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Advances in Space Research
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 2
Number of Followers: 420  
 
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ISSN (Print) 0273-1177
Published by Elsevier Homepage  [3183 journals]
  • A Pseudospectral Method based Robust-Optimal Attitude Control Strategy for
           Spacecraft
    • 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.
       
  • Indirect robust suboptimal control of two-satellite electromagnetic
           formation reconfiguration with geomagnetic effect
    • Abstract: Publication date: Available online 16 August 2019Source: Advances in Space ResearchAuthor(s): Da-wei Qi, Le-ping Yang, Yuan-wen Zhang, Wei-wei Cai As a novel approach to control the relative motion of a satellite formation, electromagnetic formation flight (EMFF) has some prominent advantages, such as no propellant consumption and no plume contamination, and has a broad prospect of application in such fields as on-orbit detection and optical interferometry. The current paper investigates the optimal control for the reconfiguration of a two-satellite electromagnetic formation using the nonlinear quadratic optimal control technique. Specifically, the effects of the Earth’s magnetic field on the EMFF satellites are analyzed, and then the nonlinear translational dynamic model of a two-satellite electromagnetic formation is derived by utilizing the analytical mechanics theory. Considering the high nonlinearity and coupling in the dynamic model and the actuator saturation, a closed-loop robust suboptimal control strategy based on the indirect robust control scheme and the θ-D technique is proposed with robust stability and optimality. To ensure a further reduction of control input, the designed suboptimal controller is modified by applying the Tracking-Differentiator. The feasibility of the derived translational dynamics and proposed control strategy for the robust reconfiguration mission is validated through theoretical analysis and numerical simulations.
       
  • 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.
       
  • Editorial
    • Abstract: Publication date: Available online 13 August 2019Source: Advances in Space ResearchAuthor(s): Pascal Willis
       
  • Estimating disk parameters of black hole X-ray binary MAXI J1543-564:
           effect of disk irradiation
    • Abstract: Publication date: Available online 12 August 2019Source: Advances in Space ResearchAuthor(s): Santanu Mondal We study the central mass accretion rate and its variation with time during the outburst of X-ray transients using disk irradiation effect once the outer boundary of the disk is defined by the binary parameters. We show that the decay of the light curve and its characteristics time are well linked to the disk aspect ratio (H/R) and the binary parameters. For that we parametrize viscosity (α) parameter with H/R, assuming that there is a vertical height dependence on the energy dissipated in the disk. We derive the central accretion rate to check the sensitivity on H/R. Mass accretion rate changes notably with disk height, orbital period (P) and with binary mass function (q). For the consistency check, we apply the solution to a low mass X-ray binary (LMXRB) 4U 1543-47, whose binary parameters are dynamically measured. Finally, we estimate the unknown binary parameters of MAXI J1543-564. Using this solution for the first time we propose some predictability on P for the unknown system. The estimated value of P varies in a range from ∼10.5-15.5hr, when the companion mass is ∼0.66M⊙. Our estimated decay time scale is ∼40d with α∼0.18.
       
  • List of Referees
    • Abstract: Publication date: 15 September 2019Source: Advances in Space Research, Volume 64, Issue 6Author(s):
       
  • Spin-to-spin slew maneuvers under spherically constrained angular
           acceleration
    • Abstract: Publication date: 15 September 2019Source: Advances in Space Research, Volume 64, Issue 6Author(s): Donghun Lee, Young-Joo Song This paper addresses a three-axis time-optimal attitude-control problem of rigid spacecraft. In this problem, an angular-acceleration vector lies within a spherically constrained space, and spin-to-spin boundary conditions are considered. The problem is converted into a two-point boundary-value problem by an indirect method, which is solved numerically because non-eigen-axis slew motions do not have a general analytical solution. To solve the problem, a homotopy algorithm is applied in which a discrete continuation method, closed-form solutions for single-axis slew maneuvers, and a costate transformation method are included. Through numerical examples, the properties of the optimal solutions are analyzed, and the efficiency of the numerical algorithm is demonstrated.
       
  • Accuracy evaluation of the latest BDGIM for BDS-3 satellites
    • Abstract: Publication date: 15 September 2019Source: Advances in Space Research, Volume 64, Issue 6Author(s): Yongxing Zhu, Shusen Tan, Qinghua Zhang, Xia Ren, Xiaolin Jia A novel model of the BeiDou Global Ionospheric delay correction Model (BDGIM) is used as the global broadcasting ionospheric correction model for the third generation of BeiDou Navigation Satellite System (BDS-3). It has been successfully implemented on five BDS-3 test satellites. The accuracy of this novel BDGIM model were evaluated using the final global ionosphere maps (GIM) products provided by the International Global Navigation Satellite System Service (IGS). Comparing with the IGS GIM final product, the root mean square (RMS) of the global correction accuracy of BDGIM was 3.57 total electron content unit (TECu) with a correction percentage of 77.2%. The average RMS at different latitudes was 3.11 TECu, with Percent of 75.2%. The mean RMS values of regions with lattilute larger than 52.5S and 62.5N were less than that of NeQuickG. Considering the distribution of the tracking stations using for calculating BDGIM coefficients, the RMS values in different regions were 3.09 TECu (Percent = 80.3%) and 3.21 TECu (Percent = 79.4%), respectively. The BDGIM coefficients was updated every two hours, comparing with NeQuickG model, the BDGIM better reflected the real changes of ionosphere. Considering that the accuracy of the non-broadcasted coefficients declines with broadcasting duration, the correction accuracy with nine broadcasted coefficients included in BDGIM was analyzed. RMS and Percent were 4.10 TECu and 72.8%, declining by about 0.53 TECu and 4.4% (maximum to 9.7%), respectively.
       
  • 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.
       
  • Targeting ultra-high energy neutrinos with the ARIANNA experiment
    • Abstract: Publication date: Available online 24 June 2019Source: Advances in Space ResearchAuthor(s): A. Anker, S.W. Barwick, H. Bernhoff, D.Z. Besson, N. Bingefors, G. Gaswint, C. Glaser, A. Hallgren, J.C. Hanson, R. Lahmann, U. Latif, J. Nam, A. Novikov, S.R. Klein, S.A. Kleinfelder, A. Nelles, M.P. Paul, C. Persichilli, S.R. Shively, J. Tatar The measurement of ultra-high energy (UHE) neutrinos (E > 1016 eV) opens a new field of astronomy with the potential to reveal the sources of ultra-high energy cosmic rays especially if combined with observations in the electromagnetic spectrum and gravitational waves. The ARIANNA pilot detector explores the detection of UHE neutrinos with a surface array of independent radio detector stations in Antarctica which allows for a cost-effective instrumentation of large volumes. Twelve stations are currently operating successfully at the Moore’s Bay site (Ross Ice Shelf) in Antarctica and at the South Pole. We will review the current state of ARIANNA and its main results. We report on a newly developed wind generator that successfully operates in the harsh Antarctic conditions and powers the station for a substantial time during the dark winter months. The robust ARIANNA surface architecture, combined with environmentally friendly solar and wind power generators, can be installed at any deep ice location on the planet and operated autonomously. We report on the detector capabilities to determine the neutrino direction by reconstructing the signal arrival direction of a 800 m deep calibration pulser, and the reconstruction of the signal polarization using the more abundant cosmic-ray air showers. Finally, we describe a large-scale design – ARIA – that capitalizes on the successful experience of the ARIANNA operation and is designed sensitive enough to discover the first UHE neutrino.
       
  • 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).
       
  • 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: Available online 6 August 2019Source: Advances in Space ResearchAuthor(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.
       
  • A solar electron event model in near-Earth space
    • Abstract: Publication date: Available online 5 August 2019Source: Advances in Space ResearchAuthor(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 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.
       
  • The capability analysis of the bistatic radar system based on Tianlai
           radio array for space debris detection
    • Abstract: Publication date: Available online 5 August 2019Source: Advances in Space ResearchAuthor(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.
       
  • Spectral analysis on the solar parameters and Empirical orthogonal
           functions of foF2 data obtained by Singular Value Decomposition
    • Abstract: Publication date: Available online 5 August 2019Source: Advances in Space ResearchAuthor(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. All the plots after performing LSP has been found out 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.
       
  • Geocentric Baltic Sea level changes along the southern coastline
    • Abstract: Publication date: Available online 5 August 2019Source: Advances in Space ResearchAuthor(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 and 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.
       
  • 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.
       
  • Small Satellites for Space Science
    • Abstract: Publication date: Available online 2 August 2019Source: Advances in Space ResearchAuthor(s): Robyn M. Millan, Rudolf von Steiger, Meir Ariel, Sergey Bartalev, Maurice Borgeaud, Stefano Campagnola, Julie C. Castillo-Rogez, René Fléron, Volker Gass, Anna Gregorio, David M. Klumpar, Bhavya Lal, Malcolm Macdonald, Jong Uk Park, V. Sambasiva Rao, Klaus Schilling, Graeme Stephens, Alan M. Title, Ji Wu This is a COSPAR roadmap to advance the frontiers of science through innovation and international collaboration using small satellites. The world of small satellites is evolving quickly and an opportunity exists to leverage these developments to make scientific progress. In particular, the increasing availability of low-cost launch and commercially available hardware provides an opportunity to reduce the overall cost of science missions. This in turn should increase flight rates and encourage scientists to propose more innovative concepts, leading to scientific breakthroughs. Moreover, new computer technologies and methods are changing the way data are acquired, managed, and processed. The large data sets enabled by small satellites will require a new paradigm for scientific data analysis. In this roadmap we provide several examples of long-term scientific visions that could be enabled by the small satellite revolution. For the purpose of this report, the term “small satellite” is somewhat arbitrarily defined as a spacecraft with an upper mass limit in the range of a few hundred kilograms. The mass limit is less important than the processes used to build and launch these satellites. The goal of this roadmap is to encourage the space science community to leverage developments in the small satellite industry in order to increase flight rates, and change the way small science satellites are built and managed. Five recommendations are made; one each to the science community, to space industry, to space agencies, to policy makers, and finally, to COSPAR.
       
  • Data-Driven Modelling of the Van Allen Belts: The 5DRBM Model for Trapped
           Electrons
    • Abstract: Publication date: Available online 1 August 2019Source: Advances in Space ResearchAuthor(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.
       
  • On-orbit Performance of the Top and Bottom Counting Detectors for the
           ISS-CREAM Experiment on the International Space Station
    • Abstract: Publication date: Available online 30 July 2019Source: Advances in Space ResearchAuthor(s): S.C. Kang, Y. Amare, T. Anderson, D. Angelaszek, N. Anthony, K. Cheryian, G.H. Choi, M. Copley, S. Coutu, L. Derome, L. Eraud, L. Hagenau, J.H. Han, H.G. Huh, Y.S. Hwang, H.J. Hyun, S. Im, H.B. Jeon, J.A. Jeon, S. Jeong The Cosmic Ray Energetics And Mass (CREAM) instrument on the International Space Station (ISS) is an experiment to study origin, propagation, acceleration and elemental composition of cosmic rays. The Top Counting Detector (TCD) and Bottom Counting Detector (BCD) are parts of the detector suite of the ISS-CREAM experiment and are designed to separate electrons and protons for studying electron and gamma-ray physics. In addition, the TCD/BCD provide a redundant trigger to that of the calorimeter and a low energy trigger to the ISS-CREAM instrument. After launching, the TCD/BCD trigger was found to be working well. Also, the TCD/BCD have been stable and their hit positions were confirmed to be well matched with other detectors on board. We present the performance and status of the TCD/BCD in flight.
       
  • The Atmospheric Coupling and Dynamics Across the Mesopause (ACaDAMe)
           Mission
    • Abstract: Publication date: Available online 29 July 2019Source: Advances in Space ResearchAuthor(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.
       
  • A New Hierarchical Method for Automatic Road Centerline Extraction in
           Urban Areas using LiDAR Data
    • Abstract: Publication date: Available online 29 July 2019Source: Advances in Space ResearchAuthor(s): Sayyed Abdullah Kianezhad 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.
       
  • Aerosol and cloud radiative forcing over various hot spot regions in India
    • Abstract: Publication date: Available online 26 July 2019Source: Advances in Space ResearchAuthor(s): C. Sivan, M.G. Manoj Twelve years of NASA CERES (Clouds and Earth’s Radiant Energy System) data have been used to examine the spatio-temporal variability of aerosol– and cloud– induced shortwave radiative forcing over selected hot spot regions in India. Four regions (northern semiarid - R1; monsoon trough - R2; densely populated urban - R3; and southern peninsula - R4) are selected with different surface characteristics and notable difference in meteorological and geographical features. The analysis shows that three out of the four regions (viz. R1, R2, and R3) experience high aerosol loading and forcing in the monsoon season followed by moderate forcing in pre-monsoon season. While all the seasons except the post-monsoon period show a positive linear relation between cloud optical depth and aerosol optical depth for all the regions, the post-monsoon season shows a negative relation. However, the relation between aerosol forcing and cloud forcing shows adequate non-linearity owing to the numerous factors that control cloud radiative effect. The estimated aerosol induced heating rate shows exponential decrease with height, but with high variability during each season. Irrespective of any region, the maximum heating rate is observed in the pre-monsoon season (2.86±0.78, 2.49±0.78, 1.89±0.57, and 0.88±0.28 K/day for R1, R2, R3, and R4, respectively). Plausible reasons for the variation in the above parameters are discussed. The results suggest that increased anthropogenic activities affect the thermodynamics and hence the dynamics through retention and exchange of heat, and it could affect the precipitation pattern adversely.
       
  • List of Referees
    • Abstract: Publication date: 1 September 2019Source: Advances in Space Research, Volume 64, Issue 5Author(s):
       
  • Experimental study on drilling basalt with small diameter drilling tools
    • Abstract: Publication date: 1 September 2019Source: Advances in Space Research, Volume 64, Issue 5Author(s): Xiaogan Peng, Ting Zeng, Zhongwang Yin, Zeng Zhao, Liang Li Basalt is one of the potential hard rock targets for drilling sampling in asteroid exploration, and low sampling reaction forces are required in drilling sampling activities of an asteroid. In this paper, the experimental study of drilling basalt with small diameter cemented carbide triangular bit and diamond trepanning drill was carried out, and the drilling thrust force models of basalt drilled by cemented carbide triangular bit and diamond trepanning drill were established, respectively. The ratio of volume removal rate to drilling thrust force was proposed as the evaluation index for the primary selection of drilling tools. The test results showed that the Φ4 mm cemented carbide triangular bit was the preferred small diameter tool for drilling basalt when the minimum drilling thrust force is 40 N. The Φ8 mm electroplated diamond trepanning drill was also the preferred small diameter tool for drilling basalt, Its minimum critical drilling thrust is between 100 and 110 N. Further analysis of the drilling thrust model of the two types of drilling tools showed that the drilling thrust force of cemented carbide triangular bit drilling basalt increased with the feed rate, and it increased with the increase of the apex angle of cemented carbide triangular bit. There was minimum and maximum critical drilling thrust force in drilling basalt with diamond trepanning drill. When the drilling thrust force was between the minimum and maximum critical drilling thrust force, the volume removal rate can be improved by increasing the rotating speed of the diamond trepanning drill. This experimental study helps to optimize the drilling tools and set the drilling thrust force and rotating speed when further studying of hard rock sampling for asteroid drilling.
       
  • Soil roughness retrieval from TerraSar-X data using neural network and
           fractal method
    • Abstract: Publication date: 1 September 2019Source: Advances in Space Research, Volume 64, Issue 5Author(s): Mohammad Maleki, Jalal Amini, Claudia Notarnicola The purpose of this study is to estimate the surface roughness (rms) using TerraSar-X data in HH polarization. Simulation of data is carried out at a wide range of moisture and roughness using the Integral Equation Model (IEM). The inversion method is based on Multi-Layer Perceptron neural network. Inversion technique is performed in two steps. In the first step, the neural network is trained using synthetic data. The inputs of the first neural network are the backscattering coefficient and incidence angle, and the moisture is the output. In the next step, three neural networks are built based on a prior and without prior information on roughness. The inputs of three neural network are backscattering coefficient, estimated moisture in the first step and incidence angle and the roughness is output. The validation of the proposed methods is carried out based on synthetic and real data. Ground roughness measurements are extracted from Digital Terrain Model (DTM) using the fractal method. The accuracy of moisture from synthetic data is 6.1 vol% without prior information on moisture and roughness. The roughness (rms) accuracy of synthetic datasets is 0. 61 cm without prior information and is 0.31 cm and 0.38 cm for rms lower than 2 cm and rms between 2 and 4 cm, with prior information on roughness. The result's analysis of the simulated data showed that the prior information on roughness strongly improves the accuracy of roughness and moisture estimates. The accuracy of rms estimates for the TerraSar-X image in the HH polarization is about 0.9 cm in the case of no prior information on roughness. The accuracy improves to 0.57 cm for rms lower than 2 cm and 0.54 cm for rms between 2 and 4 cm with prior information on roughness. An overestimation of rms for rms lower than 2 cm and an underestimation of rms for rms higher than 2 cm are observed. The results of the accuracy of the synthetic and real data showed that the X band in HH polarization has a very good potential to estimate the soil roughness.
       
  • Variation of ionospheric range errors for L1 frequency GPS users during
           the 23rd solar cycle over BAHR IGS station
    • Abstract: Publication date: 1 September 2019Source: Advances in Space Research, Volume 64, Issue 5Author(s): Abdollah Masoud Darya, Muhammad Mubasshir Shaikh, Ilias Fernini Errors induced by the ionosphere on global navigation satellite systems (GNSS) signal propagation significantly affect the positioning calculation done by ground receivers. These ionospheric errors may end up reaching tens of meters in the final positioning calculation. In this study, the ionospheric range error (IRE) was monitored over the local ionosphere of BAHR, Bahrain (26.209N, 50.608E) during the period of the 23rd solar cycle. IRE values were obtained through observation data derived from RINEX files and compared with NeQuick 2 (NQ2) model calculations. It was found that, for the region of study, NQ2 overestimated the total electron content (TEC) values as compared to observation data, resulting in higher IRE values of up to 12 m. However, IRE derived using GNSS observations and NQ2 follow similar trends over the course of the solar cycle. IRE values were also compared to the smoothed sunspot number (SSN) and F10.7 indexes which resulted in significant correlation between the seasonal calculation of IRE and solar activity. Throughout the 23rd solar cycle, the highest IRE values were found during the equinoxes and the lowest during solstices. The largest IRE value was observed in the vernal equinox of 2000 (19.13 m), while the lowest IRE value was observed in the winter solstice of 1998 (0.276 m).
       
  • Statistical relation of scintillation index S4 with ionospheric
           irregularity index ROTI over Indian equatorial region
    • Abstract: Publication date: 1 September 2019Source: Advances in Space Research, Volume 64, Issue 5Author(s): Rajat Acharya, Saibal Majumdar Ionospheric scintillation can cause severe degradation in the GNSS services, particularly at the polar and equatorial regions, by deteriorating the positioning performance in terms of accuracy. The continuity of the GNSS service is also affected as severe scintillation may lead to the loss of lock of the receiver. In this work, the occurrence probability of amplitude scintillation index S4 has been statistically related to the ionospheric irregularity index of ROTI. Simultaneously measured S4 and TEC data from the GAGAN TEC network stations, installed across India, were used for the purpose. TEC is used for the derivation of ROTI. The distribution of the S4 observed over different finite ranges in ROTI was separately matched with standard parametric models. This was done for both quiet and disturbed geomagnetic conditions. Log-normal distribution has been found to be the best match for most of the cases. The parameters for the matched log-normal distributions were found to vary systematically with the mean ROTI values in the range. Therefore, these distribution parameters were modelled in the terms of the corresponding ROTI values. The derived model was successfully validated with independent data and the conformity was established using statistical methods. This work may find usefulness in estimating the probable scintillation strength S4 once the ionospheric irregularity is known in terms of ROTI. Moreover, given an observed value of ROTI, the probability of losing receiver lock can be determined, provided the corresponding threshold S4 that the receiver can withstand is known.
       
  • Model Predictive Tether-deployment Control for Precise Landing of Tethered
           Reentry Body
    • Abstract: Publication date: Available online 25 July 2019Source: Advances in Space ResearchAuthor(s): Hirohisa Kojima, Pavel M. Trivailo This paper proposes a model predictive control method for tether deployment for the precise landing of a tethered reentry body. A set of state variables for a tethered reentry system, in which the reentry body precisely lands at the target point, is numerically obtained and expressed in the form of an approximation function. The tether state is controlled by taking into consideration its deviation from the function. The effectiveness of the proposed controller for the precise landing of the reentry body is validated through numerical simulations.
       
  • Space Debris Observation Performance Research of CSTAR at Kunlun Station
           in Antarctica
    • Abstract: Publication date: Available online 24 July 2019Source: Advances in Space ResearchAuthor(s): Gongqiang Li, Hai jiang, Haowen Cheng, Jing Liu, Chenwei Yang, Peng Jiang Increasing space debris has seriously threatened the safety of spacecraft of various countries. The polar regions are the most densely distributed regions of Low-Earth orbit (LEO) space debris, and are ideal sites for observing LEO space debris. Through the real observation data and detection capabilities simulation, the advantages of China's Kunlun Station in Antarctica in observing LEO space debris are analyzed. Firstly, the real observation data of Chinese Small Telescope Array (CSTAR) are analyzed and compared with the space objects cataloging database (mean www.space-track.org), which confirms the high performance and superiority of Kunlun Station in LEO space debris observation. Secondly, the space debris observation performance of CSTAR is simulated and compared with its historical observation data in the same period, to confirm the reliability of the simulation model. Finally, based on the real observation data and simulation results, some hypothesis simulations and prospects for future space debris observation facilities at Kunlun Station are made. The simulation results can provide support for future observations at Kunlun Station in Antarctica.
       
  • Mass composition of cosmic rays above 0.1 EeV by the Yakutsk array data
    • Abstract: Publication date: Available online 24 July 2019Source: Advances in Space ResearchAuthor(s): S. Knurenko, I. Petrov The paper presents the results of the longitudinal development of extensive air showers (Xmax) of ultra-high energies and mass composition of cosmic rays. The measurements of Xmax are based on data from observations of the Cherenkov radiation at the Yakutsk array for the period 1974-2014. The cascade curves of individual showers and the depth of maximum Xmax were reconstructed over the energy range 1016-5.7·1019 eV. It is shown that the displacement rate of the parameter dXmax / dE in the atmosphere is nonlinear and depends on the energy. Such a feature indicates a change in mass composition, which is confirmed by fluctuations of Xmax in this energy region. The composition of cosmic rays was determined by interpolation using the QGSJetII-04 model.
       
  • Behavior of the ionospheric F region prior to geomagnetic storms
    • Abstract: Publication date: Available online 24 July 2019Source: Advances in Space ResearchAuthor(s): A.D. Danilov, A.V. Konstantinova The problem of occurrence of disturbances of the ionospheric F2-layer parameters prior to the beginning of geomagnetic storms is discussed. It is shown that disturbances (substantial deviations from quiet conditions) of both the critical frequency foF2 and the total electron content (TEC) in an ionospheric column are found in many studies a few hours and sometimes two–three days before the SC (sudden storm commencement) moment. The amplitudes of the aforementioned disturbances are on the average 30–60%, however, in some cases they could exceed 100%. Deviations from the quiet conditions of both signs are possible, however positive pre-storm disturbances of foF2 and TEC are found more often. Some statistical results of the analysis of the pre-storm effects in foF2 according to the data of the Slough (Chilton) station are presented.
       
  • μ m+emission+as+observed+by+TIMED/SABER+over+Asian+sector&rft.title=Advances+in+Space+Research&rft.issn=0273-1177&rft.date=&rft.volume=">Radiative cooling due to NO at 5.3 μ m emission as observed by
           TIMED/SABER over Asian sector
    • Abstract: Publication date: Available online 24 July 2019Source: Advances in Space ResearchAuthor(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.
       
  • Composite analysis of North Atlantic extra-tropical cyclone waves from
           satellite altimetry observations
    • Abstract: Publication date: Available online 24 July 2019Source: Advances in Space ResearchAuthor(s): S. Ponce de León, J.H. Bettencourt The north Atlantic Ocean is regularly traversed by extratropical cyclones and winter low pressure systems originated in the Western part of the basin that can potentially generate dangerous extreme sea states. In this paper we study the significant wave height distribution of extratropical cyclones using merged satellite altimetry data to produce composite maps of this sea state variable. Although there are large variations among individual cyclones, the compositing method allows obtaining general features. We find that the higher waves are in the south-eastern quadrant of the cyclone, due to the extended fetch mechanism. The highest wave heights are found during the 48h period when the cyclone’s strength is maximum. The strongest cyclones have higher waves over most of the eastern half, due to their northward propagation tendency.
       
  • 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: Available online 24 July 2019Source: Advances in Space ResearchAuthor(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.
       
  • Automated Crater Detection Algorithms from a Machine Learning Perspective
           in the Convolutional Neural Network Era
    • Abstract: Publication date: Available online 22 July 2019Source: Advances in Space ResearchAuthor(s): D.M. DeLatte, S.T. Crites, N. Guttenberg, T. Yairi Convolutional Neural Networks (CNN) offer promising opportunities to automatically glean scientifically relevant information directly from annotated images, without needing to handcraft features for detection. Crater counting started with hand counting hundreds, thousands, or even millions of craters in order to determine the age of geological units on planetary bodies of the solar system. Automated crater detection algorithms have attempted to speed up this process. Previous research has employed computer vision techniques with handcrafted features such as light and shadow patterns, circle finding, or edge detection. This research continues, but now some researchers use techniques like convolutional neural networks that enable the algorithm to develop its own features. As the field of machine learning undergoes exponential growth in terms of paper count and research methods, the crater counting application can benefit from the new research, especially when conducting joint interdisciplinary projects. Despite these advancements, the crater counting community has not yet adopted standard methods for automating the process despite decades of research. This survey enumerates challenges for both planetary geologists and machine learning researchers, looks at the recent automatic crater detection advancements using machine learning techniques (primarily in methods using CNNs), and makes recommendations for the path toward greater automation.
       
  • Insights from Multi-Wavelength Observations During High and Low States of
           Non-Magnetic CVs
    • Abstract: Publication date: Available online 22 July 2019Source: Advances in Space ResearchAuthor(s): Paula Szkody Close binaries containing a white dwarf accreting from a disk that receives material from a late stellar companion show an interesting variety of behaviors that depend on their accretion rates and the changes in this rate. The highest accretion rates are evident during the bright states of novalikes, as well as the superoutbursts of the shortest period dwarf novae followed by normal outbursts and the Z Cam systems. While the normal outbursts and superoutbursts of dwarf novae can be understood from the standpoint of disk and tidal instabilities, the changes in rates in novalikes when they enter low brightness states and the cause of extremely high rates for the systems with orbital periods between 3-4 hrs remain elusive. This paper highlights some recent insights and continuing problems found from X-ray, UV and optical observations of these high and low states, as well as the prospects for increased understanding from the anticipated future ground and space missions.
       
  • Around the world with Space VLBI: a sense of many places
    • Abstract: Publication date: Available online 22 July 2019Source: Advances in Space ResearchAuthor(s): David L. Jauncey
       
  • Possibilities of the usage of the total electron content in a low-latitude
           zone
    • Abstract: Publication date: Available online 19 July 2019Source: Advances in Space ResearchAuthor(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
       
  • SWOT and the ice-covered polar oceans: An exploratory analysis
    • Abstract: Publication date: Available online 17 July 2019Source: Advances in Space ResearchAuthor(s): Thomas W.K. Armitage, Ron Kwok The Surface Water Ocean Topography mission (SWOT), scheduled for launch in 2021, is the first space-borne radar interferometer capable of providing wide-swath height maps of water surfaces with centimetric precision. In addition to its primary objectives in oceanography and hydrography, the SWOT instrument offers opportunities for other applications. Here, we explore the feasibility of sea ice freeboard and sea surface height retrievals in the ice-covered oceans from SWOT data. The quality of SWOT height estimates depends on the backscatter strength and number of samples used for multi-looking. We use near-nadir radar backscatter estimates from sea ice and water over the range of SWOT incidence angles to simulate SWOT height maps and assess the retrieval precision under different backscatter, surface type and roughness conditions. Unlike wind-roughened open water, the available observations suggest that backscatter over sea ice has a moderate dependence on look angle (specularity), and the backscatter of younger, flatter sea ice has a greater degree of specularity than older, more deformed and colder sea ice. To achieve a similar freeboard precision to conventional altimeters (∼3 cm) requires averaging over 15–40 km2 in the near- to mid-swath and 90–175 km2 in the far-swath for lower northern latitudes (
       
  • Exploring the outer emission corona spectroscopically by using Visible
           Emission Line Coronagraph (VELC) on board ADITYA–L1 mission
    • Abstract: Publication date: Available online 17 July 2019Source: Advances in Space ResearchAuthor(s): Jagdev Singh, B Raghavendra Prasad, Suresh Venkata, Amit Kumar It is very important to make the spectrographic observations of the outer emission corona in number of emission lines simultaneously in view of the results of the observations made in [Fe x] 6374 Å, [Fe xi] 7892 Å, [Fe xiv] 5303 Åand [Fe xiii] 10747 Åcoronal emission lines with the 25 cm coronagraph at Norikura Observatory in Japan. At ground based observatories, availability of number of hours of clear sky for coronagraphic observations is limited due to aerosols scattering and scattering from the internal coronagraph reflections . A space based coronagraph Visible Emission Line Coronagraph (VELC) on board ADITYA–L1 has been planned to perform spectroscopy in 3 out of the 4 emission lines mentioned above. Here, we discuss the various requirements for the parameters of the payload, given the specifications of the satellite, to observe the outer emission corona reliably with good Signal to Noise Ratio (SNR), realize the projected scientific goals and make the mission a great success.
       
  • A Charge Sharing Study of Silicon Microstrip Detectors with Electrical
           Characterization and SPICE Simulation
    • Abstract: Publication date: Available online 17 July 2019Source: Advances in Space ResearchAuthor(s): Rui Qiao, Wen-Xi Peng, Xing-Zhu Cui, Guang-Qi Dai, Yi-Fan Dong, Rui-Rui Fan, Min Gao, Ke Gong, Dong-Ya Guo, Xiao-Hua Liang, Ya-Qing Liu, Huan-Yu Wang, Jin-Zhou Wang, Di Wu, Jia-Wei Yang, Fei Zhang, Hao Zhao Silicon microstrip detectors with floating strips have nonuniform charge collection efficiency. This nonuniformity depends on the incident position and incident angle and should be corrected during charge reconstruction. A novel charge reconstruction algorithm, called the charge sharing algorithm, is introduced to correct this nonuniformity. This algorithm assumes that the nonuniformity in charge collection efficiency is due to charge sharing through the capacitors and resistors of silicon microstrip detectors. This charge sharing assumption is tested in this paper using electrical characterization and SPICE simulation.
       
  • Comparison-space selection to achieve efficient tracklet-to-object
           association
    • Abstract: Publication date: Available online 17 July 2019Source: Advances in Space ResearchAuthor(s): J.A. Siminski, T. Flohrer A major challenge when maintaining a space object catalog is the proper association of new measurements to already cataloged objects. Optical observations are typically associated by comparing the modeled observation to the measured one. The modeled observation is generated from cataloged object states by propagating them to the epoch of observation and transforming them from state space, e.g. orbital elements, to the observation space, e.g. right ascension and declination angles. In addition to propagating the states, their propagated uncertainty distribution is transformed to observation space as well. Statistical distance metrics, such as the Mahalanobis distance, are then evaluated to test whether the observation originated from the cataloged object or not. These distance measures often assume that the uncertainty can be represented with a normal distribution. Assuming that the catalog state uncertainty is properly represented by a normal distribution, it can still loose this property during the propagation in time and the transformation to observation space. The uncertainty of the catalog state is typically much larger than the one from new measurements (only a few arc seconds for optical telescopes) and is therefore more affected by transformation distortions. It is therefore beneficial to perform the comparison in a space advantageous for the state representation. This study will present a projection-based transformation of tracklet information into a favorable frame around the cataloged object state. The effect of the comparison-space selection on cataloguing performance is assessed, i.e. it is systematically tested if it is beneficial to directly compare angles and angular rates, or to compare in the newly proposed projected frame.
       
  • Noise estimation and probability of detection in non-resolved images:
           application to space object observation
    • Abstract: Publication date: Available online 16 July 2019Source: Advances in Space ResearchAuthor(s): Francois Sanson, Carolin Frueh Charged Couple Device (CCD) technology is widely used in various scientific measurement contexts. CCD equipped cameras have revolutionized astronomy and space-related optical telescope measurements in recent years. They are also used in electroscopic measurements, e.g., in fields such as geology, biology, and medicine. The signal-to-noise ratio and the probability of detection are crucial to design experiments observation setups properly and to employ further mathematical methods for data exploitation such as, e.g. multi-target tracking methods. Previous attempts to correctly characterize the signal-to-noise ratio for star observations are revisited in this work and adapted for the application of near-Earth object observations and high precision measurements, leading to a modified CCD equation. Our formulation proposes a novel distribution of the signal noise that accurately accounts for the truncation noise and the presence of ambiguous pixels. These improvements are employed to derive the probability of detection and the SNR with significant improvements compared to existing formulations when ambiguous pixels are present.
       
  • Onboard Distributed Autonomous Orbit Determination based on State Caching
           Approach
    • Abstract: Publication date: Available online 16 July 2019Source: Advances in Space ResearchAuthor(s): Jun Lai, Yongbin Zhou, Yifan Zhou, Jun Yang Autonomous Orbit Determination (AOD) using inter-satellite ranging measurement can maintain the functionality of the Global Navigation Satellite System (GNSS) for a long time without the assistance of the ground facilities, even though it has the rank deficiency problem. This paper proposes an onboard distributed algorithm to implement AOD based on the extended Kalman filter. It exploits the inter-satellite ranging schedule as a priori information and maintains a cache of the estimated global states and the corresponding covariance on each satellite. Simulation results show that the mean User Range Error (URE) of a 31-satellite GPS constellation is less than 0.5m in 120 days using our algorithm, which has a similar accuracy level as the centralized Kalman filter, and outperforms the conventional distributed algorithm. It also shows that our algorithm is robust to constellation size and ranging measurement noise level. Meanwhile, due to the distributed architecture, our algorithm does not require any additional communication among satellites. All these features make our algorithm more applicable to practical scenario compared to the existing algorithms.
       
  • An algorithm for deriving the electron temperature and electron density
           probed by Langmuir probe onboard cube satellites
    • Abstract: Publication date: Available online 15 July 2019Source: Advances in Space ResearchAuthor(s): Chen-Kang Chiang, Tse-Liang Yeh, Jann-Yenq Liu, Chi-Kuang Chao, Loren C.Chang, Li-Wu Chen, Chung-Jen Chou, Shyh-Biau Jiang The paper purposes an algorithm for a Langmuir probe (LP) onboard CubeSat to correctly probe of ionospheric electron temperature and electron density. The algorithm consists of two parts of deriving the current-voltage (I–V) curve for the probe, and refining the electron temperature and the electron density by an iteration method. The small surface area of a CubeSat’s body has a strong influence on the reference potential of the satellite body, which can significantly distort the I–V curve and affect the accuracy of electron temperature and electron density observations. Here, we utilize a digital circuit simulation to construct the circuit model, including the satellite DS (Debye-Sheath), the probe DS, and the scan voltage source. Simulation data describe that the satellite DS shares the scan voltage, which is the main causal of the distortion of the aforementioned I–V curve and the change of the turning point. We also find that an underestimated turning point is due to the ion saturation of the satellite shell DS rather than the electron saturation of the probe DS. Therefore, small satellite LPs should not directly use the turning point to calculate the electron temperature and the electron density. To resolve this small-area problem, a theoretical relationship between the satellite DS voltage, the probe DS voltage, and the scan voltage is deduced, which allows us finding the probe voltage from the scan voltage, yielding the correct I–V curve for LPs, and estimating the electron temperature/density for small satellites. To more accurately derive the electron temperature and electron density, an iteration method is introduced, that the electron current-voltage curve needs to be separated from the I–V curve, and then iterates between the electron temperature estimation and the I–V curve correction. Finally, observed ionospheric electron temperature and density are used to test our algorithm. Good agreements between derived results and the observations conform that the purposed algorithm can correctly obtain the electron temperature and the electron density.
       
  • Data processing center of RadioAstron space VLBI project
    • Abstract: Publication date: Available online 9 July 2019Source: Advances in Space ResearchAuthor(s): M.V. Shatskaya, A.A. Abramov, N.A. Fedorov, V.I. Kostenko, S.F. Likhachev, S.I. Seliverstov, D.A. Sychev In this paper, questions on development, implementation, and operation of RadioAstron project Data Processing Center (DPC) are reviewed. The main components of the dedicated DPC are the computer complex with 1 TFlops/s performance, storage with memory capacity of approximately 10 PB, the network infrastructure, and the corresponding communication channels. Performance enhancement methods and resolution of information storage, archiving, and process problems of space VLBI high-speed digital data flows are analyzed. It is shown that successful operation of DPC is mainly provided by optimal organization of computer system structure, storage, and networking transmission. Some of the important key features of RadioAstron project DPC and its comparative differences from the standard VLBI procedures are considered.
       
  • Real-time clock prediction of Multi-GNSS satellites and its application in
           precise point positioning
    • Abstract: Publication date: Available online 8 July 2019Source: Advances in Space ResearchAuthor(s): Peng Yaquan, Lou Yidong, Gong Xiaopeng, Wang Yintong, Dai Xiaolei With the development of Global Navigation Satellite System (GNSS), multi-GNSS is expected to greatly benefit precise point positioning (PPP), especially during the outage of real time service (RTS). In this paper, we focus on the performance of multi-GNSS satellite clock prediction and its application in real-time PPP. Based on the statistical analysis of multi-system satellite clock products, a model consisting of polynomial and periodic terms is employed for multi-system satellite clock prediction. To evaluate the method proposed, both post-processed and real-time satellite clock products are employed in simulated real-time processing mode. The results show that the accuracy of satellite clock prediction is related to atomic clock type and satellite type. For GPS satellites, the average standard deviations (STDs) of Cs atomic clocks will reach as high as 0.65 ns while the STD of Rb atomic clocks is only about 0.15 ns. As for BDS and Galileo, the average STD of 2-hour satellite clock prediction are 0.30 ns and 0.06 ns, respectively. In addition, it is validated that real-time PPP can still achieve positioning accuracy of one to three decimeters by using products of 2-hour satellite clock prediction. Moreover, compared to the results of GPS-only PPP, multi-system can greatly enhance the accuracy of real-time PPP from 12.5% to 18.5% in different situations.
       
  • Seasonal variation of plasma bubbles during solar cycle 23 - 24 over the
           Brazilian equatorial region
    • Abstract: Publication date: Available online 8 July 2019Source: Advances in Space ResearchAuthor(s): Ebenezer Agyei-Yeboah, Igo Paulino, Amauri Fragaso de Medeiros, Ricardo Arlen Buriti, Ana Roberta Paulino, Patrick Essien, Solomon Otoo Lomotey, Hisao Takashi, Cristiano Max Wrasse In this study, OI 630.0 nm nightglow image data obtained from an all-sky imaging station located at Sao Joao do Cariri (7.4°S, 36.5°W), have been used to study the occurrence of equatorial plasma bubbles (EPBs) over the Brazilian equatorial region. The observations, which took place from September 2000 to December 2010 (almost eleven years), covered a significant part of solar cycle 23 (descending phase of SC23) and the very beginning of solar cycle 24 (ascending phase of SC24). There were 1337 nights of observations with 666 nights with EPB events, which translates to an occurrence rate of ∼49.8 %. Of these nights, 1290 were considered quiet (Dst ≥ -50 nT) with ∼ 50 % plasma bubbles occurrence rate. The occurrence of EPBs was studied under three solar activity phases – high solar activity phase (HSA, September 2000 – March 2004), moderate solar activity phase (MSA or descending phase, March 2004 – October 2006) and low solar activity phase (LSA, October 2006 – December 2010). The low solar activity phase is part of the peculiar solar cycle 24, considered the weakest in over a century with most sunspotless days (2008 - 2009). The maximum occurrence of bubbles, equal to 54.2 %, was found during the HSA phase, with percentages characterizing MSA and LSA being respectively 52.4 % and 45.8 %. The analysis also showed clear seasonal variation in the EPB occurrence with maximum rates in summer, spring, autumn, and the minimum rates in winter for all solar activity phases. Overall, there was observed solar cycle variation in each season with maximum occurrence in HSA followed by MSA and then LSA except in autumn where higher occurrence rate was observed in LSA phase than in MSA phase.
       
  • Ionospheric Es Layer Scintillation Characteristics Studied with
           Hilbert-Huang Transform
    • Abstract: Publication date: Available online 8 July 2019Source: Advances in Space ResearchAuthor(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 observation 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 meters 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.
       
  • Downshifted peak features of stimulated electromagnetic emissions during a
           two-pump wave heating experiment
    • Abstract: Publication date: Available online 4 July 2019Source: Advances in Space ResearchAuthor(s): Guanglin Ma, Lixin Guo, Qingliang Li, Jutao Yang, Libin Lv, Jing Chen, Tong Xu, Shuji Hao, Jian Wu Experimental results of the downshifted peak (DP) in stimulated electromagnetic emissions under two-pump wave ionospheric heating near the third electron gyroharmonic frequency are presented. The European Incoherent Scatter Scientific Association heating antenna array was divided into two parts, one of which worked at constant pump wave frequency f1 and the other part worked at varied pump wave frequency f2 which was not larger than f1. It was found that when the second pump wave was turned on at different frequency with f1, the f1 DP power declined by more than 10 dB with respect to the background noise level, while the downshifted maximum belonging to f1 was further enhanced. The time needed to reach a steady state for DP was shortened from approximately 10 s under cold background conditions belonging to f1, which was nearly consistent with growth time of small-scale artificially field-aligned irregularity (AFAI), to less than 1 s under the preconditioned heating belonging to f2 with pre-existing AFAI. According to the difference in DP temporal evolution under two experimental conditions, it could be deduced that AFAI plays an important role in the DP generation process. Similar to single-pump wave heating, the frequency offset of DP decreases as f2 increases toward the third electron gyroharmonic frequency. These experimental findings provide new insights into the theoretical study of ionospheric plasma nonlinearity.
       
  • Characterizing inter-frequency bias and signal quality for GLONASS
           satellites with triple-frequency transmissions
    • Abstract: Publication date: Available online 4 July 2019Source: Advances in Space ResearchAuthor(s): Lin Pan, Xiaohong Zhang, Fei Guo The GLONASS SVNs 702K (R09), 755 (R21) and 701K (R26) satellites currently provide G1, G2 and G3 signals. The difference between satellite clocks calculated by G1/G2 and G1/G3 ionospheric-free combinations, termed inter-frequency bias (IFB), is identified. The presence of IFB limits the application of G3 signal in precise positioning. The IFB is investigated using the datasets from 70 stations with a global distribution spanning 30 consecutive days. The epoch-wise phase-specific IFB (PIFB) estimates show periodic variations with a period of eight days and an average peak-to-peak amplitude of 0.107, 0.327 and 1.663 m for the R09, R21 and R26 satellites, respectively. The daily stable code-specific IFB (CIFB) estimates also show 8-day periodic signal. The day-to-day scattering of daily stable CIFB is 0.060–0.085 m. The estimation accuracy and prediction accuracy of PIFB are 0.025 and 0.019 m, respectively, while the corresponding statistics for the daily stable CIFB are 0.452 and 0.056 m, respectively. A modified estimation approach is developed to derive the time-varying epoch-wise CIFB. The epoch-wise CIFB and PIFB shows sub-daily periodic variations with the most notable periods of 5.625 and 11.250 h, respectively. The correction rate is 32% in terms of the prediction of the time-varying part of the epoch-wise CIFB. In addition, the signal quality is assessed from such aspects as carrier-to-noise density ratio, measurement noise and multipath errors.
       
  • Analysis of the Change of Orbital Elements in the Process of Gravity
           Assist
    • Abstract: Publication date: Available online 3 July 2019Source: Advances in Space ResearchAuthor(s): Jingxi Liu, Bo Xu, Lei Zhang Gravity assist is widely applied in the deep space exploration because of its reliability and practicability. There are lots of research in the literature about the nearly coplanar situations. In this work, a three-dimensional model of gravity assist model is developed in a semi-analytical manner on the basis of the geometry relationship between the parameters of spacecraft before gravity assist and the orbital elements after gravity assist. The parameters include V∞in (the hyperbolic excess velocity vector of the spacecraft before fly-by), H (the height of fly-by) and θ (the dihedral angle between approach plane and fly-by plane). These equations can be used for analyzing the change of orbital elements in the process of gravity assist, discussing the influence of different parameters on them and deriving the condition that remains the semi-major axis unchanged. Curve fitting of the feasible region boundary of Δi and contour plot of Δi are utilized to analyze the pattern of Δi changing with different parameters. This method is a valuable reference for designing gravity assist trajectories to high inclination targets in the Solar system.
       
  • Cosmic Ray Origin: Why Cosmic Ray (Astroparticle) Phenomenon is Universal
           in the Universe' What is the Main Driver of Cosmic Ray Particle
           Generation'
    • Abstract: Publication date: Available online 2 July 2019Source: Advances in Space ResearchAuthor(s): Lev Dorman During many years energetic particles generated on the Sun were called as Solar Cosmic Rays (SCR), but now increased the tendency to rename this phenomenon as Solar Energetic Particles (SEP) event. We will show that SEP, as well as energetic particles generated in magnetospheres of the Earth, Jupiter, Saturn and other planets, in interplanetary space, and in atmospheres of stars have the same nature as Galactic and Intergalactic CR: they are all runaway particles from the Maxwell-Boltzmann distribution of background plasma where they were generated. Energy of these run-away particles is much higher than average energy of background thermal particles. It is shown in this paper that the energy of all these run-away particles have the same general nature: it is always transfer energy from the Macro-objects and Macro-processes directly to Micro World (to charged runaway particles). This transfer energy is formatted in dynamic plasma with frozen in magnetic fields: really magnetic fields ’glues’ billions thermal background particles into Macro-objects and Macro-processes. So, thank to frozen in magnetic fields runaway particles can interact not only with thermal background particles (and loose energy), but also directly with Macro-objects and Macro-processes with very high macro-energy (many order higher than energy of run-away particle). Thermodynamically Macro-objects and Macro-processes have much bigger “effective temperature” than runaway particles and though the energy always transferred from Macro World to runaway particles of Micro World. We come to conclusion that main cause of origin of all types of Cosmic Rays in the Universe is the transform energy from Macro-world directly to Micro-world through frozen in magnetic fields in plasmas. At the stage when in early Universe were formatted small density plasmas objects with frozen in magnetic fields, where formatted also Cosmic Rays of different types, but these “relict” Cosmic Ray particles have now very small energy thanks to extension Universe. So, observed now CR particles of different types are generated continuously by transfer energy from Macro World to runaway charged particles of Micro World through frozen in magnetic fields (including the main sources as Supernova explosions, Supernova remnants, and some smaller sources, as stars, star’s winds, planetary magnetospheres, and others).
       
  • Secondary cosmic rays in the NUCLEON space experiment
    • Abstract: Publication date: Available online 2 July 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 space observatory is a direct cosmic ray spectrometer designed to study cosmic ray nuclei with Z=1-30 at energies 1012-1015 eV. It was launched as an additional payload onboard the Russian Resource-P No. 2 satellite in December of 2014. In this work B/C, N/O and subFe/Fe ratios are presented. The experiment has worked for half of its expected time, so the data have preliminary status, but they already give clear indications of several astrophysical phenomena, which are briefly discussed in this paper.
       
  • Evaluation of CryoSat-2 water level derived from different retracking
           scenarios over selected inland water bodies
    • Abstract: Publication date: Available online 2 July 2019Source: Advances in Space ResearchAuthor(s): Sh. Roohi, N. Sneeuw, J. Benveniste, S. Dinardo, E.A. Issawy, G. Zhang As the first satellite altimetry mission operating in sar (delay-Doppler) mode, CryoSat-2 is an interesting mission to analyze its performance for water level monitoring over inland water bodies. It offers the opportunity to make comparison of sar and conventional altimeters by a multi-mode altimeter mounted on the same platform with a long repeat orbit. This comparison gives us more knowledge about the performance of the sar altimeter. Even tough it is not possible to perform it over same objects.In this paper we analyze the CryoSat-2 performance for water level monitoring via full- and sub-waveform retracking against in-situ gauge and L2 products of other satellite altimetry missions, e.g. Envisat and Jason-2. To this end, we retrack the full-waveforms and sub-waveforms with different empirical and physical retracking algorithms such as ocog, threshold, β-parameters and samosa3. We evaluate its capability in all measurement modes, i.e. lrm, sar and sarin, over inland water bodies located in different climatic zones. We selected study areas with different shapes and sizes.Relative to in situ measurements we find a precision of the CryoSat-2 lrm mode of 15cmrms over Qinghai lake (China) and 13cm over Erie lake (usa). This is an improvement over Envisat, yielding precision of 17cm in both cases. For the sar mode over Neagh lake (Northern Ireland) and Derg lake (Ireland) we obtain 15cm and 13cm where Envisat yields 28cm and 100cm, respectively. The sarin mode’s precision is assessed over Nasser lake (Egypt) with 25cmrms and Athabasca lake (Canada) with 16cm. Over these lakes Jason-2 achieved 54cm and Envisat 19cm, respectively. The most precise results of CryoSat-2 are obtained with our retracking and sub-waveform selection scenarios. Comparing CryoSat-2 results from our retracking scenarios using L1b data with those results obtained from L2 products (data) of this mission shows an improvement of 4–17 cm. The minimum and maximum improvements belong to Erie and Derg lakes respectively, the largest and smallest lakes.From the waveform analysis over lakes with different shapes and sizes, we found that the first and the mean-all sub-waveforms (mean correction from all sub-waveforms) retracked with the threshold and samosa3 (only for sar mode) retrackers are appropriate to retrieve water level variation of small lakes and complex shaped lakes in this study. Over large lakes the full-waveform retracking leads to better results. In the case of icy-lake objects, sub-waveform retracking scenarios (the first and mean-all sub-waveforms) are more precise than the other scenarios. These are our findings over few samples, though more samples need to be analyzed to support them strongly.
       
  • Relative equilibria of an intermediary model for the roto-orbital
           dynamics. The low rotation regime
    • Abstract: Publication date: Available online 2 July 2019Source: Advances in Space ResearchAuthor(s): J.L. Zapata, F. Crespo, S. Ferrer, F.J. Molero We address the attitude dynamics of a triaxial rigid body in a circular orbit. This task is done by means of an intermediary model, which is obtained by splitting the Hamiltonian in the form H=H0+H1, where H0 is required to be a non-degenerate integrable Hamiltonian system. A numerical study is presented comparing the dynamics of the new intermediary model with the full system (MacCullagh’s truncation) and showing a competitive performance for the cases Sun-asteroid and Earth-spacecraft. This model defines a Poisson flow endowed with invariants defining a SM2×SM2 reduced space. We analyze the coupling between the orbital mean motion and rotational variables. The key role played by the moments of inertia and the value of the angular momentum is shown in detail. The analysis of the intermediary shows that, under slow rotation regime, the classic dynamics of the free rigid body is no longer maintained: bifurcations with changes of stability are displayed for several critical inclinations of the rotational angular momentum plane and for critical orientations of the body frame. Moreover, the evolution of the angular momentum plane is given by a time dependent harmonic oscillator.
       
  • Statistical analysis and modelling of sporadic E layer over Europe
    • Abstract: Publication date: Available online 1 July 2019Source: Advances in Space ResearchAuthor(s): N.Y. Zaalov, E.V. Moskaleva This paper describes a study of the daily and yearly variability of one of the main characteristics of sporadic E layers (Es), the critical frequency (foEs). Our analysis is based on ionograms recorded by GIRO network ionosondes. The study estimates the spatial and temporal variability of the Es layer parameters and generates their statistics at different seasons and phases of the solar cycle. In turn, the statistics of the Es layer parameters can provide an assessment of the capability of the HF propagation forecasting. Further, maps of the distribution of Es layer critical frequency are produced. This paper implements the “cloud” model of Es layer in HF propagation model (Northern Ionosphere Model & Ray Tracing, NIM-RT) that can accurately reproduce many features observed in experimental measurements. Within this framework, a number of vertical sounding ionograms with the presence of Es layer are simulated based on the NIM-RT software.
       
  • 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: Available online 28 June 2019Source: Advances in Space ResearchAuthor(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.
       
  • Attitude Control for Tethered Towing debris under Actuators and Dynamics
           Uncertainty
    • Abstract: Publication date: Available online 27 June 2019Source: Advances in Space ResearchAuthor(s): Cheng Jia, Zhongjie Meng, Panfeng Huang Tethered towing is regarded as a promising debris removal technology to decrease the population of space debris. Owing to the debris rotation, the debris and tether are vulnerable to entanglement in the towing process. After capture, the untight capture leads to relative motion between gripper and debris and changes the actuator configuration matrix inevitably. Thus, except the traditional dynamics uncertainties, it is also necessary to consider the control allocation of multi-actuators under the nonnegative unilateral magnitude constraint and configuration matrix uncertainty. To tackle these problems, a novel scheme was proposed to stabilize the attitude of debris using adaptive backstepping control with robust allocation technique. Specifically, the adaptive attitude stabilization law is designed to generate control torques in the presence of dynamics uncertainties. A robust control allocation algorithm is developed to distribute the three axis torques to redundant actuators, in which the optimal control vector of actuator is obtained by interior-point method, under the actuator configuration matrix uncertainty and saturation constraints. Finally, numerical simulation results are employed to validate the effectiveness of the proposed scheme.
       
  • Advanced Technologies for Satellite Navigation and Geodesy
    • Abstract: Publication date: Available online 27 June 2019Source: Advances in Space ResearchAuthor(s): G. Giorgi, T.D. Schmidt, C. Trainotti, R. Mata-Calvo, C. Fuchs, M.M. Hoque, J. Berdermann, J. Furthner, C. Günther, T. Schuldt, J. Sanjuan, M. Gohlke, M. Oswald, C. Braxmaier, K. Balidakis, G. Dick, F. Flechtner, M. Ge, S. Glaser, R. König This manuscript reviews recent progress in optical frequency references and optical communication systems and discusses their utilizations in global satellite navigation systems and satellite geodesy. Lasers stabilized with optical cavities or spectroscopy of molecular iodine are analyzed, and a hybrid architecture is proposed to combine both forms of stabilization with the aim of achieving a target frequency stability of 10-15 [s/s] over a wide range of sampling intervals.The synchronization between two optical frequency references in real-time is realized by means of time and frequency transfer on optical carriers. The technologies enabling coherent optical links are reviewed, and the development of an optical communication system for synchronization, ranging and data communication in space is described. An infrastructure exploiting the capabilities of both optical technologies for the realization of a modernized constellation of navigation satellites emitting highly synchronized signals is reviewed. Such infrastructure, named Kepler system, improves satellite navigation in terms intra-system synchronization, orbit determination accuracy, as well as system monitoring and integrity. The potential impact on geodetic key parameters is addressed.
       
  • Numerical modeling of cosmic-ray transport in the heliosphere and
           interpretation of the proton-to-helium ratio in Solar Cycle 24
    • Abstract: Publication date: Available online 27 June 2019Source: Advances in Space ResearchAuthor(s): Nicola Tomassetti, Fernando Barão, Bruna Bertucci, Emanuele Fiandrini, Miguel Orcinha Thanks to space-borne experiments of cosmic-ray (CR) detection, such as the AMS and PAMELA missions in low-Earth orbit, or the Voyager-1 spacecraft in the interstellar space, a large collection of multi-channel and time-resolved CR data has become available. Recently, the AMS experiment has released new precision data, on the proton and helium fluxes in CRs, measured on monthly basis during its first six years of mission. The AMS data reveal a remarkable long-term behavior in the temporal evolution of the proton-to-helium ratio at rigidity R≡p/Z≲,3 GV. As we have argued in a recent work, such a behavior may reflect the transport properties of low-rigidity CRs in the inteplanetary space. In particular, it can be caused by mass/charge dependence of the CR diffusion coefficient. In this paper, we present our developments in the numerical modeling of CR transport in the Milky Way and in the heliosphere. Within our model, and with the help of approximated analytical solutions, we describe in details the relations between the properties of CR diffusion and the time-dependent evolution of the proton-to-helium ratio.
       
  • CHAMP and GOCE thermospheric wind characterization with improved
           gas-surface interactions modelling
    • Abstract: Publication date: Available online 27 June 2019Source: Advances in Space ResearchAuthor(s): G. March, T. Visser, P.N.A.M. Visser, E.N. Doornbos The CHAMP and GOCE satellites provided high-resolution thermosphere data between 2000 and 2013, improving our knowledge of atmosphere dynamics in the thermosphere–ionosphere region. However, the currently available data sets contain inconsistencies with each other and with external data sets and models, arising to a large extent from errors in the modelling of aerodynamic forces. Improved processing of the wind data for the two satellites would benefit the further development and validation of thermosphere models and improve current understanding of atmospheric dynamics and long-term trends. The first step to remove inconsistencies has been the development of high-fidelity models of the satellite surface geometry. Next, an improved characterization of the collisions between atmospheric particles and satellite surfaces is necessary. In this article, the effect of varying the energy accommodation coefficient, which is a key parameter for describing gas-surface interactions (GSI) is investigated. For past versions of the thermosphere density and wind data from these satellites a value of the energy accommodation coefficient of αE=0.93 was selected. The satellite accelerometer measurements, from which the thermospheric data are derived, have now been reprocessed using high-fidelity geometries and a wide range of αE values. Lowering the αE value used in the processing leads to an increase in the lift over drag ratio for those satellite panels that are inclined to the flow. This changes the direction of the modelled acceleration, and therefore the interpretation of the measured acceleration in terms of wind. The wrong choice of αE therefore leads to the introduction of satellite attitude-dependent wind errors. For the CHAMP and GOCE satellites, we have found that values of the energy accommodation coefficient significantly lower than 0.93 (0.85 for CHAMP and 0.82 for GOCE) result in increased consistency of the wind data. A comparison between the two missions and an overview of the influence on the results of filtering for solar activity and seasonal and diurnal variations is presented.
       
  • InfraRed Astronomy Satellite Swarm Interferometry (IRASSI): Overview and
           Study Results
    • Abstract: Publication date: Available online 27 June 2019Source: Advances in Space ResearchAuthor(s): Hendrik Linz, Divya Bhatia, Luisa Buinhas, Matthias Lezius, Eloi Ferrer, Roger Förstner, Kathrin Frankl, Mathias Philips-Blum, Meiko Steen, Ulf Bestmann, Wolfgang Hänsel, Ronald Holzwarth, Oliver Krause, Thomas Pany The far-infrared (FIR) regime is one of the few wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist yet. Neither of the medium-term satellite projects like SPICA, Millimetron or OST will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO) and especially from water lines would open the door for transformative science. These demands call for interferometric concepts. We present here first results of our feasibility study IRASSI (Infrared Astronomy Satellite Swarm Interferometry) for an FIR space interferometer. Extending on the principal concept of the previous study ESPRIT, it features heterodyne interferometry within a swarm of five satellite elements. The satellites can drift in and out within a range of several hundred meters, thereby achieving spatial resolutions of
       
  • Secondary cameras onboard the Mini-EUSO experiment: Control Software and
           Calibration
    • Abstract: Publication date: Available online 21 June 2019Source: Advances in Space ResearchAuthor(s): S. Turriziani, J. Ekelund, K. Tsuno, M. Casolino, T. Ebisuzaki Mini-EUSO is a space experiment selected to be installed inside the International Space Station. It has a compact telescope with a large field of view (44 × 44 sq. deg.) focusing light on an array of photo-multipliers tubes in order to observe UV emission coming from Earth’s atmosphere. Observations will be complemented with data recorded by some ancillary detectors. In particular, the Mini-EUSO Additional Data Acquisition System (ADS) is composed by two cameras, which will allow us to obtain data in the near infrared, and in the visible range. These will be used to monitor the observation conditions, and to acquire useful information on several scientific topics to be studied with the main instrument, such as the physics of atmosphere, meteors, and strange quark matter. Here we present the ADS control software developed to stream cameras together with the UV main instrument, in order to grab images in an automated and independent way, and we also describe the calibration activities performed on these two ancillary cameras before flight.
       
  • Quasi-Periodic Pulsations in Hard X-rays of Partially Occulted Solar
           Flares
    • Abstract: Publication date: Available online 21 June 2019Source: Advances in Space ResearchAuthor(s): Ż. Szaforz, M. Tomczak We investigated solar flares partially occulted by the solar disk observed by the Yohkoh satellite. We found that about 30–40% of them show quasi-periodic pulsations (QPPs) in hard X-rays (HXR). A lack of usually brighter footpoint sources allowed us to reconstruct coronal HXR sources with a higher quality. We analyzed 28 partially occulted flares showing the QPPs and for the first time present results for such events as a group. In our opinion, the majority of the observed HXR loop-top sources can be explained as successive compression and rarefaction of magnetic traps described in a model of oscillating magnetic traps (OMT). In this model a particular value of a ratio between the diameter of traps and the period of pulsations is postulated. In our modification of this model, different values of the ratio are possible, with the exception of a lower range, where low values of magnetic field strength and high values of electron density number can excess the plasma-β parameter above unity (ballooning instability).
       
  • Features of downshifted maximum spectra during a dual-pump ionospheric
           heating experiment
    • Abstract: Publication date: Available online 20 June 2019Source: Advances in Space ResearchAuthor(s): Libin Lv, Zhensen Wu, Qingliang Li, Shuji Hao, Guanglin Ma, JuTao Yang, Jian Ding, Jian Wu An ionospheric heating experiment was conducted using the dual-pump mode at the EISCAT/HEATING facility in Tromsø, Norway. Some new features were found in the downshifted maximum (DM) component of the stimulated electromagnetic emission (SEE) spectra. During the experiment, the DM1 generated by pump 1 was enhanced under the action of pump 2 with the peak intensity being increased by ∼4.8–9.8 dB to achieve maximum value, when the frequency of pump 2 was 4.100 MHz. The gyro resonance at the upper hybrid altitude played an important role in this phenomenon. It was also observed that the development time of DM2 generated by pump 2 was greatly shorter than that of DM1 due to the precondition provided by the artificial field-aligned irregularities (AFAIs) stimulated by pump 1. Additionally, the frequency offset and peak intensity of the DM1 spectrum showed a significant negative correlation, where the correlation coefficient reached a value of -0.91.
       
  • Impact of GPS receiver antenna GRAPHIC residual variations on
           single-frequency orbit determination of LEO satellites
    • Abstract: Publication date: Available online 19 June 2019Source: Advances in Space ResearchAuthor(s): Kai Shao, Defeng Gu, Xiao Chang, Bin Yi, Zhengming Wang Single-frequency (SF) precise orbit determination (POD) using space-borne Global Positioning System (GPS) measurements is a prerequisite for the success of many low-cost small/micro low Earth orbit (LEO) satellite missions. The first-order ionospheric effects are usually eliminated by group and phase ionospheric correction (GRAPHIC) combinations. GPS receiver antenna GRAPHIC residual variations (GRVs) are important systematic error sources in SF orbit determination. Azimuth and elevation dependent GRVs are estimated and obtained based on the GRAPHIC combination residuals in an in-flight calibration. One month of data from GRACE-A, GRACE-B, CHAMP and HY-2A satellites is used to assess the potential of receiver antenna GRVs in SF orbit determination. It is the first time to study the impact of receiver antenna GRVs on SF orbit determination for different LEO satellites, which exhibit different altitudes and data qualities. The impact of receiver antenna GRVs on SF orbit determination is significant. The use of in-flight determined receiver antenna GRVs leads to a better consistency between SF and dual-frequency POD solutions. The improvements are more obvious for GRACE-A and CHAMP satellites, whose receiver antenna GRV patterns demonstrate clear characteristics of systematic deviations. After correcting the receiver antenna GRVs, the root-mean-square of satellite laser ranging validation residuals are 3.11 cm, 2.31 cm, 2.86 cm and 5.29 cm for GRACE-A, GRACE-B, CHAMP and HY-2A satellites, respectively, which are reduced by 11.1%, 4.6%, 14.6% and 4.7%, respectively. At last, a set of a priori GDV corrections of GPS transmitter antennas are used in SF orbit determination and its effects on receiver antenna GRVs estimation and SF orbit determination are analyzed. Applying these corrections can slightly improve the SF orbit quality of GRACE-A satellite.
       
  • The Spörer minimum was deep
    • Abstract: Publication date: Available online 17 June 2019Source: Advances in Space ResearchAuthor(s): M.G. Ogurtsov Seventeen reconstructions of past solar activity, based on cosmogenic isotope and auroral data, were analyzed for the time interval AD 1402–1850 covering three prolonged periods of weak solar activity – the Spoerer, Maunder and Dalton minima. The information contained in these proxies has been generalized and sunspot number reconstructed. It was shown that from the point of view of solar paleoastrophysics the Spoerer minimum (15th–16th centuries) was a prolonged (ca 140 years) period of very quiet Sun with a mean solar activity level lower than that during the minimum of Maunder.
       
  • Rapid determination of source parameters for the 2017 Mw 8.2 Mexico
           earthquake based on high-rate GPS data
    • Abstract: Publication date: Available online 10 June 2019Source: Advances in Space ResearchAuthor(s): Yunfei Xiang, Jianping Yue, Dongjian Cai, Hao Wang Aiming to rapidly determine source parameters (i.e., static offset, seismic wave arrival, moment magnitude, and hypocentral location) for the Mexico 8.2 earthquake, the records of 7 high-rate GPS stations are utilized. Smoothness Priors Method (SPM) is introduced to rapidly extract the static offset from GPS displacement waveforms, and the result suggests this approach is feasible. The seismic wave arrival detection is carried out with the aid of S-transform, and the propagation velocity of seismic wave detected by most GPS stations are within 4−5 km/s, implying the seismic wave captured by GPS station may be S wave or surface wave. After that, an empirical regression model is adopted to characterize the moment magnitude for this earthquake, and this empirical formula can obtain reliable magnitude in comparison with the reference magnitude. The convergence time of average moment magnitude is 298 s, suggesting that a reliable and robust magnitude (Mw 8.37) can be estimated by the 7 GPS stations with about 298 s after earthquake occurrence. Considering the influence of the spatial distribution of GPS stations, 4 nearest GPS stations evenly distributed on both sides of the fault are selected to determine the warning-magnitude for the Earthquake Early Warning (EEW). A reliable and robust moment magnitude (Mw 8.2) can be estimated by the 4 stations with about 251 s, which is 57 s ahead of 7 stations. Finally, the coordinates of 6 GPS stations and corresponding seismic wave arrival time are utilized to determine the hypocentral location, and the latitude and longitude of estimated location is 14.925°N and 93.765°W, which is 17.9 km from the reference location. The results indicate that the source parameters required for EEW can be rapidly determined based on high-rate GPS displacement waveforms, and integrating real-time GPS into a joint EEW system will be crucial going forward.
       
  • Decomposition of geodetic time series: a combined simulated annealing
           algorithm and Kalman filter approach
    • Abstract: Publication date: Available online 10 June 2019Source: Advances in Space ResearchAuthor(s): Ming Feng, Yang Yuanxi, Zeng Anmin, Zhao Bin In this paper we propose a network-based Kalman filter combined generalized simulated annealing algorithm approach to decompose a group of GPS position time series into secular trend, annual and semi-annual signals as well as noise components. This approach treats east, north and vertical components of the whole network separately and estimates network-average process-noise parameters to contrain the time variability of the seasonal signals and noise components. Each coordinate component for each station is modeled in state-space model (SSM) individually. The noise components are described as the combination of flicker noise (FN), random walk noise (RWN) and observation white noise (WN). Each component, except for the trend, is allowed to variate over the time, and their amplitudes are estimated by maximization of likelihood function using a generalized simulated annealing (GSA) algorithm. The proposed approach is applied to 10 reprocessed GPS position time series from the Tectonic and Environmental Observation Network of Mainland China (CMONOC II), and its output is compared with that of ordinary maximum likelihood estimation (MLE). The results show that the proposed approach is an effective tool for the decomposition of GPS position time series. Finally, the advantages and limitations of the proposed approach are also discussed.
       
 
 
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