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Advances in Space Research
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 2
Number of Followers: 397  
 
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ISSN (Print) 0273-1177
Published by Elsevier Homepage  [3162 journals]
  • A comparative study of ionospheric spread-F and scintillation at low- and
           mid-latitudes in China during the 24th solar cycle
    • Abstract: Publication date: Available online 15 October 2018Source: Advances in Space ResearchAuthor(s): Ning Wang, Lixin Guo, Zhenwei Zhao, Zonghua Ding, Tong Xu, Shuji Sun The spread-F echo of ionograms and scintillation of satellite signal propagation along the Earth-space path are two typical phenomena induced by ionospheric irregularities. In this study, we obtained spread-F data from HF (high frequency) digital ionosonde and scintillation index (S4) data from L-band and UHF receivers at low- and mid-latitudes in China during the 24th solar cycle. These four sites were located at Haikou (HK) (20°N, 110.34°E), Kunming (KM) (25.64°N, 103.72°E), Qingdao (QD) (36.24°N, 120.42°E), and Manzhouli (MZL) (49.56°N, 117.52°E). We used these data to investigate spread-F and scintillation occurrence percentages and variations with local time, season, latitude and solar activity. A comparative study of spread-F and scintillation occurrence rates has been made. The main conclusions are as follows: (a) FSF occurred mostly during post-midnight, while RSF and scintillation appeared mainly during pre-midnight at HK and KM; (b) FSF occurrence rates were larger at QD and MZL than expected; (C) the FSF occurrence percentages were anti-correlated with solar activity at HK and KM; meanwhile RSF and scintillation occurrence rates increased with the increase of solar activity at this two sites; (d) the highest FSF occurrence rates mostly appeared during the summer months, while RSF and scintillation occurred mostly in the equinoctial months at HK and KM; (e) the scintillation occurrence was usually associated with the appearance of RSF, probably due to a different physical mechanism comparing with FSF. Some of these results verified the conclusions of previous papers, whereas some show slight difference. These results are important in understanding ionospheric irregularities variations characteristic at low- and mid-latitudes in China.
       
  • RTK model and positioning performance analysis using Galileo
           four-frequency observations
    • Abstract: Publication date: Available online 15 October 2018Source: Advances in Space ResearchAuthor(s): Rui Tu, Jinhai Liu, Rui Zhang, Pengfei Zhang, Xiaodong Huang, Xiaochun Lu This paper proposes a real-time kinematic (RTK) model that uses one common reference satellite for the Galileo system with four frequency observations. In the proposed model, the double-differenced (DD) pseudorange and carrier phase biases among the different frequencies are estimated as unknown parameters to recover the integer features of the DD ambiguities among the different frequencies for ambiguity resolution and precise positioning. Analysis results show that the E5a, E5b, and E5 frequencies have virtually the same performance in terms of the positioning accuracy, observation residuals, and ratio values of ambiguity resolution. However, the E1 frequency performs worse than the E5a, E5b, and E5 frequencies. The RTK results for the combination of multiple frequencies are much better than those for a single-frequency observation, the coordinates’ standard deviation is improved about 20-30%, and the ambiguity fix time is improved about 10%.
       
  • Comparison between statistical properties of Forbush decreases caused by
           solar wind disturbances from coronal mass ejections and coronal holes
    • Abstract: Publication date: Available online 13 October 2018Source: Advances in Space ResearchAuthor(s): A.A. Melkumyan, A.V. Belov, M.A. Abunina, A.A. Abunin, E.A. Eroshenko, V.G. Yanke, V.A. Oleneva In this paper, we compare Forbush decreases associated with solar wind disturbances from two types of solar sources: coronal mass ejections (sporadic Forbush decreases) and coronal holes (recurrent Forbush decreases). We used Forbush Effects and Interplanetary Disturbances database created and maintained by IZMIRAN and associated a certain amount of Forbush decreases in this database with interplanetary disturbances from coronal mass ejections (207 cases) as well as high speed streams from coronal holes (350 cases). Large number of events allows to apply statistical methods (distribution analysis, correlation analysis, multiple linear regression analysis) to compare those two groups of events. The results reveal that Forbush decreases associated with solar wind disturbances from the two types of solar sources differ significantly in their statistical characteristics: distributions, descriptive statistics, correlation and multiple regression coefficients.
       
  • Hierarchical scheduling for real-time agile satellite task scheduling in a
           dynamic environment
    • Abstract: Publication date: Available online 13 October 2018Source: Advances in Space ResearchAuthor(s): Lei He, Xiao-Lu Liu, Ying-Wu Chen, Li-Ning Xing, Ke Liu The imaging processes of optical satellites can be easily affected by unexpected environmental changes, such as changes in cloud coverage. Given the difficulty to predict environmental uncertainties, traditional offline scheduling methods need a follow-up re-scheduling process that responds to real-time environmental information. This repetitive scheduling processes make the offline fine scheduling process a waste of computational resources. Additionally, the offline scheduling method is quite complex owing to its lack of a hierarchy mechanism. To solve these problems, we propose a hierarchical scheduling method for the real-time scheduling problem. This method divides the scheduling process into three steps: pre-assignment, rough scheduling, and fine scheduling. A hierarchical scheduling algorithm based on ant colony algorithm is proposed. Tests with 36 scenarios show that the calculation time is efficiently reduced with this new mechanism. With this consideration of the dynamic environment, the re-scheduling process becomes unnecessary, meaning the wasting of computational resources is avoided and the solution profit is improved.
       
  • Lineament mapping and fractal analysis using SPOT-ASTER satellite imagery
           for evaluating the severity of slope weathering process
    • Abstract: Publication date: Available online 12 October 2018Source: Advances in Space ResearchAuthor(s): Saeedeh Hosseini, Gholam Reza Lashkaripour, Naser Hafezi Moghadas, Mohammad Ghafoori, Amin Beiranvand Pour The present study describes a remote sensing approach for preparing lineament map that subsequently indicates the influence of lineament density in the severity of weathering development. In this study, SPOT-5 data, the integration of SPOT-ASTER and Digital Elevation Model (DEM) data were used and processed. The existence of an active fault system in the south of Mashhad city, NE Iran and presence of schistose rocks in this area result in the development of numerous lineament features. This region was selected for this research. Lineament features including fractures, bedding plane, cleavage, shear zones and schistosity were mapped in the study area. The results indicate that the highest concentration of lineaments occurred in the central-western and south-eastern parts of the study area, which coincide with metamorphic outcrops and NW-SE trending fault system. A comparison of lineament statistical analysis and field survey demonstrated that the structural discontinuities have a significant effect on forming and distribution of weathering profiles. It was observed that increasing the number, length and density of structural discontinuities led to strong severity in weathering, which can produce deep residual soils susceptible to landslide occurrence. The remote sensing approach developed in this study can be applicable for preparing lineament maps and evaluating the severity of weathering development in other active fault zones around the world.
       
  • Dual-frequency carrier smoothed code filtering with dynamical ionospheric
           delay modeling
    • Abstract: Publication date: Available online 12 October 2018Source: Advances in Space ResearchAuthor(s): Chao Chen, Guobin Chang, Fei Luo, Shubi Zhang In GNSS applications, carrier-smoothed-code is a widely used technique to combine code pseudo-range and carrier phase measurements. A dynamical ionospheric delay modeling method is proposed based on Kalman filter and least-squares theory. The level of the process noise is adaptively tuned along with the real-time KF state estimation, based on the online variance component estimation method. Meanwhile, the correlations of the time differenced carrier phase measurements are considered. This approach avoids overly optimistically evaluating the estimate and improves the transient accuracy of the estimates. A real GPS dataset is employed to check the performance of the proposed method under different conditions. The results show that the new algorithm can model the ionospheric delay variation well with different sampling intervals or even in ionospheric abnormal environment. The positioning accuracy can be confirmed, about 21%, 35% and 16% better are obtained in the N, E, and U direction than raw dataset.
       
  • Nonlinear Filtering for Sequential Spacecraft Attitude Estimation with
           Real Data: Cubature Kalman Filter, Unscented Kalman Filter and Extended
           Kalman Filter
    • Abstract: Publication date: Available online 11 October 2018Source: Advances in Space ResearchAuthor(s): R.V. Garcia, P.C.P.M. Pardal, H.K. Kuga, M.C. Zanardi This article compares the attitude estimated by nonlinear estimator Cubature Kalman Filter with results obtained by the Extended Kalman Filter and Unscented Kalman Filter. Currently these estimators are the subject of great interest in attitude estimation problems, however, mostly the Extended Kalman Filter has been applied to real problems of this nature. In order to evaluate the behavior of the Extended Kalman Filter, Unscented Kalman Filter and Cubature Kalman Filter algorithms when submitted to realistic situations, this paper uses real data of sensors on-board the CBERS-2 remote sensing satellite (China Brazil Earth Resources Satellite). It is observed that, for the case studied in this article, the filters are very competitive and present advantages and disadvantages that should be dealt with according to the requirements of the problem.
       
  • Task Allocation Strategies for Cooperative Task Planning of
           Multi-autonomous Satellite Constellation
    • Abstract: Publication date: Available online 10 October 2018Source: Advances in Space ResearchAuthor(s): Feng Yao, Jiting Li, Yuning Chen, Xiaogeng Chu, Bang Zhao In recent years, the application of imaging satellites has entered a completely new stage, with the new demands such as rapid response to emergency events, observation of large-scale regional targets, multivariate data fusion and etc., the multi-autonomous satellite constellation has been proposed. This paper first designs the structure of multi-autonomous satellite constellation, and a centralized-distributed structure is proposed. This structure could improve the dynamic response capacity of the whole constellation. Then, this paper adds adapted filtering mechanism to single autonomous satellite online scheduling algorithm to enhance its performance. This article also pays more attention on task allocation strategies of the master satellite in constellation, and ten different task allocation strategies based on five dimensions are analyzed by simulation experiments. At last, this paper extracts several characteristic features of the regular observation targets and designs a selector based on support vector machine (SVM). This selector could select an appropriate strategy according to the features of each experiment scenario.
       
  • Puzzles of the Cosmic Ray Anisotropy
    • Abstract: Publication date: Available online 9 October 2018Source: Advances in Space ResearchAuthor(s): A.D. Erlykin, S.K. Machavariani, A.W. Wolfendale We discuss three of the known puzzles of the cosmic ray anisotropy in the PeV and sub-PeV energy region. They are 1) the so called inverse anisotropy, 2) the irregularity in the energy dependence of the amplitude and phase of the first harmonic and 3) the contribution of the single source.
       
  • Attitude stability and periodic attitudes of rigid spacecrafts on the
           stationary orbits around asteroid 216 Kleopatra
    • Abstract: Publication date: Available online 4 October 2018Source: Advances in Space ResearchAuthor(s): Hanlun Lei, Christian Circi, Emiliano Ortore, Bo Xu In this work, equilibrium attitude configurations, attitude stability and periodic attitude families are investigated for rigid spacecrafts moving on stationary orbits around asteroid 216 Kleopatra. The polyhedral approach is adopted to formulate the equations of rotational motion. In this dynamical model, six equilibrium attitude configurations with non-zero Euler angles are identified for a spacecraft moving on each stationary orbit. Then the linearized equations of attitude motion at equilibrium attitudes are derived. Based on the linear system, the necessary conditions of stability of equilibrium attitudes are provided, and stability domains on the spacecraft’s characteristic plane are obtained. It is found that the stability domains are distributed in the first and third quadrants of the characteristic plane and the stability domain in the third quadrant is separated into two regions by an unstable belt. Subsequently, we present the linear solution around a stable equilibrium attitude point, indicating that there are three types of elemental periodic attitudes. By means of numerical approaches, three fundamental families of periodic solutions are determined in the full attitude model.
       
  • Uncertainties in gravity wave parameters, momentum fluxes, and flux
           divergences estimated from multi-layer measurements of mesospheric
           nightglow layers
    • Abstract: Publication date: Available online 3 October 2018Source: Advances in Space ResearchAuthor(s): Fabio Vargas Measurements of dynamic parameters of atmospheric gravity waves, mainly the vertical wavelength, the momentum flux and the momentum flux divergence, are affected by large uncertainties crudely documented in the scientific literature. By using methods of error analysis, we have quantified these uncertainties for frequently observed temporal and spatial wave scales. The results show uncertainties of ∼10% , ∼35%, and ∼65%, at least, in the vertical wavelength, momentum flux, and flux divergence, respectively. The large uncertainties in the momentum flux and flux divergence are dominated by uncertainties in the Brunt-Väisälä frequency and in spatial separation of the nightglow layers, respectively. The measured uncertainties in fundamental wave parameters such as the wave amplitude, intrinsic period, horizontal wavelength, and wave orientation are ∼10% or less and estimated directly from our nightglow image data set. Other key environmental quantities such as the scale height and the Brunt-Väisälä frequency, frequently considered as constants in gravity wave parameter estimations schemes, are actually quite variable, presenting uncertainties of ∼4% and ∼9%, respectively, according to the several solar activity and seasonal atmosphere scenarios from the NRLMSISE-00 model simulated here.
       
  • A Longitudinal & Longitudinal-Torsional Vibration Actuator for
           Rotary-Percussive Ultrasonic Planetary Drills
    • Abstract: Publication date: Available online 1 October 2018Source: Advances in Space ResearchAuthor(s): Deen Bai, Qiquan Quan, Yinchao Wang, Dewei Tang, Zongquan Deng Ultrasonic drills, which can sample rocks using a lower weight on bit and lower power, are more suitable for sampling on a minor planet than conventional drills. To remove cutting chips and improve drilling efficiency, rotary-percussive ultrasonic drills (RPUD) drive drill tools for rotary-percussive motion. This paper proposes a novel longitudinal & longitudinal-torsional (L-LT) actuator, which is composed of a stepped horn, a piezoelectric stack, and a longitudinal-torsional (LT) coupler, for the RPUD. The horn magnifies the longitudinal vibration on the front surface of the piezoelectric stack, which is clamped between the horn and the LT coupler, and impacts the drill tool. The LT coupler transforms the longitudinal vibration on the back surface into longitudinal-torsional vibration, which generates elliptical movements that drive the rotor to rotate. Then, the rotor drives the drill tool to rotate. A method of adjusting the displacement amplitudes of the horn and the driving tips is discussed. The prototype achieved a maximum speed and torque of 193 r/min and 0.065 N·m, respectively. The maximum drilling speed through sandstone under a weight on bit of 5 N was 13 mm/min.
       
  • List of Referees
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s):
       
  • Investigation of microwave optical constants of bulk iron oxides
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): V.V. Tikhonov, D.A. Boyarskii, O.N. Polyakova The paper presents an analysis of microwave optical constants of iron oxides (magnetite and hematite) by means of the Kramers–Kronig method. Spectral reflectivities of magnetite and hematite in a wide frequency range (from extreme ultraviolet to microwave) were derived based on multiple experimental data found in the literature. The obtained dependencies were used to calculate optical constants of the minerals at 12–145 GHz and compare the results with other reported theoretical and laboratory studies.
       
  • Empirical values of branching ratios in the three-body recombination
           reaction for O(1S) and O2(0,0) airglow chemistry
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Yolián Amaro-Rivera, Tai-Yin Huang, Julio Urbina, Fabio Vargas The branching ratios ε and α in the three-body recombination reaction for O(1S) greenline and O2(0,0) atmospheric band airglow chemistry represent the fraction of O2 that branch into the b1∑g+ and c1∑u- electronic states, respectively. In the present work, the empirical values of these branching ratios have been deduced using a numerical optimization approach. They were obtained using the optimization scheme known as the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) with our MACD-00 model and simultaneous volume emission rate (VER) measurements of the O(1S) greenline and O2(0,0) atmospheric band emissions. The CMA-ES was employed as the optimization algorithm that would match the O(1S) and O2(0,0) VER profiles simulated by the MACD-00 model to observations made by OXYGEN/S35, S310.10, NASA Flight 4.339, ETON flights P229H and P230H, OASIS, SOAP/WINE, MULTIFOT, and WINDII. We found that most of the values deduced for ε were in the [0.1, 0.3] range, while most of the values of α were in the [0.01, 0.03] range. Excluding the outliers, the average branching ratio values involving the production of O2(b1∑g+) and O2(c1∑u-) were determined to be ε = 0.15 ± 0.02 and α = 0.018 ± 0.004, respectively. Overall, the simulations showed good agreement with the observations albeit with some discrepancies in the peak altitudes and shape of the profiles, possibly due to small perturbations in the observed VER profiles that are not considered in our simulations.
       
  • Motion estimation of uncooperative space objects: A case of multi-platform
           fusion
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Mahboubeh Zarei-Jalalabadi, Seyed Mohammad-Bagher Malaek This work describes an efficient technique to sequentially combine estimates resulting from individual sets of measurements provided by a network of satellites. The prescribed method is especially effective to estimate motion states of an uncooperative space object using range image data. The technique, which is fast and suitable for on-line applications, could also be effective to capture stray objects or those satellites that require periodic servicing. Such missions call for high degree of precision and reliable estimation methods. In fact, the proposed estimation architecture consists of a network of synchronized platforms, i.e., Observer Satellites (OS), each with processing power and transmission capability, that are observing a common Target Space Object (TSO). All OSs are expected to have suitable measuring devices, such as active vision sensor, that provide sensory range image data. Each platform could also independently estimate its objective based on its own observations. The estimates are then transmitted to a fusion center to assimilate the fused estimate that is more accurate than any individual estimates. As a specific example, we show exploiting efficient algorithms in processing of range image data, filtering, and fusion of estimates enables the proposed method to be especially effective for active debris removal. Different case studies confirm that the method is capable of processing measured data fairly quickly and producing fused estimates with a tangible decrease in estimation error.
       
  • The semi-analytical analysis of orbital evolution around an asteroid under
           the effects of the C20 term, the solar radiation pressure and the
           asteroid’s orbital eccentricity
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Jinglang Feng, Xiyun Hou This paper aims to develop a semi-analytical method of propagating orbital motion near the equatorial plane of an asteroid, considering the combined effects of the asteroid’s oblateness (the C20 term), the solar radiation pressure (SRP) and the asteroid’s orbital eccentricity around the Sun (es). In the asteroid-centered frame, the Hamiltonian of the orbital motion is derived with Poincaré variables. It is firstly averaged over the orbital motion around the asteroid and then averaged over the asteroid’s eccentric orbital motion around the Sun. Time-explicit analytical solutions of the orbital eccentricity and inclination are obtained. The Lie transformation is applied to recover the eliminated oscillating terms of the inclination during the second average for a complete solution. We analyze the validity of these solutions for different semi-major axes and different values of area-to-mass ratios (A/m). We demonstrate the importance of considering the asteroid’s orbital eccentricity around the Sun and its role in enlarging the amplitude of orbital eccentricity for different A/m and orbital geometries. The solutions developed in this paper improve the knowledge of secular orbital evolution around asteroid. They can be applied to fast prediction of long-term orbital evolutions around near Earth asteroids (NEAs).
       
  • Robust fault tolerant nonfragile H ∞ attitude control for spacecraft via
           stochastically intermediate observer
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Chuang Liu, George Vukovich, Keke Shi, Zhaowei Sun The observer-based fault tolerant attitude control problem for spacecraft is addressed, wherein the constraints of H∞ performance, quadratic stability, model parameter uncertainty, measurement errors, external disturbances, controller perturbation, and actuator fault and saturation are considered simultaneously. A novel fault estimation approach is proposed, where a stochastically intermediate variable is introduced. Based on the exactly available expectation of such a variable, a new kind of intermediate observer is proposed to estimate the attitude information and fault signals simultaneously. Compared with the traditional fault estimation methods, the approach proposed in this paper is less conservative for it requires neither equation constraints nor observer matching condition and can tolerate stochastic failure. To achieve fault tolerant and nonfragile control performance, the estimation of fault signals and explicit controller perturbation are also exploited in the controller design. Based on Lyapunov stability theory, sufficient conditions for the existence of the observer-based fault tolerant nonfragile H∞ controller are given based on linear matrix inequalities (LMIs) in terms of additive perturbation and multiplicative perturbation. Numerical simulations are performed to demonstrate the effectiveness of the proposed method and also illustrate the advantage over the existing state feedback control method in terms of great reduction in energy consumption.
       
  • Multi-spacecraft attitude cooperative control using model-based
           event-triggered methodology
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Chengxi Zhang, Jihe Wang, Ran Sun, Dexin Zhang, Xiaowei Shao The attitude cooperative control of multi-spacecraft under undirected information flow is studied in this paper based on a novel state-irrelevant event-triggered control (ETC) strategy. In the proposed algorithm, the control updating and data-transfer among spacecraft need only be executed when certain conditions are triggered. Then, the system model is utilized to predict the future state based on the last transmission and to calculate the time of the next transmission event. Firstly, the proposed algorithm reduces the control updating frequency remarkably and avoids continuous communication; secondly, each spacecraft updates its controller independently, without requiring all members to update simultaneously; thirdly, it is still effective in the presence of input limitation. The consensus can be guaranteed under such control strategy. It has proved that there exists a lower bound for the update interval, avoiding a phenomenon that the infinite number of events may appear in a finite time interval, also called the Zeno phenomenon. The efficacy of the proposed algorithm is verified via simulations.
       
  • Equal-collision-probability-curve method for safe spacecraft close-range
           proximity maneuvers
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Yi Wang, Yuzhu Bai, Jianjun Xing, Gianmarco Radice, Qing Ni, Xiaoqian Chen An equal-collision-probability-curve (ECPC) method is developed in this paper to address the problem of safe spacecraft proximity maneuvers. Considering the uncertainties’ influence, the ECPC, which represents the curve of equal-collision-probability-points in the space around the target spacecraft, is firstly established. It is optimal to maneuver along the gradient direction of the ECPC, which is the fastest change in the ECPC. To calculate this direction, a novel auxiliary function, which has the same gradient direction as the collision probability function, is proposed. Compared to traditional collision probability functions, the proposed function does not contain transcendental elements and hence the computational burden can be greatly decreased while maintaining the necessary accuracy. Then, the safe close-range proximity maneuver generated by ECPC method can be implemented along the estimated gradient direction. Analytical validation is performed to assess the use of such collision avoidance scheme for safety critical operations. Furthermore, an improved Linear Quadratic Regulator (LQR) is designed to track the reference trajectory and a Lyapunov-based analysis verifies the stability of the overall closed-loop system. Numerical simulations show that the novel ECPC method is more computationally efficient than traditional methods while maintaining the same accuracy. Moreover, the novel scheme can be easily validated to guarantee the safety of the mission.
       
  • Potential function based robust safety control for spacecraft rendezvous
           and proximity operations under path constraint
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Qi Li, Bo Zhang, Jianping Yuan, Huan Wang This paper deals with the safety control problem for spacecraft rendezvous and docking with coupled position and attitude dynamics under external disturbances and unknown model parameters. Given the path constraint, a semi-cubical parabola based curve is employed to restrict the motion area of the chaser spacecraft during the process of rendezvous and proximity operations. By combining the sliding mode technique with the artificial potential function, a robust adaptive control strategy is presented for driving the chaser spacecraft to rendezvous and dock with a space target without violating the path constraint. The stability of the closed-loop system is then proved within the Lyapunov framework. Numerical simulations are carried out to illustrate the effectiveness of the proposed control strategy.
       
  • GPS/GLONASS carrier phase elevation-dependent stochastic modelling
           estimation and its application in bridge monitoring
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Ruijie Xi, Xiaolin Meng, Weiping Jiang, Xiangdong An, Qusen Chen The Global Positioning System (GPS) based monitoring technology has been recognised as an essential tool in the long-span bridge health monitoring throughout the world in recent years. However, the high observation noise is still a big problem that limits the high precision displacement extraction and vibration response detection. To solve this problem, GPS double-difference model and many other specific function models have been developed to eliminate systematic errors e.g. unmodeled atmospheric delays, multipath effect and hardware delays. However, relatively less attention has been given to the noise reduction in the deformation monitoring area. In this paper, we first proposed a new carrier phase elevation-dependent precision estimation method with Geometry-Free (GF) and Melbourne-Wübbena (MW) linear combinations, which is appropriate to regardless of Code Division Multiple Access (CDMA) system (GPS) or Frequency Division Multiple Access (FDMA) system (GLONASS). Then, the method is used to estimate the receiver internal noise and the realistic GNSS stochastic model with a group of zero-baselines and short-baselines (served for the GNSS and Earth Observation for Structural Health Monitoring of Bridges (GeoSHM) project), and to demonstrate their impacts on the positioning. At last, the contribution of integration of GPS and GLONASS is introduced to see the performance of noise reduction with multi-GNSS. The results show that the higher level receiver internal noise in cost effective receivers has less influences on the short-baseline data processing. The high noise effects introduced by the low elevation satellite and the geometry variation caused by rising and dropping satellites, can be reduced by 10–20% with the refined carrier phase elevation-dependent stochastic model. Furthermore, based on observations from GPS and GLONASS with the refined stochastic model, the noise can be reduced by 30–40%, and the spurious signals in the real-life bridge displacements tend to be completely eliminated.
       
  • A suboptimal excitation torque for parameter estimation of a 5-DOF
           spacecraft simulator
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Zheyao Xu, Yukun Chen, Zhexuan Xu Five degrees of freedom spacecraft simulators are designed to verify spacecraft control strategies, rendezvous and docking techniques. The accurate knowledge of simulator inertia parameters which can be calculated by parameter estimation is of vital importance in these experiments. However, the rotation limits of the simulator must be considered during estimation process. This paper presents an approach to determine a suboptimal excitation torque for the system identification of the inertia parameters. The continuous optimization problem is transcribed into a discrete nonlinear programming problem by integral gauss pseudospectral method. To reduce the effect of noise, the states and inertia parameters are estimated simultaneously by joint filter within Extended Kalman Filter (EKF) or Unscented Kalman Filter (UKF). The proposed method is validated by simulations and the results indicate that this method not only satisfies the constraints of simulator rotation angles, but also improves the efficiency of parameter estimation.
       
  • An experimental setup for hollow cathode independent life test simulating
           Hall thruster discharge current oscillations
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Wenbo Li, Hong Li, Yongjie Ding, Liqiu Wei, Haifeng Lu, Qian Gao, Zhongxi Ning, Daren Yu The reliability of cathode is critical to electric propulsion systems. Although researchers have carried out many life tests on hollow cathode, the discharge current is almost steady when the cathode is independently tested for life. Actually, when it is coupled with the thruster, the discharge current is with large amplitude low-frequency oscillation. Therefore, we suggest a new external circuit for a cathode-independent life test, which could simulate the characteristics of discharge current oscillation when the cathode is coupled with Hall thruster. We carried out 160 h of life test using the normal external circuit and the new external circuit, and the variation characteristics of the cathode orifice area are also studied during the life test. The results show that under the normal external circuit, the growth rate of the cathode orifice area initially increases and then decreases gradually with the increase of the time of life test, whilst the cathode orifice area in the new external circuit linearly increases. The new external circuit can provide a new method to simulate the discharge current oscillation when the cathode is coupled with Hall thruster during the independent life test of the cathode.
       
  • Satellite constellation design algorithm for remote sensing of diurnal
           cycles phenomena
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Sung Wook Paek, Luzius G. Kronig, Anton B. Ivanov, Olivier L. de Weck This paper proposes an algorithm to find the smallest satellite constellation satisfying a given set of Earth observation requirements. This methodology is exemplified with the Satellites Observing Lakes and Vegetation Environments (SOLVE) study, which aims at deploying a fleet of small satellites carrying miniaturized hyperspectral spectrometers. A key requirement of this mission is a high temporal resolution through which the ground target can be observed several times a day. Hourly observations are required in this mission in order to capture diurnal changes in water quality and vegetation environments. Given sensor specifications and observation requirements, the proposed algorithm determines orbital parameters of an optimal constellation design via a semi-analytical approach. This approach reveals trade-offs amongst performance metrics and deployment cost, providing better physical intuition for decision-making compared to stochastic optimization.
       
  • Indoor and outdoor positioning system based on navigation signal simulator
           and pseudolites
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Chao Ma, Jun Yang, Jianyun Chen, Yinyin Tang In positioning technology, indoor positioning is known as the “last kilometer” problem because the global navigation satellite system (GNSS) cannot work indoors. A wide range of indoor positioning technologies have been developed, notably Bluetooth and Wi-Fi, and others using LED and ultra-wideband light sources. Although these technologies have had good success indoors, the indoor use of GNSS is still being pursued, and an indoor and outdoor joint location system remains a development aim. In this paper, we propose a new indoor positioning scheme that adopts pseudo-satellite (pseudolite) technology combined with a navigation signal simulator. Positioning is achieved by indoor pseudolite antennas that transmit the ‘actual’ satellite signals in space handled by the navigation signal simulator to an indoor user. However, the ‘actual’ satellite ephemeris stored in the pseudolites will bring false pseudoranges, which makes it necessary to adopt map matching technology to determine the real position. The results of our computer simulation showed that when the measurement error mainly multipath error in the room was within 1 m, the positioning results were better than 2 m in about 94% of instances. The proposed method provides a feasible solution for indoor and outdoor joint positioning. The advantages of this system include a better dilution-of-precision (DOP) than an independent pseudolite system indoors, no singular matrix, and initial point selection without limitation in the positioning equation. In addition, the introduction of a navigation signal simulator makes the system more flexible.
       
  • Odometer and MEMS IMU enhancing PPP under weak satellite observability
           environments
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Zhouzheng Gao, Maorong Ge Accuracy of dynamic precise point positioning (PPP) degrades significantly under users’ challenging environments because of the limited or unavailable GPS observations. To overcome such weakness, a tight-integration system of micro-electromechanical systems (MEMS) inertial measurement unit (IMU), odometer, and GPS ionospheric delay constrained PPP is investigated to provide users positions and attitudes with higher accuracy, reliability, and continuity under the weak GPS observability environments. In this approach, the data from different sensors are integrated in two joint extend Kalman filters (EKF). One is for PPP/INS tight-integration and the other one is for odometer aiding the solutions from INS or PPP/INS tight-integration modes. Here, the advantages of slow time-varying ionospheric delay, high-accuracy in short time of inertial navigation system (INS), and hardly-disturbed odometer are utilized effectively to enhance PPP solutions. The corresponding mathematical models are provided and are evaluated by a set of one-hour real land-borne test data collected from a MEMS IMU, an odometer, and a dual-frequency GPS receiver in suburbs of Wuhan city, China, and also a set of simulated weak satellites availability data which is to imitate the GPS availability under unban canyons. Results indicate that the fusion system can improve navigation accuracy of GPS or GPS/INS significantly. That are, more than fifty percentages position enhancements in north-east-down components, and about forty percentages attitude enhancements in roll-pitch-yaw direction under the weak GPS availability.
       
  • Extraction and analysis of geological lineaments combining a DEM and
           remote sensing images from the northern Baoji loess area
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Ling Han, Zhiheng Liu, Yuming Ning, Zhongyang Zhao Geological lineaments are important reactant of geological structure on the surface, and control the distribution of regional groundwater, geohazards, geothermal and earthquakes. The technology of geological lineaments extraction is of great significance for the analysis of regional plate movement and ore forming prognosis. However, the traditional methods are mainly based on the semi-automatic or manual visual interpretation, which consuming time and labor for the dependence on the rich professional experience and knowledge of the interpreter experts, and involving less in the special geomorphological regions. Taking Loess areas in northern Baoji as an example, this paper proposed a lineaments extraction algorithm based on tensor voting coupled Hough Transform, with the help of DEM and Landsat 8 OLI remote sensing images. Firstly, the best independent band combination of Landsat 8 OLI images for lineaments extraction were selected by using principal component analysis. Secondly, Gaussian high-pass filter was applied to sharpen the edge in the DEM and composite Landsat 8 OLI images. Linear boundary was extracted by tensor voting according to the conspicuousness of the vector sum superposition feature based on edge points. Finally, the Hough Transform was employed to search the edges and extracted the geological lineaments in this region. The experimental results showed that the orientation of lineaments was dominated by NW-SE and NE- SW, supplemented by NNW-SSE. Under the influence of the uplift of the eastern foot of Liupan Mountains and the southern margin of Ordos, the lineaments were mainly distributed over linear landforms, which were better consistent with previous studies about the direction of tectonics in this region. Compared with the segment tracing algorithm, this method has more applicability, efficiency, high practical value and scientific significance in the analysis of tectonic movement and evolution in special landform area.
       
  • GLONASS real-time wide-lane ambiguity resolution with an enhanced
           geometry-based model for medium-range baselines
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Longwei Xu, Hui Liu, Bao Shu, Fu Zheng, Ming Zhang, Chuang Qian, Yingzi Duan Double-difference wide-lane integer ambiguities are determined first to assist narrow-lane ambiguity resolution in real-time medium-range baseline resolution. The Hatch-Melbourne-Wübbena (HMW) is the conventional strategy for wide-lane ambiguity resolution, which works well for GPS/Galileo/BDS. However, the un-canceled inter frequency bias (IFB) on double-difference measurement causes that the HMW combination is invalid on GLONASS wide-lane ambiguity resolution. The residual IFB in double-difference measurement may be several meters, especially between inhomogeneous stations. There is no effective method to model or tabulate ranging-codes IFB. In this paper, we propose a device-independent geometry-based model to achieve GLONASS real-time wide-lane ambiguity resolution for medium-range baselines. Since zenith tropospheric delay and slant ionospheric delay of satellites are estimated as unknown parameters, we utilize atmosphere-weighted algorithm to enhance the model strength and decrease the dependence on pseudorange measurement. For medium-range baseline, GLONASS wide-lane ambiguity float solutions can converge quickly by the geometry-based model. The cumulative frequency of WL AR can exceed 99% during 10 epochs. Benefiting from rapid and reliable wide-lane ambiguity resolution, the positioning accuracy of GPS/GLONASS RTK fixed solution are greater than 3 cm in level direction and 5 cm in upward direction for 40–100 km baselines. An approximately 35% improvement rate is observed in each direction compared with that of single GPS RTK. Since less available satellites for single-GLONASS mode, the convergence of wide-lane ambiguity becomes slower. For base stations with known coordinates, the enhanced geometry-based model can be developed to the enhanced geometry-fixed model and are applied to longer baselines. Assisting with the geometry-fixed model, more than 90% of GLONASS narrow-lane ambiguities can be fixed quickly for 80–160 km baselines. It should be noted that the accuracy of external atmospheric delay is critical to the performance of the geometry-based method. Its benefit may weaken with the increasing of baseline length, when external atmospheric delays are set as 0 directly.
       
  • Aliasing effect due to convective rain in Doppler spectrum observed by
           micro rain radar at a tropical location
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Soumyajyoti Jana, Gargi Rakshit, Animesh Maitra The spectral reflectivity in terms of Doppler velocity obtained by micro rain radar (MRR) at a tropical location can reveal the splitting of Doppler spectrum of falling rain drops caused by strong downdraft. The phenomenon, known as aliasing, occurs in Doppler spectrum of MRR during intense convective events. In this case, the rain drop velocity exceeds the unambiguous Doppler velocity range that can be sensed by MRR. The downdraft affecting the raindrop velocity significantly causes an ambiguity in the Doppler spectrum of the radar signal scattered from raindrops. The aliasing effect is most prominent near the boundary layer height (0.8–2 km) for convective rain. Also at this altitude range, the resultant height gradient obtained from ECMWF vertical velocity of air mass data and drop terminal velocity, is maximum. The importance of the present study lies in the fact that the split in Doppler spectrum can be utilized to estimate downdraft velocity during rain. The de-aliasing technique has been applied to the raw Doppler spectrum of MRR to retrieve the rain drop size distribution conforming to ground based measurements.
       
  • Diurnal variations in seasonal precipitation in Iran from TRMM
           measurements
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Mohammad Sadegh Keikhosravi Kiany, Robert C. Balling, Randall S. Cerveny, Daniel S. Krahenbuhl We analyzed three-hourly TRMM precipitation data for Iran over the period 1998–2013. During the winter season when cyclonic storms dominate the precipitation, 66% of the country does not display a significant diurnal cycle in precipitation; however, the more mountainous portions of the country display a diurnal cycle with the time of maximum occurring near 12.50 LST. During the spring season when convective precipitation dominates, 55% of the country has a significant diurnal cycle in precipitation with a time of maximum near 15.50 LST; the result clearly shows the convective nature of the precipitation in this season. In summer season, only the northern and southern regions of the country receive much precipitation with most of it occurring between 15.50 and 18.50 LST, with the pattern being strongest in the southern areas. In fall season 42% of the country displays a significant diurnal cycle in precipitation. In this season, south regions of the country have their maximum precipitation frequency between 12.50 and 15.50 LST. Nearly identical patterns exist for precipitation amounts when compared to frequency.
       
  • Use of Landsat 8 data for characterizing dynamic changes in physical and
           acoustical properties of coastal lagoon and estuarine waters
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Theenathayalan Varunan, Palanisamy Shanmugam This study intends to develop methodologies that use high resolution satellite data from Landsat 8 (Operational Land Imager) OLI and (Thermal Infrared Sensor) TIRS sensors for characterizing spatial and temporal changes in physical and acoustical properties of coastal lagoon and estuarine waters. It employs multiple steps to achieve this possibility: a novel atmospheric correction algorithm is applied to OLI spectral data to retrieve water-leaving radiances which are key inputs for the applied models; appropriate parameterizations are developed for the OLI bands and used in conjugation with a hybrid model to produce the spectral absorption coefficients of coloured dissolved organic matter (aCDOM) and to derive surface salinity fields which inversely correspond with the aCDOM values; an efficient algorithm is employed to estimate surface water temperature using thermal infrared bands, and well-known models are employed with the satellite-derived products to determine the acoustical properties (sound attenuation and speed). Results from the above methodology were evaluated using in-situ data and Landsat 8 OLI matchup data acquired over the coastal lagoon systems (e.g., Chilika Lagoon on the coast of Bay of Bengal) during monsoon and non-monsoon seasons. The uncertainties associated with the derived products such as CDOM, salinity, temperature, sound attenuation and speed were found to be within the desirable mission goal. Recognizing the importance of the salinity gradient that plays a unique and fundamental role in defining a transitional ecosystem, spatial and temporal patterns in the structure of the salinity gradient were examined together with the CDOM patterns. High resolution OLI products exhibited a general horizontal gradient with salinity decreasing from the lagoon mouth in the eastern and central sectors to the river mouth in the northern sector and a near uniform gradient with moderate salinity in the adjacent locations (southern sector) of the lagoon. The time-series of OLI products further showed that spatial and temporal structures of the salinity are modulated by the terrestrially delivered freshwater inputs, tidal forcing at the lagoon mouth, mixing of these two waters sources, and local geomorphology. Surface water temperature products derived from the TIRS sensor for the lagoon and its adjoining locations depicted a well pronounced seasonal cycle with warmer temperatures modulated by reduced mixing and increased solar heating and stratification during non-monsoon, summer months and cooler temperatures during monsoon, winter months. The effect of salinity and temperature on the sound attenuation and sound speed was prominent in the locations of the freshwater discharge and tidal mixing regimes, where the salinity exerted a greater influence on both sound attenuation and speed despite the opposing effects of surface water temperatures. In areas of surface heating and stratification, both salinity and temperature increased causing an increase in sound attenuation and speed over the ranges found in the lagoon. These results are important for sonar performance modelling and operation of acoustic devices in such shallow water environments impacted by the terrestrial and ocean forcing factors.
       
  • Real-time cycle slip correction for a single triple-frequency BDS receiver
           based on ionosphere-reduced virtual signals
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): Xiao Gao, Zhiqiang Yang, Ying Liu, Bing Yang Being an essential part of GNSS processing, cycle slip detection and repair has been intensively investigated. This paper develops an improved real-time cycle slip correction method based on three types of independent linear combinations of time-difference triple-frequency BDS observables. At first, one geometry-free pseudorange minus phase linear combination is selected as extra-wide lane (EWL) virtual signal and its cycle slips can be easily detected and repaired due to the long wavelength. Then, one geometry-free phase combination, treated as wide lane (WL) signal, is used to detect and repair cycle slips on WL combination based on fixed EWL ambiguity. Similarly, another one geometry-free phase combination is adopted to correct cycle slips on narrow lane (NL) signal. As a result of the short wavelength of NL combination, the residual ionospheric delay cannot be ignored and should be accurately estimated by the original observables. When the time-difference ambiguities of EWL, WL and NL signals are determined, the cycle slips on the original observables can be uniquely corrected by matrix operation. As the ionospheric delay plays a vital role in estimating ambiguities of combination signals, the second-order time-difference of ionospheric delay is used to detect the epoch with cycle slips and participate in estimating the time-difference ambiguity of NL signal. Considering that satellite elevation can be treated as quality factor of observables, we build a model to calculate the standard deviations of the selected combinations and 20° can be used as threshold value to correct cycle slips or not. The method has been tested on real 30 s triple-frequency BDS data with artificial cycle slips. Results show that the three-step method can detect and repair cycle slips correctly and effectively when the elevation is higher than 20°. While the elevation is lower than the threshold, the cycle slips should just be detected without repair to avoid miscalculation.
       
  • Prospects of probing the radio emission of lunar UHECRv events
    • Abstract: Publication date: 1 November 2018Source: Advances in Space Research, Volume 62, Issue 9Author(s): A. Aminaei, L. Chen, H. Pourshaghaghi, S. Buitink, M. Klein-Wolt, L.V.E. Koopmans, H. Falcke Radio detection of Ultra High Energetic Cosmic Rays and Neutrinos (UHECRv) which hit the Moon has been investigated in recent years. In preparation for near-future lunar science missions, we discuss technical requirements for radio experiments onboard lunar orbiters or on a lunar lander. We also develop an analysis of UHECRv aperture by including UHECv events occurring in the sub-layers of lunar regolith. It is verified that even using a single antenna onboard lunar orbiters or a few meters above the Moon’s surface, dozens of lunar UHECRv events are detectable for one-year of observation at energy levels of 1018–1023 eV. Furthermore, it is shown that an antenna 3 m above the Moon’s surface could detect lower energy lunar UHECR events at the level of 1015–1018 eV which might not be detectable from lunar orbiters or ground-based observations.
       
  • Motion Prediction of an Uncontrolled Space Target
    • Abstract: Publication date: Available online 1 October 2018Source: Advances in Space ResearchAuthor(s): Bang-Zhao Zhou, Xiao-Feng Liu, Guo-Ping Cai, Yun-Meng Liu, Pan Liu Capturing an uncontrolled space target is a tremendously challenging research topic. Target capture by a space robot can be well planned according to predicted motion of the target. In this paper, motion prediction of an uncontrolled space target is studied and a motion prediction algorithm is proposed. In the proposed algorithm, firstly a method for identifying the parameters of motion state and inertial property of the target is established; and then through substituting the identified parameters into the dynamic equations of the target, the motion of the target can be predicted as the solution of the equations. In the identification of the parameters, the unscented Kalman filter (UKF) is applied. In order to support the UKF, a method for estimating noise level of the observation data is developed, so our motion prediction algorithm is noise adaptive. A practical convergent criterion is also designed to determine the time when the estimated result of the UKF is accurate enough, such that the predicted motion is credible enough. After that, the accuracy of the prediction is further improved by an optimization method. In the end of this paper, numerical simulations are done to verify the validity of the proposed motion prediction algorithm. Simulation results indicate that the proposed algorithm is able to predict the motion of the target precisely.
       
  • Longitudinal variations of the ionospheric trough position
    • Abstract: Publication date: Available online 1 October 2018Source: Advances in Space ResearchAuthor(s): A.T. Karpachev, M.V. Klimenko, V.V. Klimenko For the first time a comprehensive pattern of the longitudinal effect of the ionospheric trough position was obtained. We present new results with longitudinal variations of the winter trough position as a function of geomagnetic latitude for both hemispheres and conditions of high and low solar activity and all local time hours. We used a large observational data set obtained onboard the Kosmos-900, Interkosmos-19 and CHAMP satellites for quiet geomagnetic conditions. We found that a magnitude of the trough position longitudinal effect averaged for a fixed local time is greater in the daytime (6-8°) than in the nighttime (3-5°). The longitudinal effect magnitude reaches its maximum (16°) in the morning (at 08 LT) in the Southern hemisphere at high solar activity. But on certain days at any solar activity the longitudinal effect magnitude can reach 9-10° even at night. The shape of the longitudinal effect was found to differ significantly in two hemispheres. In the Northern hemisphere the trough is usually closest to the pole in the eastern (American) longitudinal sector, and in the Southern hemisphere the trough is closest in the western (Eurasian) longitudinal sector. The magnitude and shape of the longitudinal effect is also different during low and high solar activity. The Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP) simulations demonstrate that during low solar activity, the longitudinal variations of the daytime trough position is mainly determined by longitudinal variations of the ionization function, formed due to the longitudinal variations in the solar zenith angle and the atomic oxygen density distribution. The longitudinal variations of the nighttime trough position is formed by the longitudinal variations in ionization of precipitating auroral particles, neutral atmosphere composition, and electric field.
       
  • Simulation of the land surface temperature from moon-based Earth
           observations
    • Abstract: Publication date: Available online 29 September 2018Source: Advances in Space ResearchAuthor(s): Chenwei Nie, Jingjuan Liao, Guozhuang Shen, Wentao Duan The land surface temperature (LST) is a key parameter for the Earth’s energy balance. As a natural satellite of the Earth, the orbital of the moon differs from that of current Earth observation satellites. It is a new way to measure the land surface temperature from the moon and has many advantages compared with artificial satellites. In this paper, we present a new method for simulating the LST measured by moon-based Earth observations. Firstly, a modified land-surface diurnal temperature cycle (DTC) method is applied to obtain the global LST at the same coordinated universal time (UTC) using the Moderate Resolution Imaging Spectroradiometer (MODIS) LST products. The lunar elevation angles calculated using the ephemeris data (DE405) from the Jet Propulsion Laboratory (JPL) were then applied to simulate the Earth coverage observed from the moon. At the same time, the modified DTC model was validated using in situ data, MODIS LST products, and the FengYun-2F (FY-2F) LST, respectively. The results show that the fitting accuracy (root-mean-square error, RMSE) of the modified DTC model is not greater than 0.72°C for eight in situ stations with different land cover types, and the maximum fitting RMSE of the modified model is smaller than that of current DTC models. By the comparison of the simulated LST with MODIS and FY-2F LST products, the errors of the results were feasible and accredited, and the simulated global LST has a reasonable spatiotemporal distribution and change trend. The simulated LST data can therefore be used as base datasets to simulate the thermal infrared imagery from moon-based Earth observations in future research.
       
  • Rigidity dependence of Forbush decreases in the energy region exceeding
           sensitivity of neutron monitors
    • Abstract: Publication date: Available online 28 September 2018Source: Advances in Space ResearchAuthor(s): M. Savić, N. Veselinović, A. Dragić, D. Maletić, D. Joković, R. Banjanac, V. Udovičić Applicability for solar modulation studies of our present setup in a shallow underground laboratory is tested on four prominent examples of Forbush decrease during solar Cycle 24. Forbush decreases are of interest for space weather application as well as study of energy dependent solar modulation and they have been studied extensively. The characteristics of these events, as recorded by various neutron monitors and our detectors, were compared and rigidity spectrum was found. Linear regression was performed to find power indices that correspond to each event. As expected, steeper spectrum during more intense extreme solar events with strong X-flares shows greater modulation of galactic cosmic rays. Presented comparative analysis illustrates applicability of our setup for studies of solar modulation process in the energy region exceeding sensitivity of neutron monitors.
       
  • Single Crater-aided inertial navigation for autonomous asteroid landing
    • Abstract: Publication date: Available online 28 September 2018Source: Advances in Space ResearchAuthor(s): Meng Yu, Shuang Li, Shuquan Wang, Xiangyu Huang In this paper, a novel crater-aided inertial navigation approach for autonomous asteroid landing mission is developed. It overcomes the major deficiencies of existing approaches in the literature, which mainly focuses on the case where craters are abundant in the camera field of view. As a result, traditional crater based methods require at least three craters to achieve crater matching, which limits their application in final landing phase where craters are scarce in the camera’s field of view. In contrast, the proposed algorithm enables single crater based crater matching based on a novel 2D-3D crater re-projection model. The re-projection model adopts inertial measurements as a reference, and re-projects the 3D crater model onto descent images to achieve the matching to its counterpart. An asteroid landing simulation toolbox is developed to validate the performance of the proposed approach. Through comparison with the state-of-the-art local image feature and crater based navigation algorithms, the proposed approach is validated to achieve a competitive performance in terms of feature matching and pose estimation accuracy with a much lighter computational cost.
       
  • Water movement on the convex surfaces of porous media under microgravity
    • Abstract: Publication date: Available online 28 September 2018Source: Advances in Space ResearchAuthor(s): Risa Nagura, Yuki Watanabe, Naoto Sato, Shujiro Komiya, Shinya Suzuki, Kentaro Katano, Hayato Minami, Kosuke Noborio A plant growth system for crop production under microgravity is part of a life supporting system designed for long-duration space missions. A plant growth in soil in space requires the understanding of water movement in soil void spaces under microgravity. Under 1G-force condition, on earth, water movement in porous media is driven by gradients of matric and gravitational potentials. Under microgravity condition, water movement in porous media is supposed to be driven only by a matric potential gradient, but it is still not well understood. We hypothesized that under microgravity water in void spaces of porous media hardly moved comparing in void spaces without obstacles because the concave surfaces of the porous media hindered water movement. The objective of this study was to investigate water movement on the convex surfaces of porous media under microgravity. We conducted parabolic flight experiments that provided 20-25 s of microgravity at the top of a parabolic flight. We observed water movement in void spaces in soil-like porous media made by glass beads and glass spheres (round-bottomed glass flasks) in the different conditions of water injection under microgravity. Without water injection, water did not move much in neither glass beads nor glass spheres. When water was injected during microgravity, water accumulated in contacts between the particles, and the water made thick fluid films on the particles surface. When the water injection was stopped under microgravity, water was held in the contacts between the particles. This study showed that water did not move upward in the void spaces with or without the water injection. In addition, our results suggested that the difficulty of water movement on the convex (i.e. particle surfaces) might result in slower water move in porous media under microgravity than at 1G-force.
       
  • The dynamic chromosphere: pushing the boundaries of observations and
           models
    • Abstract: Publication date: Available online 27 September 2018Source: Advances in Space ResearchAuthor(s): Tiago M.D. Pereira The interface between the bright solar surface and the million-degree corona continues to hold the key to many unsolved problems in solar physics. Advances in instrumentation now allow us to observe the dynamic structures of the solar chromosphere down to less than 0″.1 with cadences of just a few seconds and in multiple polarisation states. Such observational progress has been matched by the ever-increasing sophistication of numerical models, which have become necessary to interpret the complex observations. With an emphasis on the quiet Sun, I will review recent progress in the observation and modelling of the chromosphere. Models have come a long way from 1D static atmospheres, but their predictions still fail to reproduce several key observed features. Nevertheless, they have given us invaluable insight into the physical processes that energise the atmosphere. With more physics being added to models, the gap between predictions and observations is narrowing. With the next generation of solar observatories just around the corner, the big question is: will they close the gap'
       
  • Kalman Filter based estimation of differential hardware biases with
           Triangular Interpolation technique for IRNSS
    • Abstract: Publication date: Available online 27 September 2018Source: Advances in Space ResearchAuthor(s): Megha Maheshwari, S. Nirmala, S. Kavitha, S.C. Ratanakara Ionosphere delay correction is the main error correction to the computation of single frequency user position using satellite navigation. However ionosphere delay consists of not only delay but also frequency dependent differential hardware biases from satellite and receiver ends. For ionosphere point of view, Indian Regional Navigation Satellite System (IRNSS) service area comes in equatorial anomaly region. It is a unique satellite navigation system which operates at L5 and S frequencies and consists of Geostationary Earth Orbit (GEO) and Geo Synchronous Orbit (GSO) satellite constellation. With IRNSS measurements availability, there is a good opportunity to estimate and analyse differential hardware biases with GEO/GSO combination and with equatorial ionosphere variation. In this paper, Kalman filter based estimation with triangular interpolation technique is used to estimate differential hardware biases for all IRNSS satellites and reference receivers at L5 frequency. The standard deviation of the 15 days of daily estimation of satellite differential hardware biases is in the range of 0.32 to 1.17 TECU for all IRNSS satellites. Similarly, the standard deviation of the 15 days of daily estimation varies up to 2.85 and 6.0 TECU for receiver differential hardware biases during calm and stormy period respectively. The ionosphere delay computed using estimated differential hardware biases is compared with Global Ionosphere Map (GIM) data. A rigorous analysis is carried out to study the error in the estimation in terms of input data noise level, satellite constellation and effect of latitude. Our result reveals that over IRNSS service area, there is an exponential increase in the error in the estimation of receiver differential hardware biases with respect to latitude.
       
  • Perturbation Theory Based Solution of the Pitch-Angle Dependent Cosmic Ray
           Diffusion Equation
    • Abstract: Publication date: Available online 27 September 2018Source: Advances in Space ResearchAuthor(s): A. Shalchi, M. Gammon The motion of cosmic rays and energetic particles in general is described via transport equations. If a pitch-angle dependent description is desired, a Fokker-Planck equation provides the basis for exploring the particle motion. To date, no exact and pure analytical solution to the two-dimensional cosmic ray Fokker-Planck equation has been found. Previous attempts are either solutions of the pitch-angle averaged equation or the space integrated equation. Of course, numerical calculations can easily be performed but those are not very useful in astrophysical applications. In the current paper we employ perturbation theory in order to solve the cosmic ray Fokker-Planck equation. Corrections up to fourth-order to the eigenvalues and second-order eigenfunctions are computed. Our results are compared with previous solutions. Furthermore, we discuss applications such as estimating higher order correlations occurring in analytical treatments of perpendicular transport.
       
  • J 2 -perturbed+Orbits&rft.title=Advances+in+Space+Research&rft.issn=0273-1177&rft.date=&rft.volume=">Real-time Spacecraft Intercept Strategy on J 2 -perturbed Orbits
    • Abstract: Publication date: Available online 26 September 2018Source: Advances in Space ResearchAuthor(s): Snyoll Oghim, Henzeh Leeghim, Donghoon Kim A real-time intercept strategy for spacecraft under the non-uniform gravitational perturbation of Earth is addressed in this paper. To intercept a target spacecraft on general conic sections, an interceptor considered in this work makes use of a thruster propelling the constant thrust which is comparable to unrealistic impulse-type thrust. The J2 perturbation introduces critical dynamic variations of spacecraft orbiting the Earth, which results in a considerable amount of position error of the interceptor at the final intercept point. In order to release the burden of J2 disturbance and make the miss distance between the target and interceptor small, a real-time intercept technique with an optimal intercept algorithm is suggested. The strategy proposed is to obtain an optimized output iteratively for a given time interval with previously obtained optimal values. These parameters are evaluated by the optimal intercept algorithm suggested. Once the optimal velocity change is obtained to satisfy intercept requirements, although the orbital system is perturbed, it is easy to regenerate a new solution by setting the previous solution as new initial guesses. This strategy is employed iteratively until the interceptor meets the target. Several numerical simulations are performed to highlight the proposed real-time strategy for spacecraft intercept missions.
       
  • Combining MHD and kinetic modelling of solar flares
    • Abstract: Publication date: Available online 25 September 2018Source: Advances in Space ResearchAuthor(s): Mykola Gordovskyy, Philippa Browning, Rui F. Pinto Solar flares are explosive events in the solar corona, representing fast conversion of magnetic energy into thermal and kinetic energy, and hence radiation, due to magnetic reconnection. Modelling is essential for understanding and predicting these events. However, self-consistent modelling is extremely difficult due to the vast spatial and temporal scale separation between processes involving thermal plasma (normally considered using magnetohydrodynamic (MHD) approach) and non-thermal plasma (requiring a kinetic approach). In this mini-review we consider different approaches aimed at bridging the gap between fluid and kinetic modelling of solar flares. Two types of approaches are discussed: combined MHD/test-particle (MHDTP) models, which can be used for modelling the flaring corona with relatively small numbers of energetic particles, and hybrid fluid-kinetic methods, which can be used for modelling stronger events with higher numbers of energetic particles. Two specific examples are discussed in more detail: MHDTP models of magnetic reconnection and particle acceleration in kink-unstable twisted coronal loops, and a novel reduced-kinetic model of particle transport in converging magnetic fields.
       
  • An Optimal Selection of Probability Distribution Functions for
           Unsupervised Land Cover Classification of PALSAR-2 Data
    • Abstract: Publication date: Available online 25 September 2018Source: Advances in Space ResearchAuthor(s): Ankita Jain, Dharmendra Singh Different types of classification techniques are available in the literature for the classification of synthetic aperture radar (SAR) data into various land cover classes. Various SAR images are available for land cover classification such as ALOS PALSAR (PALSAR-1, PALSAR-2), RADARSAT, ENVISAT, etc. In this paper, we have attempted to explore probability distribution function (pdf) based land cover classification using PALSAR-2 data. Over 20 different statistical distribution functions are analyzed for different classes based on statistical parameters. Probability distribution functions are selected based on Chi-squared goodness of fit test for each individual class. A decision tree based classifier is developed for classification based on the selected pdf functions and its statistical parameters. The proposed classification approach has an accuracy of 83.93%.
       
  • Alfvén Gravity Waves in Viscous Solar Plasma: Effect of the
           Background Flow
    • Abstract: Publication date: Available online 25 September 2018Source: Advances in Space ResearchAuthor(s): Mukul Kumar, Wang Chi We study the Propagation and damping properties of Alfvén gravity waves in the presence of the vertical magnetic field in the viscous solar plasma under influence of the background flow by deriving a fourth order dispersion relation in terms of the Doppler shifted frequency. We derive the dispersion relation under WKB and Boussinesq approximation. We study the damping of Alfvén gravity waves for the wave frequencies less than and greater than the Brunt-Väisälä frequency. We find that the Brunt-Väisälä frequency divides the frequency ranges where the weakly or strongly damped oscillations occur. The background flow exhibits a strong effect on weakly damped oscillations and a weak effect on the strongly damped oscillations. We also notice that the damping of both the strong and weakly damped oscillations depend on the Brunt-Väisälä frequency and wave number. The effect of the background flow is also being governed by the Brunt-Väisälä frequency and wave number. We also study the properties of gravity wave mode after filtering the Alfvén wave mode by minimizing the magnetic field and noticed that the background flow shows a very strong effect on the gravity wave mode.
       
  • A Balloon-Borne Very Long Baseline Interferometry Experiment in the
           Stratosphere: Systems Design and Developments
    • Abstract: Publication date: Available online 25 September 2018Source: Advances in Space ResearchAuthor(s): Akihiro Doi, Yusuke Kono, Kimihiro Kimura, Satomi Nakahara, Tomoaki Oyama, Nozomi Okada, Yasutaka Satou, Kazuyoshi Yamashita, Naoko Matsumoto, Mitsuhisa Baba, Daisuke Yasuda, Shunsaku Suzuki, Yutaka Hasegawa, Mareki Honma, Hiroaki Tanaka, Kosei Ishimura, Yasuhiro Murata, Reiho Shimomukai, Tomohiro Tachi, Kazuya Saito The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has been developed. A balloon-borne VLBI station will be launched to establish interferometric fringes with ground-based VLBI stations distributed over the Japanese islands at an observing frequency of approximately 20 GHz as the first step. This paper describes the system design and development of a series of observing instruments and bus systems. In addition to the advantages of avoiding the atmospheric effects of absorption and fluctuation in high frequency radio observation, the mobility of a station can improve the sampling coverage (“uv-coverage”) by increasing the number of baselines by the number of ground-based counterparts for each observation day. This benefit cannot be obtained with conventional arrays that solely comprise ground-based stations. The balloon-borne VLBI can contribute to a future progress of research fields such as black holes by direct imaging.
       
  • Mars entry fault-tolerant control via neural network and structure
           adaptive model inversion
    • Abstract: Publication date: Available online 25 September 2018Source: Advances in Space ResearchAuthor(s): Yixin Huang, Shuang Li, Jun Sun The capability of autonomous fault detection and reconstruction is essential for future manned Mars exploration missions. Considering actuator failures and atmosphere uncertainties, we present a new active fault-tolerant control algorithm for Mars entry by use of neural network and structure adaptive model inversion. First, the online BP neural network is adopted to conduct the fault detection and isolation. Second, based on the structure adaptive model inversion, an adaptive neural network PID controller is developed for Mars entry fault-tolerant control. The normal PID controller will be automatically switched into neural network PID controller when an actuator fault is detected. Therefore, the error between the reference model and the output of the attitude control system would be adjusted to ensure the dynamic property of the entry vehicle. Finally, the effectiveness of the algorithm developed in this paper is confirmed by computer simulation.
       
  • Hierarchical approach for fast searching optimal launch opportunity in a
           wide range
    • Abstract: Publication date: Available online 24 September 2018Source: Advances in Space ResearchAuthor(s): Bin Yang, Hongwei Yang, Shuang Li Launch opportunity search is crucial for preliminary design of interplanetary trajectories. However, it is difficult to obtain the optimum solution efficiently when the range of search is wide. In this paper, a new fast search algorithm based on a modified hierarchical approach is proposed. At the top level, a simplified Pork-Chop diagram is plotted by sampling interpolation to delimit the candidate regions of the optimal solution. Each candidate region contains only one optimal solution, which fundamentally avoids the local optimal problem of genetic algorithms. At the bottom level, a hybrid optimization approach combining the genetic algorithm and the conjugate directions method is used to solve the accurate optimal solution of each candidate region and obtain the global optimal launch opportunity in the whole wide range of search. Simulation results show that the proposed hierarchical approach can quickly and robustly find the global optimal launch opportunity in a wide search space.
       
  • List of Referees
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s):
       
  • Exospheric escape: A parametrical study
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Rosemary M. Killen, Matthew H. Burger, William M. Farrell The study of exospheres can help us understand the long-term loss of volatiles from planetary bodies due to interactions of planets, satellites, and small bodies with the interplanetary medium, solar radiation, and internal forces including diffusion and outgassing. Recent evidence for water and OH on the Moon has spurred interest in processes involving chemistry and sequestration of volatile species at the poles and in voids. In recent years, NASA has sent spacecraft to asteroids including Vesta and Ceres, and ESA sent Rosetta to comet 67P/Churyumov–Gerasimenko and the asteroids Lutetia and Steins. Japan's Hayabusa spacecraft returned a sample from asteroid Itakowa, and OSIRIS-REX will return a sample from a primitive asteroid, Bennu, to Earth. In a surface-bounded exosphere, the gases are derived from the surface and thus reflect the composition of the body's regolith, although not in a one-to-one ratio. Observation of an escaping exosphere, termed a corona, is challenging. We have therefore embarked on a parametrical study of exospheres as a function of mass of the exospheric species, mass of the primary body and source velocity distribution, specifically thermal (Maxwell-Boltzmann) and sputtering. The goal is to provide a quick look to determine under what conditions and for what mass of the primary body the species of interest are expected to be bound or escaping and to quickly estimate the observability of exospheric species. This work does not provide a comprehensive model but rather serves as a starting point for further study. These parameters will be useful for mission planning as well as for students beginning a study of planetary exospheres.
       
  • Genetic analysis of parameters of near earth asteroids for determining
           parent bodies of meteoroid streams
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): M. Sokolova, M. Sergienko, Y. Nefedyev, A. Andreev, L. Nefediev The present paper is focusing on determining genetic connections between small bodies of the Solar system and their parent bodies (PB) on the basis of analysis of Near Earth Asteroids (NEAs) parameters. In order to search for parent bodies of meteoroid streams, the asteroid groups, including Atira, Apollo, Amor and Aten, have been investigated. Currently, it is considered that surface of asteroids with elongated orbit is exposed to temperature fall: in perihelion it is heated and in aphelion it is cooled. At small orbital periods around the Sun (about 2–4 years) this may lead to formation of meteoroid clusters. On the basis of comparative analysis of orbit, size and chemical and mineralogical composition of NEAs, it is found that asteroids from Apollo group are most likely to be parent bodies of the studied meteoroid streams.
       
  • Continuum definition for ∼3.1, ∼3.4 and ∼4.0 µm absorption bands in
           Ceres spectra and evaluation of effects of smoothing procedure in the
           retrieved spectral parameters
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): A. Galiano, E. Palomba, A. Longobardo, A. Zinzi, M.C. De Sanctis, A. Raponi, F.G. Carrozzo, M. Ciarniello, F. Dirri NASA’s Dawn spacecraft acquired images and hyperspectral data of Ceres by means of FC and VIR instruments, and identified some widespread bright areas or bright spots (BS). The most peculiar BS is inside Occator crater and it is characterized by spectral properties very dissimilar from the rest of Ceres’ surface. To perform a mineralogical analysis, absorption bands in reflectance spectra must be properly isolated by removal of continuum, and related descriptors (such as band centers and band depths) can be computed. The method for continuum removal must be applicable to all Ceres spectra, relative to different areas, so that a comparison among spectral parameters can be made and mineralogical interpretation can be achieved. This work focuses on the definition of the most appropriate continuum to isolate absorption bands located at ∼3.1, ∼3.4 and ∼4.0 µm. The ∼3.1 µm feature is related to ammoniated phyllosilicates, while the ∼3.4 and ∼4.0 µm absorption bands are indicative of carbonates. Thermal emission affects the continuum for these bands in the VIR spectral range, which extends up to 5.1 µm, moreover all thermal-removed reliable data stop at 4.2 µm. This implies that the shoulder of bands at longer wavelength cannot be identified. We therefore defined alternative continua, i.e., a linear and two polynomial ones, able to describe spectra of any area (i.e. bright or dark) and regardless of spatial resolution. We found that the linear definition satisfies these requirements best. For the first time, we performed an error evaluation on band depths and band centers introduced by the applied method, which is relevant for comparison of spectral parameters of Ceres regions and to better interpret mineralogy and photometric effects.
       
  • Small Bodies Near and Far (SBNAF): A benchmark study on physical and
           thermal properties of small bodies in the Solar System
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): T.G. Müller, A. Marciniak, Cs. Kiss, R. Duffard, V. Alí-Lagoa, P. Bartczak, M. Butkiewicz-Bąk, G. Dudziński, E. Fernández-Valenzuela, G. Marton, N. Morales, J.-L. Ortiz, D. Oszkiewicz, T. Santana-Ros, R. Szakáts, P. Santos-Sanz, A. Takácsné Farkas, E. Varga-Verebélyi The combination of visible and thermal data from the ground and astrophysics space missions is key to improving the scientific understanding of near-Earth, main-belt, trojans, centaurs, and trans-Neptunian objects. To get full information on a small sample of selected bodies we combine different methods and techniques: lightcurve inversion, stellar occultations, thermophysical modelling, radiometric methods, radar ranging and adaptive optics imaging. The SBNAF project will derive size, spin and shape, thermal inertia, surface roughness, and in some cases bulk densities and even internal structure and composition, for objects out to the most distant regions in the Solar System. The applications to objects with ground-truth information allows us to advance the techniques beyond the current state-of-the-art and to assess the limitations of each method. We present results from our project’s first phase: the analysis of combined Herschel-KeplerK2 data and Herschel-occultation data for TNOs; synergy studies on large MBAs from combined high-quality visual and thermal data; establishment of well-known asteroids as celestial calibrators for far-infrared, sub-millimetre, and millimetre projects; first results on near-Earth asteroids properties from combined lightcurve, radar and thermal measurements, as well as the Hayabusa-2 mission target characterisation. We also introduce public web-services and tools for studies of small bodies in general.
       
  • Production and 3D visualization of high-level data of minor bodies: The
           MATISSE tool in the framework of VESPA-Europlanet 2020 activity
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): A. Longobardo, A. Zinzi, M.T. Capria, S. Erard, M. Giardino, S. Ivanovski, S. Fonte, E. Palomba, G. Di Persio, L.A. Antonelli The main goal of the VESPA (Virtual European Solar and Planetary Access) activity, developed in the framework of the EU-funded project Europlanet 2020 Research Infrastructure, is the application of Virtual Observatory standards to planetary data, in order to increase their sharing, visualization, interoperability and combination. The VESPA main search interface already uses some tools for analysis of planetary data, whereas other developed tools are going to be integrated on VESPA, e.g. MATISSE (Multi-purpose Advanced Tool for Instruments for the Solar System Exploration). This tool works on PDS data allowing analysis and 3D visualization of hyperspectral images. It is particularly suitable for minor bodies, where data projection on the shape model is fundamental to relate data to topographic and geological context.This paper shows the new functions implemented on the MATISSE tool for the study of minor bodies, aimed at the development of derived and high-level products, such as reflectance, photometrically corrected reflectance, absorption band descriptors and spectral ratios, and at their visualization on shape models. The developed products are commonly used to analyze hyperspectral data and hence a web based tool allowing their retrieval and visualization is important to hasten and support research activity on minor bodies.
       
  • The SSDC contribution to the improvement of knowledge by means of 3D data
           projections of minor bodies
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Angelo Zinzi, Mauro Ciarniello, Vincenzo Della Corte, Stavro Ivanovski, Andrea Longobardo, Alessandra Migliorini, Maria Teresa Capria, Ernesto Palomba, Alessandra Rotundi The latest developments of planetary exploration missions devoted to minor bodies required new solutions to correctly visualize and analyze data acquired over irregularly shaped bodies.ASI Space Science Data Center (SSDC – ASI, formerly ASDC – ASI Science Data Center) worked on this task since early 2013, when started developing the web tool MATISSE (Multi-purpose Advanced Tool for the Instruments of the Solar System Exploration) mainly focused on the Rosetta/ESA space mission data.In order to visualize very high-resolution shape models, MATISSE uses a Python module (vtpMaker), which can also be launched as a stand-alone command-line software.MATISSE and vtpMaker are part of the SSDC contribution to the new challenges imposed by the “orbital exploration” of minor bodies: (1) MATISSE allows to search for specific observations inside datasets and then analyze them in parallel, providing high-level outputs; (2) the 3D capabilities of both tools are critical in inferring information otherwise difficult to retrieve for non-spherical targets and, as in the case for the GIADA instrument onboard Rosetta, to visualize data related to the coma.New tasks and features adding valuable capabilities to the minor bodies SSDC tools are planned for the near future thanks to new collaborations.
       
  • Preliminary orbital analysis for a CubeSat mission to the Didymos binary
           asteroid system
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Riccardo Lasagni Manghi, Dario Modenini, Marco Zannoni, Paolo Tortora Nanosatellite missions represent a promising option for the exploration of the near-Earth asteroid population since they provide low-cost versatile platforms for scientific observations. This paper describes the preliminary orbital and navigation analyses for the DustCube mission, which was pre-selected to reach the binary asteroid system Didymos on-board ESA’s AIM spacecraft. Possible candidate orbits that exploit the binary nature of the system are identified and traded off to produce a preliminary concept of operations. The overall feasibility of the proposed scenario is then addressed by integrating the spacecraft trajectories in a realistic dynamical environment, evaluating their sensitivity to state errors, and estimating the accuracy of the orbit determination system.Preliminary results suggest that autonomous navigation of a Cubesat platform within a binary asteroid system is technically feasible. The proposed solution, which combines an initial parking orbit at the L4 equilibrium point with a Distant Retrograde Orbit for proximity operations, is shown to be consistent with the estimated orbit determination accuracy and allows to fulfil the mission requirements.
       
  • Radio science investigations with the Asteroid impact mission
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Marco Zannoni, Giacomo Tommei, Dario Modenini, Paolo Tortora, Ruaraidh Mackenzie, Mehdi Scoubeau, Ulrich Herfort, Ian Carnelli The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint ESA/NASA collaboration to study the binary Near-Earth Asteroid (65,803) Didymos and assess the feasibility of the kinetic impactor technique to deflect an asteroid. The European contribution to AIDA is the Asteroid Impact Mission (AIM), which will characterize in detail the Didymos system, investigating the surface, subsurface, and internal properties of the asteroid.This paper presents a possible Radio Science Experiment (RSE) to be performed with AIM focused at its precise orbit determination within the Didymos system, providing an assessment of the accuracies achievable in the estimation of the scientific parameters of interest, like the masses and the extended gravity fields of Didymos primary and secondary, their relative orbit, and their rotational states. The experiment expected performances were assessed through numerical simulations, based upon a complete and realistic dynamical model of the Didymos system and the AIM spacecraft.Given the small mass of the Didymos system, optical navigation images proved to be crucial to obtain good accuracies for the scientific parameters of interest, even keeping AIM at relatively large distances from Didymos. At 10 km, after 8 flybys dedicated to gravity science, the masses of the primary and secondary can be estimated to about 0.2% and 1.6% (1-sigma), respectively, with the mass of the secondary being mainly given by observing the wobble of the primary around the common center of mass due to the mutual orbital motion; the orbital motion of the secondary around the primary can be estimated to about 1 m, and the pole orientation of the primary and the secondary can be estimated to about 0.1 deg and 0.4 deg, respectively (1-sigma).
       
  • European component of the AIDA mission to a binary asteroid:
           Characterization and interpretation of the impact of the DART mission
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Patrick Michel, Michael Kueppers, Holger Sierks, Ian Carnelli, Andy F. Cheng, Karim Mellab, Mikael Granvik, Antti Kestilä, Tomas Kohout, Karri Muinonen, Antti Näsilä, Antti Penttila, Tuomas Tikka, Paolo Tortora, Valérie Ciarletti, Alain Hérique, Naomi Murdoch, Erik Asphaug, Andy Rivkin, Olivier Barnouin The European component of the joint ESA-NASA Asteroid Impact & Deflection Assessment (AIDA) mission has been redesigned from the original version called Asteroid Impact Mission (AIM), and is now called Hera. The main objectives of AIDA are twofold: (1) to perform an asteroid deflection test by means of a kinetic impactor under detailed study at NASA (called DART, for Double Asteroid Redirection Test); and (2) to investigate with Hera the changes in geophysical and dynamical properties of the target binary asteroid after the DART impact. This joint mission will allow extrapolating the results of the kinetic impact to other asteroids and therefore fully validate such asteroid deflection techniques. Hera leverages technology and payload pre-developments of the previous AIM, and focuses on key measurements to validate impact models such as the detailed characterisation of the impact crater. As such, AIDA will be the first documented deflection experiment and binary asteroid investigation. In particular, it will be the first mission to investigate a binary asteroid, and return new scientific knowledge with important implications for our understanding of asteroid formation and solar system history. Hera will investigate the smallest asteroid visited so far therefore providing a unique opportunity to shed light on the role cohesion and Van der Waals forces may play in the formation and resulting internal structure of such small bodies.
       
  • Ballistic landing design on binary asteroids: The AIM case study
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Fabio Ferrari, Michèle Lavagna The close-proximity exploration of small celestial bodies of our Solar System is the current frontier of space exploration. Trajectory design and exploitation of the natural dynamics around such bodies represents a very challenging astrodynamics problem, due to their weak and highly chaotic gravitational environment. The paper discusses design solutions for the ballistic landing of a small and passive probe, released to land on the smaller of a binary asteroid couple. The work is focused on the Asteroid Impact Mission (AIM) case study, although the methods and analyses presented are general and applicable to any binary asteroid scenario. The binary system is modeled using a shape-based three-body problem and three-body solutions are investigated within the Didymos binary system. Manifold dynamics near libration points associated to the asteroid three-body system are exploited to find low-energy and high-success landing trajectories. The validity of implemented approach and solutions found are discussed and results in terms of success rate and landing dispersion are shown.
       
  • Feasibility of asteroid exploration using CubeSats—ASPECT case study
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Tomas Kohout, Antti Näsilä, Tuomas Tikka, Mikael Granvik, Antti Kestilä, Antti Penttilä, Janne Kuhno, Karri Muinonen, Kai Viherkanto, Esa Kallio Operation of a small CubeSat in the deep-space microgravity environment brings additional challenging factors including the increased radiation environment, the significant contribution of non-gravitational forces to the satellite orbit, or the limited communication opportunities. These factors need to be taken into account in the form of modifications to the classic CubeSat architecture. Increased radiation resistance, the semi-autonomous satellite operation, navigation, and the active orbit correction are required. Such a modified CubeSat platform can potentially deliver a high performance to mass and cost ratios. The Asteroid Spectral Imaging Mission (ASPECT) is a three unit (3U) CubeSat mission built on these principles. It is part of the AIDA (Asteroid Impact & Deflection Assessment) project to the binary asteroid Didymos. ASPECT is equipped with a visible to near-infrared hyperspectral imager and will deliver both technological knowledge as well as scientific data about the origin and evolution of Solar System small bodies.
       
  • DePhine – The Deimos and Phobos Interior Explorer
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Jürgen Oberst, Kai Wickhusen, Konrad Willner, Klaus Gwinner, Sofya Spiridonova, Ralph Kahle, Andrew Coates, Alain Herique, Dirk Plettemeier, Marina Díaz-Michelena, Alexander Zakharov, Yoshifumi Futaana, Martin Pätzold, Pascal Rosenblatt, David J. Lawrence, Valery Lainey, Alison Gibbings, Ingo Gerth DePhine – Deimos and Phobos Interior Explorer – is a mission proposed in the context of ESA’s Cosmic Vision program, for launch in 2030. The mission will explore the origin and the evolution of the two Martian satellites, by focusing on their interior structures and diversity, by addressing the following open questions: Are Phobos and Deimos true siblings, originating from the same source and sharing the same formation scenario' Are the satellites rubble piles or solid bodies' Do they possess hidden deposits of water ice in their interiors' The DePhine spacecraft will be inserted into Mars transfer and will initially enter a Deimos quasi-satellite orbit to carry out a comprehensive global mapping. The goal is to obtain physical parameters and remote sensing data for Deimos comparable to data expected to be available for Phobos at the time of the DePhine mission for comparative studies. As a highlight of the mission, close flybys will be performed at low velocities, which will increase data integration times, enhance the signal strength and data resolution. 10–20 flyby sequences, including polar passes, will result in a dense global grid of observation tracks. The spacecraft orbit will then be changed into a Phobos resonance orbit to carry out multiple close flybys and to perform similar remote sensing as for Deimos. The spacecraft will carry a suite of remote sensing instruments, including a camera system, a radio science experiment, a high-frequency radar, a magnetometer, and a Gamma Ray/Neutron Detector. A steerable antenna will allow simultaneous radio tracking and remote sensing observations (which is technically not possible for Mars Express). Additional instrumentation, e.g. a dust detector and a solar wind sensor, will address further science goals of the mission. If Ariane 6–2 and higher lift performance are available for launch (the baseline mission assumes a launch on a Soyuz Fregat), we expect to have greater spacecraft mobility and possibly added payloads.
       
  • Shaking as means to detach adhered regolith for manned Phobos exploration
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Christine M. Hartzell, William Farrell, John Marshall Recent work has shown that cohesion drives the behavior of surficial regolith grains up to centimeters in size on the surface of small planetary bodies such as asteroids. Mars’ moon Phobos is similar in morphology and size to asteroids. Additionally, Phobos has been discussed as a possible target for human exploration, due to its relatively small gravity well. Dust adhering to spacesuits (and subsequently detaching in a pressurized spacecraft) was a source of concern during the Apollo era. We apply improved understanding of the forces active on regolith grains to compare their relative strength, showing that Phobian regolith up to millimeters in size is likely to be dominated by Van der Waals cohesion. Additionally, we show that astronauts will be unable to detach dust grains smaller than 1–100 μm that are adhered to their gloves through shaking alone, with the size range for detachment depending on the material properties of the regolith and spacesuit.
       
  • The possible contribution of dielectric breakdown to space weathering on
           Phobos
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): A.P. Jordan, T.J. Stubbs, J.K. Wilson, N.A. Schwadron, H.E. Spence The origins of Phobos and Deimos are uncertain; both are so space weathered that their surface compositions are difficult to determine using spectral reflectance measurements. We show how the winter temperatures and associated conditions in the polar regions of Phobos could make the regolith susceptible to space weathering from dielectric breakdown caused by solar energetic particles (SEPs). During SEP events, charged particles accumulate throughout the top ∼1 mm of the regolith, which has low conductivity, and create subsurface electric fields that act to dissipate any net buildup of charge. The faster the net charge accumulates, the larger the electric field needed to dissipate it. If the magnitude of the subsurface electric field exceeds ∼106 V m−1, then dielectric breakdown is likely. This process rapidly dissipates the buildup of charge by vaporizing electrically conducting channels through the regolith. Dielectric breakdown is expected to be more prevalent in colder regions, where the electrical conductivity of the regolith is lower and the dissipation of charge is consequently slower. If the regolith on Phobos is made of silicates, or possibly phyllosilicates, we predict that dielectric breakdown weathering has melted or vaporized 5–10% of the impact gardened regolith in the polar regions, although this percentage depends on how long the regolith has been exposed to SEPs. This, in addition to the long exposure time of the regolith to other forms of space weathering, may help explain why both Phobos and Deimos are highly space weathered compared to other airless bodies in the Solar System, such as Earth’s Moon.
       
  • Science exploration architecture for Phobos and Deimos: The role of Phobos
           and Deimos in the future exploration of Mars
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Ariel N. Deutsch, James W. Head, Kenneth R. Ramsley, Carle M. Pieters, Ross W.K. Potter, Ashley M. Palumbo, Michael S. Bramble, James P. Cassanelli, Erica R. Jawin, Lauren M. Jozwiak, Hannah H. Kaplan, Connor F. Lynch, Alyssa C. Pascuzzo, Le Qiao, David K. Weiss Phobos and Deimos are the only natural satellites of the terrestrial planets, other than our Moon. Despite decades of revolutionary Mars exploration and plans to send humans to the surface of Mars in the 2030’s, there are many strategic knowledge gaps regarding the moons of Mars, specifically regarding the origin and evolution of these bodies. Addressing those knowledge gaps is itself important, while it can also be seen that Phobos and Deimos are positioned to support martian surface operations as a staging point for future human exploration. Here, we present a science exploration architecture that seeks to address the role of Phobos and Deimos in the future exploration of Mars. Phobos and Deimos are potentially valuable destinations, providing a wealth of science return, as well as telecommunications capabilities, resource utilization, radiation protection, transportation and operations infrastructure, and may have an influence on the path of the martian exploration program. A human mission to the moons of Mars would maintain programmatic focus and public support, while serving as a catalyst for a successful human mission to the surface of Mars.
       
  • The exploration of PHOBOS: Design of a Sample Return mission
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Antonella Ferri, Stewart Pelle, Maurizio Belluco, Thomas Voirin, Rolando Gelmi The long-term goal of enabling human exploration of the Moon and Mars drives International space exploration plans. Robotic space missions must therefore develop and demonstrate the feasibility and robustness of the enabling technologies and capabilities.The Phobos Sample Return mission is a candidate mission of the Mars Robotic Exploration Preparation programme. Its objective is to acquire and return a sample from the Mars moon Phobos. The main science goal of this mission will be to understand the formation of the Martian moons Phobos and Deimos and acquire further data on the evolution of the solar system. From a technology standpoint, it would be a big step forward in the development of many technologies, ranging from low-gravity body landing capabilities to Earth re-entry of samples from deep space, from semi-autonomous robotic acquisition of surface samples to sample preservation and further analysis in dedicated ground laboratories.Thales Alenia Space represents one of two industrial contractors studying the mission to Phase A level. This phase involves investigation of all aspects of the mission and spacecraft design to ensure its feasibility and robustness. The planned launch date for the mission is between 2025 and 2027. The Ariane 5 ECA launch vehicle will be launched from Kourou. A chemical propulsion module will transfer the spacecraft composite to the Martian system, and will then be separated at Phobos. A full characterization campaign of Phobos at different altitudes from orbit will follow. This will include quasi-satellite orbits and flybys, using a payload suite of cameras and spectrometers. When the preferred landing site is identified, a controlled descent and touchdown onto the surface of Phobos will be performed, with a touchdown accuracy of 50 m. A robotic arm and sampling mechanism will obtain and verify a sample of surface regolith, and insert it into the Earth re-entry capsule. Part of the Spacecraft will return to the Earth from Phobos and deliver the re-entry capsule to the Earth’s atmosphere. The capsule will perform a fully passive Earth entry, descent and landing in Woomera, Australia. It will then be recovered and transferred to a sample curation facility for sample extraction and analysis. This paper summarises the results of the Thales Alenia Space Phobos Sample Return mission and spacecraft design, with a focus on the key elements and mass drivers.
       
  • Direct observations of asteroid interior and regolith structure: Science
           measurement requirements
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): A. Herique, B. Agnus, E. Asphaug, A. Barucci, P. Beck, J. Bellerose, J. Biele, L. Bonal, P. Bousquet, L. Bruzzone, C. Buck, I. Carnelli, A. Cheng, V. Ciarletti, M. Delbo, J. Du, X. Du, C. Eyraud, W. Fa, J. Gil Fernandez Our knowledge of the internal structure of asteroids is, so far, indirect – relying entirely on inferences from remote sensing observations of the surface, and theoretical modeling of formation and evolution. What are the bulk properties of the regolith and deep interior' And what are the physical processes that shape asteroid internal structures' Is the composition and size distribution observed on the surface representative of the bulk' These questions are crucial to understand small bodies’ history from accretion in the early Solar System to the present, and direct measurements are needed to answer these questions for the benefit of science as well as for planetary defense or exploration.Radar is one of the main instruments capable of sounding asteroids to characterize internal structure from sub-meter to global scale. In this paper, we review the science case for direct observation of the deep internal structure and regolith of a rocky asteroid of kilometer size or smaller. We establish the requirements and model dielectric properties of asteroids to outline a possible instrument suite, and highlight the capabilities of radar instrumentation to achieve these observations. We then review the expected science return including secondary objectives contributing to the determination of the gravitational field, the shape model, and the dynamical state. This work is largely inherited from MarcoPolo-R and AIDA/AIM studies.
       
  • Spacecraft design of a multiple asteroid orbiter with re-docking lander
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Alena Probst, Roger Förstner Almost two years after the landing of Rosetta’s Philae on the comet 67P/Churyumov-Gerasimenko, the triggered enthusiasm for small planetary bodies has not stagnated. Moreover, the interest has spread from mostly scientific enlargement of knowledge to a beginning curiosity about the exploitation of resources and their usage in space.Within this context, this paper is focusing on the design of the multiple asteroid orbiter Titius-Bode. Titius-Bode consist of an orbiter Titius and a lander Bode which aims for the characterization, resource determination and internal composition of a sequence of asteroids in the main belt. The mission objectives and spacecraft systems are described in detail, taking into account the constraints of the overall mission goal and concept. The mass and power budget for both lander and orbiter are listed as final result.The overall spacecraft design can be used for asteroid mining prospection as well as for purely scientific missions.
       
  • Numerical simulations of the contact between the lander MASCOT and a
           regolith-covered surface
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Clara Maurel, Patrick Michel, Jens Biele, Ronald-Louis Ballouz, Florian Thuillet In 2018, the mother spacecraft of the Hayabusa2 mission will release the lander MASCOT above the surface of the asteroid (162173) Ryugu. The lander will impact the regolith layer of the asteroid at low speed. While the descent trajectory of MASCOT is well determined before its release, its behavior once it touches the surface of Ryugu remains a great unknown. Predictions of the contact properties as a function of the assumed regolith properties and landing geometry (e.g., energy after bounce if not zero, collision duration…) are extremely valuable in terms of landing site selection and interpretation of the data acquired during and after landing. In this study, we use the N-body code pkdgrav to perform more than 480 numerical simulations of the first contact between the lander MASCOT and a granular medium representing the regolith layer. We explore the influence of several input parameters on the outcomes of the contact. These parameters are related to the lander, the grains of the regolith and the layer thickness. We identify a certain number of trends for the lander’s behavior, depending on the configuration of the contact, and perform a statistical analysis of the most critical output parameters. We also investigate the ejected material and show that, in addition to the data acquired from the lander itself, a post-impact visualization of the contact site(s) may help to infer non-observable properties of the regolith layer. Our results provide some insights on several input parameters that are implemented in the study of MASCOT’s whole trajectory. This work is a starting point of a much broader study, aiming to explore as widely as possible the parameter space associated with a low-speed impact of a lander onto a regolith layer.
       
  • Multiple near-earth asteroid rendezvous mission: Solar-sailing options
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Alessandro Peloni, Bernd Dachwald, Matteo Ceriotti The scientific interest in near-Earth asteroids (NEAs) and the classification of some of those as potentially hazardous for the Earth stimulated the interest in their exploration. Close-up observations of these objects will drastically increase our knowledge about the overall NEA population. For this reason, a multiple NEA rendezvous mission through solar sailing is investigated, taking advantage of the propellantless nature of this propulsion technology. Considering a spacecraft based on the DLR/ESA Gossamer technology, this work focuses on a method for searching possible sequences of NEA encounters. The effectiveness of the approach is demonstrated through a number of fully-optimised trajectories. The results show that it is possible to visit five NEAs within 10 years with near-term solar-sail technology. Moreover, a study on a reduced NEA database demonstrates the reliability of the approach used, showing that 58% of the sequences found with an approximated trajectory model can be converted into real feasible solar-sail trajectories. Overall, the study shows the effectiveness of the proposed automatic optimisation algorithm, which is able to find solutions for a large number of mission scenarios without any input required from the user.
       
  • Exploring small bodies: Nano- and microlander options derived from the
           Mobile Asteroid Surface Scout
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Caroline Lange, Tra-Mi Ho, Christian D. Grimm, Jan T. Grundmann, Christian Ziach, Roy Lichtenheldt The MASCOT lander currently flying on-board of the Japanese Hayabusa2 spacecraft, both set to explore the C-type Near-Earth Asteroid (162173) Ryugu, is not the first, but certainly one of the more complex nanolander systems having been designed for being carried along a bigger interplanetary spacecraft. Other concepts and current missions have shown the attractiveness of the class of nanosystems now increasing its application range from Earth orbiting cubesats to interplanetary scientific exploration endeavors, from orbiting to landing missions. This paper is intended to investigate nanolander options derived based on the MASCOT lander concept. For this purpose we gather interesting target bodies and analyze their respective environmental properties as well as their influence on the nanolander design, for example the landing system, the surface mobility, the power subsystem and the communication architecture. Further, an expansion of the scientific objectives of the current MASCOT lander from geological surface scout to other scientific objectives opens a range of new possibilities. For deeper analysis on this, we provide an overview over possible alternative payloads to the ones already flying on MASCOT and analyze their influence on the system design as it is. Obviously, the experience that has been gained with MASCOT provides us with a head start for future missions, if it is properly exploited. With this paper we intend to recommend MASCOT type of nanolanders for a range of possible future applications.
       
  • Robust finite time control of heliostationary flight over asteroids
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Fengdi Zhang, Jisheng Zhang, Yonglong Zhang, Zhanggang Lv Maintaining a heliostationary flight over an asteroid is challenging because of the complex dynamical environment. During exploration, external disturbances and uncertainties make it difficult for a spacecraft to stably hover at the libration point to complete its mission. In this paper, a globally robust finite time control law is proposed to solve this problem. First, we design a time variant sliding mode control law for the convergence of the tracking error to zero. Based on this, a nonsingular terminal sliding mode control law is designed to maintain the underlying track error at zero. The performance of the proposed control law is demonstrated through numerical simulations.
       
  • Low-thrust tour of the main belt asteroids
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Marilena Di Carlo, Massimiliano Vasile, Jamie Dunlop This work presents some initial results on a possible low-thrust tour of the main asteroid belt. The asteroids are visited through a series of fly-by’s to be completed within a given time-frame and limit on the mass of the spacecraft at launch. The asteroids to be visited are automatically selected out of a large database of possible candidates. The initial shortlist of targets is based on the Minimum Orbit Intersection Distance (MOID) between the orbit of the asteroids in the database and the initial orbit of the spacecraft traversing the main belt. The final sequence is then obtained with an efficient deterministic branch and prune algorithm. The transfers between asteroids are designed using a low-thrust analytical model that provides a good estimation of the propellant consumption and transfer time. The mission analysis is completed with a study of the cost of the launch. In this paper two databases will be analysed: one containing only targets with a particular scientific relevance and one containing all available asteroids.
       
  • CASTAway: An asteroid main belt tour and survey
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): N.E. Bowles, C. Snodgrass, A. Gibbings, J.P. Sanchez, J.A. Arnold, P. Eccleston, T. Andert, A. Probst, G. Naletto, A.C. Vandaele, J. de Leon, A. Nathues, I.R. Thomas, N. Thomas, L. Jorda, V. Da Deppo, H. Haack, S.F. Green, B. Carry, K.L. Donaldson Hanna CASTAway is a mission concept to explore our Solar System’s main asteroid belt. Asteroids and comets provide a window into the formation and evolution of our Solar System and the composition of these objects can be inferred from space-based remote sensing using spectroscopic techniques. Variations in composition across the asteroid populations provide a tracer for the dynamical evolution of the Solar System. The mission combines a long-range (point source) telescopic survey of over 10,000 objects, targeted close encounters with 10–20 asteroids and serendipitous searches to constrain the distribution of smaller (e.g. 10 m) size objects into a single concept. With a carefully targeted trajectory that loops through the asteroid belt, CASTAway would provide a comprehensive survey of the main belt at multiple scales. The scientific payload comprises a 50 cm diameter telescope that includes an integrated low-resolution (R = 30–100) spectrometer and visible context imager, a thermal (e.g. 6–16 µm) imager for use during the flybys, and modified star tracker cameras to detect small (∼10 m) asteroids. The CASTAway spacecraft and payload have high levels of technology readiness and are designed to fit within the programmatic and cost caps for a European Space Agency medium class mission, while delivering a significant increase in knowledge of our Solar System.
       
  • Imaging the interior of a comet from bistatic microwave measurements: Case
           of a scale comet model
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): C. Eyraud, A. Hérique, J.-M. Geffrin, W. Kofman Imaging the internal structure of comets and asteroids is an important way to provide information about their formation process. In this paper, we investigate the possibility to image the interior of such structures with electromagnetic waves in the microwave domain (radar system) using an inverse algorithm adapted to take advantage of a bistatic configuration, considering the polarization effects, and which presents low memory requirement. To this end, a scale model of a comet/asteroid was built and was used for an experimental simulation. The scattered fields of this scale model were measured in a perfectly controlled environment, in an anechoic chamber, to avoid measurement disturbances and to focus this study only on which structural information can be obtained with such measurements. To profit from the spatial diversity of information, a vectorial-induced current reconstruction algorithm was used. Two configurations were tested and analyzed including one with very few measurements. From the qualitative reconstructed maps, we have shown that it is possible to detect the presence of a core in both cases.
       
  • The Castalia mission to Main Belt Comet 133P/Elst-Pizarro
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): C. Snodgrass, G.H. Jones, H. Boehnhardt, A. Gibbings, M. Homeister, N. Andre, P. Beck, M.S. Bentley, I. Bertini, N. Bowles, M.T. Capria, C. Carr, M. Ceriotti, A.J. Coates, V. Della Corte, K.L. Donaldson Hanna, A. Fitzsimmons, P.J. Gutiérrez, O.R. Hainaut, A. Herique We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these.
       
  • The proposed Caroline ESA M3 mission to a Main Belt Comet
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Geraint H. Jones, Jessica Agarwal, Neil Bowles, Mark Burchell, Andrew J. Coates, Alan Fitzsimmons, Amara Graps, Henry H. Hsieh, Carey M. Lisse, Stephen C. Lowry, Adam Masters, Colin Snodgrass, Cecilia Tubiana We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in response to the Cosmic Visions M3 call for medium-sized missions. Caroline would have travelled to a Main Belt Comet (MBC), characterizing the object during a flyby, and capturing dust from its tenuous coma for return to Earth. MBCs are suspected to be transition objects straddling the traditional boundary between volatile–poor rocky asteroids and volatile–rich comets. The weak cometary activity exhibited by these objects indicates the presence of water ice, and may represent the primary type of object that delivered water to the early Earth. The Caroline mission would have employed aerogel as a medium for the capture of dust grains, as successfully used by the NASA Stardust mission to Comet 81P/Wild 2. We describe the proposed mission design, primary elements of the spacecraft, and provide an overview of the science instruments and their measurement goals. Caroline was ultimately not selected by the European Space Agency during the M3 call; we briefly reflect on the pros and cons of the mission as proposed, and how current and future mission MBC mission proposals such as Castalia could best be approached.
       
  • Formamide-based prebiotic chemistry in the Phlegrean Fields
    • Abstract: Publication date: 15 October 2018Source: Advances in Space Research, Volume 62, Issue 8Author(s): Lorenzo Botta, Raffaele Saladino, Bruno M. Bizzarri, Beatrice Cobucci-Ponzano, Roberta Iacono, Rosario Avino, Stefano Caliro, Antonio Carandente, Fabio Lorenzini, Alessandra Tortora, Ernesto Di Mauro, Marco Moracci Understanding the formation of biogenic molecules in abiotic conditions is a prerequisite in the origin-of-life studies. Determining the conditions allowing an efficient one-pot synthesis of the largest possible panel of biogenic compounds may shed light on the plausible scenario in which the processes that kick-started life might have occurred. We report a set of experiments describing the syntheses taking place from formamide (NH2CHO) and thermal water in the presence of meteorites, in the hydrothermal physical-chemical environment of the Phlegrean Fields. The results show that meteorites catalyse the synthesis of a large panel of organic compounds of biological relevance, including carboxylic acids, nucleobases, amino acids and sugars. The simplicity of the system (a one-carbon molecule as starting compound, a volcanic hydrothermal environment, meteorites as catalysts) hints to a possible extension of the results to similar environments present in other planetary bodies and space objects.
       
  • How do interplanetary shock impact angles control the size of the
           geoeffective magnetosphere'
    • Abstract: Publication date: Available online 22 September 2018Source: Advances in Space ResearchAuthor(s): J.T. Rudd, D.M. Oliveira, A. Bhaskar, A.J. Halford In this paper, we investigate temporal and spatial magnetosphere response to the impact of interplanetary (IP) shocks with different inclinations and speeds on the Earth’s magnetosphere. A data set with more than 500 IP shocks is used to identify positive sudden impulse (SI+) events as expressed by the SuperMAG partial ring current index. The SI+ rise time (RT), defined as the time interval between compression onset and maximum SI+ signature, is obtained for each event. We use RT and a model suggested by Takeuchi et al. (2002) to calculate the geoeffective magnetospheric distance (GMD) in the shock propagation direction as a function of shock impact angle and speed for each event. GMD is a generalization of the geoeffective magnetosphere length (GML) suggested by Takeuchi et al. (2002), defined from the subsolar point along the X line toward the tail. We estimate statistical GMD and GML values which are then reported for the first time. We also show that, similarly to well-known results for RT, the highest correlation coefficient for the GMD and impact angle is found for shocks with high speeds and small impact angles, and the faster and more frontal the shock, the smaller the GMD. This result indicates that the magnetospheric response depends heavily on shock impact angle. With these results, we argue that the prediction and forecasting of space weather events, such as those caused by coronal mass ejections, will not be accurately accomplished if the disturbances’ angles of impact are not considered as an important parameter within model and observation scheme capabilities.
       
  • A method for automatic detection of equatorial spread-F in ionograms
    • Abstract: Publication date: Available online 21 September 2018Source: Advances in Space ResearchAuthor(s): Carlo Scotto, Alessandro Ippolito, Dario Sabbagh A method is presented for automatic detection of spread-F. The method is based on an image recognition technique and is applied to ionograms recorded at the ionospheric station of Tucumán (-26.9°, 294.6°). The performance achieved is statistically evaluated and demonstrated with significant examples. The proposed method improves Autoscala's ability to reject ionograms with insufficient information, including those featuring Spread-F. Automatic identification of cases of spread-F is of additional interest in Space Weather applications, when it helps detect degraded radio propagation conditions.The present data analysis is a retrospective study but forms the basis for real-time application as an extension of Autoscala’s capabilities.
       
  • Object-based rice mapping using time-series and phenological data
    • Abstract: Publication date: Available online 21 September 2018Source: Advances in Space ResearchAuthor(s): Meng Zhang, Hui Lin Remote sensing techniques are often used in mapping rice, but high quality time-series remote sensing data are difficult to obtain due to the cloudy weather of rice growing areas and long satellite revisit interval. As such, rice mapping is usually based on mono-temporal Landsat TM/ETM+ data, which have large uncertainties due to the spectral similarity of different vegetation types. Moreover, conventional pixel-based classification method is unable to meet the required accuracy for rice mapping. Therefore, this study proposes a new strategy for mapping rice in cloud-prone areas using fused data of Landsat-8 OLI time-series and phenological parameters, based on the object-based method. We determine the critical growth stages of paddy rice from observed phenological data and MODIS-NDVI time-series data. The spatial and temporal adaptive reflectance fusion model (STARFM) is used to blend the MODIS and Landsat data to obtain a multi-temporal Landsat-like dataset for classification. Finally, an object-oriented algorithm is used to extract rice paddies from the Landsat-like, time-series dataset. The validation experiments show that the proposed method can provide high accuracy rice mapping, with an overall accuracy of 92.38% and a kappa coefficient of 0.85.
       
  • Comparison of Ionospheric Total Electron Content (TEC) over Sonmiani
           (Pakistan) with NeQuick-2 and IRI-2012 during July 2014 - June 2015
    • Abstract: Publication date: Available online 20 September 2018Source: Advances in Space ResearchAuthor(s): Muhammmad Ayyaz Ameen, Mehak Abdul Jabbar, Xiao YU, Weimin Zhen, Ghulam Murtaza, Farrukh Chishtie, Haqqa Khursheed, Muhammad Atiq In this study, Total Electron Content (TEC) observations acquired by a GNSS receiver installed at Sonmiani (Geog. Coord. 25.19°N, 66.74°E, Geomag. Coord. 17.62°N, 141.5°E) are being reported for the first time. The data utilized is hourly instantaneous TEC values during 10 International Quiet Days (IQDs) per month from Jul-14 to Jun-15, totaling 120 observation days for monitoring nominal TEC. The findings confirm the semi-annual trend of TEC over Sonmiani, which lies at the northern crest of Equatorial Ionization Anomaly (EIA) region. The TEC measurements are then compared with NeQuick-2 and International Reference Ionosphere (IRI-2012) models. It was found that the TEC values derived from NeQuick-2 are in better agreement with GNSS measurements than those from IRI-2012. The TEC measurements also show seasonal variation which is largest during Equinox months. The TEC value in Dec solstice is higher than the Jun solstice, which confirms that the seasonal anomaly is playing a major role in this region during the course of study.
       
  • Application of an Evolution Strategy in Planetary Ephemeris Modeling
    • Abstract: Publication date: Available online 19 September 2018Source: Advances in Space ResearchAuthor(s): Enrico Mai, Jürgen Müller, Jürgen Oberst Classical planetary ephemeris construction comprises three major steps which are to be performed iteratively: numerical integration of coupled equations of motion of a multi-body system (propagator step), reduction of observations (reduction step), and optimization of model parameters (adjustment step). In future, this approach may become challenged by further refinements in force modeling (e.g. inclusion of much more significant minor bodies than in the past), an ever-growing number of planetary observations (e.g. the vast amount of spacecraft tracking data), and big data issues in general. In order to circumvent the need for both the inversion of normal equation matrices and the determination of partial derivatives, and to prepare the ephemeris for applications apart from stand-alone solar-system planetary orbit calculations, here we propose an alternative ephemeris construction method. The main idea is to solve it as an optimization problem by straightforward direct evaluation of the whole set of mathematical formulas, rather than to solve it as an inverse problem with all its tacit mathematical assumptions and potential numerical difficulties. The usual gradient search is replaced by a stochastic search, namely an evolution strategy, the latter of which is perfect for the exploitation of parallel computing capabilities. Furthermore, this new approach allows for multi-criteria optimization and time-varying optima. These issues will become important in future once ephemeris construction is just one part of even larger optimization problems, e.g. the combined and consistent determination of a generalized physical state (orbit, size, shape, rotation, gravity,…) of celestial bodies (planets, satellites, asteroids, or comets), and/or if one seeks near real-time solutions. Here, we outline the general idea and exemplarily optimize high-correlated asteroidal ring model parameters (total mass and heliocentric radius), and individual asteroid masses, based on simulated observations.
       
  • Past, Present and Future of Small Body Science and Exploration
    • Abstract: Publication date: Available online 25 August 2018Source: Advances in Space ResearchAuthor(s): Ernesto Palomba, M.A. Shea
       
 
 
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