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Advances in Space Research
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ISSN (Print) 0273-1177
Published by Elsevier Homepage  [3183 journals]
  • Propagation of grid-scale density model uncertainty to orbital
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Fabian Schiemenz, Jens Utzmann, Hakan Kayal Accurate knowledge of the orbital state-vector uncertainty is required for the computation of reliable collision probabilities, the association of tracks, as well as the optimal planning of sensor resources. In low Earth Orbits (LEO) neutral atmospheric density uncertainty is the main contributor to orbital state vector uncertainty. Grid-scale model uncertainty on the other hand is, in most cases, the dominating component of atmospheric density uncertainty.Prior research in the field of density uncertainty has been broad. Nowadays multiple authors seem to agree that a first-order stochastic Gauss-Markov process, also known as Ornstein-Uhlenbeck process (OUP), is an appropriate stochastic representation for density model uncertainties. While many have studied orbital variations due to stochastic grid-scale density uncertainty, it is believed that the work at hand provides for the first time explicit analytic equations for the estimation of orbital uncertainties due to an underlying Ornstein-Uhlenbeck process that has been optimized for the representation of atmospheric density. It is shown that the long-term in-track position error due to this modified OUP grows with ∼t3.The presented derivations and their validation build upon prior work by Emmert et al. and Sagnières and Sharf. Numerical Monte-Carlo simulations are used to validate the findings with two different semi-empirical density models. We also demonstrate that the resulting orbital uncertainty due to the modified OUP in atmospheric density can be estimated using a classical OUP in the relative density error.
  • Families of halo orbits in the elliptic restricted three-body problem for
           a solar sail with reflectivity control devices
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Jia Huang, James D. Biggs, Naigang Cui Solar sail halo orbits designed in the Sun-Earth circular restricted three-body problem (CR3BP) provide inefficient reference orbits for station-keeping since the disturbance due to the eccentricity of the Earth’s orbit has to be compensated for. This paper presents a strategy to compute families of halo orbits around the collinear artificial equilibrium points in the Sun-Earth elliptic restricted three-body problem (ER3BP) for a solar sail with reflectivity control devices (RCDs). In this non-autonomous model, periodic halo orbits only exist when their periods are equal to integer multiples of one year. Here multi-revolution halo orbits with periods equal to integer multiples of one year are constructed in the CR3BP and then used as seeds to numerically continue the halo orbits in the ER3BP. The linear stability of the orbits is analyzed which shows that the in-plane motion is unstable while the out-of-plane motion is neutrally stable and a bifurcation is identified. Finally, station-keeping is performed which shows that a reference orbit designed in the ER3BP is significantly more efficient than that designed in the CR3BP, while the addition of RCDs improve station-keeping performance and robustness to uncertainty in the sail lightness number.
  • Analysis of a long-duration AR throughout five solar rotations: Magnetic
           properties and ejective events
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Francisco A. Iglesias, Hebe Cremades, Luciano A. Merenda, Cristina H. Mandrini, Fernando M. López, Marcelo C. López Fuentes, Ignacio Ugarte-Urra Coronal mass ejections (CMEs), which are among the most magnificent solar eruptions, are a major driver of space weather and can thus affect diverse human technologies. Different processes have been proposed to explain the initiation and release of CMEs from solar active regions (ARs), without reaching consensus on which is the predominant scenario, and thus rendering impossible to accurately predict when a CME is going to erupt from a given AR. To investigate AR magnetic properties that favor CMEs production, we employ multi-spacecraft data to analyze a long duration AR (NOAA 11089, 11100, 11106, 11112 and 11121) throughout its complete lifetime, spanning five Carrington rotations from July to November 2010. We use data from the Solar Dynamics Observatory to study the evolution of the AR magnetic properties during the five near-side passages, and a proxy to follow the magnetic flux changes when no magnetograms are available, i.e. during far-side transits. The ejectivity is studied by characterizing the angular widths, speeds and masses of 108 CMEs that we associated to the AR, when examining a 124-day period. Such an ejectivity tracking was possible thanks to the mulit-viewpoint images provided by the Solar-Terrestrial Relations Observatory and Solar and Heliospheric Observatory in a quasi-quadrature configuration. We also inspected the X-ray flares registered by the GOES satellite and found 162 to be associated to the AR under study. Given the substantial number of ejections studied, we use a statistical approach instead of a single-event analysis. We found three well defined periods of very high CMEs activity and two periods with no mass ejections that are preceded or accompanied by characteristic changes in the AR magnetic flux, free magnetic energy and/or presence of electric currents. Our large sample of CMEs and long term study of a single AR, provide further evidence relating AR magnetic activity to CME and Flare production.
  • Multi-GNSS contributions to differential code biases determination and
           regional ionospheric modeling in China
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Xiaodong Ren, Jun Chen, Xingxing Li, Xiaohong Zhang Due to the limited number and uneven distribution globally of Beidou Satellite System (BDS) stations, the contributions of BDS to global ionosphere modeling is still not significant. In order to give a more realistic evaluation of the ability for BDS in ionosphere monitoring and multi-GNSS contributions to the performance of differential code biases (DCBs) determination and ionosphere modeling, we select 22 stations from Crustal Movement Observation Network of China (CMONOC) to assess the result of regional ionospheric model and DCBs estimates over China where the visible satellites and monitoring stations for BDS are comparable to those of GPS/GLONASS. Note that all the 22 stations can track the dual- and triple- frequency GPS, GLONASS, and BDS observations. In this study, seven solutions, i.e., GPS-only (G), GLONASS-only (R), BDS-only (C), GPS+BDS (GC), GPS+ GLONASS (GR), GLONASS+BDS (RC), GPS+GLONASS+BDS (GRC), are used to test the regional ionosphere modeling over the experimental area. Moreover, the performances of them using single-frequency precise point positioning (SF-PPP) method are presented. The experimental results indicate that BDS has the same ionospheric monitoring capability as GPS and GLONASS. Meanwhile, multi-GNSS observations can significantly improve the accuracy of the regional ionospheric models compared with that of GPS-only or GLONASS-only or BDS-only, especially over the edge of the tested region which the accuracy of the model is improved by reducing the RMS of the maximum differences from 5-15 to 2-3 TECu. For satellite DCBs estimates of different systems, the accuracy of them can be improved significantly after combining different system observations, which is improved by reducing the STD of GPS satellite DCB from 0.243 to 0.213, 0.172, and 0.165 ns after adding R, C, and RC observations respectively, with an increment of about 12.3%, 29.4%, and 32.2%. The STD of GLONASS satellite DCB improved from 0.353 to 0.304, 0.271, and 0.243 ns after adding G, C, and GC observations, respectively. The STD of BDS satellite DCB reduced from 0.265 to 0.237, 0.237 and 0.229 ns with the addition of G, R and GR systems respectively, and increased by 10.6%, 10.4%, and 13.6%. From the experimental positioning result, it can be seen that the regional ionospheric models with multi-GNSS observations are better than that with a single satellite system model.
  • Differential code bias estimation based on uncombined PPP with LEO onboard
           GPS observations
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Peiyuan Zhou, Zhixi Nie, Yan Xiang, Jin Wang, Lan Du, Yang Gao Differential Code Bias (DCB) is an essential correction that must be provided to the Global Navigation Satellite System (GNSS) users for precise position determination. With the continuous deployment of Low Earth Orbit (LEO) satellites, DCB estimation using observations from GNSS receivers onboard the LEO satellites is drawing increasing interests in order to meet the growing demands on high-quality DCB products from LEO-based applications, such as LEO-based GNSS signal augmentation and space weather research. Previous studies on LEO-based DCB estimation are usually using the geometry-free combination of GNSS observations, and it may suffer from significant leveling errors due to non-zero mean of multipath errors and short-term variations of receiver code and phase biases. In this study, we utilize the uncombined Precise Point Positioning (PPP) model for LEO DCB estimation. The models for uncombined PPP-based LEO DCB estimation are presented and GPS observations acquired from receivers onboard three identical Swarm satellites from February 1 to 28, 2019 are used for the validation. The results show that the average Root Mean Square errors (RMS) of the GPS satellite DCBs estimated with onboard data from each of the three Swarm satellites using the uncombined PPP model are less than 0.18 ns when compared to the GPS satellite DCBs obtained from IGS final daily Global Ionospheric Map (GIM) products. Meanwhile, the corresponding average RMS of GPS satellite DCBs estimated with the conventional geometry-free model are 0.290, 0.210, 0.281 ns, respectively, which are significantly larger than those obtained with the uncombined PPP model. It is also noted that the estimated GPS satellite DCBs by Swarm A and C satellites are highly correlated, likely attributed to their similar orbit type and space environment. On the other hand, the Swarm receiver DCBs estimated with uncombined PPP model, with Standard Deviation (STD) of 0.065, 0.037 and 0.071 ns, are more stable than those obtained from the official Swarm Level 2 products with corresponding STD values of 0.115, 0.101, and 0.109 ns, respectively. The above indicates that high-quality DCB products can be estimated based on uncombined PPP with LEO onboard observations.
  • Plasma polarization electric field derived from radio sounding of solar
           wind acceleration region with spacecraft signals
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Yuri V. Pisanko, Oleg I. Yakovlev Presented is the analytical approximation of averaged solar wind velocity radial dependence in the solar wind acceleration region at heliolatitudes below 60o under low and moderate solar activity. This empirical approximation is based on the data of radio sounding of the solar corona with radio signals from various spacecraft. Deduced is an equation connecting the solar wind velocity radial dependence and the radial dependence of solar wind plasma polarization electric field intensity. This allows constructing a semi-empirical radial dependence of plasma polarization electric field corresponding to the empirical radial dependence of solar wind velocity. Main properties of the semi-empirical dependence, which is based on radio sounding data, are described.
  • Ascent Guidance Law for a Horizontal Take-Off Vehicle with a
           Multi-Combined Cycle Engine
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Hongyu Zhou, Xiaogang Wang, Wenzhao Shan, Naigang Cui This paper researches the ascent guidance law for the vehicle with a multi-combined cycle propulsion. The guidance law comprises two parts, namely, the off-line optimal trajectories generation and online guidance. With respect to the off-line part, disturbances are discretized and incorporated into the trajectory optimization problem; subsequently, a set of trajectories is calculated to constitute a database. To quickly obtain a database that comprises a large number of trajectories, a novel ascent profile is proposed with respect to height and velocity. Based on this profile, only inequity constraints exist in the optimization model, and the original optimization problem is converted to a parameter searching problem. The optimal trajectories are calculated using a hybrid optimization method that comprises a particle swarm optimization (PSO) method and the Hooke-Jeeves (HJ) method. With respect to online guidance, the profile is updated using a radial basis function neural network (RBFNN) based on the current flight states and the database. Simulation validates the efficiency of the proposed optimization method by comparing the method with the pseudospectral method; the robustness of the guidance law is also validated using Monte Carlo simulation.
  • Separation process of multi-spheres in hypersonic flow
    • Abstract: Publication date: Available online 16 October 2019Source: Advances in Space ResearchAuthor(s): Seong-Hyeon Park, Gisu Park The separation process of multi-spheres in hypersonic flow has been experimentally investigated. The experiments were conducted in a shock tunnel at a nominal freestream Mach number of 6. Iron or acetal small light spheres with different sizes, varying from 2.38 to 6 mm, were considered. They were mounted by a thin wire. The trajectory of the spheres was analyzed using optical images. By varying the radius and the number of spheres from a single to multiple spheres, the lateral velocity and the separation behavior including the phenomenon known as ‘shock wave surfing’ were measured and analyzed. A new equation to account for the lateral velocity of the multi-spheres was proposed by extending the well-known Passey and Melosh’s theory based on two bodies. The theoretical results were compared with the presented experimental data and a good agreement was found. Using the derived equation, the re-entry trajectory analysis of multi-spheres, that is regarded as the hypothetical break-up, was performed. The ground footprint and downrange due to the separation of the multi-spheres were compared with that of single- and two-spheres. The results showed that as the number of spheres increased, the lateral velocity increased while the ballistic coefficient decreased. This led to a large discrepancy in the ground footprint as well as the downrange when compared to the single sphere. Caution should therefore be exercised in the trajectory analysis when the effect of separation induced due to fragmentation is not considered.
  • Annual, seasonal and diurnal variations of integrated water vapor using
           GPS observations over Hyderabad, a tropical station
    • Abstract: Publication date: Available online 14 October 2019Source: Advances in Space ResearchAuthor(s): Nirmala Bai Jadala, Miriyala Sridhar, Nirvikar Dashora, Gopa Dutta This paper presents annual, seasonal and diurnal variations of integrated water vapor (IWV) derived from Global Positioning System (GPS) measurements for a tropical site, Hyderabad (17.4˚ N, 78.46˚ E). The zenith wet delay (ZWD) due to the troposphere has been computed using GPS observations and collocated meteorological data. ZWD is converted to IWV with very little added uncertainty. Mean monthly IWV values show maximum in July (∼ 50 kg m-2) and minimum in December (∼ 15 kg m-2). Fast Fourier Transform (FFT) and Harmonic analyses methods have been adopted to extract amplitudes and phases of diurnal (24 h), semi-diurnal (12 h) and ter-diurnal (8 h) oscillations which yielded comparable results. Amplitude of the 24 h component is observed to be maximum in spring whereas 12 h and 8 h components maximize in summer. A cross-correlation study between available daily IWV values and corresponding surface temperatures over one year produced a good correlation coefficient (0.44). The correlation obtained for different seasons got reduced to 0.25, 0.02, -0.39 and 0.21 for winter, spring, summer and autumn seasons respectively. The correlation between IWV and rainfall is poor. The coefficients obtained for the whole year is 0.05 and - 0.13 for the rainy season.
  • Quantitative Analyses of Complexity and Nonlinear trend of Radio
           Refractivity Gradient in the troposphere
    • Abstract: Publication date: Available online 14 October 2019Source: Advances in Space ResearchAuthor(s): A.O. Adelakun, J.S. Ojo, O.V. Edward In this paper, the complexity and nonlinear trends of Radio Refractivity Gradient (RRG) in the troposphere over selected locations in Nigeria are analyzed and discussed extensively. The RRG is an important parameter in estimating path clearance and propagation effects such as ducting, surface reflection and multi-path on terrestrial line of-sights links. Also, radio wave signal propagating in the troposphere is affected by unpredictability of a weather condition which includes the variations of meteorological parameters such as temperature, pressure and relative humidity. The complex state of the atmosphere, which is the medium for the transmission of radio signals tend to have very strong influence such as scintillation, ducting, e.t.c on the quality of the radio signal, amplitude and phase. Variations in the meteorological parameters also induce variations in the refractive index of the atmosphere which in-turn results in the effect known as radio refractivity. For effective prediction and modeling of radio signal propagation, one should be able to characterize the nature and predictability of the computed RRG information. Chaotic Quantifiers (CQ) such as Phase Plot Reconstruction (PPR), Average Mutual Information (AMI), False Nearest Neighbor (FNN), Recurrence Plot (RP) and Recurrence Quantification Analyses (RQA) are used to assess the RRG. The information reveal, however, is based on the prediction techniques, design and frequency planning of microwave networks which may be useful for optimum performances during atmospheric turbulence.
  • Gravity Wave Mixing Effects on the OH*-layer
    • Abstract: Publication date: Available online 11 October 2019Source: Advances in Space ResearchAuthor(s): E. Becker, M. Grygalashvyly, G.R. Sonnemann Based on an advanced numerical model for excited hydroxyl (OH*) we simulate the effects of gravity waves (GWs) on the OH*-layer in the upper mesosphere. The OH* model takes into account 1) production by the reaction of atomic hydrogen (H) with ozone (O3), 2) deactivation by atomic oxygen (O), molecular oxygen (O2), and molecular nitrogen (N2), 3) spontaneous emission, and 4) loss due to chemical reaction with O. This OH* model is part of a chemistry-transport model (CTM) which is driven by the high-resolution dynamics from the KMCM (Kühlungsborn Mechanistic general Circulation Model) which simulates mid-frequency GWs and their effects on the mean flow in the MLT explicitly. We find that the maximum number density and the height of the OH*-layer peak are strongly determined by the distribution of atomic oxygen and by the temperature. As a results, there are two ways how GWs influence the OH*-layer: 1) through the instantaneous modulation by O and T on short time scales (a few hours), and 2) through vertical mixing of O (days to weeks). The instantaneous variations of the OH*-layer peak altitude due to GWs amount to 5-10 km. Such variations would introduce significant biases in the GW parameters derived from airglow when assuming a constant pressure level of the emission height. Performing a sensitivity experiment we find that on average, the vertical mixing by GWs moves the OH*-layer down by ∼2-7 km and increases its number density by more than 50%. This effect is strongest at middle and high latitudes during winter where secondary GWs generated in the stratopause region account for large GW amplitudes.
  • Probing afternoon detached aurora and high-latitude trough based on DMSP
    • Abstract: Publication date: Available online 10 October 2019Source: Advances in Space ResearchAuthor(s): Su Zhou, Kazuo Shiokawa, Igor Poddelsky, Yuqing Chen, Jin Zhang The present work displays the observations of an afternoon detached aurora along with ionospheric high-latitude trough. The event was observed by DMSP F17 on 19 September 2014. The afternoon detached aurora was isolated from the auroral oval and was located between 12:00–18:00 magnetic local time (MLT) and 65°–70° geomagnetic latitude (MLAT). Particle observations indicate that the afternoon detached aurora was produced by energetic ring current ions with energies above ∼10 keV where the main ion energy was likely to be above the upper limit of DMSP measurement (∼30 keV). Magnetometer observation from the ground implies that the energetic ions were likely scattered by EMIC waves. Both the detached aurora and the auroral oval are found to be well inside the high-latitude trough with MLAT between ∼64° and ∼76° (68°– 80° GLAT). The auroral oval corresponds to a westward (sunward) plasma drift. It is expected that the westward drift transports the low-density plasma in the nightside toward the dayside, leading to the high-latitude trough formation. The afternoon detached aurora was well equatorward of the high-latitude trough, and the corresponding plasma drift was nearly zero. The plasma associated with the detached aurora is expected to be stagnant, and broaden the high-latitude trough equatorward.
  • Energy spectra of abundant cosmic-ray nuclei in the NUCLEON experiment
    • Abstract: Publication date: Available online 10 October 2019Source: Advances in Space ResearchAuthor(s): V. Grebenyuk, D. Karmanov, I. Kovalev, I. Kudryashov, A. Kurganov, A. Panov, D. Podorozhny, A. Tkachenko, L. Tkachev, A. Turundaevskiy, O. Vasiliev, A. Voronin The NUCLEON satellite experiment is designed to directly investigate the energy spectra of cosmic-ray nuclei and the chemical composition (Z=1−30) in the energy range of 2–500 TeV. The experimental results are presented, including the energy spectra of different abundant nuclei measured using the new Kinematic Lightweight Energy Meter (KLEM) technique. The primary energy is reconstructed by registration of spatial density of the secondary particles. The particles are generated by the first hadronic inelastic interaction in a carbon target. Then additional particles are produced in a thin tungsten converter, by electromagnetic and hadronic interactions. The deconvolution of spectra was peformed. Statistical errors were presented.
  • Corsica: A 20-Yr Multi-Mission Absolute Altimeter Calibration Site
    • Abstract: Publication date: Available online 9 October 2019Source: Advances in Space ResearchAuthor(s): P. Bonnefond, P. Exertier, O. Laurain, T. Guinle, P. Féménias Initially developed for monitoring the performance of TOPEX/Poseidon and follow-on Jason legacy satellite altimeters, the Corsica geodetic facilities that are located both at Senetosa Cape and near Ajaccio have been developed to calibrate successive satellite altimeters in an absolute sense. Since 1998, the successful calibration process used to calibrate most of the oceanographic satellite altimeter missions has been regularly updated in terms of in situ instruments, geodetic measurements and methodologies. In this study, we present an assessment of the long-term stability of the in situ instruments in terms of sea level monitoring that include a careful monitoring of the geodetic datum. Based on this 20-yr series of sea level measurements, we present a review of the derived absolute Sea Surface Height (SSH) biases for the following altimetric missions based on the most recent reprocessing of their data set: TOPEX/Poseidon and Jason-1/2/3, Envisat and ERS-2, CryoSat-2, SARAL/AltiKa and Sentinel-3A&B. For the longest time series the standard error of the absolute SSH biases is now at a few millimeters level which is fundamental to maintain the high level of confidence that scientists have in the global mean sea level rise.
  • On the uncertainty associated with validating the global mean sea level
           climate record
    • Abstract: Publication date: Available online 9 October 2019Source: Advances in Space ResearchAuthor(s): Christopher S. Watson, Benoit Legresy, Matt A. King Satellite altimetry provides the ongoing sea level climate data record that provides evidence for one of the most significant manifestations of climate change on Earth. External and independent validation of satellite altimetry is a core component of mission design, providing confidence in such a seminal climate record. The global tide gauge network, corrected for the effects of vertical land motion, forms one of a suite of approaches used to validate satellite altimetry. Used as a tool to identify potential systematic error, the altimeter minus tide gauge approach ultimately leads to an improved geophysical data record through iterative diagnosis, correction and reprocessing of the mission record. A recent example includes the detection of a small but significant drift in the early part of the record associated with the TOPEX record. Here, we return to the approach that quantified the apparent drift in the TOPEX record and focus on further elucidating the uncertainty of that technique as a function of mission duration. We show that approximately 2.9 years is required to reach a validation uncertainty of ±1 mm/yr (1σ). This result appears optimistic by a factor of 1.5 to 2.2 in comparison to an error budget approach reported in the literature. Our results highlight the challenge of validating the altimeter record using a sparse and irregularly distributed network of tide gauges and points towards possible areas of future improvement in the validation approach.
  • Juno/JIRAM: Planning and Commanding activities
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): R. Noschese, A. Cicchetti, R. Sordini, M. Cartacci, A. Mura, S. Brooks, M. Lastri, G. Filacchione, A. Migliorini, M.L. Moriconi, A. Adriani, H.N. Becker, A. Bini, C. Pasqui, D. Grassi, F. Altieri, B.M. Dinelli, G. Piccioni, S. Stefani, F. Tosi In the context of space missions, where science is the most important goal, careful planning and detailed commanding are fundamental. The planning and commanding phases are activities whose complexity depends on the instrument characteristics, environmental constraints and scientific goals. The purpose of this work is to describe in detail these activities for the Jovian Infrared Auroral Mapper (JIRAM) on board the Juno spacecraft, a NASA mission to Jupiter.To maximize the scientific return, we fully employ the flexibility offered by the JIRAM operational modes to efficiently plan observations of various Jovian targets, in spite of the harsh Jovian radiation environment and the spinning state of the Juno spacecraft. Moreover, the JIRAM observations are limited by the challenging pointing and timing scheme of the mission, which impose constraints on both the observation planning and instrumental commanding.
  • PDE Model-Based Boundary Control of a Spacecraft with Double Flexible
           Appendages under Prescribed Performance
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): Junteng Ma, Hao Wen, Dongping Jin This paper investigates a boundary control scheme of a spacecraft with double flexible appendages under prescribed performance. The flexible spacecraft system comprises a rigid central hub and two flexible appendages regarded as continuum models, so that the motion of the system can be portrayed by using partial differential equations (PDEs). In this paper, only one control torque and two control forces are applied to guarantee the desired attitude angle of the spacecraft and simultaneously suppress the vibration of the two flexible appendages. Moreover, the angle tracking error of the spacecraft can be restricted in a small residual set under a minimum convergence rate by adopting the prescribed performance technique (PPT). The stability of the boundary control is analyzed by employing LaSalle’s invariance principle. Finally, the feasibility of the proposed controller is verified through numerical results.
  • Nonthermal effects on the cylindrical dusty ion shocks in nonthermal
           viscous space plasma
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): Abdelwahed, E.K. El-Shewy, A.A. El-Rahman, N.F. Abdo The propagating cylindrical shock dust ion wave (CDISW) in dusty four component plasma with three viscous component (ion and two polarity charged grains) has been introduced. The three dimensional (3D) Cylindrical Burgers (CB) equation is derived. The propagating cylindrical shock characteristics are established to becomes a very significantly improved by the supports of electron nonthermality, ion and negative (positive) kinematics viscosity coefficients. Furthermore, the shock strength depends on cylindrical directions. The obtained results may be profitable in understanding both the laboratory and space applications of plasmas.
  • GPS and BDS Combined PPP Model with Inter-system Differenced Observations
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): Rui Tu, Ju Hong, Rui Zhang, Junqiang Han, Lihong Fan, Pengfei Zhang, Jinhai Liu, Xiaochun Lu This study proposes a combined precise point positioning (PPP) model, called the inter-system differenced PPP model, in which it formed the satellite-differenced observation between different satellite systems. Compared with the traditional combined PPP model, the inter-system differenced PPP model has the following characteristics: (1) The satellite difference between various systems can eliminate the receiver clock bias parameter, it enhances the strength of the PPP model. (2) Inter-satellite differences can eliminate some common model errors and reduce the impact of observation errors. (3) The system time difference can be calculated directly to provide the basis for time offset monitoring. In order to verify the positioning results of the inter-system differenced model, static PPP and dynamic PPP experiments were carried out to test the positioning accuracy and convergence time, and the results were compared with those of the traditional combination PPP model. In addition, the offset characteristics introduced by the inter-system differenced model were analysed, and the optimal estimation strategy was determined by dynamic PPP tests. Preliminary results are as follows: (1) For inter-system differenced static PPP, the convergence time of stations is less than 20 min. The standard deviation (STD) of the position bias for the East (E), North (N), and Up (U) components are better than 2.5 cm, 1.0 cm and 3.0 cm, respectively, and the corresponding root mean square deviation (RMS) are better than 3.0 cm, 1.5 cm and 6.0 cm, respectively. Compared with the traditional combined PPP model, the average convergence time of the inter-system differenced model is nearly the same, but its overall positioning accuracy is better. (2) For the inter-system differenced dynamic PPP model, the convergence time of stations is better than 30 min. The STD of the position bias for the E, N, and U components is better than 3.0 cm, 2.0 cm and 4.5 cm respectively, and the RMS is better than 4.0 cm, 2.5 cm and 7.0 cm respectively. Compared with the traditional combined PPP model, the convergence of the inter-system differenced model is slightly better, and the positioning accuracy does not differ significantly. Moreover, the inter-system differenced model is much better than the traditional model when fewer satellites are available. (3) The offset between GPS and BDS corresponding with the precise products of GFZ is related to the type of receiver, and the daily standard of offset is less than 0.5 ns. In addition, we determined optimum process noise of the offset parameter to be a 10-3/3(m2/s) random walk after comparing several options.
  • Simulation of Cosmic Rays in the Earth’s Atmosphere and Interpretation
           of Observed Counts in an X-ray Detector at Balloon Altitude Near Tropical
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): Ritabrata Sarkar, Abhijit Roy, Sandip K. Chakrabarti The study of secondary particles produced by the cosmic-ray interaction in the Earth’s atmosphere is very crucial as these particles mainly constitute the background counts produced in the high-energy detectors at balloon and satellite altitudes. In the present work, we calculate the abundance of cosmic-ray generated secondary particles at various heights of the atmosphere by means of a Monte Carlo simulation and use this result to understand the background counts in our X-ray observations using balloon-borne instruments operating near the tropical latitude (geomagnetic latitude: ∼14.50° N). For this purpose, we consider a 3D description of the atmospheric and geomagnetic field configurations surrounding the Earth, as well as the electromagnetic and nuclear interaction processes using Geant4 simulation toolkit. Subsequently, we use a realistic mass model description of the detector under consideration, to simulate the counts produced in the detector due to secondary cosmic-ray particles.
  • On a century of extragalactic novae and the rise of the rapid recurrent
    • Abstract: Publication date: Available online 8 October 2019Source: Advances in Space ResearchAuthor(s): Matthew J. Darnley, Martin Henze Novae are the observable outcome of a transient thermonuclear runaway on the surface of an accreting white dwarf in a close binary system. Their high peak luminosity renders them visible in galaxies out beyond the distance of the Virgo Cluster. Over the past century, surveys of extragalactic novae, particularly within the nearby Andromeda Galaxy, have yielded substantial insights regarding the properties of their populations and sub-populations. The recent decade has seen the first detailed panchromatic studies of individual extragalactic novae and the discovery of two probably related sub-groups: the ‘faint–fast’ and the ‘rapid recurrent’ novae. In this review we summarise the past 100 years of extragalactic efforts, introduce the rapid recurrent sub-group, and look in detail at the remarkable faint–fast, and rapid recurrent, nova M31N 2008-12a. We end with a brief look forward, not to the next 100 years, but the next few decades, and the study of novae in the upcoming era of wide-field and multi-messenger time-domain surveys.
  • Accuracy and consistency of different global ionospheric maps released by
           IGS ionosphere associate analysis centers
    • Abstract: Publication date: Available online 4 October 2019Source: Advances in Space ResearchAuthor(s): Peng Chen, Hang Liu, Yongchao Ma, Naiquan Zheng Due to the differences of ionospheric modeling methods and selected tracking stations, the accuracy and consistency of Global Ionospheric Maps (GIMs) released by Ionosphere Associate Analysis Centers (IAACs) are different. In this study, we evaluate and analyze in detail the accuracy and consistency of GIMs final products provided by six IAACs from three different aspects. Firstly, the comparison of these GIMs shows that the mean bias (MEAN) is related to the modeling methods of various IAACs. The variation trend of the standard deviation (STD) is consistent with the solar activities, and accompanied by certain seasonal and annual periodic variations. The MEAN between IGS and each center is about -1.3∼1.0 TECU, and the STD is about 1.4∼2.5 TECU. Secondly, the validation with GPS TEC shows that the STD of CODE is the smallest at various latitudes, and the STD is about 0.7∼4.5 TECU. Thirdly, The validation with the Jason2 VTEC shows that the STD between Jason2 and IAACs is about 4.4∼5.2 TECU. In addition, the STD between Jason2 and six GIMs in the areas with more tracking stations is better than that of the regions with fewer tracking stations in different latitude regions. Regardless of whether the tracking stations are more or less, the MEAN and STD in high solar activity are larger than in low solar activity.
  • Large constellations assessment and optimization in LEO space debris
    • Abstract: Publication date: Available online 4 October 2019Source: Advances in Space ResearchAuthor(s): Lorenzo Olivieri, Alessandro Francesconi Recent plans for large constellations in Low-Earth Orbit have opened the debate on both their vulnerability and their influence on the already hazardous space debris environment. In fact, given that large constellations normally employ satellites of small size, there might be situations in which cm-size debris could have enough energy to cause fragmentation of a significant part of these spacecraft upon impact, while smaller debris could affect the functionalities of critical subsystems, even compromising the success of disposal operations planned at end-of-life. In this context, this paper investigates: (1) collisions with large objects that could initiate the fragmentation of a significant part of the satellite, and (2) impacts with small debris that might perforate the spacecraft hull thus causing relevant performance/functionality degradation. These two points are merged in a simple statistical tool for risk assessment, which analyses the effects of the main parameters of the constellations on its vulnerability (i.e. operational life, number of satellites, spacecraft cross section, satellites reliability). In more details, the tool relates impact probability (for both small and large debris) to the ballistic response of spacecraft structures and protections, defining the critical configurations that might compromise the expected disposal operations. This method requires a limited knowledge of the spacecraft internal layout, as it is based on a statistical analysis of impact damage instead of a complete evaluation of the vulnerability of each subsystem. In parallel, non-debris related failures are also investigated and statistic models of spacecraft reliability characteristic are proposed. Among the results, it is shown that reducing the lifetime of individual satellites in a constellation might improve the success rate of post-mission disposal, thanks to the reduction of the spacecraft exposure to the space environment with the consequential degradation of its performance. On the other hand, reducing the lifetime would seriously affect the debris environment: the increase in traffic in the most crowded altitudes would be not counterbalanced by the higher post mission disposal success rate, causing an overall increase of the total number of uncontrolled resident objects.
  • Automatic extraction of lineaments based on wavelet edge detection and
           aided tracking by hillshade
    • Abstract: Publication date: Available online 4 October 2019Source: Advances in Space ResearchAuthor(s): Junlong Xu, Xingping Wen, Haonan Zhang, Dayou Luo, Jinbo Li, Lianglong Xu, Min Yu Lineaments refer to the linear or curvilinear textures on remote sensing image, whose general spatial distribution characteristics are often the response of deep crustal structures at the surface. Firstly, we use wavelet modulus maxima transformation to detect the edges with 4 scale on Landsat - 8 OLI B5 image and analyze their multi-scale characteristics. As the result, it is determined that the optimal scale of edge detection is 4, and the outline that consist of the edge pixels is roughly corresponding to the geological structure of mine area. Thus the incomplete lineaments have been extracted by using the 2D otsu algorithm. Secondly, the hillshade map generated based on DEM is processed to generate binarized linear shadow. Finally, the linear shadow is superimposed on the lineaments preliminarily extracted to obtain the optimized lineaments. Experiment results show that, based on the method, there will be some deformation and displacement between the lineaments extracted and the actual geological structure, and it fail to effectively extract the Qilinchang Fault, but lineaments are in good correspondence with Kuangshanchang Fault, Dongtou Fault and Niulan River Fault, which are basically in accord with the geological structure framework of the mine area.
  • List of Referees
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s):
  • Statistics of spread F characteristics across different sectors and IRI
           2016 prediction
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): A.O. Afolayan, J.S. Mandeep, M. Abdullah, S.M. Buhari The occurrence of the plasma irregularity and the related scintillation have been extensively investigated as a result of the impact on radio signal propagation. This study focused on the equatorial spread F (ESF) occurrence using ionogram data and IRI prediction taken across different longitude sectors, including the Jicamarca, Fortaleza, Ilorin, Chumphon and Kwajalein ionosonde stations. We have briefly discussed the varying range type spread F (RSF) occurrence features across these stations such as the duration, onset time and seasonal asymmetry. The largest seasonal average of the RSF occurrence percentage was recorded at the Ilorin station during the low solar activity, while the occurrence rate at the Chumphon and Kwajalein stations increases significantly with the solar flux intensity. Furthermore, we presented a comparative analysis of the observed RSF occurrence rate and the IRI model prediction. The result exhibited a significant error percentage across these longitudes. The IRI could not reproduce significant features such as the delayed RSF onset at the Kwajalein station during June solstice or the equinox asymmetry in the RSF occurrence across these longitudes. Surprisingly, the IRI model also performed poorly at the Brazilian longitude. These observations highlight the strong dynamic nature of the RSF features across the different regions. Hence, an extensive dataset of the RSF occurrence distribution selected with cognizance for the longitudinal pattern of the major factors controlling the phenomenon is considered necessary for the further improvement of the empirical model.
  • Abnormal behaviour of sporadic E-layer during the total solar eclipse of
           22 July 2009 near the crest of EIA over India
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Prabhakar Tiwari, Navin Parihar, Adarsh Dube, Rajesh Singh, S. Sripathi In this study we present the behaviour of sporadic E-layer during a total solar eclipse (TSE) which occurred during the dawn/sunrise hours over a site located in the path of totality. A Canadian Advanced Digital Ionosonde (CADI) was operated at Allahabad (25.4° N, 81.9° E), a low latitude station located near the crest of equatorial ionization anomaly (EIA) in the Indian subcontinent to study the ionospheric effects of 22 July 2009 TSE. Corresponding to the eclipse period, a gradual increase of ftEs (top frequency of Es layer) in the 4–5 MHz range was seen on the control days. On 22 July (the TSE day), correlated changes in ftEs coinciding with the TSE progression was noted – (i) sharp decrease near first and second contact of TSE, (ii) an increase after first and second contact, and (iii) wavelike fluctuations in ftEs variation during eclipse hours and beyond. Much higher ftEs values were noted during the TSE hours in comparison to that seen on usual days. Strong blanketing Es layer developed during the TSE hours and persisted for slightly longer duration than its usual occurrence time. Near the TSE totality, slight lowering of the base height of Es layer was also noted.
  • Ionospheric Es layer scintillation characteristics studied with
           Hilbert-Huang transform
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): S.-Y. Su, L.-C. Tsai, C.H. Liu, C. Nayak, R. Caton, K. Groves A coincident event of daytime ionospheric Es layer scintillation observations is analyzed with the Hilbert-Huang transform (HHT) to study its layer structure. One of the coincident observations is made by a radio beacon passing through the Es layer at a slant angle received by the SCINDA (Scintillation Decision Aide) receivers located at southern Taiwan. The data indicates that the Es layer consists of scattering blocks of  ∼ 650 to 970 m in size as revealed in the dominant components of the HHT analysis. The time shift in the two spaced receiving antennas implies that the daytime E region westward drift is about 36 m/s. On the other hand, the same Es layer is observed by the radio occultation (RO) experiment with the L1 signal from the Global Positioning System (GPS) satellites to the FORMOSAT-3/Constellation-Observing-System-for-Meteorology (FS-3/COSMIC) satellites. The GPS L1 signal passes through the Es layer horizontally. The observed signal variations reveal a dense slab structure that blocks the L1 signal to cause a diffraction pattern. The slab thickness in the vertical direction is about 780 m. The HHT analyses of the coincident observations thus conclude that the observed daytime Es layer has a vertical dense slab structure and patches of scattering blocks in the horizontal structure.
  • Possibilities of the usage of the total electron content in a low-latitude
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): O.A. Maltseva, N.S. Mozhaeva Last years, the small quantity of ionosondes at low latitudes could not give a sufficient picture of behavior of the ionosphere in these areas. Now, reception of experimental data, their analysis and detection of total electron content (TEC) variations at low latitudes are an actual problem. When moving from describing the state of the ionosphere using vertical sounding parameters to describing using TEC, it is important to identify similarities and differences in their behavior in order to assess the possibilities of using TEC. This paper carries out research on four ways of TEC usage in low-latitude zone: (1) research of climatological peculiarities of the TEC behavior, (2) validation of up-to-date TEC models, (3) foF2 calculation according to observational TEC, and (4) peculiarities of TEC behavior during geomagnetic disturbances. Results for station Hainan show the following. 1. In addition to previous investigation it is shown, that the empirical global and local models of TEC provide the values close to observational ones, however climatological features of TEC behavior described by various models may still differ from each other and from the experimental data showing in this case TEC maxima of diurnal variation in the afternoons, seasonal variations in March and October, some slight winter anomaly. 2. In contrast to previous investigation it is shown that the closest to the experimental values of TEC are provided by the IRI-Plas model, while this model overestimates values, and the model NeQuick underestimates values compared to the observational ones. 3. For the first time, the ionospheric equivalent slab thickness τ, which plays the role of the coefficient of proportionality between TEC and NmF2, was compared for the IRI, IRI-Plas, NeQuick models with the experimental median τ(med) and it was shown, that the usage of observational TEC data and τ(med) for calculation of critical frequencies foF2 allows improving correspondence with experimental data by 1.2–2 times compared to the models. 4. Comparison of foF2 and TEC behavior has a particular importance during disturbances. Using the example of 15 strong magnetic storms (Dst 
  • On the difference between real-time and research simulations with CTIPe
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Isabel Fernandez-Gomez, Mariangel Fedrizzi, Mihail V. Codrescu, Claudia Borries, Martin Fillion, Timothy J. Fuller-Rowell Understanding the thermosphere and ionosphere conditions is crucial for spacecraft operations and many applications using radio signal transmission (e.g. in communication and navigation). In this sense, physics based modelling plays an important role, since it can adequately reproduce the complex coupling mechanisms in the magnetosphere-ionosphere-thermosphere (MIT) system. The accuracy of the physics based model results does not only depend on the appropriate implementation of the physical processes, but also on the quality of the input data (forcing). In this study, we analyze the impact of input data uncertainties on the model results. We use the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics model (CTIPe), which requires satellite based solar wind, interplanetary field and hemispheric power data from ACE and TIROS/NOAA missions. To identify the impact of the forcing uncertainties, two model runs are compared against each other. The first run uses the input data that were available in real-time (operational) and the second run uses the best estimate obtained in post-processing (research or historical run). The analysis is performed in a case study on the 20th November 2003 extreme geomagnetic storm, that caused significant perturbations in the MIT system. This paper validates the thermosphere and ionosphere response to this storm over Europe comparing both CTIPe model runs with measurements of Total Electron Content (TEC) and thermosphere neutral density. In general, CTIPe results show a good agreement with measurements. However, the deviations between the model and observations are larger in the ionosphere than in the thermosphere. The comparison of the two model runs reveals that the deviations between model results and measurements are larger for the operational run than the research run. It is evident for the storm analyzed here, that data gaps in the input data are impacting considerably the model performance. The consistency between simulation and measurements allows the interpretation of the physical mechanisms behind the ionosphere perturbations and the changes in neutral composition during this event. Joule heating in the Auroral region, generating meridional winds and large scale surges, is suggested to be the main driver of the positive ionospheric storm over central Europe. In the polar cap and Auroral region, convection processes dominate the thermosphere-ionosphere conditions. This study does not only illustrate the importance of working with a good estimate of the model forcing, but also indicates the necessity of using measurements and models, to get a better understanding of the most likely responsible processes for the observed storm effects.
  • An evaluation of the IRI-Plas-TEC for winter anomaly along the
           mid-latitude sector based on GIM-TEC and foF2 values
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): G.I. Gordiyenko, O.A. Maltseva, F. Arikan, A.F. Yakovets Total Electron Content (TEC) has become one of the most widely used observable parameters of the ionosphere. IRI-Plas is an empirical climatic model of the ionosphere and plasmasphere that extends up to GPS orbital height of 20,000 km. The purpose of the study is to reveal whether the winter anomaly (a phenomenon where the mid-latitude daytime NmF2 (or foF2) is greater in winter than in summer at approximately the same solar activity level) occurs in TEC over the Asian sector and how well it is “captured” by IRI-Plas. The study is based on GPS-TEC data derived from Global Ionospheric Maps (GIM-TEC) for January and July months of high (2000), low (2009) and moderate (2012) levels of solar activity. Ionosonde data recorded at a number of mid-latitude Russian and Kazakhstan ionospheric stations in winter and summer seasons for different levels of solar activity are used along with corresponding IRI-Plas calculations to illustrate some specific features of seasonal variations of the midlatitude ionosphere. A comparative study made between IRI-Plas-foF2 and ionosonde foF2 indicates that the IRI-Plas-foF2 variations are found to be in good agreement with the observations showing similar structures, similar magnitudes reflecting the winter anomaly in the diurnal variations. When the IRI-Plas-TEC values are examined for the difference between winter and summer seasons, it is found that their variations are mainly similar to those of IRI-Plas-foF2. Different from that of IRI-Plas-TEC, the winter anomaly in GIM-TEC is not so strong, appears for both high and moderate levels of solar activity, and it is more pronounced at higher latitudes. In low solar activity, the winter anomaly in GIM-TEC is almost absent at the region considered. Finally, the comparison of the IRI-Plas-TEC and GIM-TEC results for winter conditions show that the IRI-Plas-TEC values are significantly larger than those of daytime GIM-TEC at all locations of Russia and Kazakhstan and for all levels of solar activity that coincides with results of previous studies. However, unlike the previous studies, in summer solstice, IRI-Plas-TEC systematically underestimates the GIM-TEC values during high solar activity year and mostly overestimates them for low solar activity. In moderate solar activity year, IRI-Plas-TEC and GIM-TEC values are practically comparable. Thus, the IRI-Plas-TEC model represents the seasonal anomaly observed in foF2 in mid-latitude region for all levels of solar activity but there is a certain deviation from the behavior of GIM-TEC. One of the main reasons of this discrepancy may be the difference of the model Ne(h)-profile from a realistic profile in the upper ionosphere and plasmasphere, that demands additional updating of models for those upper atmosphere regions.
  • The nature and origins of the day-to-day variability in Earth’s
           surface magnetic field
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Jeffrey M. Forbes, Astrid Maute, Xiaoli Zhang Numerical experiments are performed with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) to reveal the characteristics and origins of daytime magnetic field variations on the ground (ΔB) at planetary-wave (PW) periods (2–20 days). Simulations are performed to separate the responses to forcing in the lower atmosphere from solar-magnetospheric forcing. Lower-atmosphere forcing is specified at the 97-km lower boundary of the TIE-GCM by NCAR's Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM), which itself is forced at 30 km by MERRA (Modern Era Retrospective-analysis for Research and Applications) outputs. Solar and magnetospheric inputs to the TIE-GCM are specified according to parameterizations based on F10.7 and Kp. The study focuses on latitudes 0°–65°N during October 1–31, 2009, when F10.7 (range 68–80), Kp (range 0–4), and Ap (range 0–13) are typical of quiet-time “weather”. Neutral dynamics in the dynamo region (ca. 100–150 km) during this period is dominated by winds due to PW modulated tides, where the PW include the quasi-6, 10 and 16-day westward-propagating normal modes with zonal wavenumber s = 1, and eastward-propagating ultra-fast Kelvin waves (UFKW) with s = −1 and periods between 2 and 5 days.Results and conclusions are as follows. PW-period perturbations in daytime ΔB at the ground are dominated by variability originating in the lower atmosphere. The only exception is the 45°–65° latitude regime around noon, where the ΔB variability due to lower atmospheric forcing exceeds that due to solar-magnetospheric forcing by only about 50%. Broadband zonally-symmetric oscillations also occur in ΔB due to dissipation of the tidal spectrum at PW periods in the E-region. These results raise the possibility that some level of contamination from the lower atmosphere may exist in magnetic indices such as ap, Kp, and Ap that are used as measures solar-magnetosphere-ionosphere coupling strength, under levels of geomagnetic activity similar to that characterizing October 2009. It is also found that variations in conductivities play a minor role compared with neutral winds in producing PW-period variations in ΔB, and that there is not a robust one-to-one correspondence between spectral peaks in ΔB and those in the neutral winds. Several factors contribute to this latter result, which are explained in the text.
  • The possibility of estimating the height of the ionospheric
           inhomogeneities based on TEC variations maps obtained from dense GPS
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Grzegorz Nykiel, Yevgen Zanimonskiy, Aleksander Koloskov, Mariusz Figurski A state of the ionosphere can be effectively studied using electromagnetic signals received from global navigation satellite systems (GNSS). Utilization of the dual frequency observations allows estimating values of the total electron content (TEC). They can be used for a number of scientific studies such as detection and monitoring of traveling ionospheric disturbances or plasma bubbles. Moreover, maps of TEC variations allow to classify ionospheric heterogeneities and to evaluate their parameters. However, most of the research describes ionospheric parameters only in 2D space and time. In this paper, we focus on the determination of the height of the ionospheric inhomogeneities. We used a dense network of GPS receivers to obtain the sequences of TEC variation maps for different heights of the ionospheric layer. For each satellite observed above 70°, we constructed separate sets of maps. For each ionospheric height, the cross-correlation function between maps corresponding to different satellites was calculated. The biggest cross-correlation coefficient value determines the height of the ionospheric irregularities. This paper describes the methodology and the results obtained for a geomagnetic storm on St. Patrick’s Day in March 2013. We have found that in quiet geomagnetic conditions the ionospheric irregularities are localized predominantly within the interval 180–220 km close to the maximum of the ionospheric F2 layer. In disturbed conditions, the height of their localization was increased up to several hundreds of kilometers. These estimations correspond to the changes in the slab thickness of the ionosphere.
  • μ m+emission+as+observed+by+TIMED/SABER+over+Asian+sector&rft.title=Advances+in+Space+Research&rft.issn=0273-1177&">Radiative cooling due to NO at 5.3 μ m emission as observed by
           TIMED/SABER over Asian sector
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Gaurav Bharti, M.V. Sunil Krishna, Vir Singh The effect of geomagnetic storms on the peak emission of NO Volume Emission Rate (NO VER) at 5.3 μm, in mesosphere and lower thermosphere (MLT) region, is studied over the Asian sector during 26–29 September 2011 (storm 1) and 18–21 February 2014 (storm 2). The data for peak emission of NO VER is obtained from SABER instrument onboard the NASA’s TIMED satellite. The SABER retrieved data along with the neutral densities obtained from NRLMSISE-00 model have been used to study the latitudinal and longitudinal variation of peak NO VER during the storm period. The variations induced in the peak emission of NO VER is understood with the help of fluctuations in neutral species and the resulting changes in chemistry. It has been found that the peak emission of NO VER is strongly influenced by the storm conditions. The peak emission of NO VER at 5.3 μm is found to be maximum at higher latitudes during the storms. However, the magnitude of peak NO VER gradually decreases towards the equator during the storms. The modeled atomic oxygen number density shows depletion at the higher latitudes corresponding to peak altitude of NO VER. There is a negative correlation between the peak emission of NO VER and Dst index during the main phase of the storm. The peak emission of NO VER and modeled atomic oxygen number density shows the positive correlation at the equator region, while negative correlation at the higher latitudes. At higher latitudes modeled atomic oxygen number density shows positive correlation with Dst index, while negative correlation at the equator. The correlation factors obtained between various parameters related to the storm time radiative cooling strongly support the existing understanding of the variation of NO VER during extreme space weather events.
  • Signatures of substorm related overshielding electric field at equatorial
           latitudes under steady southward IMF Bz during main phase of magnetic
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Bhaskara Veenadhari, Takashi Kikuchi, Sandeep Kumar, S. Tulasiram, D. Chakrabarty, Yusuke Ebihara, G.D. Reeves During the geomagnetic storm periods, the convection electric field penetrates promptly to equatorial latitudes, causing an eastward electric field in the dayside ionosphere. Occasionally, the polarity of the dayside ionospheric electric field is inverted when the Interplanetary Magnetic Field (IMF) turns northward. In this paper, interesting observations of the strong westward electric field in the day side equatorial latitudes are presented, as evidenced by strong Counter Electrojet (CEJ) at Indian and Japanese sectors under the steady southward IMF Bz. The westward electric field perturbations are quite large with CEJ amplitude of ∼−120 nT over the Indian sector (14–15 December 2006) and ∼−220 nT for Japanese sector (7–8 November 2004). The plausible mechanisms for the observed overshielding electric fields under steady southward IMF Bz have been investigated in light of the possible role of substorm activity. The clear signatures of substorm were observed at geosynchronous particle flux measurements from LANL (Los Alamos National Laboratory) satellite and associated with sudden decrease in AL index. The observed variations of asymmetric ring current shows the enhancement of Partial Ring Current (PRC) at the dusk sector further supporting the substorm onset during that period which will probably enhance the overshielding due to increased Region 2 Field-Aligned Currents (R2 FACs). The observations of such significantly large amplitudes of CEJ associated with the substorm related overshielding events are sparse and the results bring out the important role of substorm onset and the development of PRC in accordance with the R2 FACs during intense magnetic storms which alter the day time equatorial electric field perturbations.
  • Turbopause range measured by the method of the artificial periodic
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): A.V. Tolmacheva, N.V. Bakhmetieva, G.I. Grigoriev, M.N. Egerev A new opportunity for estimating the level of the turbopause is presented. It is based on the method of determining atmospheric parameters using artificial periodic irregularities of the ionospheric plasma (the API techniques). The obtained data show the presence of variations of the level of the turbopause. Experiments were carried out using SURA heating facility (56.1°N, 46.1°E) for API creation. Above the observation point the turbopause region occupies the altitude interval between 94 and 106 km. There are changes in the level of the turbopause during the day: in the evening hours the turbopause level can go down. Temporal variations of the turbopause level are observed. They are compared with variations in the atmospheric parameters at these heights.
  • New techniques for retrieving the [O(3P)], [O3] and [CO2] altitude
           profiles from dayglow oxygen emissions: Uncertainty analysis by the Monte
           Carlo method
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Valentine Yankovsky, Ekaterina Vorobeva, Rada Manuilova This study presents methods for retrieving the altitude profiles of atomic oxygen, [O(3P)], ozone, [O3], and carbon dioxide, [CO2], concentrations in the daytime mesosphere and lower thermosphere (MLT) in the framework of the YM2011 model of the electronic-vibrational oxygen kinetics. The emissions of singlet oxygen molecules O2(b1Σ+g, v ≤ 2), O2(a1Δg, v = 0) and the O(1D) atom are used as proxy of the [O(3P)], [O3] and [CO2]. For all the proposed techniques, we compare the uncertainty values of the retrieved [O(3P)], [O3] and [CO2], obtained by the Monte Carlo method, with estimations obtained by the sensitivity analysis method in the earlier works. For all the above mentioned methods for retrieving the [O(3P)], [O3] and [CO2] profiles, we obtained analytical expressions that include the concentrations of excited substances considered as proxies. In addition, the optimal altitude ranges for using these remote sensing methods were determined based on the results of numerical experiments by the Monte Carlo method.
  • The Atmospheric Coupling and Dynamics Across the Mesopause (ACaDAMe)
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): D. Janches, A.W. Yu, M.A. Krainak, C. Gardner, B. Kaifler, S. Etemad, D.C. Fritts, S.D. Eckermann, R.L. Collins, E.C.M. Dawkins, R.S. Lieberman, D.R. Marsh, G. Liu, W. Jarvis The Atmospheric Coupling and Dynamics Across the Mesopause (ACaDAMe) is a mission designed to uniquely address critical questions involving multi-scale wave dynamics at key space weather (SWx) “gateway altitudes” of the mesosphere and lower thermosphere (MLT) at ~70–150 km. ACaDAMe observes with a nadir-pointing resonant lidar that utilizes the fluorescence of atomic Na present in the MLT. By tuning a laser to the Na absorption wavelength (589 nm), ACaDAMe would perform very high resolution measurements of temperature and Na densities across the mesopause during both day and night. In this manner, Na is used as tracer for observing and characterizing MLT waves generated by tropospheric weather that represent the dominant terrestrial source of energy and momentum affecting space weather and transport of mesospheric species.
  • Chemical physics of D and E layers of the ionosphere
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): V.V. Kuverova, S.O. Adamson, A.A. Berlin, V.L. Bychkov, A.V. Dmitriev, Y.A. Dyakov, L.V. Eppelbaum, G.V. Golubkov, A.A. Lushnikov, M.I. Manzhelii, A.N. Morozov, S.S. Nabiev, V.L. Shapovalov, A.V. Suvorova, M.G. Golubkov The main chemical reactions that lead to formation of the nonequilibrium two-temperature plasma and highly excited Rydberg complexes are considered. A special attention is given to l-mixing reaction responsible for the formation of quantum resonance properties for radio wave propagation medium. A detailed analysis of the influence of Rydberg states to the behavior of GPS signals in D and E layers of the ionosphere is presented. It is shown that the transition frequencies between the excited states of orbitally degenerate Rydberg complex are resonant with respect to the carrier frequencies of GPS. That is why these states are the main cause of the GPS signal distortion. The mechanism of GPS signal delay in D and E layers is also discussed.
  • Observation of mesospheric wave using collocated OH airglow temperature
           and radar wind measurements over Indian low latitude
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): R.N. Ghodpage, Alok Taori, O.B. Gurav, P.T. Patil, S. Gurubaran, Devendraa Siingh, G.P. Naniwadekar We analyzed the mesospheric winds and temperature data for investigating the waves scaling from the period of few hours to several hours (and few days) based on the airglow observations at Kolhapur (16.8°N, 74.2°E, 10.6°N dip. lat.). The data presented in this study are collected using medium frequency radar and Multispectral Scanning Photometer at low latitude station Kolhapur. We scrutinized the wind and temperature relation of these waves for the observed period from January to May 2011. The data of 56 clear nights were collected and out of which 22 nights of data shows a conspicuous wavelike features. The nocturnal variability reveals the prominent wave signatures with a period which range from 7 to 12 h (h) as a dominant nocturnal wave. The presence of quasi 2.8–4 days waves with significant amplitudes is also detected. The comparison of the winds and temperatures suggests the temperature waves to be near in phase with meridional wind component and a time delayed relation with the zonal wind component.
  • The dependence of four-peak longitudinal structure of the tropical
           electric field on the processes in the lower atmosphere and geomagnetic
           field configuration
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): V.V. Klimenko, M.V. Klimenko, F.S. Bessarab, T.V. Sukhodolov, E.V. Rozanov In this article, we estimate the influence of the atmospheric-ionospheric interaction and the differences in the location of the geographic and geomagnetic poles on the longitudinal variability of the ionospheric electric field in the vicinity of the geomagnetic equator. For the study, we applied the upper atmosphere model (GSM TIP) and the recently created entire atmosphere model (EAGLE). The simulation results confirm that the four-peak structure of the longitudinal variation and the pre-reversal enhancement of the eastward electric field at the equator are caused by the atmosphere-ionosphere coupling. The role of F-region dynamo in the formation of pre-reversal enhancement of the eastward electric field is beyond the scope of this paper. These structures appear during the minimum of solar activity periods and are formed by the longitudinal variations of the horizontal thermospheric wind and the Pedersen conductivity arising from the action of the mesospheric tides. During solar activity minimum periods, the difference in the locations of geographic and geomagnetic poles leads to some complication and smoothing of the obtained picture of longitudinal variations in the electric field. We suggest that mesospheric tides have a significant effect on the longitudinal variation of the Pedersen conductivity, while the longitudinal variation of the Hall conductivity is mainly determined by the mismatch of geographic and geomagnetic poles. The amplitudes of the equatorial electric field longitudinal variations are three to four times smaller than the amplitudes of their diurnal variations, however, they can have a significant impact on the spatial distribution of the electron density in the F region of the low-latitude ionosphere.
  • On the field validation of α-μ fading coefficients estimator based on
           the autocorrelation function for ionospheric amplitude scintillation
    • Abstract: Publication date: 15 November 2019Source: Advances in Space Research, Volume 64, Issue 10Author(s): Leonardo Marini-Pereira, Kelias de Oliveira, Lucas A. Salles, Alison de O. Moraes, Eurico R. de Paula, Marcio Tadeu de Assis Honorato Muella, Waldecir J. Perrella The ionosphere in low-latitude regions has intense dynamics with great variability – not only spatially but also temporally. The most critical effect found in the low-latitude region is the scintillation in phase and amplitude due to plasma bubble occurrence in the ionospheric layer. To augmentation systems like GBAS or SBAS, designed to provide Category-I (CAT I) precision approach service in low-visibility conditions, plasma bubbles can compromise the performance requirements for air navigation precision approach in a way that the service provided by the system is considered unviable. In practical terms, this is the main reason why the Brazilian Department of Airspace Control (DECEA) still has not implemented any augmentation system in Brazil. Scintillation may lead to loss of signal lock of the affected satellite. In this context, a better understanding of the scintillation pattern and its statistical properties gain particular relevance, once this is the most concerning issue for the performance of any GNSS receiver in low-latitude regions especially in the context of augmentation systems for air navigation. Previous works validated the use of the α-μ distribution to characterize amplitude scintillation. The present work is concerned with proposing a new method for the estimation of the α-μ coefficients based on the α-μ autocorrelation function. The method is validated using field data and comparing the results from empirical autocorrelation function with the results obtained from the moment-based estimator. Additionally, the efficiency of the method is proven by analyzing measurements of Level-Crossing Rate (LCR) and Average Fading Duration (AFD) with their respective theoretical formulation.
  • List of Referees
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s):
  • Geocentric Baltic Sea level changes along the southern coastline
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Adam Łyszkowicz, Anna Bernatowicz Sea level is a unique indicator in climate impact studies on any changes on the surface of the Earth. Traditionally, tide gauges allow observation of relative (relative to land) sea level changes at specific locations with a high resolution in time. Common method of sea level determination in XXI century is the combination of tide gauge observations with satellite observation data. So determined sea level changes are absolute changes and they are referred to the beginning of the ITRF system.Geocentric changes in the Baltic Sea level are monitored, inter alia, by the SONEL network. This network system does not include the southern coast of the Baltic Sea. The aim of this work is to fill this gap and to compute geocentric changes in the Baltic Sea at the stations: Hel, Władysławowo, Łeba, Ustka, Kołobrzeg, Świnoujście.The tide gauge data needed for the analysis were made available by the Institute of Meteorology and Water Management and the GNSS data was taken from web page Nevada Geodetic Laboratory. The analysis of the time series of tide gauge and GNSS observations was carried out using the TSAnalyzer software. We assumed that GNSS and tide gauge series have a seasonal signal (annual plus semi-annual) and a trend. First the outliers were removed from observation, then the jumps were viewing. The trend, annual and semi-annual terms were calculated for GNSS and tide gauge series.The results of the work are calculated geocentric changes in the Baltic Sea level along southern coast and they are at a level of 0.3 mm/year except Ustka where it reach value 4.68 mm/year.
  • A new hierarchical method for automatic road centerline extraction in
           urban areas using LIDAR data
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Sayyed Abdullah Kianejad Tejenaki, Hamid Ebadi, Ali Mohammadzadeh Road detection and road extraction are important and challenging issues in the fields of photogrammetry and remote sensing. Researchers have conducted wide research in this regard based on multispectral images and achieved relatively useful results. Image-data driven methods have some shortcomings such as shadows, eliminating small and long vehicles, geometric distortions, and occlusions. In recent years, in order to overcome the above limitations and complexities, several attempts have been done based on LIDAR data. The present paper proposes an automatic hierarchical road detection and extraction method. The main goal of this research is to increase the level of continuity of the road detection and extraction processes. This method includes the preprocessing of intensity data using a local minima filter, applying the Mean Shift segmentation to the refined intensity data, and finally integrating it with various nDSM-based Products. The proposed method involves not only considering both small and long vehicles as road features but also neglecting some parts of large parking lots based on the nearby neighborhood of parked vehicles as much as possible as non-road features. The next step was the process of road centerline extraction by adopting a Voronoi-diagram based approach and then removing dangle lines in several iterations. The proposed method was applied to the Vaihingen and Toronto datasets (ISPRS). The completeness of the two datasets is 95.85% and 88%, and the correctness of these datasets are 83.68% and 72.2%, respectively. The results were indicative of the great potential of the proposed method for effective road centerline extraction in urban areas.
  • Spectral analysis on the solar parameters and empirical orthogonal
           functions of foF2 data obtained by singular value decomposition
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Junmi Gogoi, Kalyan Bhuyan The geomagnetic storm is an important weather issue in the earth’s ionosphere-magnetosphere system. Many linear and nonlinear systems are involved in this earth-space environment. In order to understand the nonlinearly evolving dynamical system of magnetosphere and ionosphere, Time series analysis of foF2 data, Disturbance Storm Index Dst, Geomagnetic activity Index Ap and some other parameters during various solar cycles has been carried out in this work. The hourly data of critical frequency of F2 layer (foF2) for three ionosonde stations [Townsville (TV51R) 19.7°S, 146.9°E; Canberra (CB53N) 35.3°S, 149.1°E; Juliusruh (JR055) 54.6°N, 13.4°E] have been noted for 4 solar cycles viz., Solar Cycle 20, 21, 22 and 23. Hourly time series analysis has been performed to achieve some functional approaches such as statistical, analytical and spectral approach etc. to examine for the presence of periodicities in the data. Time Series is a sequential set of data which can be measured over time, and since the data being used for this work had been recorded as a function of time under various conditions, the appearance of missing observations in time series data is a very common issue. Different series may require different approaches to estimate these missing values. As such, to vanquish the problem of missing data we have attempted to estimate the missing value of foF2 data for various stations using the technique of Singular Value Decomposition (SVD). Another important method, Lomb Scargle Periodogram (LSP) has been performed on the Empirical Orthogonal Functions (EOFs) u1 and u2 (that has been obtained by SVD) along with the solar parameters such as solar flux f10.7, sun spot number (SSN) etc. and geomagnetic indices such as Dst index, Kp index & Ap index etc. for the four solar cycles to find the correlation, if any. For all the plots after performing LSP the power has been found out at 99% confidence level to see how much significant the generated data with respect to the parameters is. The periodicity obtained after performing LSP are divided into three terms namely:– (a) short-term periodicity, in which 27 days periodicity is found to be prominent, (b) mid-term periodicity, in which 1.3 year periodicity is found to be very common and (c) long-term periodicity, in which 11 years periodicity is very regular in almost among all the parameters and in the EOFs.
  • Data-driven modelling of the Van Allen Belts: The 5DRBM model for trapped
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Lionel Métrailler, Guillaume Bélanger, Peter Kretschmar, Erik Kuulkers, Ricardo Pérez Martínez, Jan-Uwe Ness, Pedro Rodriguez, Mauro Casale, Jorge Fauste, Timothy Finn, Celia Sanchez, Thomas Godard, Richard Southworth The magnetosphere sustained by the rotation of the Earth’s liquid iron core traps charged particles, mostly electrons and protons, into structures referred to as the Van Allen Belts. These radiation belts, in which the density of charged energetic particles can be very destructive for sensitive instrumentation, have to be crossed on every orbit of satellites traveling in elliptical orbits around the Earth, as is the case for ESA’s INTEGRAL and XMM-Newton missions. This paper presents the first working version of the 5DRBM-e model, a global, data-driven model of the radiation belts for trapped electrons. The model is based on in situ measurements of electrons by the radiation monitors on board the INTEGRAL and XMM-Newton satellites along their long elliptical orbits for respectively 16 and 19 years of operations. This model, in its present form, features the integral flux for trapped electrons within energies ranging from 0.7 to 1.75 MeV. Cross-validation of the 5DRBM-e with the well-known AE8min/max and AE9mean models for a low eccentricity GPS orbit shows excellent agreement, and demonstrates that the new model can be used to provide reliable predictions along widely different orbits around Earth for the purpose of designing, planning, and operating satellites with more accurate instrument safety margins. Future work will include extending the model based on electrons of different energies and proton radiation measurement data.
  • The capability analysis of the bistatic radar system based on Tianlai
           radio array for space debris detection
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Jiawei Li, Pengqi Gao, Ming Shen, You Zhao The bistatic radar system has been one of the effective methods to detect the space debris in low earth orbit (LEO). Tianlai radio array with cylindrical-parabolic antennas is designed for dark energy detection, which has large field of view and high sensitivity, offering a fan-beam during the observation. We propose a bistatic radar system, which consists of Tianlai radio array and an incoherent scattering radar (ISR) assumed as a transmitter in the Qujing city of China, to detect space debris. In this paper, we calculate and analyze the detection capabilities of this system. The results show the bistatic radar system has the potential to detect small space debris of less than 10 cm in LEO. We provide a space debris detection method to obtain the position of the cross-beam satisfying the observation requirement with the TLE data of the space debris. The method can solve the problem of space synchronization between the radio array and ISR. We used the long-short baseline method of the radio array to locate the space target. The relationship among positioning error, the azimuth and the elevation angle are also discussed.
  • A solar electron event model in near-Earth space
    • Abstract: Publication date: 1 November 2019Source: Advances in Space Research, Volume 64, Issue 9Author(s): Jian-zhao Wang, Ying Wang, Shu-wu Dai, Chen Wang, Ji-nan Ma, Xiao-yu Jia, Yan-cun Li, Dai Tian, Jia-wen Qiu A new solar electron event model is developed based on Virtual Timeline Method (VTM). We study events individually by analyzing the 17-year data of 3DP instrument on WIND spacecraft. This model is established in different solar cycle phases and is based on statistics of duration, fluence, and waiting time of solar electron events. The fluences follow a log-normal distribution and logarithmic durations fit well with logarithmic fluences linearly. We prove that waiting times of events significantly deviates from the Poisson process by investigating the stationary and event independence property of Poisson distribution. After a comparison study on waiting times, we choose the Lévy distribution in solar minimum and maximum years. During solar minimum, the event frequency is much lower than that of solar maximum, but the event magnitude is independent of solar cycle period. Large events also happen in solar minimum years. In different solar cycle phases, this model can output a spectrum with confidence level and mission duration by generating many series of virtual timelines composed of many pseudo-events based on Monte Carlo method. On the other hand, spectra in solar minimum years are softer than that in solar maximum years. The fluences in solar maximum years are about one order of magnitude higher than that in solar minimum years in a given mission period. We also compare this model with Interplanetary Electron Model (IEM) quantitatively and prove that this model is advanced.
  • Preface: Variability and coupling of the equatorial, low- and mid-latitude
           mesosphere, thermosphere and ionosphere: Latest developments of monitoring
           and modeling techniques
    • Abstract: Publication date: Available online 17 September 2019Source: Advances in Space ResearchAuthor(s): Michael Pezzopane, Kavutarapu Venkatesh
  • Variations in the Ionosphere-Thermosphere System from Tides, Ultra-Fast
           Kelvin Waves, and Their Interactions
    • Abstract: Publication date: Available online 23 August 2019Source: Advances in Space ResearchAuthor(s): Colin C. Triplett, Thomas J. Immel, Yen-Jung Wu, Chihoko Cullens Large scale waves, such as the atmospheric tides and ultra-fast Kelvin waves (UFKW), have direct effects on the neutral wind and temperature fields of the ionosphere-thermosphere (I-T) system. In this study we examine the response of the I-T system to the atmospheric tides, one UFKW, and the secondary waves generated from their interactions using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). We find that forcing an UFKW at the lower boundary of the TIEGCM is all that is required for it to setup in the model. We see variations around 10% in the zonal winds that lead to similar variations in the total electron content (TEC) depending on the phase of the UFKW. From these simulations, we expect the Ionospheric Connection Explorer (ICON) mission will be able to fully capture these wave interactions by observing winds and temperatures at the mesopause and above.
  • A discussion on the mode conversion from purely perpendicular upper-hybrid
           mode waves to LO mode waves in an inhomogeneous plasma
    • Abstract: Publication date: Available online 20 August 2019Source: Advances in Space ResearchAuthor(s): Mohammad Javad Kalaee, Yuto Katoh We consider the equatorial region of the magnetosphere, where the magnetic field is perpendicular (or near to perpendicular) to the density gradient and mode conversion process from UH to LO-mode waves or reverse process are expected. We review and study the mode conversion from UH (upper hybrid) to LO (left hand polarized ordinary) mode waves by a spatially two dimensional plasma fluid code. Several simulations with different initial wave vectors under the same background plasma condition have been performed. We focus on the conversion efficiency from the UH-mode waves with purely perpendicular wave normal angle to the LO-mode waves, since one of the source of generation UH wave can be Bernstein mode as the purely perpendicular electrostatic waves. For this special case, the UH wave normal is kept in perpendicular direction with respect to the magnetic field, and difficult to be in matching direction for conversion to LO mode. Simulation results show that the mode conversion efficiency in this particular case is very weak, since two branches of Z-mode wave and LO mode wave in the dispersion relation are disconnected. We present a discussion to show that for this case (purely perpendicular propagation) a special angle (except 90 degrees), between the magnetic field and the density gradient is necessary for occurrence of efficient mode conversion. For the case (purely perpendicular propagation and the magnetic field perpendicular to the density gradient), the mode conversion just occurred via the tunneling effect, where a steepness of the inhomogeneity plays an essential role.
  • A Pseudospectral Method based Robust-Optimal Attitude Control Strategy for
    • Abstract: Publication date: Available online 16 August 2019Source: Advances in Space ResearchAuthor(s): Arunava Banerjee, Syed Muhammad Amrr, M. Nabi This paper proposes an optimal integral sliding mode control (ISMC) scheme for attitude regulation of the rigid spacecraft. This control technique is capable of handling inertial matrix uncertainties as well as external disturbances. To incorporate optimality into the robust control law, the ISMC is integrated with Legendre pseudospectral method (LPSM). The minimization of the cost function and constraint handling of the spacecraft is obtained by LPSM, while the ISMC provides disturbance rejection. LPSM is chosen for its relatively high rate of convergence and its capability of solving a wide range of challenging optimal control problems. Theoretical stability analysis of closed loop system using Lyapunov theorem guarantees the convergence of attitude states. A comparative analysis between the proposed LPSM-ISMC and Chebyshev Pseudospectral Method(CPSM) based ISMC, is also presented in this paper. The effectiveness of the proposed robust-optimal control strategy is established through simulation results.
  • Dynamics Modeling and Simulation of Self-Collision of Tether-Net for Space
           Debris Removal
    • Abstract: Publication date: Available online 14 August 2019Source: Advances in Space ResearchAuthor(s): Jiyue Si, Zhaojun Pang, Zhonghua Du, Chun Cheng Tether-net is a new active removal technology for space debris, and its deployment and capture have attracted considerable attention. This study focuses on the dynamics and simulation of self-collision of tether-net. First, the mass-spring-damper method is used to model tether-net and a line–line self-collision detection algorithm is proposed according to the geometric characteristics of tether-net. Thereafter, combined with the nonlinear collision model, the self-collision process of tether-net is studied. Two simulations of the close-up of a net with or without a target are executed to show the difference between considering and not considering the self-collision of tether-net. Results reveal that the capture process of tether-net with consideration for self-collision is different from the one without self-collision, especially after the corners of the net begin to contact each other.
  • Study of the relative geoeffectiveness of high-speed solar wind streams of
           different speed and different durations
    • Abstract: Publication date: Available online 9 August 2019Source: Advances in Space ResearchAuthor(s): F. Mustajab, Badruddin, H. Asiri We consider high speed streams (HSS) identified from 16 years (1996-2011) of continuous solar wind plasma and field data. We compare the geomagnetic response of the HSS of different speed and different durations based on statistical distribution, the superposed epoch analysis as well as the regression analysis. We analyse the geomagnetic responses of the HSS of different speed and durations together with the solar wind plasma and field data. The observed differences in the amplitudes, time profiles and recovery characteristics of geomagnetic disturbances during the passage of the HSS of different speed and durations are compared with the differences in the simultaneous solar wind plasma/field behaviour. Implications of these results on the solar wind-magnetosphere coupling are discussed.
  • Smart-RTK: Multi-GNSS Kinematic Positioning Approach on Android Smart
    • Abstract: Publication date: Available online 7 August 2019Source: Advances in Space ResearchAuthor(s): Kaishi Zhang, Wenhai Jiao, Liang Wang, Zishen Li, Jianwen Li, Kai Zhou Global Navigation Satellite System (GNSS), once dedicated to military and geodetic applications, is entering civilian life with the development of low-cost internal multi-GNSS chips in mass-market smart devices. The recently enabled Application Programming Interface (API) to GNSS raw measurement in Android Nougat operating system, make it possible to implement precise positioning technology on Android smart devices, such as Real-Time Kinematic Positioning (RTK) and Precise Point Positioning (PPP). An optimized kinematic positioning approach on Android smart devices with Doppler-Smoothed-Code (DSC) filter and Constant Acceleration (CA) model is assessed in this paper. In this optimized approach, DSC filter is used to reduce the code measurement noise, which is extremely high on smart devices and CA model is used to accurately predict the kinematic state of smart devices. The optimized approach is named Smart-RTK for its applicability to smart devices, respectively. The performance of the Smart-RTK approach is validated by two Google/HTC Nexus 9 tablets separately under stationary, walking, and vehicular condition. The numerical experiments show the significant improvement on positioning accuracy and continuity. The positioning Root Mean Square Error (RMSE) in horizontal component reaches about 0.3 ∼ 0.6 m in stationary condition and 0.4 ∼ 0.7 m in walking condition, improved by about 85% compared with that of chipset original solutions. In the subsequent vehicular experiment, the horizontal positioning RMSE is about 0.85 m, 50% better than that of chipset solutions.
  • Invariance of conveying capacity for drilling into lunar soil simulant
    • Abstract: Publication date: Available online 7 August 2019Source: Advances in Space ResearchAuthor(s): Tao Chen, Zhen Zhao, Stephen R. Schwartz, Caishan Liu, Qi Wang In this paper, we study the conveying dynamics in the helical groove of an auger drilling into lunar simulant. We demonstrate that the stress-coupling effect of the conveyed granules by the groove of a drill auger plays a significant role on the dynamics of conveyance. For this, a discrete element method (DEM) is adopted first to uncover the motion and the stress characteristics of conveyed granules in a working auger. Then, a simplified dynamic model following the stress characteristics of DEM is established. The simplified model can not only reflect the results by the discrete element method, but can also explain well the proportional relationship between the maximum conveying rate and the rotating speed of the auger in the experiment (Zhao et al., 2019).
  • Designing Observation Scheme in X-ray Pulsar-Based Navigation with
           Probability Ellipsoid
    • Abstract: Publication date: Available online 5 August 2019Source: Advances in Space ResearchAuthor(s): Haoye Lin, Bo Xu, Jingxi Liu The accuracy in pulsar-based navigation system can be improved with a well-designed observation scheme. In this paper, based on the idea that minimises the size of position probability ellipsoid at each updating time, four strategies are put forward for determining observation order. As the calculation of posterior probability ellipsoid only requires a priori orbit information, the observation scheme can be designed during preliminary mission analysis. These strategies can be employed in both situations with single detector and multiple detectors. Numerical simulations show that the proposed observation strategies achieve good performance.
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