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Advances in Space Research
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 2
Number of Followers: 413  
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ISSN (Print) 0273-1177
Published by Elsevier Homepage  [3185 journals]
  • High energy interactions of cosmic rays
    • Abstract: Publication date: Available online 12 June 2019Source: Advances in Space ResearchAuthor(s): Sergey OstapchenkoAbstractA discussion of a number of important topics related to modeling of high energy cosmic ray interactions is presented. Special attention is devoted to novel theoretical approaches employed in event generators of hadronic interactions and to the impact of experimental data from the Large Hadron Collider (LHC). In relation to studies of ultra-high energy cosmic rays (UHECRs), differences between various predictions for basic characteristics of UHECR-induced extensive air showers in the atmosphere are analyzed and traced down to differences in the respective treatments of hadronic interactions. Possibilities to discriminate between the alternative approaches, based on LHC and UHECR data, are demonstrated and the relation to UHECR primary composition is outlined. Finally, in relation to direct studies of charged cosmic rays, potential improvements of the treatment of cosmic ray interactions at low and intermediate energies are discussed.
  • Masers: precision probes of molecular gas
    • Abstract: Publication date: Available online 11 June 2019Source: Advances in Space ResearchAuthor(s): A.M.S. Richards, A. Sobolev, A. Baudry, F. Herpin, L. Decin, M.D. Gray, S. Etoka, E.M.L. Humphreys, W. VlemmingsAbstractMaser emission from water, methanol, silicon monoxide and other molecules can reach brightness temperatures ≫1010 K. Such observations can achieve sub-pc precision for discs around black holes or sub-au scale interactions in protostellar discs and the regions where evolved star winds reach escape velocity. Ultra-high resolution maser observations also provide photon statistics, for fundamental physics experiments. RadioAstron has shown the success – and limitations – of cm-wave maser observations on scales ≪1 mas with sparse baseline coverage. ALMA, APEX and earlier single dish searches have found a wealth of mm and sub-mm masers, some of which probably also attain high brightness temperatures. Masers are ideal for high-resolution observations throughout the radio regime and we need to consider the current lessons for the best observational strategies to meet specific science cases.
  • 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 WangAbstractAiming 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 BinAbstractIn 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.
  • List of Referees
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s):
  • Seismology on small planetary bodies by orbital laser Doppler vibrometry
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Paul Sava, Erik AsphaugAbstractThe interior structure of small planetary bodies holds clues about their origin and evolution, from which we can derive an understanding of the solar system’s formation. High resolution geophysical imaging of small bodies can use either radar waves for dielectric properties, or seismic waves for elastic properties. Radar investigation is efficiently done from orbiters, but conventional seismic investigation requires landed instruments (seismometers, geophones) mechanically coupled to the body.We propose an alternative form of seismic investigation for small bodies using Laser Doppler Vibrometers (LDV). LDVs can sense motion at a distance, without contact with the ground, using coherent laser beams reflected off the body. LDVs can be mounted on orbiters, transforming seismology into a remote sensing investigation, comparable to making visual, thermal or electromagnetic observations from space. Orbital seismometers are advantageous over landed seismometers because they do not require expensive and complex landing operations, do not require mechanical coupling with the ground, are mobile and can provide global coverage, operate from stable and robust orbital platforms that can be made absolutely quiet from vibrations, and do not have sensitive mechanical components.Dense global coverage enables wavefield imaging of small body interiors using high resolution terrestrial exploration seismology techniques. Migration identifies and positions the interior reflectors by time reversal. Tomography constrains the elastic properties in-between the interfaces. These techniques benefit from dense data acquired by LDV systems at the surface, and from knowledge of small body shapes. In both cases, a complex body shape, such as a comet or asteroid, contributes to increased wave-path diversity in its interior, and leads to high (sub-wavelength) imaging resolution.
  • Influence of optical properties of alumina particles on the radiative base
           heating from solid rocket plume
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Ju Yong Ko, Euntaek Lee, Sejin KwonAbstractThe radiative properties are obtained from the optical properties of alumina particles and applied to the discrete ordinate interpolation method to calculate the radiative base heating. During this process, the radiative properties are thoroughly investigated by considering particle size and temperature variation. The plume model is divided into two cases depending on whether the scattering effect is included or not. In the case of the plume emission only model, the optical properties including the absorption index significantly affect radiative base heating. However, when scattering is also considered, the influence of the optical properties on base heating is reduced due to the effect of the large scattering coefficient acting as a barrier for the optically thick condition. However, the maximum heating rate is still approximately 2.2 times larger than minimum one. As such, the appropriate selection of optical properties is important. To determine the feasibility of this study, calculated heating values for the plume model whose shape, mass portion of alumina, etc. are obtained from the KSLV-I kick motor are compared to the measured data derived from the kick motor test. Although the conditions are not the same, the calculated data range is from 34.2 kW/m2 to 74.1 kW/m2 based on the optical properties, which is not much far from the measured data. This implies that the results obtained are at least reasonable to a certain extent.
  • Algorithms for space-based anomaly detection of GEO objects
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Rong Xu, Fei ZhaoAbstractBeyond catalog maintenance, a sun-synchronous sensor can provide valuable information about GEO objects’ characteristics. Algorithms were designed for attitude anomaly detection of GEO satellites and spin axis determination for tumbling objects using space-based non-resolved optical data. The spin axis orientation of a tumbling GEO object can be estimated by analyzing its observed tumble rate variations with an orbiting sensor. Simulated space-based observations using a GEO satellite model, with variable spin rates and axial tilt angles, have suggested that the algorithms are effective at estimating a GEO satellite’s spin rates and orientation.
  • Approximately optimal manoeuvre strategy for aero-assisted space mission
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Mehdi Moghadasian, Jafar RoshanianAbstractAn innovative aerodynamically assisted spacecraft manoeuvre strategy is introduced in this study which benefits from the higher order powers of the state variables as the feedback signal for online calculation of trajectory correction commands. The proposed manoeuvre policy is exploited from nonlinear optimal control theory formulation by incorporating a novel form of High Order Expansions method which results in an approximately optimal manoeuvre commands in practice. To extract such a manoeuvre policy, a specific approach of dealing with High Order Expansions method, namely Vectorised High Order Expansions, is illustrated comprehensively. Then, the implementation of this method is described to extract the solution of general optimal control problems by use of sensitivity variables. By means of this novel approach, the higher order manoeuvre policy is designed for the aero-assisted mission up to and including the 8th order expansions to better reveal the quality of the proposed approach. The performance of the proposed method is investigated by the means of planar point mass simulations; the results are compared with a state dependent Riccati equation method and the numerical open loop solution of the problem, and the quality of the higher order terms is investigated.
  • Characteristic of modelling spatial processes using geostatistical
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Oksana Grynyshyna-PoliugaAbstractOur work presents the analysis of the data following the steps as given below: identification of data set periods, constructing and modelling the empirical semivariogram for single location and using the Kriging mapping function as modelling of TEC maps in mid-latitude during disturbed and quiet days. Based on the semivariogram, weights for the Kriging interpolation are estimated.
  • Large-scale altitude distribution profile of auroral parallel electric
           potentials: A statistical analysis of Cluster data
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Soheil Sadeghi, M. Reza EmamiAbstractIt is generally believed that the heart of the Auroral Acceleration Region (AAR) is located between 5000 and 8000 km altitude above the auroral oval. Various altitude distribution profiles are suggested by different theories, including the transition layer model, which predicts that the strongest electric fields can be found at about 1 RE, and can vary depending on the plasma and geomagnetic conditions. However, there have been no specific experimental results that cover regions both below and well above such altitude. This paper presents a method for obtaining such a profile from AAR satellite crossings, applies it to a data set gathered from 116 Cluster spacecraft encounters with acceleration potential structures, and discusses the results. The crossings cover an altitude range between 0.63 RE and 2.9 RE. The outcome is the first empirical altitude distribution profile of the auroral acceleration potentials. The results suggest that the region within the altitude range of 0.9245 RE and 1.158 RE statistically contains 30% of the total potential, which is the largest fraction of the parallel potentials among all altitude segments of the same size. The altitude which equally divides the distribution of acceleration potentials was found at 1.076 RE (6863 km). The obtained parallel potential distribution is in agreement with both the magnetic mirror force theory and the transition layer model, and can hence provide a proper baseline for future missions to the AAR.
  • Simulating the impact of climate change on soil erosion in sub-tropical
           monsoon dominated watershed based on RUSLE, SCS runoff and MIROC5 climatic
    • Abstract: Publication date: 15 July 2019Source: Advances in Space Research, Volume 64, Issue 2Author(s): Subodh Chandra Pal, Rabin ChakraborttyAbstractClimate change due to precipitation is one of the important dominant variables that determine the trend of soil loss in future period. In the present study the MIROC5 model of RCP 2.6, 4.5, 6.0 and 8.5 scenarios have been used to estimate the future period precipitation in storm rainfall event. Statistical downscaling approaches have been applied to estimate the precipitation for the time period of 1900 to 2010 and 2070 to 2100. Then the rainfall and runoff erosivity (R) factor has been estimated from the predicted precipitation scenario with the help of Modified Fourier Index from 2070 to 2100 in different return period such as 5 year, 10 year and 15 year return period. SRTM (Shuttle Radar Topographic Mission) DEM (Digital Elevation Model) and Landsat 8 OLI (Operational Land Imager) have been used to prepare the necessary thematic inputs for RUSLE (Revised Universal Soil Loss Equation) model in GIS environment. In this study the information regarding the soil characteristics have been accounted based on the primary information. In the present study, 2 sq km * 2 sq km grids of the entire basin have been taken into consideration randomly for collecting the soil samples within this region. Then the soil texture has been estimated and identified through the automatic sieve shaker in laboratory. Despite the soil texture, the soil pH and organic matter have also been estimated in the laboratory for estimating the soil erodibility factor (Kfactor) more accurately. Slope length and steepness factor (LS) have been estimated from the SRTM DEM in GIS environment. NDVI (Normalized Difference Vegetation Index) was derived from the Landsat 8 OLI data for estimating the cover and management factor (C), support practice factor (P) related to slope direction has been estimated based on the primary observation during the field visit. Apart from that the SCS curve number values and the weighted curve number values for each and every individual LULC classes have been derived to estimate the R factor. It was revealed that the average annual soil loss in the severe region (very high) in the base year is 12.6% and it would be 25.12% (5 year return period), 26.48% (10 year return period), 27.59% (15 year return period) in RCP 2.6 scenario. The average annual soil loss in this region would be28.53% (5 year return period), 30.00% (10 year return period), 30.97% (15 year return period) in RCP 4.5 scenario. The amount of soil in the severe region would be 32.19% (5 year return period), 33.48% (10 year return period), 34.05% (15 year return period) in RCP 6.0 scenario. In the RCP 8.5 scenario the average annual soil loss would be32.78% (5 year return period), 32.97% (10 year return period), 33.28% (15 year return period). This type of study is more helpful for the decision makers and regional planner for adopting the suitable measures with keeping in the view the local environment.
  • Space VLBI: from first ideas to operational missions
    • Abstract: Publication date: Available online 8 June 2019Source: Advances in Space ResearchAuthor(s): Leonid I. GurvitsAbstractThe operational period of the first generation of dedicated Space VLBI (SVLBI) missions commenced in 1997 with the launch of the Japan-led mission VSOP/HALCA and is coming to closure in 2019 with the completion of in-flight operations of the Russia-led mission RadioAstron. They were preceded by the SVLBI demonstration experiment with the Tracking and Data Relay Satellite System (TDRSS) in 1986–1988. While the comprehensive lessons learned from the first demonstration experiment and two dedicated SVLBI missions are still awaiting thorough attention, several preliminary conclusions can be made. This paper addresses some issues of implementation of these missions as they progressed over four decades from the original SVLBI concepts to the operational status.
  • The nature and origins of the day-to-day variability in Earth's surface
           magnetic field
    • Abstract: Publication date: Available online 7 June 2019Source: Advances in Space ResearchAuthor(s): Jeffrey M. Forbes, Astrid Maute, Xiaoli ZhangAbstractNumerical experiments are performed with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) to reveal the characteristics and origins of daytime magnetic field variations on the ground (ΔB) at planetary-wave (PW) periods (2-20 days). Simulations are performed to separate the responses to forcing in the lower atmosphere from solar-magnetospheric forcing. Lower-atmosphere forcing is specified at the 97-km lower boundary of the TIE-GCM by NCAR's Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM), which itself is forced at 30 km by MERRA (Modern Era Retrospective-analysis for Research and Applications) outputs. Solar and magnetospheric inputs to the TIE-GCM are specified according to parameterizations based on F10.7 and Kp. The study focuses on latitudes 0°-65°N during October 1-31, 2009, when F10.7 (range 68-80), Kp (range 0-4), and Ap (range 0-13) are typical of quiet-time “weather”. Neutral dynamics in the dynamo region (ca. 100-150 km) during this period is dominated by winds due to PW modulated tides, where the PW include the quasi-6, 10 and 16-day westward-propagating normal modes with zonal wavenumber s = 1, and eastward-propagating ultra-fast Kelvin waves (UFKW) with s = -1 and periods between 3 and 5 days.Results and conclusions are as follows. PW-period perturbations in daytime ΔB at the ground are dominated by variability originating in the lower atmosphere. The only exception is the 45°-65° latitude regime around noon, where the ΔB variability due to lower atmospheric forcing exceeds that due to solar-magnetospheric forcing by only about 50%. Broadband zonally-symmetric oscillations also occur in ΔB due to dissipation of the tidal spectrum at PW periods in the E-region. These results raise the possibility that some level of contamination from the lower atmosphere may exist in magnetic indices such as ap, Kp, and Ap that are used as measures solar-magnetosphere-ionosphere coupling strength, under levels of geomagnetic activity similar to that characterizing October, 2009. It is also found that variations in conductivities play a minor role compared with neutral winds in producing PW-period variations in ΔB, and that there is not a robust one-to-one correspondence between spectral peaks in ΔB and those in the neutral winds. Several factors contribute to this latter result, which are explained in the text.
  • Chemical physics of D and E layers of the ionosphere
    • Abstract: Publication date: Available online 7 June 2019Source: Advances in Space ResearchAuthor(s): V.V. Kuverova, S.O. Adamson, A.A. Berlin, V.L. Bychkov, A.V. Dmitriev, Y.A. Dyakov, L.V. Eppelbaum, G.V. Golubkov, A.A. Lushnikov, M.I. Manzhelii, A.N. Morozov, S.S. Nabiev, V.L. Shapovalov, A.V. Suvorova, M.G. GolubkovAbstractThe main chemical reactions that lead to formation of the nonequilibrium two-temperature plasma and highly excited Rydberg complexes are considered. A special attention is given to l-mixing reaction responsible for the formation of quantum resonance properties for radio wave propagation medium. A detailed analysis of the influence of Rydberg states to the behavior of GPS signals in D and E layers of the ionosphere is presented. It is shown that the transition frequencies between the excited states of orbitally degenerate Rydberg complex are resonant with respect to the carrier frequencies of GPS. That is why these states are the main cause of the GPS signal distortion. The mechanism of GPS signal delay in D and E layers is also discussed.
  • A new method to estimate cloud effective radius using Meteosat Second
           Generation SEVIRI over Middle East
    • Abstract: Publication date: Available online 5 June 2019Source: Advances in Space ResearchAuthor(s): Mostafa Hadizadeh, Mehdi Rahnama, Mehdi Kamali, Mona Kazemi, Ali MohammadiAbstractThe cloud particle size distribution varies with height and the phase may change from water to mixed phase to ice through the vertical profile of the cloud, giving rise to different radiative characteristics. Researchers suggested an empirical equation for an approximation of the relation between cloud-particle effective radius and reflectance of channel IR3.7 for Advanced Very High Resolution Radiometer (AVHRR) and Multi-Functional Transport Satellite (MTSAT)-1R satellites. However, when we examined this empirical equation for MSG satellites, there was no correlation between the cloud particle effective radius and those from the Terra and Aqua/MODIS (Moderate Resolution Imaging Spectrometers) products. Given the fact that this relationship is empirical and not applicable for Meteosat satellites with 3.9 µm cloud properties, we need to introduce a new nonlinear equation that is independent from other cloud properties, to retrieve the cloud effective radius from MSG satellite over Middle East. Thus, in this study, a development of the mentioned method, based on a nonlinear regression model, was introduced to estimate the water/ice-cloud particle effective radius from the 3.9 µm wavelength reflectivity of the Meteosat Second Generation Indian Ocean Data Coverage (MSG-1(IODC)) satellite over the Middle East region. For this purpose, the LibRadTran radiative transfer model was used. This approach is almost independent from other cloud properties, which makes this relationship more efficient for retrieving a cloud’s effective radius. To evaluate this approach, the results have been compared to the effective-radius product of the MODIS on board the Terra and Aqua satellites, and cloud effective radius parameter from the MSG-1satellite’s optimal cloud analysis (OCA) data. The average of correlation coefficient, standard deviation, and RMSE (root mean square error) of this retrieved algorithm method for 29 randomly selected case studies, in comparison to the corresponding MODIS product, are 0.93, 3.093, and 3.639, and compared with OCA product, 0.88, 4.015, and 4.51, respectively. Therefore, the results of analysis in the Middle East region show that the retrieved effective particle radius from Meteosat satellites corresponds strongly with MODIS data from the Terra and Aqua satellites, and also with the OCA products of the MSG-1. Furthemore, using the algorithm that is presented in this paper, a nonlinear regression relationship can be made for retrieving cloud effective radius in the intended place.
  • List of Referees
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s):
  • Balloon ascent prediction: Comparative study of analytical, fuzzy and
           regression models
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Kanika Garg, M. Reza EmamiAbstractThe ascent prediction of high-altitude zero-pressure stratospheric balloons is an important aspect of targeted test flight. Prediction of the balloon ascent rate is the prerequisite for many of the flights as it helps in planning ballasting and valving manoeuvres. In this paper, a standard analytical model, a fuzzy model and a statistical regression model are developed and compared to predict the zero-pressure balloon ascent. The flight data is extracted from the Esrange balloon service system for zero-pressure balloons with different payload capability, and several potential explanatory variables are computed for every sampled climbed segment. For the fuzzy modelling approach, a fuzzy c-mean clustering algorithm is used for system identification and prediction. For the regression approach, a Gaussian process regression is used, and principal component analysis is applied for finding the significant inputs. The result shows that the data driven approaches are more efficient than the standard analytical model.
  • Preprocessing observation vectors to increase attitude estimation accuracy
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Russell P. PateraAbstractThe recently developed Vector Inertia Tensor Attitude Estimation, VITAE, method is enhanced by the addition of two different preprocessing algorithms that modify the observation vectors prior to attitude estimation. The first preprocessing algorithm is for use in cases that have one observation vector that is much more accurate than the other observation vectors. Such cases suffer numerical error caused by the large relative weight of the very accurate observation vector. Use of the preprocessing algorithm eliminates large variation in vector weights and resulting numerical error. The second preprocessing algorithm enables VITAE to generate results equivalent to a very accurate suboptimal attitude determination algorithm that produces results extremely close to the optimum solution. Preprocessing algorithms eliminate the need to select observation vector weights to remove eigenvalue degeneracy and allows the weights to be based solely on optimality, thereby improving estimation accuracy. When optimum weights are used, the inertia matrix is recognized as the information matrix, which links VITAE to other attitude estimation algorithms. The preprocessing algorithms used with VITAE were able to uncover erroneous results in a few published test cases. The VITAE solutions were validated analytically, through the inertia matrix’s inverse relationship to the error covariance matrix. A loss function comparison is also included to further validate the preprocessing algorithms and related VITAE solution.
  • Research on multi-pipe drilling and pneumatic sampling technology for deep
           Martian soil
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Xuyan Hou, Tianxiang Ding, Kairui Cao, Tao Chen, Long Li, Zhaoji Yu, Zongquan DengAbstractOne of the main objectives of Mars sampling is to understand the geological structure, and the sampling technology for deep Martian soil is a key problem. In this study, a multi-pipe drilling and pneumatic sampling device for deep Martian soil was developed, which is the first application in the field of deep space exploration. Firstly, the multi-pipe drilling and pneumatic sampling schemes were determined, and the drilling and sampling feasibility were tested by means of a simulation based on DEM-CFD. Secondly, the structural design of the multi-pipe drilling and pneumatic sampling device were carried out, including key components such as the feeding mechanical, rotary mechanical, clamping and turning mechanical mechanisms. Thirdly, the control system for the multi-pipe drilling and pneumatic sampling device were developed, which can be used for real-time motor control and measurement of state parameters. Finally, multi-pipe assembling and pneumatic sampling experiments were carried out using the prototype. Furthermore, the multi-pipe drilling and pneumatic sampling device functioning were verified.
  • Estimation of equivalent ground-based total electron content using
           CHAMP-based GPS observations
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Patrick Mungufeni, Yenca Migoya-Orué, John Bosco Habarulema, Sandro M. RadicellaAbstractIn this study, we derived for the African region a scaling factor, RTEC to estimate equivalent Total Electron Content (TEC) observed by ground-based Global Navigation Satellite System (GNSS) receiver. The sources of TEC data used to derive RTEC include 11 International GNSS Service (IGS) stations and GNSS receiver on-board CHallenging MiniPay load (CHAMP) satellite. The computed TEC ratios from simultaneous observations of CHAMP satellite and IGS during the years 2001–2008 were found to minimally depend on the (i) locations of the stations, (ii) seasons, and (iii) solar activity. The average of TEC ratios for the local time intervals 09:01–15:00, 15:01–18:00, 18:01–24:00, and 00:01–09:00 were determined as 0.532, 0.561, 0.724, and 0.765 respectively. These average ratios of CHAMP TEC to Ground-based TEC were considered as RTEC. The IGS observed TEC over 4 spatially different stations that were not used in determining RTEC and TEC data measured using CHAMP satellite within vicinity of the stations that were scaled (equivalent Ground TEC) correlated highly (r⩾0.91). Moreover, the percentage of absolute differences between the equivalent Ground and IGS observed TEC over the stations that were ⩽5 TECU ranged from 64 to 84%. Comparison of simultaneously IGS observed and equivalent Ground TEC over the 4 stations showed that the RTEC captures TEC variation with solar activity, seasons and spatially.
  • Investigation of incoherent scatter radar spectra features with stimulated
           electromagnetic emissions at EISCAT
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): A. Mahmoudian, A. Senior, M. Kosch, W.A. Scales, M.T. Rietveld, B. Isham, X. Shi, M. RuohoniemiAbstractElectromagnetic (EM) and electrostatic (ES) emissions can be generated in the ionosphere by high-power high-frequency (HF) radio waves transmitted from the ground. The signatures of the EM emissions observed on the ground are known as Stimulated Electromagnetic Emissions (SEE) and can be employed for remote measurement of ionospheric parameters. The experimental data from recent HF heating experiments near the fourth electron gyro-frequency (4fce) at EISCAT are presented. This paper compares the temporal behavior of SEE within a few Hertz up to 50 kHz of the transmission frequency to the time evolution of enhanced ion line (EHIL) in the incoherent scatter radar (ISR) spectrum. The correlation of Wideband SEE (WSEE) spectral lines within 1 kHz to 100 kHz such as the downshifted maximum (DM), downshifted peak (DP), and broad upshifted maximum (BUM), with HF enhanced ion lines (EHIL) is shown. It is shown that WSEE spectral lines can be used to reproduce the EHIL characteristics including altitude range, rise and decay time, maximum and minimum amplitude. A data reduction technique is developed to derive ionospheric parameters such as the electron density profile near the interaction altitude, magnetic field strength B0 as well as the altitude profile of the EHIL using the temporal evolution of WSEE spectral lines near nfce.
  • Assessment of agroclimatology NASA POWER reanalysis datasets for
           temperature types and relative humidity at 2 m against ground
           observations over Egypt
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Hassan Aboelkhair, Mostafa Morsy, Gamal El AfandiAbstractThe climatic reanalysis datasets are one of the most important data types that could help to overcome scarce of observations. Therefore, the main objective of this study is to evaluate NASA POWER reanalysis data for surface monthly average temperatures at 2 m (maximum (Tmax), minimum (Tmin), mean (Tmean) and dew point (Td), all in °C) and relative humidity (RH) in percentage compared to the observed data at 20 Egyptian weather stations. The results showed that there are a significant correlation and goodness of fit between NASA POWER reanalysis and observed data for all parameters except RH. For temperature variables, the coefficient of determination (R2) and Willmott Index of agreement (WI) attain around 0.75 and 0.90 respectively, while the root mean square error (RMSE) reaches to less than 5 °C; and the mean bias error (MBE) ranges from −3 to +3 °C for 85% of stations. In addition, NASA POWER accuracy of temperature parameters increases gradually northward with the highest ratio at the northern coast of Egypt. Where, it is slightly overestimated (under 3 °C) Tmax, Tmin, and Tmean at 80, 75 and 65% of the stations respectively. While it is slightly underestimated Td with 3 °C at 90% of the stations. Contrarily, NASA POWER data accuracy of RH increases southward, particularly in Aswan. Additionally, NASA POWER reanalysis has a considerable underestimation for RH data at most stations, where the dominant MBE percentage ranges from −12 to −5% for about 75% of the stations. As well as, the maximum RMSE and MBE for all elements were recorded in the Malwi station at Middle Egypt. Consequently, R2, WI, RMSE, and MBE for temperature parameters are almost within an acceptable range for most selected Egyptian stations which are located in the area that dominated by the influence of the Mediterranean Sea (northern of 30°N) and western of 30°E with a distance between 2.5 and 14.5 km from the Sea. While, the good RH estimation is recorded at stations that are located south of the area that dominated by the influence of the Mediterranean Sea (south of 26°N). Finally, NASA POWER reanalysis datasets can be used in case of missing or scarce of observations in Egypt. Nevertheless, it still needs improvements by taking into consideration the influence of the Mediterranean Sea and the locality of (especially middle) Egypt on temperature and in particular on relative humidity estimations.
  • Mass sea level variation in the South China Sea from GRACE, altimetry and
           model and the connection with ENSO
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Hui Xi, Zizhan Zhang, Yang Lu, Yan LiAbstractMass sea level variation (SLV) in the South China Sea (SCS) is explored through three independent approaches. One is the mass change observed by the Gravity Recovery and Climate Experiment (GRACE) mission since 2002. The second approach is the steric-corrected altimetry. Mass SLV is calculated by subtracting steric SLV related to the seawater temperature and salinity from altimetry-based total SLV. This approach benefits from the accurate sea surface height observed by Topex/Poseidon since 1992 and its follow on missions. The third approach is based on ocean mass balance theory. Considering the SCS is a semi-closed basin, mass SLV is estimated by taking account of water balance among the precipitation (P), evaporation (E) and flux (F) of ocean currents, indicated as PEF (P-E-F) mass estimation. Consistent comparisons show that mass SLVs from Estimation of the Circulation and Climate of the Ocean (ECCO)-based and Ishii-based steric-corrected altimetry agree well with GRACE observations, whereas PEF (OFES, ocean general circulation model for the Earth Simulator) mass estimation is 86% larger than GRACE observations. On the annual scale, both ECCO-based and Ishii-based steric-corrected altimetry are similar with respect to GRACE, whereas PEF(OFES) mass estimation has significantly larger amplitudes and some outliers. On the interannual scale, ECCO-based steric-corrected altimetry has less ability to capture the interannual variation in the mass SLV. The mass SLVs from Ishii-based steric-corrected altimetry and PEF(OFES) are positively correlated with El Niño and Southern Oscillation (ENSO). The positive influence of ENSO on the mass SLV is mainly imposed by its effects on precipitation and flux of ocean currents in the SCS.
  • Manifestation and possible reasons of ∼60-year oscillations in
           solar-atmospheric links
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): S. Veretenenko, M. OgurtsovAbstractIn this work we continue studying possible reasons for temporal variability observed in correlation links between characteristics of the lower atmosphere and solar activity phenomena at the multidecadal time scale. Temporal variations of correlation coefficients between troposphere pressure at extratropical latitudes and sunspot numbers are compared with the evolution of the large-scale circulation forms according to the Vangengeim-Girs classification, as well as the characteristics of the stratospheric polar vortex and global temperature anomalies. The results obtained show that temporal variability of solar activity/galactic cosmic ray (SA/GCR) effects on troposphere pressure (the development of extratropical baric systems) is characterized by a roughly 60-year periodicity and closely related to changes in the regime of large-scale circulation which accompany transitions between the different states of the polar vortex. It was suggested that the character of SA/GCR effects depends on the polar vortex strength influencing the troposphere-stratosphere coupling. It was shown that the evolution of the polar vortex may be associated with global temperature variations, with a possible reason for these variations being long-term changes of total solar irradiance.
  • A novel algorithm for differentiating cloud from snow sheets using Landsat
           8 OLI imagery
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Tingting Wu, Ling Han, Qing LiuAbstractThe separation of clouds from snow is fundamentally very challenging because of their similar spectral signature. A new algorithm was proposed to detect clouds from snow in Landsat 8 imagery. Taking the Hetian District region, where there is frequent cloud and snow cover, in northwestern China as one of the typical case areas. The typical case is presented in detail to illustrate the approach produces and results. A band math method for cloud and snow discrimination index (CSDI) was firstly conducted in this paper, fractal digital number-frequency (DN-N) algorithm and hotspot analyses were applied to determine the threshold of the CSDI and eliminate false anomalies. The results showed that an overall accuracy exceeding 95% in areas with very bright land surfaces, which indicate that this algorithm is effective for detecting clouds in specific situations where the ground objects have some reflectance characteristics similar to cloud.
  • A Gaussian random field model for de-speckling of multi-polarized
           Synthetic Aperture Radar data
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Masoud Mahdianpari, Mahdi Motagh, Vahid Akbari, Fariba Mohammadimanesh, Bahram SalehiAbstractSynthetic Aperture Radar (SAR) data have gained interest for a variety of remote sensing applications, given the capability of SAR sensors to operate independent of solar radiation and day/night conditions. However, the radiometric quality of SAR images is hindered by speckle noise, which affects further image processing and interpretation. As such, speckle reduction is a crucial pre-processing step in many remote sensing studies based on SAR imagery. This study proposes a new adaptive de-speckling method based on a Gaussian Markov Random Field (GMRF) model. The proposed method integrates both pixel-wised and contextual information using a weighted summation technique. As a by-product of the proposed method, a de-speckled pseudo-span image, which is obtained from the least-squares analysis of the de-speckled multi-polarization channels, is also produced. Experimental results from the medium resolution, fully polarimetric L-band ALOS PALSAR data demonstrate the effectiveness of the proposed algorithm compared to other well-known de-speckling approaches. The de-speckled images produced by the proposed method maintainthe mean value of the original image in homogenous areas, while preserving the edges of features in heterogeneous regions. In particular, the equivalent number of look (ENL) achieved using the proposed method improves by about 15% and 47% compared to the NL-SAR and SARBM3D de-speckling approaches, respectively. Other evaluation indices, such as the mean and variance of the ratio image also reveal the superiority of the proposed method relative to other de-speckling approaches examined in this study.
  • Lunar gravity assists using patched-conics approximation, three and four
           body problems
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Rodolfo Batista Negri, Alexander Sukhanov, Antônio Fernando Bertachini de Almeida PradoAbstractThe gravity assist is a maneuver greatly applied to space missions, with the main goal of giving or removing energy of a spacecraft through a passage near a celestial body. The patched-conics approximation is the first approximation that is usually considered in the mission planning. It gives a good accuracy in the majority of the situations. However, when using the Moon for the close approach, the results have a tendency to diverge from a more complete three body dynamics. This is due to the large mass of the Moon compared to the Earth. In that sense, the goal of the present paper is to study the errors given by the patched-conics approximation in a lunar gravity assist maneuver. To find those errors we compare the results coming from this approximation with the equivalent results obtained from the circular restricted three body problem and the bi-circular restricted four body problem for a same periselenium condition. This comparison is made in the orbital elements before the maneuver and the C3 of the spacecraft after the maneuver under the three models considered. Different values for the initial conditions of the spacecraft are used to obtain general conclusions about the behavior of the errors involved. We conclude that there is a tendency to a better agreement between the patched-conics and the three body problem for retrograde transfer orbits. We also find that the effects of the Sun in the maneuver needs to be included only in more accurate steps of the mission.
  • Lunar far side positioning enabled by a CubeSat system deployed in an
           Earth-Moon halo orbit
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Hongru Chen, Jiangkai Liu, Long Long, Zhenyu Xu, Yazhe Meng, Hao ZhangAbstractFor explorations of the far side of the Moon, it is necessary to tackle the challenge of navigation and communication as the far side is invisible to the Earth. This paper proposes a low-cost mission concept that consists of four CubeSats in an Earth-Moon L2 (EML2) halo orbit. The mission objective is to provide real-time positioning service for lunar far-side assets, taking advantage of the visibility of EML2 halo orbits to both the Earth and lunar far side. Being miniature, CubeSats can be carried by a mother spacecraft and deployed during the mid-course. As CubeSat missions are generally constrained by limited communication, power, and propulsion capacities, this paper presents a feasibility study that takes into account the high-fidelity dynamical environment and system constraints. This paper analyzes the positioning performance in terms of accuracy, and spatial and temporal coverage. In addition, the requirement of deployment in terms of Δv budget and thrust magnitude is also investigated. Results show that (1) a positioning accuracy of 2.7 km is achievable; and (2) several state-of-the-art propulsion systems can meet the requirement of deployment and the stationkeeping for an acceptable duration.
  • Sliding mode and SDRE control laws on a tethered satellite system to
           de-orbit space debris
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Pouria Razzaghi, Ehab Al Khatib, Shide BakhtiariAbstractSince space debris is a problem that has been continuously increasing, removal missions should be considered. Tethered space system (TSS) has wide application prospects in the future on-orbit missions such as debris removal. However, it is rather complex and difficult for TSS to realize stabilization of tumbling combinations after connecting to the debris. In this paper, the stabilization problem of this combination is studied.An adaptive sliding mode and State-Dependent Riccati Equation control methods are applied on a TSS to stabilize the system and de-orbit the space debris. The tether tension and stability of the in-plane and out-of-plane libration angles of the system are taken into account. The tether can only resist axial stretching. The thrusters, which are the sources of the system inputs are equipped on the satellite. The controllers regulate the tether to remain fully stretched and to decrease the altitude of the orbit continuously. The numerical simulation validates the proposed control schemes for de-orbiting the debris and put it in lower altitude orbit. This makes the debris retrieve to the atmosphere in less time than the actual orbit lifetime. The comparison between two control schemes is discussed.
  • Extension of the King-Hele orbit contraction method for accurate,
           semi-analytical propagation of non-circular orbits
    • Abstract: Publication date: 1 July 2019Source: Advances in Space Research, Volume 64, Issue 1Author(s): Stefan Frey, Camilla Colombo, Stijn LemmensAbstractNumerical integration of orbit trajectories for a large number of initial conditions and for long time spans is computationally expensive. Semi-analytical methods were developed to reduce the computational burden. An elegant and widely used method of semi-analytically integrating trajectories of objects subject to atmospheric drag was proposed by King-Hele (KH). However, the analytical KH contraction method relies on the assumption that the atmosphere density decays strictly exponentially with altitude. If the actual density profile does not satisfy the assumption of a fixed scale height, as is the case for Earth’s atmosphere, the KH method introduces potentially large errors for non-circular orbit configurations.In this work, the KH method is extended to account for such errors by using a newly introduced atmosphere model derivative. By superimposing exponentially decaying partial atmospheres, the superimposed KH method can be applied accurately while considering more complex density profiles. The KH method is further refined by deriving higher order terms during the series expansion. A variable boundary condition to choose the appropriate eccentricity regime, based on the series truncation errors, is introduced. The accuracy of the extended analytical contraction method is shown to be comparable to numerical Gauss-Legendre quadrature. Propagation using the proposed method compares well against non-averaged integration of the dynamics, while the computational load remains very low.
  • Variation of Ionospheric Range Errors for L1 Frequency GPS Users During
           the 23rd Solar Cycle Over BAHR IGS Station
    • Abstract: Publication date: Available online 4 June 2019Source: Advances in Space ResearchAuthor(s): Abdollah Masoud Darya, Muhammad Mubasshir Shaikh, Ilias FerniniAbstractErrors 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 (26.209 N, 50.608 E) 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 meters. 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).
  • Cut-off features in interplanetary solar radio type IV emission
    • Abstract: Publication date: Available online 4 June 2019Source: Advances in Space ResearchAuthor(s): Silja Pohjolainen, Nasrin Talebpour SheshvanAbstractSolar radio type IV bursts can sometimes show directivity, so that no burst is observed when the source region in located far from the solar disk center. This has recently been verified also from space observations, at decameter wavelengths, using a 3D-view to the Sun with STEREO and Wind satellites. It is unclear whether the directivity is caused by the emission mechanism, by reduced radio wave formation toward certain directions, or by absorption/blocking of radio waves along the line of sight. We present here observations of three type IV burst events that occurred on 23, 25, and 29 July 2004, and originated from the same active region. The source location of the first event was near the solar disk center and in the third event near the west limb. Our analysis shows that in the last two events the type IV bursts experienced partial cut-offs in their emission, that coincided with the appearance of shock-related type II bursts. The type II bursts were formed at the flanks and leading fronts of propagating coronal mass ejections (CMEs). These events support the suggestion of absorption toward directions where the type II shock regions are located.
  • Experimental study on drilling basalt with small diameter drilling tools
    • Abstract: Publication date: Available online 1 June 2019Source: Advances in Space ResearchAuthor(s): Xiaogan Peng, Ting Zeng, Zhongwang Yin, Zeng Zhao, Liang LiAbstractBasalt 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 100-110N. 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.
  • A novel adaptive beamforming algorithm against impulsive noise with
           alpha-stable process for satellite navigation signal acquisition
    • Abstract: Publication date: Available online 1 June 2019Source: Advances in Space ResearchAuthor(s): Haichuan Zhang, Fangling Zeng, Daqian Lv, Huishu WuAbstractAdaptive beamforming is an effective spatial filtering technique for overcoming the vulnerability to interference of global navigation satellite system (GNSS) receivers. Although beamforming-based satellite system has the capability of nulling electronic interference sources, the distortions to GNSS receiver induced by impulsive noises are always neglected. This paper addresses the satellite navigation signal acquisition problem in the presence of impulsive noises with alpha-stable noise using the maximum correntropy criterion in framework of the GNSS system. In addition, in order to decrease the number of active elements for avoiding overmuch energy consumption, a sparse regularization is introduced to the constraints of the novel criterion. From the analysis, the novel constraint sparse maximum correntropy (CSMC) beamforming technique that can achieve robustness against impulsive noises which uses less power is developed in this manuscript for satellite signal acquisition. The proposed CSMC, maintains the robustness against impulsive outliers and achieve better performance in conjunction with less power consumption. A mean square analysis of the CSMC algorithm is presented to verify the validity of our theory. Simulation results demonstrate the superiority of the proposed methods over other previously developed beamforming techniques in GNSS.
  • Optimal Transfer between Elliptic Orbits with Three Tangential Impulses
    • Abstract: Publication date: Available online 31 May 2019Source: Advances in Space ResearchAuthor(s): Andrea Caruso, Alessandro A. Quarta, Giovanni MengaliAbstractThis paper introduces a mathematical model that can be used to evaluate the total velocity variation required to accomplish a given two-dimensional orbit transfer, using up to three tangential impulsive maneuvers. The problem is addressed in an optimal framework, by looking for the transfer trajectory that minimizes the total velocity variation. In particular, by exploiting the boundary nonlinear constraint equations, the total velocity variation can be calculated as a function only of the spacecraft angular position at which the impulses are applied. The small number of control variables involved in the algorithm allows the optimization problem to be solved in a simple and robust way, with a small computational effort. The algorithm is able to find the optimal transfer strategy in a generic ellipse-to-ellipse, two-dimensional, mission scenario.
  • Adaptive anti-windup control of post-capture combination via tethered
           space robot
    • Abstract: Publication date: Available online 29 May 2019Source: Advances in Space ResearchAuthor(s): Yingbo Lu, Panfeng Huang, Zhongjie MengAbstractStabilization control is an essential mission for the tethered space robot-target combination during the post-capture phase of tethered space robot (TSR). With the consideration of the space tether and the three dimensional attitude of the post-capture combination, dynamic model of the combination is derived by using Lagrange method. Considering the unknown dynamic parameters (the tether attachment point, unknown target inertia parameters) of the post-capture combination, an adaptive anti-windup control approach is presented to overcome the problem of dynamic uncertainty and control input saturation. Complete stability and performance analyses are presented and illustrative simulation results of application to the post-capture combination system verify the effectiveness of the proposed algorithm.
  • Safe deployment of cluster-flying nano-satellites using relative E/I
           vector separation
    • Abstract: Publication date: Available online 28 May 2019Source: Advances in Space ResearchAuthor(s): Pengfei Liu, Xiaoqian Chen, Yong ZhaoAbstractNano-satellites cluster flight has attracted an increasing interest in the domain of distributed spacecraft system in recent years. As the first phase of a cluster flight mission, on-orbit deployment process constitutes a great technical challenge, since not only safe relative trajectories, but also practical operational constraints must be considered. To deal with these issues, the concept of relative Eccentricity/Inclination (E/I) vector separation was utilized in the safety concept design and the sequent release parameters solving, as it provides direct insight into the safety characteristics of relative motion. Accordingly, a novel operational methodology for the safe deployment of cluster-flying nano-satellites is provided. It can deterministically generate deployment sequences that ensure safe relative trajectories between released satellite (RS) pairs, as well as that between the launch vehicle (LV) and RSs, for enough long time interval. Particularly, according to our methodology, no maneuver efforts are required for the LV and RSs either during the deployment process or after deployment. Moreover, the proposed methodology adheres to practical constraints from either the LV or ground station. A typical simulation scenario was setup for the deployment process of the pioneering cluster flight mission - Satellite Mission for Swarming and Geolocation (SAMSON). Results demonstrate the feasibility and efficiency of our methodology.
  • Equatorial and low-latitude positive ionospheric phases due to moderate
           geomagnetic storm during high solar activity in January 2013
    • Abstract: Publication date: Available online 28 May 2019Source: Advances in Space ResearchAuthor(s): B.A.G. Ribeiro, P.R. Fagundes, K. Venkatesh, A. Tardelli, V.G. Pillat, G.K. SeemalaAbstractThe day-to-day variability of the equatorial and low-latitude ionosphere during quiet and disturbed periods is one of the ionospheric highlighted Space Weather research topics, particularly the ionospheric electrodynamics during geomagnetic storms. This study investigates the response of ionospheric F-region from the equatorial region to beyond the Equatorial Ionization Anomaly (EIA) crest during moderate geomagnetic storm (minimum Dst = -53 nT) that took place on January 17 to 18, 2013, during the high solar activity period of solar cycle 24. The Total Electron Content (TEC) obtained through a network of 82 dual frequency GPS receivers, spanning over an area of 30° x 30° in latitude and longitude are used. Also the F-layer virtual height (h’F) and critical frequency (foF2) observations from 3 ionosondes, in the South American sector are used. Specifically, these GPS-TEC receivers and ionosondes are used to investigate how the F-layer was disturbed by two positive ionospheric phases occurred during the aforementioned disturbed period. The first positive ionospheric phase was probably due to a travelling ionospheric disturbance (TID). When this TID reached the Brazilian coast at low-latitude, the EIA crest was in the growth phase and makes it challenging to separate the spatial-temporal evolution of both phenomena. The second positive ionospheric phase was caused by an anomalous nighttime equatorial positive ionospheric cloud travelling from the east sector towards the west sector. In addition, how the EIA was disturbed by these two positive ionospheric phases in the eastern and western Brazilian sectors is also investigated.
  • Ionospheric scintillation impact on ambiguity resolution using ADOP in
           closed form
    • Abstract: Publication date: Available online 28 May 2019Source: Advances in Space ResearchAuthor(s): C.M. Silva, D.B.M. Alves, E.M. Souza, P.T. Setti JuniorAbstractThe Ambiguity Dilution of Precision (ADOP) is a well-known scalar measure that can be used to infer the strength of the Global Navigation Satellite System (GNSS) model of the carrier phase ambiguities involved in precise relative GNSS positioning. Odijk and Teunissen (2008a) derived closed-form expressions for single-baseline GNSS models that allow verifying the factors affecting the ambiguity resolution as well as the probability of its correct resolution as integer values. However, this weighted-ionosphere ADOP closed form assumes that the standard deviation of the ionosphere delay is dependent on a function associated with the baseline length. This means that a baseline of the same length at different locations around the world and in different moments in time would have the same standard deviation, which in practice is not true. This becomes even worse in regions like Brazil, where the ionospheric anomalies are more intense and frequent, especially in periods of high solar activity. In this work, a new method for calculating the ionospheric delay standard deviation that considers the ionospheric scintillation S4 index is proposed to improve the closed-form ADOP performance. Experiments with a baseline of 280m located in Presidente Prudente, Brazil (magnetic latitude of around -13⁰), were carried out. The results showed that in periods of both weak and strong ionospheric scintillation, the introduction of S4 into the ionospheric delay standard deviation was beneficial for ADOP. The average improvement of the ADOP closed form was of around 72% in the analyzed period of weak scintillation and of 35% in the period of strong scintillation. In addition, the results showed that in periods of strong scintillation, relative positioning accuracy is around 100 times worse, up to 30 meters, when compared to periods of weak ionospheric scintillation.
  • Operations dynamics analysis of Solar thermal propulsion for CubeSats
    • Abstract: Publication date: Available online 23 May 2019Source: Advances in Space ResearchAuthor(s): Zaynulla S. Zhumaev, Georgy A. ShcheglovAbstractThis article considers operational dynamics of a solar thermal propulsion unit (STPU) with a solar energy concentrator for CubeSat nanosatellites. It was shown that for a 6U CubeSat with a 1U propulsion system, a resulting ΔV of more than 35m/s in less than 24hours is possible. This ΔV is enough to move apart two satellites to opposite points of a 600km circular orbit in less than 5days. An original scheme of the engine with a capillary feeder system and a Fresnel lens as the solar energy concentrator is proposed. A simplified mathematical model of the engine was created to make it possible to calculate hundreds of thruster operating cycles with different parameters in the chamber. The ODEs were numerically integrated using the Matlab-Simulink software package.
  • Calculating Risk and Payoff in Planetary Exploration and Life Detection
    • Abstract: Publication date: Available online 23 May 2019Source: Advances in Space ResearchAuthor(s): Ralph D. LorenzAbstractA framework for quantitative assessment of different mission architectures is described using historical data and formal (Bayesian) information value measures. The science value of the result is argued for binary questions (e.g. 'is there life on Europa') to be proportional to the logarithm of the posterior likelihood ratio of the answers, and can be derived from estimates of the false positive rates of instrumentation and of the presence (PD) of biosignatures at a given site. The expectation payoff is the product of the sought result with Markovian success probabilities of the required steps of launch, landing, sample acquisition etc., and historical planetary mission data are reviewed to derive (sometimes dismaying) estimates of these probabilities, e.g. historical landing successes rates are of the order of 66% and when landing is successful, the conditional rates of individual sample acquisition/analysis/return have similar values. The history of seafloor exploration on Earth is used as an analog, and indicates that in the absence of close reconnaissance data, PD may have rather low values of the order of 1% or less. The data acquisition success framework is demonstrated on the value of single versus multiple landers, on the choice of flyby altitudes for multiple plume fly-through missions, and on the value of surface mobility, which for small values of PD multiplies the science return by the number of sites visited. Bayesian reasoning requires encapsulation of prior information : while such estimates (of biosignature presence, false alarm rates, etc.) are inevitably subjective, the decomposition of that information onto specific factors affords transparency into their contribution to the final result and provides a basis for rational mission evaluation.
  • Analysis of pre-telescopic sunspots and auroras from 8th to 16th century
    • Abstract: Publication date: Available online 22 May 2019Source: Advances in Space ResearchAuthor(s): Mohamed Reda Bekli, Ilhem ChadouAbstractIn this paper, we use non-parametric kernel approach to estimate the probability density function (pdf) of auroral-night and naked-eye-sunspot series over multi-century timescale. We selected the events observed in medieval epoch, and auroral records from low geographical latitude (< 45°). These astronomical phenomena are recorded mainly in the Oriental historical sources and much less in Occidental sources. The collected events are published in many recent catalogues. The density function are calculated using the Gaussian kernel, including 95% CI obtained by bootstrapping.Results confirm the existence of strong connection between auroras and sunspot activity, especially from 11th to 16th century. Indeed, a high correlation degree r=0.72 is obtained for the period AD 800 – 1500 between the two pdf of sunspots (pdfS) and auroras (pdfA) for bandwidth h=10 years, and exceed 0.8 for h>43 years. However, we notice a time-shift between the two density functions. To calculate it, we use the cross-correlation technique, and we find τ =-5.9 years, that is strangely close to the half of solar cycle period. It is very important to note that our results revealed that the high frequency of low latitude auroras occurs before the maximum of naked-eye sunspots activity, and not afterward, on contrary to what is expected.The pdf curves show multiple peaks occurring at quasi-periodic times and show clearly the three grand minima of solar activity: Oort, Wolf and Spörer. In auroral-night data, the mean period at 95% CI obtained is:T¯=61±7years. Using power spectrum analysis, we observe clearly a strong signal of 60 years period that is a new evidence of the existence of such cycle. More importantly, we identified a cycle of 262 years period in the sunspot data, and a new oscillation of 310 years in auroral-night data. These two cycles appear clearly in the pdf curves using optimized bandwidth obtained by the direct plug-in approach of Sheather and Jones.
  • Two-phase framework for footprint prediction of space object reentry
    • Abstract: Publication date: Available online 22 May 2019Source: Advances in Space ResearchAuthor(s): Siwoo Kim, Byeong-Un Jo, Eun-Jung Choi, Sungki Cho, Jaemyung AhnAbstractThis paper proposes a two-phase framework to predict the impact dispersion area of a reentering space object. A semi-analytic approach is developed that predicts the dispersion area by combining an analytic impact point sensitivity model with corrections to account for aerodynamic drag. The first phase of the framework (preparation phase) generates a database storing the coefficients used in the correction model; this applies the least-squares method to the results of numerical experiments on the space object reentry for various initial states (position and velocity) and aerodynamic characteristics (i.e., ballistic coefficient). The second phase (execution phase: during the reentry event) predicts the dispersion area of the falling object using the correction coefficients database generated in the preparation phase. The validity and computational efficiency of the proposed method are demonstrated through a case study.
  • Statistical relation of scintillation index S4 with ionospheric
           irregularity index ROTI over Indian equatorial region
    • Abstract: Publication date: Available online 21 May 2019Source: Advances in Space ResearchAuthor(s): Rajat Acharya, Saibal MajumdarAbstractIonospheric 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.
  • Performance of BeiDou-3 satellites: Signal Quality Analysis and Precise
           Orbit Determination
    • Abstract: Publication date: Available online 21 May 2019Source: Advances in Space ResearchAuthor(s): Bo Zhang, Xiaolin Jia, Fuping Sun, Kai Xiao, Hailiang DaiAbstractA new generation of satellites aimed for the BeiDou-3 global positioning system (BDS-3) has recently been launched. These satellites will play a crucial role in its globalization process. The performance of the BDS-3 experimental satellites has been addressed in previous works. However, performance analysis of the orbits of BDS-3 satellites is still lacking. Using the observation data of the B1I and B3I frequency signals across different stations, this paper provides quality analysis, precise orbit determination (POD), and orbit comparison. The results presented here show that the ranging accuracy of BDS-3 is superior to that of the BeiDou-2 system (BDS-2). The satellite-induced code bias of BDS-2 satellite is not obvious on BDS-3 satellite. The orbit accuracy of BDS-3 satellite is superior to the BDS-2 satellite. The average three-dimensional root-mean-square error (RMS) of two-day overlapping arcs for BDS-3 satellite orbits is within 0.1 m, and the satellite laser ranging (SLR) validation reports that the orbit radial-track is within 6 cm.
  • Dynamics of ion-acoustic waves in Thomas-Fermi plasmas with source term
    • Abstract: Publication date: Available online 20 May 2019Source: Advances in Space ResearchAuthor(s): Laxmikanta Mandi, Asit Saha, Prasanta ChatterjeeAbstractDynamics of ion acoustic waves are studied in Thomas-Fermi plasmas with source term consisting of electrons, positrons and positive ions, where electrons and positrons follow zero-temperature Fermi-gas statistics, but ions behave as classical fluid. Using RPT (reductive perturbation technique) the forced KdV and modified KdV equations are obtained. Employing the concept of planar dynamical systems, periodic, quasiperiodic and chaotic features of ion-acoustic waves are studied in Thomas-Fermi plasmas with space debris depending on positron concentration (α), speed (vd) of the space debris and strength (f0) of source perturbation. The results of this work may have relevance in the Thomas-Fermi plasma environments with space debris.
  • Transient nature of radio source NVSS J1957+35
    • Abstract: Publication date: Available online 18 May 2019Source: Advances in Space ResearchAuthor(s): Sabyasachi Pal, Dusmanta Patra, Monique Hollick, Sandip K. ChakrabartiAbstractWe have searched for transient and variable radio sources in the field of Galactic micro-quasar Cygnus X-1 near 1.4 GHz (L band) using data from the Karl G. Jansky Very Large Array. We used twenty years of data between 1983 and 2003. We found a source NVSS J1957+35 showing transient behavior. The source was also mentioned earlier in NVSS and WENSS catalog but its transient nature was not reported earlier. The source is located 23.8 arcminutes far from Cygnus X-1. It is detected many times during the span of our study and it varied between less than 1.9 mJy (3σ) to 201 mJy. NVSS J195754+353513 also showed high intra-day variability. In one occasion, the source rose from ∼15 mJy to ∼170 mJy within 700 seconds. We detected circularly polarized emission from the source for a limited number of cases with fractional circular polarization varies between 0.14 to 0.17. 2MASS J19575420+3535152 may be the near-infrared counterpart of the source. We compared the properties of the source with other Galactic transient sources having similar properties. The nature of the source is still unknown. We discussed the possible nature of the source.
  • RadioAstron probes the ultra-fine spatial structure in the H2O maser
           emission in the star forming region W49N
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Space ResearchAuthor(s): N.N. Shakhvorostova, A.M. Sobolev, J.M. Moran, A.V. Alakoz, H. Imai, V.Y. AvdeevAbstractH2O maser emission associated with the massive star formation region W49N were observed with the Space-VLBI mission RadioAstron. The procedure for processing of the maser spectral line data obtained in the RadioAstron observations is described. Ultra-fine spatial structures in the maser emission were detected on space-ground baselines of up to 9.6 Earth diameters. The correlated flux densities of these features range from 0.1% to 0.6% of the total flux density. These low values of correlated flux density are probably due to turbulence either in the maser itself or in the interstellar medium.
  • - 56+with+Suzaku&rft.title=Advances+in+Space+Research&rft.issn=0273-1177&">A study of the composite supernova remnant MSH 15 - 56 with Suzaku
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Space ResearchAuthor(s): Nergis Cesur, Aytap Sezer, Jelle de Plaa, Jacco VinkAbstractThe Galactic supernova remnant (SNR) MSH 15-56 is a member of the class of composite SNRs that consists of the remnant shell and a displaced pulsar wind nebula (PWN). The earlier X-ray observations reported the comet-like morphology of the PWN and the ejecta distribution of the SNR. In this work, we present a study of MSH 15-56 using archival Suzaku data. We investigate the nature of the emission and spectral parameters of the remnant. The X-ray spectra are well fitted with a combination of a thermal and non-thermal model with temperature ∼0.6 keV and photon index ∼2.0. The slightly enhanced abundances of Ne, Mg, S and enhanced abundance of Si confirm the presence of ejected material.
  • Monitor link assignment for reentry users based on BeiDou inter-satellite
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Space ResearchAuthor(s): Leyuan Sun, Wende Huang, Yifan Zhou, Jun Yang, Yueke WangAbstractThe BeiDou Navigation Satellite System (BDS) has equipped its new-generation satellites with inter-satellite link (ISL) payloads to improve navigation services and system operation. When the inter-satellite ranging and communication are satisfied, we analyze the exploitation of the spare ISL capability for serving atmospheric reentry users. These users can be monitored over the atmospheric reentry segment with ISL transmission, even in the absence of visibility to ground stations and escaping the blackout. We modeled the problem and proposed a link assignment method combining parallel assignment of ISLs and dynamic access of monitor links. First, ISLs were assigned for inter-satellite ranging and communication, which were quantified with the number of different links and timeslot delays respectively. Corresponding assignment algorithm operated in the stations and the computing resource was abundant. Therefore, the heuristic algorithm was used to search the shortest route and the fitness function was determined with a shortest path algorithm. Based on the ISL assignment, extended users were accessed to the ISL network dynamically without influencing performances of the constellation. Because of the uncertainty of users’ states, the monitor link assignment was implemented onboard with short-term predicted states and therefore the computing resource was scarce. Short-term predicted states conquered the deviation of satellite-user visibility. And a simple smallest delay strategy was used to determine the access nodes for users. To evaluate performances of the algorithm, link assignments were implemented for the BeiDou global constellation with 3 users. Each satellite was linked with at least 10 satellites and communicated with stations within 3 timeslots on the basis of ISL assignments. The assignment of monitor links demonstrated the user access did not influence the ranging and communication index of the ISL network and 1-, 2-, and 3-timeslot route delays of users occupy the main parts and the total ratio is larger than 95%.
  • Control of Nonlinear Spacecraft Attitude Motion via State Augmentation,
           Lyapunov-Floquet Transformation and Normal Forms
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Space ResearchAuthor(s): Peter M.B. Waswa, Sangram RedkarAbstractThis article analyzes and controls the quasi-periodic attitude motion of a gravity-gradient stabilized spacecraft in eccentric orbit by way of system states augmentation, Lyapunov-Floquet and Normal Forms transformations. Perturbing torques in the ambient space environment can be shown to engender attitude motion represented by nonlinear dynamics coupled in the roll-yaw axes; and, uncoupled planar dynamics in the pitch axis. The non-planar dynamics equations are homogeneous and analytically solvable. However, the pitch attitude motion is nonlinear, possesses parameter-varying coefficients and is subjected to external periodic excitations. Consequently, we transform the unwieldy pitch attitude dynamics into relatively more amenable schemes for analysis and control law synthesis. Subsequently, we demonstrate the implementation of linear and nonlinear control laws (i.e. bifurcation and sliding mode control laws) on the relatively acquiescent transformed attitude dynamics. By employing a two-pronged approach, the quasi-periodic planar motion is independently shown to be stabilizable via the nonlinear control approaches.
  • Rocket Investigation of Current Closure in the Ionosphere (RICCI): A novel
           application of CubeSats from a sounding rocket platform
    • Abstract: Publication date: Available online 15 May 2019Source: Advances in Space ResearchAuthor(s): Ian J. Cohen, Brian J. Anderson, John W. Bonnell, Robert L. Lysak, Marc R. Lessard, Robert G. Michell, Roger H. VarneyAbstractThe Rocket Investigation of Current Closure in the Ionosphere (RICCI) sounding rocket mission concept will use the novel deployment of multiple CubeSats as miniature sub-payloads to obtain the first direct in-situ measurement of ionospheric closure currents. These ionospheric currents are critical to understanding the nature of atmosphere-ionosphere-magnetosphere coupling and have relevance to space weather parameters such as ionospheric densities, thermospheric heating, and satellite drag. Previous attempts to measure these ionospheric closure current in-situ have been limited by poor attitude knowledge resulting in large uncertainties in the magnetic field measurement that compromise the ability to measure the gradient of the magnetic field beyond the precision necessary to resolve the current densities. To address this, RICCI uses dedicated star trackers and currently-available CubeSat subsystems to obtain the high-precision attitude knowledge necessary to directly measure these elusive currents.
  • Imaging Strong Blazars with Space VLBI
    • Abstract: Publication date: Available online 13 May 2019Source: Advances in Space ResearchAuthor(s): J. Anton Zensus, Laura Vega-García, Eduardo Ros, Andrei P. Lobanov, Manel Perucho, Gabriele Bruni, Yuri Y. KovalevAbstractThe RadioAstron mission has obtained a series of detailed multi-frequency images of the brightest blazars of the radio sky concentrated in three key science programs. We present here results of the program on powerful jets in blazars. In the first two years of the mission, observations of compact relativistic jets in 0836+710, 3C 345, 3C 273, and 4C +69.21 were made at λλ 18, 6, and 1.3 cm. The resulting images have revealed compact emitting regions with brightness temperature in excess of 1013 K and a complex jet structure that can be explained by plasma instability developing in a relativistic outflow.We present here some highlights of these space-VLBI observations, designed to resolve the innermost regions in these powerful targets and address some of the still unanswered questions on their physical nature.
  • RadioAstron orbit determination and evaluation of its results using
           correlation of space-VLBI observations
    • Abstract: Publication date: Available online 13 May 2019Source: Advances in Space ResearchAuthor(s): M.V. Zakhvatkin, A.S. Andrianov, V.Yu. Avdeev, V.I. Kostenko, Y.Y. Kovalev, S.F. Likhachev, I.D. Litovchenko, D.A. Litvinov, A.G. Rudnitskiy, M.A. Shchurov, K.V. Sokolovsky, V.A. Stepanyants, A.G. Tuchin, P.A. Voitsik, G.S. Zaslavskiy, V.E. Zharov, V.A. ZugaAbstractA crucial part of a space mission for very-long baseline interferometery (VLBI), which is the technique capable of providing the highest resolution images in astronomy, is orbit determination of the mission's space radio telescope(s). In order to successfully detect interference fringes that result from correlation of the signals recorded by a ground-based and a space-borne radio telescope, the propagation delays experienced in the near-Earth space by radio waves emitted by the source and the relativity effects on each telescope's clock need to be evaluated, which requires accurate knowledge of position and velocity of the space radio telescope. In this paper we describe our approach to orbit determination (OD) of the RadioAstron spacecraft of the RadioAstron space-VLBI mission. Determining RadioAstron's orbit is complicated due to several factors: strong solar radiation pressure, a highly eccentric orbit, and frequent orbit perturbations caused by the attitude control system. We show that in order to maintain the OD accuracy required for processing space-VLBI observations at cm-wavelengths it is required to take into account the additional data on thruster firings, reaction wheel rotation rates, and attitude of the spacecraft.We also investigate into using the unique orbit data available only for a space-VLBI spacecraft, i.e. the residual delays and delay rates that result from VLBI data processing, as a means to evaluate the achieved OD accuracy. We present the results of the first experience of OD accuracy evaluation of this kind, using more than 5,000 residual values obtained as a result of space-VLBI observations performed over 7 years of the RadioAstron mission operations.
  • Interstellar Scintillation, ISS, and Intrinsic Variability of Radio AGN
    • Abstract: Publication date: Available online 13 May 2019Source: Advances in Space ResearchAuthor(s): David L. Jauncey, Jun Yi Koay, Hayley Bignall, Jean-Pierre Macquart, Tapio Pursimo, Marcello Giroletti, Talvikki Hovatta, Sebastian Kiehlmann, Barney Rickett, Anthony Readhead, Walter Max-Moerbeck, Harish Vedantham, Cormac Reynolds, James Lovell, Roopesh Ojha, Lucyna Kedziora-ChudczerAbstractWe investigate the relationship between the 5 GHz interstellar scintillation (ISS) and the 15 GHz intrinsic variability of the compact, radio-selected active galactic nuclei (AGN) common to the Microarcsecond Scintillation-Induced Variability (MASIV) Survey and the Owens Valley Radio Observatory blazar flux density monitoring program. As part of this investigation, we also re-examine the reported intrinsic nature of the February 1990 VLA observations of the blazar S5 0716+714. We are also examining the presence of IDV/ISS in the Owens Valley 15 GHz flux density monitoring data. We find a significant relationship between the Owens Valley 15 GHz modulation index and the MASIV modulation index. We also discuss the implications of these findings for RadioAstron.
  • A new multi-target tracking algorithm for a large number of orbiting
    • Abstract: Publication date: Available online 13 May 2019Source: Advances in Space ResearchAuthor(s): E. Delande, J. Houssineau, J. Franco, C. Frueh, D. Clark, M. JahAbstractThis paper presents the filter for Hypothesised and Independent Stochastic Populations (HISP), a multi-object joint detection/tracking algorithm derived from a recent estimation framework for stochastic populations, in the context of Space Situational Awareness. Designed for multi-object estimation problems where the data association between tracks and collected observations is moderately ambiguous, the HISP filter has a linear complexity with the number of objects and the number of observations. Because of its scalable complexity, the HISP filter is a promising solution for the construction of a large-scale catalogue of Resident Space Objects. We illustrate the HISP filter on a challenging surveillance scenario built from real data for 115 satellites of PlanetLabs’ Dove constellation, and simulated observations collected from two sensors with limited coverage and measurement noise, in the presence of false positives and missed detection.
  • Effects of vertical accuracy of digital elevation model (DEM) data on
           automatic lineaments extraction from shaded DEM
    • Abstract: Publication date: Available online 11 May 2019Source: Advances in Space ResearchAuthor(s): Ayman Soliman, Ling HanAbstractRemote sensing data, such as satellite images, and remote sensing derived digital elevation models (DEMs) are credited by simplifying many geological processes that require costly and laborious field work, such as lineament extraction. Furthermore, the recent increase in the availability of DEMs from many free open sources as well as their advantages over satellite imagery have promoted their wide application as remote sensing methods for lineament extraction. The quality of a DEM affects the results of its application, and this quality is controlled by its vertical accuracy and spatial resolution. The objectives of this study were to assess and verify the effects of the vertical accuracies of DEMs on lineament extraction. The area around Baoji city, Shaanxi province, China, was selected as a case study and the lineaments were automatically extracted using the LINE algorithm of PCI Geomatica from three DEMs with different vertical accuracies: tri stereo ZY3 imagery derived DEM, SRTM1V3, and ASTGDEMV2. All of these DEMs have 1″ spatial resolution (approx. 30 m). The results showed that the vertical accuracy of the applied DEM affects the number, length, and density of the extracted lineaments, where these quantities increase with increasing vertical accuracy of the DEM.
  • Finite Element Analysis for Nightside Transfer Function Lunar
           Electromagnetic Induction Studies
    • Abstract: Publication date: Available online 11 May 2019Source: Advances in Space ResearchAuthor(s): H. Fuqua Haviland, G.T. Delory, I. de PaterAbstractThe global electromagnetic induction response of the Moon has been solved numerically for several electrical conductivity profiles using the finite-element method. Here we demonstrate the capability and applicability in both two and three spatial dimensions for any input magnetic field time series measured at the Moon. We discuss the applicability of a vacuum approximation to the induced magnetic field response to the lunar plasma environment and the challenges of isolating geomagnetic induced fields including the interaction with the lunar wake structure. We perform three validation analyses comparing our vacuum model response to analytic solutions: (1) the time domain response to a step impulse or tangential discontinuity within the solar wind, (2) the time domain response to a ramp driving function, and (3) the broadband frequency domain response. We fit the analytic solutions to a root-mean-square error of better than 1% for all cases. We analyze the accuracy range and demonstrate our model’s capability of resolving interior structure from Apollo magnetometer data. We present the first time domain numerical solution of the induced magnetic field response of the Moon in vacuum for any driving input signal and any interior conductivity profile, building on previous Apollo era work. Lastly, we discuss the trade-offs between model accuracy and performance, which is of particular concern for large datasets and iterative optimizations. The transfer function method developed here is applicable to other airless body two-point magnetometer measurements including Apollo, ARTEMIS, and future lunar geophysical networks.
  • Analysis of deterministic and stochastic models of GPS stations in the
           Crustal Movement Observation Network of China
    • Abstract: Publication date: Available online 11 May 2019Source: Advances in Space ResearchAuthor(s): Shuguang Wu, Guigen Nie, Jingnan Liu, Changhu Xue, Jing Wang, Haiyang Li, Fengyou PengAbstractThe Crustal Movement Observation Network of China (CMONOC) has been accumulating GPS observation data for nearly 20 years since its trial operation in March 1999. It is an important task to comprehensively utilize the existing data from different research organizations and institutes, which will be beneficial to the research field of geosciences. Focusing on GPS coordinate time series of 27 CMONOC stations, this paper analyses the change of its characteristics before and after land surface environmental loading corrections (ELCs) and further studies the effect of surface displacements derived from environmental loadings on deterministic and stochastic models in this long-term GPS coordinate time series. Results show that the annual periodic signal in environmental loading displacement series may reasonably explain the seasonal signals in the vertical components of CMONOC stations but fails to account for the annual variation in the horizontal components. After ELCs, velocity estimations of 63.0% of station components decrease, while velocity uncertainties have an increasing trend. Non-integer spectral indices of GPS coordinate time series have also changed, especially in the vertical component. The optimal noise models in 14.8% of station components have changed, and the two principal models are WN+FN and WN+PL. The amplitudes of white noise and random walk noise have not been weakened, while the amplitude of flicker noise in the vertical component has reduced by 17.8% on average. Velocity uncertainties have a certain linear correlation with annual average rainfall and latitudes of these CMONOC stations, and the correlation with latitudes is stronger than with rainfall. Through a comprehensive analysis of the deterministic and stochastic models contained in the GPS time series, we may gain a further understanding of the features of crustal deformation in China.
  • Turbopause Range Measured by the Method of the Artificial Periodic
    • Abstract: Publication date: Available online 11 May 2019Source: Advances in Space ResearchAuthor(s): A.V. Tolmacheva, N.V. Bakhmetieva, G.I. Grigoriev, M.N. EgerevAbstractA new opportunity for estimating the level of the turbopause is presented. It is based on the method of determining atmospheric parameters using artificial periodic irregularities of the ionospheric plasma (the API techniques). The obtained data show the presence of variations of the level of the turbopause. Experiments were carried out using SURA heating facility (56.1°N, 46.1°E) for API creation. Above the observation point the turbopause region occupies the altitude interval between 94 and 106 km. There are changes in the level of the turbopause during the day: in the evening hours the turbopause level can go down. Temporal variations of the turbopause level are observed. They are compared with variations in the atmospheric parameters at these heights.
  • Detecting the Angular Momentum of the Galactic Dark Halo
    • Abstract: Publication date: Available online 11 May 2019Source: Advances in Space ResearchAuthor(s): Angelo TartagliaAbstractGeneral relativity predicts the presence of a gravito-magnetic component of the gravitational interaction induced by a rotating mass. It is currently assumed that our galaxy (as well as the others) is immersed in a dark halo. If so, it is reasonable to expect the halo to rotate, then to produce a gravito-magnetic field. Here we present a proposal to measure such effect exploiting the fully relativistic version of the Sagnac effect. When an electromagnetic signal is led to travel along a spacely closed path immersed in a gravito-magnetic field the time of flight for a complete turn depends on the direction of rotation. The proposed physical loop would be based on the Lagrange points of the Sun-Earth pair. An evaluation of the sensitivity of such a measurement, together with a discussion of more opportunities that the experiment would offer is also presented.
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