical analysis is conducted to show that the original problem and the converted problem have the same solution. Numerical results are presented to demonstrate that the proposed approach is efficient and effective.

      PubDate: 2017-04-23T08:02:41Z
      DOI: 10.1016/j.actaastro.2017.04.013
      Issue No: Vol. 137 (2017)
  • Crack cause analysis of a graphite nozzle throat insert
    • Authors: Lin Sun; Futing Bao; Yu Zhao; Lian Hou; Weihua Hui; Ning Zhang; Wei Shi
      Pages: 70 - 77
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Lin Sun, Futing Bao, Yu Zhao, Lian Hou, Weihua Hui, Ning Zhang, Wei Shi
      With an objective to determine the failure cause of a throughout crack at an angle of 45° and a breach during a firing test, a simplified analysis procedure with consideration of the structure gap was established to simulate the thermo-structural response of a nozzle. By neglecting erosion and pyrolysis of the insulating materials and establishing temperature-dependent or anisotropic material models, ANSYS Parameter Design Language codes were written to perform the fully coupled thermal-structural simulation. A Quasi-1D flow was calculated for supplying boundary conditions. Study on mesh independence and time step independence was also conducted to evaluate simulated results. It was found that shortly after ignition, compressive stress in the x direction and tensile stress in the y direction contributed to anomalies. And through contact status analysis, inappropriate gap design was regarded as the origin of the too large stress, which was the primary cause of these anomalies during firing test. Simulation results were in good agreement with firing test results. In addition, the simplified analysis procedure was proven effective. Gap size should be seriously dealt with in the future design.

      PubDate: 2017-04-23T08:02:41Z
      DOI: 10.1016/j.actaastro.2017.04.016
      Issue No: Vol. 137 (2017)
  • Teófilo Tabanera, Father of the Argentine Space Program
    • Authors: Pablo de León; Marcela Tabanera; Marisol Tabanera
      Pages: 91 - 97
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Pablo de León, Marcela Tabanera, Marisol Tabanera
      No other figure was able to organize and catalyze the seminal interest of space exploration in Argentina more than Teófilo Tabanera. Born in 1909, Tabanera showed an early interest in the possibilities of space travel and dedicated most of his life to popularize it in his country. He created the Sociedad Argentina Interplanetaria (1949), which was the first space enthusiast's organization in Latin America. Present in the first meeting of representatives of various space societies, which led to the creation of the International Astronautical Federation, Tabanera was able to bring his enthusiasm to this new organization. A prolific writer, Tabanera wrote the first books about space exploration in Spanish, and organized many courses and conferences on the subject. When the Comisión Nacional de Investigaciones Espaciales (the Argentine Space Agency) was created in 1960 by a decree of President Arturo Frondizi, Tabanera was appointed as its first administrator. There, with meager funds, he organized launch campaigns and international projects on sounding rockets. Thanks to his knowledge of the international space sector, Tabanera invited many experts to Argentina, among them Wernher von Braun and even the Apollo XI crew, just a few months after their return from the Moon. He continued his activities in the IAF (International Astronautical Federation) serving as vice president for seven terms, and was a cofounder of the International Academy of Astronautics (I.A.A.). His many contributions, both to the Argentine and international space sector, are a testimony to his undying enthusiasm and interest in space as a way of advancing humankind.

      PubDate: 2017-04-23T08:02:41Z
      DOI: 10.1016/j.actaastro.2017.04.003
      Issue No: Vol. 137 (2017)
  • Manufacturing of a high-temperature resistojet heat exchanger by selective
           laser melting
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): F. Romei, A.N. Grubišić, D. Gibbon
      The paper presents the design, manufacturing and postproduction analysis of a novel high-temperature spacecraft resistojet heat exchanger manufactured through selective laser melting to validate the manufacturing approach. The work includes the analysis of critical features of a heat exchanger with integrated converging-diverging nozzle as a single piece element. The metrology of the component is investigated using optical analysis and profilometry to verify the integrity of components. High-resolution micro-Computed Tomography (CT) is applied as a tool for volumetric non-destructive inspection and conformity since the complex geometry of the thruster does not allow internal examination. The CT volume data is utilised to determine a surface mesh on which a novel perform coordinate measurement technique is applied for nominal/actual comparison and wall thickness analysis. A thin-wall concentric tubular heat exchanger design is determined to meet dimensional accuracy requirements. The work indicates the production of fine structures with feature sizes below 200 μm in 316L stainless via selective laser melting is feasible and opens up new possibilities for the future developments in multiple industries.

      PubDate: 2017-06-27T02:31:24Z
  • Silicon solar cell performance deposited by diamond like carbon thin film
           “Atomic oxygen effects”
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Abbas Ail Aghaei, Akbar Eshaghi, Esmaeil Karami
      In this research, a diamond-like carbon thin film was deposited on p-type polycrystalline silicon solar cell via plasma-enhanced chemical vapor deposition method by using methane and hydrogen gases. The effect of atomic oxygen on the functioning of silicon coated DLC thin film and silicon was investigated. Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and attenuated total reflection–Fourier transform infrared spectroscopy were used to characterize the structure and morphology of the DLC thin film. Photocurrent–voltage characteristics of the silicon solar cell were carried out using a solar simulator. The results showed that atomic oxygen exposure induced the including oxidation, structural changes, cross-linking reactions and bond breaking of the DLC film; thus reducing the optical properties. The photocurrent–voltage characteristics showed that although the properties of the fabricated thin film were decreased after being exposed to destructive rays, when compared with solar cell without any coating, it could protect it in atomic oxygen condition enhancing solar cell efficiency up to 12%. Thus, it can be said that diamond-like carbon thin layer protect the solar cell against atomic oxygen exposure.

      PubDate: 2017-06-27T02:31:24Z
  • Development of small solid rocket boosters for the ILR-33 sounding rocket
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Pawel Nowakowski, Adam Okninski, Michal Pakosz, Dawid Cieslinski, Bartosz Bartkowiak, Piotr Wolanski
      This paper gives an overview of the development of a 6000 Newton-class solid rocket motor for suborbital applications. The design configuration and results of interior ballistics calculations are given. The initial use of the motor as the main propulsion system of the H1 experimental in-flight test platform, within the Polish Small Sounding Rocket Program, is presented. Comparisons of theoretical and experimental performance are shown. Both on-ground and in-flight tests are discussed. A novel composite-case manufacturing technology, which enabled to reach high propellant mass fractions, was validated and significant cost-reductions were achieved. This paper focuses on the process of adapting the design for use as the booster stage of the ILR-33 sounding rocket, under development at the Institute of Aviation in Warsaw, Poland. Parallel use of two of the flight-proven rocket motors along with the main stage is planned. The process of adapting the rocket motor for booster application consists of stage integration, aerothermodynamics and reliability analyses. The separation mechanism and environmental impact are also discussed within this paper. Detailed performance analysis with focus on propellant grain geometry is provided. The evolution of the design since the first flights of the H1 rocket is covered and modifications of the manufacturing process are described. Issues of simultaneous ignition of two motors and their non-identical performance are discussed. Further applications and potential for future development are outlined. The presented results are based on the initial work done by the Rocketry Group of the Warsaw University of Technology Students' Space Association. The continuation of the Polish Small Sounding Rocket Program on a larger scale at the Institute of Aviation proves the value of the outcomes of the initial educational project.

      PubDate: 2017-06-27T02:31:24Z
  • Experimental and numerical studies on the treatment of wet astronaut trash
           by forced-convection drying
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): J.M.R. Apollo Arquiza, Jean B. Hunter, Robert Morrow, Ross Remiker
      During long-term space missions, astronauts generate wet trash, including food containers with uneaten portions, moist hygiene wipes and wet paper towels. This waste produces two problems: the loss of water and the generation of odors and health hazards by microbial growth. These problems are solved by a closed-loop, forced-convection, heat-pump drying system which stops microbial activity by both pasteurization and desiccation, and recovers water in a gravity-independent porous media condensing heat exchanger. A transient, pseudo-homogeneous continuum model for the drying of wet ersatz trash was formulated for this system. The model is based on the conservation equations for energy and moisture applied to the air and solid phases and includes the unique trash characteristic of having both dry and wet solids. Experimentally determined heat and mass transfer coefficients, together with the moisture sorption equilibrium relationship for the wet material are used in the model. The resulting system of differential equations is solved by the finite-volume method as implemented by the commercial software COMSOL. Model simulations agreed well with experimental data under certain conditions. The validated model will be used in the optimization of the entire closed-loop system consisting of fan, air heater, dryer vessel, heat-pump condenser, and heat-recovery modules.

      PubDate: 2017-06-27T02:31:24Z
  • Thermodynamic efficiency analysis and cycle optimization of deeply
           precooled combined cycle engine in the air-breathing mode
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Jianqiang Zhang, Zhenguo Wang, Qinglian Li
      The efficiency calculation and cycle optimization were carried out for the Synergistic Air-Breathing Rocket Engine (SABRE) with deeply precooled combined cycle. A component-level model was developed for the engine, and exergy efficiency analysis based on the model was carried out. The methods to improve cycle efficiency have been proposed. The results indicate cycle efficiency of SABRE is between 29.7% and 41.7% along the flight trajectory, and most of the wasted exergy is occupied by the unburned hydrogen in exit gas. Exergy loss exists in each engine component, and the sum losses of main combustion chamber(CC), pre-burner(PB), precooler(PC) and 3# heat exchanger(HX3) are greater than 71.3% of the total loss. Equivalence ratio is the main influencing factor of cycle, and it can be regulated by adjusting parameters of helium loop. Increase the maximum helium outlet temperature of PC by 50 K, the total assumption of hydrogen will be saved by 4.8%, and the cycle efficiency is advanced by 3% averagely in the trajectory. Helium recirculation scheme introduces a helium recirculation loop to increase local helium flow rate of PC. It turns out the total assumption of hydrogen will be saved by 9%, that's about 1740 kg, and the cycle efficiency is advanced by 5.6% averagely.

      PubDate: 2017-06-27T02:31:24Z
  • The effect of hypergravity on the lens, cornea and tail regeneration in
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): E.N. Grigoryan, N. Dvorochkin, V.A. Poplinskaya, R. Yousuf, E.A. Radugina, E.A. Almeida
      In previous experiments onboard Russian Bion/Foton satellites it was found that exposure to microgravity causes changes in eye lens regeneration of Urodela. The changes included higher rate of regeneration, increased cell proliferation in lens anlage, and synchronization of lens restoration. Similar changes were observed regarding tail regeneration. Recently, investigations were performed to find out whether exposure to hypergravity could also alter lens, cornea and tail regeneration in the newt P. waltl. Nine days prior to exposure the left lens was surgically removed through corneal incision and distal 1/3 of the tail was amputated, thus initiating regeneration. The experimental animals were allowed to recover for 9 days at 1 g and then exposed to 2 g for 12 days in an 8 ft diameter centrifuge at NASA Ames Research Center. The experimental animals were divided into 1 g controls, 2 g centrifugation animals, basal controls, and aquarium controls. Lens and corneal regeneration appeared to be inhibited in 2 g group compared to 1 g animals. In all 1 g controls, lens regeneration reached stages VII-IX in a synchronous fashion and corneal regeneration was nearly complete. In the 2 g newts, neural retinal detachment from the pigmented epithelium was seen in most operated eyes. It was also observed in the non-operated (right) eyes of the animals exposed to 2 g. The level of retinal detachment varied and could have been caused by hypergravity-induced high intraocular pressure. Regeneration (when it could be assessed) proceeded asynchronously, reaching stages from II to IX. Corneal restoration was also noticeably delayed and corneal morphology changed. Cell proliferation was measured using BrdU; the results were not comparable to the 1 g data because of retinal detachment. Previous investigations demonstrated that lens regeneration was controlled by the neural retina; therefore, lower regeneration rate at 2 g was, at least in part, associated with retinal detachment. FGF2 release by the neural retina and FGFR2 expression in the iris and other tissues could accelerate lens proliferation whereas its delay could be caused by retinal detachment, which may explain compromised regeneration at 2 g. Hypergravity (both 1 g and 2 g) increased tissue growth compared to aquarium control (as measured by regenerate volume) and altered the shape of tail regenerates – they became curved downwards. The experimental results emphasize the important and versatile role gravity plays in tissue regeneration. They also suggest that, when considering hypergravity as a countermeasure that can be used in future space missions, its potential impact on the eye should not be ignored.

      PubDate: 2017-06-27T02:31:24Z
  • A virtual maintenance-based approach for satellite assembling and
           troubleshooting assessment
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Jie Geng, Ying Li, Ranran Wang, Zili Wang, Chuan Lv, Dong Zhou
      In this study, a Virtual Maintenance (VM)-based approach for satellite troubleshooting assessment is proposed. By focusing on various elements in satellite assemble troubleshooting, such as accessibility, ergonomics, wiring, and extent of damage, a systematic, quantitative, and objective assessment model is established to decrease subjectivity in satellite assembling and troubleshooting assessment. Afterwards, based on the established assessment model and satellite virtual prototype, an application process of this model suitable for a virtual environment is presented. Finally, according to the application process, all the elements in satellite troubleshooting are analyzed and assessed. The corresponding improvements, which realize the transformation from a conventional way to a virtual simulation and assessment, are suggested, and the flaws in assembling and troubleshooting are revealed. Assembling or troubleshooting schemes can be improved in the early stage of satellite design with the help of a virtual prototype. Repetition in the practical operation is beneficial to companies as risk and cost are effectively reduced.

      PubDate: 2017-06-27T02:31:24Z
  • Rover deployment system for lunar landing mission
    • Abstract: Publication date: September 2017
      Source:Acta Astronautica, Volume 138
      Author(s): Masataku Sutoh, Takeshi Hoshino, Sachiko Wakabayashi
      For lunar surface exploration, a deployment system is necessary to allow a rover to leave the lander. The system should be as lightweight as possible and stored retracted when launched. In this paper, two types of retractable deployment systems for lunar landing missions, telescopic- and fold-type ramps, are discussed. In the telescopic-type system, a ramp is stored with the sections overlapping and slides out during deployment. In the fold-type system, it is stored folded and unfolds for the deployment. For the development of these ramps, a design concept study and structural analysis were conducted first. Subsequently, ramp deployment and rover release tests were performed using the developed ramp prototypes. Through these tests, the validity of their design concepts and functions have been confirmed. In the rover release test, it was observed that the developed lightweight ramp was sufficiently strong for a 50-kg rover to descend. This result suggests that this ramp system is suitable for the deployment of a 300-kg-class rover on the Moon, where the gravity is about one-sixth that on Earth. The lightweight and sturdy ramp developed in this study will contribute to both safe rover deployment and increase of lander/rover payload.

      PubDate: 2017-06-27T02:31:24Z
  • IFC - Publication Information
    • Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137

      PubDate: 2017-06-19T20:23:55Z
  • Transfer orbits to L4 with a solar sail in the Earth-Sun system
    • Authors: Ariadna
      Abstract: Publication date: August 2017
      Source:Acta Astronautica, Volume 137
      Author(s): Ariadna Farrés
      Solar sails are enablers for long interplanetary transfers, but also offer many advantages in Libration Point Orbits missions. The extra effect of the Solar Radiation Pressure allows a space vehicle, by changing the sail orientation, to be artificially displaced from the classical Lagrangian equilibrium points, L 1 , … , L 5 , as well perturbed from the Lyapunov, Halo and Lissajous orbits that appear around them. Most of these equilibrium points are linearly unstable and have stable and unstable invariant manifolds associated with them. In this paper we explore the possibilities that these invariant manifolds offer to navigate in a natural way around a circular, restricted, three-body system. We take the Earth-Sun Restricted Three Body Problem as a model and, for different fixed sail orientations, we compute the stable and unstable manifolds associated with the equilibrium points of the system. We find natural trajectories that allow the vehicle to move around the family of equilibria in a controlled way and to go from a region close to L 1 or L 2 to a region close to L 4.

      PubDate: 2017-04-23T08:02:41Z
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