Journal Cover Advances in Space Research
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   Published by Elsevier Homepage  [3177 journals]
  • Simultaneous response of NmF2 and GPS-TEC to storm events at Ilorin
    • Authors: B.W. Joshua; J.O. Adeniyi; O.A. Oladipo; P.H. Doherty; I.A. Adimula; A.O. Olawepo; S.J. Adebiyi
      Pages: 2904 - 2913
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): B.W. Joshua, J.O. Adeniyi, O.A. Oladipo, P.H. Doherty, I.A. Adimula, A.O. Olawepo, S.J. Adebiyi
      A comparative study of both TEC and NmF2 variations during quiet and disturbed conditions has been investigated using simultaneous measurements from dual frequency Global Positioning System (GPS) receiver and a DPS-4 Digisonde co-located at Ilorin (Geog. Lat. 8.50°N, Long. 4.50°E, dip. – 7.9°). The results of the quiet time variations of the two parameters show some similarities as well as differences in their structures. The values of both parameters generally increase during the sunrise period attaining a peak around the noon and then decaying towards the night time. The onset time of the sunrise growth is observed to be earlier in TEC than in NmF2. The rate of decay of TEC was observed to be faster than that of the NmF2 in most cases. Also, the noon ‘bite-outs’, leading to the formation of pre-noon and post-noon peaks, are prominent in the NmF2 structure and was hardly noticed in TEC. Results of the variations of both TEC and NmF2 during the 5 April, 10 May and 3 August 2010 geomagnetic storm events showed a simultaneous deviations of both parameters from the quiet time behavior. The magnitude of the deviations is however most pronounced in NmF2 structure than in TEC. We also found that the enhancement observed in the two parameters during the storm events generally corresponds to decrease in hmF2.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.031
       
  • Time-nonlocal kinetic equations, jerk and hyperjerk in plasmas and solar
           physics
    • Authors: Rami Ahmad El-Nabulsi
      Pages: 2914 - 2931
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): Rami Ahmad El-Nabulsi
      The simulation and analysis of nonlocal effects in fluids and plasmas is an inherently complicated problem due to the massive breadth of physics required to describe the nonlocal dynamics. This is a multi-physics problem that draws upon various miscellaneous fields, such as electromagnetism and statistical mechanics. In this paper we strive to focus on one narrow but motivating mathematical way: the derivation of nonlocal plasma-fluid equations from a generalized nonlocal Liouville derivative operator motivated from Suykens's nonlocal arguments. The paper aims to provide a guideline toward modeling nonlocal effects occurring in plasma-fluid systems by means of a generalized nonlocal Boltzmann equation. The generalized nonlocal equations of fluid dynamics are derived and their implications in plasma-fluid systems are addressed, discussed and analyzed. Three main topics were discussed: Landau damping in plasma electrodynamics, ideal MHD and solar wind. A number of features were revealed, analyzed and confronted with recent research results and observations.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.032
       
  • Refining surface net radiation estimates in arid and semi-arid climates of
           Iran
    • Authors: Foroogh Golkar; William B. Rossow; Ali Akbar Sabziparvar
      Pages: 2932 - 2941
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): Foroogh Golkar, William B. Rossow, Ali Akbar Sabziparvar
      Although the downwelling fluxes exhibit space-time scales of dependency on characteristic of atmospheric variations, especially clouds, the upward fluxes and, hence the net radiation, depends on the variation of surface properties, particularly surface skin temperature and albedo. Evapotranspiration at the land surface depends on the properties of that surface and is determined primarily by the net surface radiation, mostly absorbed solar radiation. Thus, relatively high spatial resolution net radiation data are needed for evapotranspiration studies. Moreover, in more arid environments, the diurnal variations of surface (air and skin) temperature can be large so relatively high (sub-daily) time resolution net radiation is also needed. There are a variety of radiation and surface property products available but they differ in accuracy, space-time resolution and information content. This situation motivated the current study to evaluate multiple sources of information to obtain the best net radiation estimate with the highest space-time resolution from ISCCP FD dataset. This study investigates the accuracy of the ISCCP FD and AIRS surface air and skin temperatures, as well as the ISCCP FD and MODIS surface albedos and aerosol optical depths as the leading source of uncertainty in ISCCP FD dataset. The surface air temperatures, 10-cm soil temperatures and surface solar insolation from a number of surface sites are used to judge the best combinations of data products, especially on clear days. The corresponding surface skin temperatures in ISCCP FD, although they are known to be biased somewhat high, disagreed more with AIRS measurements because of the mismatch of spatial resolutions. The effect of spatial resolution on the comparisons was confirmed using the even higher resolution MODIS surface skin temperature values. The agreement of ISCCP FD surface solar insolation with surface measurements is good (within 2.4–9.1%), but the use of MODIS aerosol optical depths as an alternative was checked and found to not improve the agreement. The MODIS surface albedos differed from the ISCCP FD values by no more than 0.02–0.07, but because these differences are mostly at longer wavelengths, they did not change the net solar radiation very much. Therefore to obtain the best estimate of surface net radiation with the best combination of spatial and temporal resolution, we developed a method to adjust the ISCCP FD surface longwave fluxes using the AIRS surface air and skin temperatures to obtain the higher spatial resolution of the latter (45 km), while retaining the 3-h time intervals of the former. Overall, the refinements reduced the ISCCP FD longwave flux magnitudes by about 25.5–42.1 W/m2 RMS (maximum difference −27.5 W/m2 for incoming longwave radiation and −59 W/m2 for outgoing longwave radiation) with the largest differences occurring at 9:00 and 12:00 UTC near local noon. Combining the ISCCP FD net shortwave radiation data and the AIRS-modified net longwave radiation data changed the total net radiation for summertime by 4.64 to 61.5 W/m2 and for wintertime by 1.06 to 41.88 W/m2 (about 11.1–39.2% of the daily mean).

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.026
       
  • Evaluation and analysis of real-time precise orbits and clocks products
           from different IGS analysis centers
    • Authors: Liang Zhang; Hongzhou Yang; Yang Gao; Yibin Yao; Chaoqian Xu
      Pages: 2942 - 2954
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): Liang Zhang, Hongzhou Yang, Yang Gao, Yibin Yao, Chaoqian Xu
      To meet the increasing demands from the real-time Precise Point Positioning (PPP) users, the real-time satellite orbit and clock products are generated by different International GNSS Service (IGS) real-time analysis centers and can be publicly received through the Internet. Based on different data sources and processing strategies, the real-time products from different analysis centers therefore differ in availability and accuracy. The main objective of this paper is to evaluate availability and accuracy of different real-time products and their effects on real-time PPP. A total of nine commonly used Real-Time Service (RTS) products, namely IGS01, IGS03, CLK01, CLK15, CLK22, CLK52, CLK70, CLK81 and CLK90, will be evaluated in this paper. Because not all RTS products support multi-GNSS, only GPS products are analyzed in this paper. Firstly, the availability of all RTS products is analyzed in two levels. The first level is the epoch availability, indicating whether there is outage for that epoch. The second level is the satellite availability, which defines the available satellite number for each epoch. Then the accuracy of different RTS products is investigated on nominal accuracy and the accuracy degradation over time. Results show that Root-Mean-Square Error (RMSE) of satellite orbit ranges from 3.8 cm to 7.5 cm for different RTS products. While the mean Standard Deviations of Errors (STDE) of satellite clocks range from 1.9 cm to 5.6 cm. The modified Signal In Space Range Error (SISRE) for all products are from 1.3 cm to 5.5 cm for different RTS products. The accuracy degradation of the orbit has the linear trend for all RTS products and the satellite clock degradation depends on the satellite clock types. The Rb clocks on board of GPS IIF satellites have the smallest degradation rate of less than 3 cm over 10 min while the Cs clocks on board of GPS IIF have the largest degradation rate of more than 10 cm over 10 min. Finally, the real-time kinematic PPP is carried out to investigate the effects of different real-time products. The CLK90 has the best performance and mean RMSE of 26 globally distributed IGS stations in three components are 3.2 cm, 6.6 cm and 8.5 cm. And the second-best positioning results are using IGS03 products.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.029
       
  • MSE-impact of PPP-RTK ZTD estimation strategies
    • Authors: K. Wang; A. Khodabandeh; P.J.G. Teunissen
      Pages: 2955 - 2971
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): K. Wang, A. Khodabandeh, P.J.G. Teunissen
      In PPP-RTK network processing, the wet component of the zenith tropospheric delay (ZTD) cannot be precisely modelled and thus remains unknown in the observation equations. For small networks, the tropospheric mapping functions of different stations to a given satellite are almost equal to each other, thereby causing a near rank-deficiency between the ZTDs and satellite clocks. The stated near rank-deficiency can be solved by estimating the wet ZTD components relatively to that of the reference receiver, while the wet ZTD component of the reference receiver is constrained to zero. However, by increasing network scale and humidity around the reference receiver, enlarged mismodelled effects could bias the network and the user solutions. To consider both the influences of the noise and the biases, the mean-squared errors (MSEs) of different network and user parameters are studied analytically employing both the ZTD estimation strategies. We conclude that for a certain set of parameters, the difference in their MSE structures using both strategies is only driven by the square of the reference wet ZTD component and the formal variance of its solution. Depending on the network scale and the humidity condition around the reference receiver, the ZTD estimation strategy that delivers more accurate solutions might be different. Simulations are performed to illustrate the conclusions made by analytical studies. We find that estimating the ZTDs relatively in large networks and humid regions (for the reference receiver) could significantly degrade the network ambiguity success rates. Using ambiguity-fixed network-derived PPP-RTK corrections, for networks with an inter-station distance within 100 km, the choices of the ZTD estimation strategy is not crucial for single-epoch ambiguity-fixed user positioning. Using ambiguity-float network corrections, for networks with inter-station distances of 100, 300 and 500 km in humid regions (for the reference receiver), the root-mean-squared errors (RMSEs) of the estimated user coordinates using relative ZTD estimation could be higher than those under the absolute case with differences up to millimetres, centimetres and decimetres, respectively.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.04.012
       
  • Atmospheric interaction with nanosatellites from observed orbital decay
    • Authors: A. Macario-Rojas; K.L. Smith; N.H. Crisp; P.C.E. Roberts
      Pages: 2972 - 2982
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): A. Macario-Rojas, K.L. Smith, N.H. Crisp, P.C.E. Roberts
      Nanosatellites have gained considerable presence in low Earth orbits wherein the atmospheric interaction with exposed surfaces plays a fundamental role in the evolution of motion. These aspects become relevant with the increasing applicability of nanosatellites to a broader range of missions objectives. This investigation sets out to determine distinctive drag coefficient development and attributes of atmospheric gas-surface interactions in nanosatellites in the common form of standard 3U CubeSats from observed orbital decay. As orbital decay can be measured with relative accuracy, and its mechanism broken down into its constituent sources, the value of drag-related coefficients can be inferred by fitting modelled orbit predictions to observed data wherein the coefficient of interest is the adjusted parameter. The analysis uses the data of ten historical missions with documented passive attitude stabilisation strategies to reduce uncertainties. Findings indicate that it is possible to estimate fitted drag coefficients in CubeSats with physical representativeness. Assessment of atomic oxygen surface coverage derived from the fitted drag coefficients is broadly consistent with theoretical trends. The proposed methodology opens the possibility to assess atmospheric interaction characteristics by using the unprecedented opportunity arising from the numerous observed orbital decay of nanosatellites.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.022
       
  • A truly international lunar base as the next logical step for human
           spaceflight
    • Authors: R. Bonneville
      Pages: 2983 - 2988
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): R. Bonneville
      A human mission to Mars has been highlighted as the long term goal for space exploration, with intermediate stages such as missions to the Moon and/or to asteroids, but a human mission to Mars will not be feasible before several decades. For the time being the major ambitious accomplishment in the field of human spaceflight is the International Space Station but a human spaceflight programme which would be restricted to Low Earth orbit (LEO) has indeed little interest. Thus the next step in the field of human exploration should be the definition of a new exploration programme beyond LEO, built within a long term perspective. We must acknowledge that science is not the main driver of human space exploration and that the main success of the ISS is to have allowed its partners to work together. The main goal of a new human exploration programme will be to promote international cooperation between the major space-faring countries. The only sensible and feasible objective of a near/mid-term human spaceflight programme should be the edification of a lunar base, under the condition that this base is built as a truly international venture. The ISS in the 1990s had illustrated a calmed relation between the USA, together with Europe, Canada and Japan, and Russia; a lunar base would be the symbol of a similar calmed relation between the same partners and China, and possibly others such as India. For the benefit of all humankind this extra continent, the Moon, should be used only for peaceful purposes like Antarctica today, and should not become the theatre or the stake of conflicts. Such a programme is technically feasible and financially affordable in a rather short term. So let us go to the Moon, but let us get there together.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.035
       
  • A surrogate model for thermal characteristics of stratospheric airship
    • Authors: Da Zhao; Dongxu Liu; Ming Zhu
      Pages: 2989 - 3001
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): Da Zhao, Dongxu Liu, Ming Zhu
      A simple and accurate surrogate model is extremely needed to reduce the analysis complexity of thermal characteristics for a stratospheric airship. In this paper, a surrogate model based on the Least Squares Support Vector Regression (LSSVR) is proposed. The Gravitational Search Algorithm (GSA) is used to optimize hyper parameters. A novel framework consisting of a preprocessing classifier and two regression models is designed to train the surrogate model. Various temperature datasets of the airship envelope and the internal gas are obtained by a three-dimensional transient model for thermal characteristics. Using these thermal datasets, two-factor and multi-factor surrogate models are trained and several comparison simulations are conducted. Results illustrate that the surrogate models based on LSSVR-GSA have good fitting and generalization abilities. The pre-treated classification strategy proposed in this paper plays a significant role in improving the accuracy of the surrogate model.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.036
       
  • An iterative analytical technique for the design of interplanetary direct
           transfer trajectories including perturbations
    • Authors: S.P. Parvathi; R.V. Ramanan
      Pages: 3002 - 3019
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): S.P. Parvathi, R.V. Ramanan
      An iterative analytical trajectory design technique that includes perturbations in the departure phase of the interplanetary orbiter missions is proposed. The perturbations such as non-spherical gravity of Earth and the third body perturbations due to Sun and Moon are included in the analytical design process. In the design process, first the design is obtained using the iterative patched conic technique without including the perturbations and then modified to include the perturbations. The modification is based on, (i) backward analytical propagation of the state vector obtained from the iterative patched conic technique at the sphere of influence by including the perturbations, and (ii) quantification of deviations in the orbital elements at periapsis of the departure hyperbolic orbit. The orbital elements at the sphere of influence are changed to nullify the deviations at the periapsis. The analytical backward propagation is carried out using the linear approximation technique. The new analytical design technique, named as biased iterative patched conic technique, does not depend upon numerical integration and all computations are carried out using closed form expressions. The improved design is very close to the numerical design. The design analysis using the proposed technique provides a realistic insight into the mission aspects. Also, the proposed design is an excellent initial guess for numerical refinement and helps arrive at the four distinct design options for a given opportunity.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.034
       
  • Multi-GNSS signal-in-space range error assessment – Methodology and
           results
    • Authors: Oliver Montenbruck; Peter Steigenberger; André Hauschild
      Pages: 3020 - 3038
      Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12
      Author(s): Oliver Montenbruck, Peter Steigenberger, André Hauschild
      The positioning accuracy of global and regional navigation satellite systems (GNSS/RNSS) depends on a variety of influence factors. For constellation-specific performance analyses it has become common practice to separate a geometry-related quality factor (the dilution of precision, DOP) from the measurement and modeling errors of the individual ranging measurements (known as user equivalent range error, UERE). The latter is further divided into user equipment errors and contributions related to the space and control segment. The present study reviews the fundamental concepts and underlying assumptions of signal-in-space range error (SISRE) analyses and presents a harmonized framework for multi-GNSS performance monitoring based on the comparison of broadcast and precise ephemerides. The implications of inconsistent geometric reference points, non-common time systems, and signal-specific range biases are analyzed, and strategies for coping with these issues in the definition and computation of SIS range errors are developed. The presented concepts are, furthermore, applied to current navigation satellite systems, and representative results are presented along with a discussion of constellation-specific problems in their determination. Based on data for the January to December 2017 time frame, representative global average root-mean-square (RMS) SISRE values of 0.2 m, 0.6 m, 1 m, and 2 m are obtained for Galileo, GPS, BeiDou-2, and GLONASS, respectively. Roughly two times larger values apply for the corresponding 95th-percentile values. Overall, the study contributes to a better understanding and harmonization of multi-GNSS SISRE analyses and their use as key performance indicators for the various constellations.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.041
       
  • An optimization approach for observation association with systemic
           uncertainty applied to electro-optical systems
    • Authors: Johnny L. Worthy; Marcus J. Holzinger; Daniel J. Scheeres
      Pages: 2709 - 2724
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Johnny L. Worthy, Marcus J. Holzinger, Daniel J. Scheeres
      The observation to observation measurement association problem for dynamical systems can be addressed by determining if the uncertain admissible regions produced from each observation have one or more points of intersection in state space. An observation association method is developed which uses an optimization based approach to identify local Mahalanobis distance minima in state space between two uncertain admissible regions. A binary hypothesis test with a selected false alarm rate is used to assess the probability that an intersection exists at the point(s) of minimum distance. The systemic uncertainties, such as measurement uncertainties, timing errors, and other parameter errors, define a distribution about a state estimate located at the local Mahalanobis distance minima. If local minima do not exist, then the observations are not associated. The proposed method utilizes an optimization approach defined on a reduced dimension state space to reduce the computational load of the algorithm. The efficacy and efficiency of the proposed method is demonstrated on observation data collected from the Georgia Tech Space Object Research Telescope.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.041
       
  • Roto-orbital dynamics of a triaxial rigid body around a sphere. Relative
           equilibria and stability
    • Authors: F. Crespo; S. Ferrer
      Pages: 2725 - 2739
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): F. Crespo, S. Ferrer
      We study the roto-orbital motion of a triaxial rigid body around a sphere, which is assumed to be much more massive than the triaxial body. The associated dynamics of this system, which consists of a normalized Hamiltonian with respect to the fast angles (partial averaging), is investigated making use of variables referred to the total angular momentum. The first order approximation of this model is integrable. We carry out the analysis of the relative equilibria, which hinges principally in the dihedral angle between the orbital and rotational planes and the ratio among the moments of inertia ρ = ( B - A ) / ( 2 C - B - A ) . In particular, the dynamics of the body frame, though formally given by the classical Euler equations, experiences changes of stability in the principal directions related to the roto-orbital coupling. When ρ = 1 / 3 , we find a family of relative equilibria connected to the unstable equilibria of the free rigid body.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.013
       
  • On the lunar node resonance of the orbital plane evolution of the
           Earth’s satellite orbits
    • Authors: Ting-Lei Zhu
      Pages: 2761 - 2776
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Ting-Lei Zhu
      This paper aims to investigate the effects of lunar node resonance on the circular medium Earth orbits (MEO). The dynamical model is established in classical Hamiltonian systems with the application of Lie transform to remove the non-resonant terms. Resonant condition, stability and phase structures are studied. The lunar node resonance occurs when the secular changing rates of the orbital node (with respect to the equator) and the lunar node (with respect to the ecliptic) form a simple integer ratio. The resonant conditions are satisfied for both inclined and equatorial orbits. The orbital plane would have long period (with typical timescales of several centuries) fluctuation due to the resonance.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.017
       
  • An optimal beam alignment method for large-scale distributed space
           surveillance radar system
    • Authors: Jian Huang; Dongya Wang; Shuangzhi Xia
      Pages: 2777 - 2786
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Jian Huang, Dongya Wang, Shuangzhi Xia
      Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.019
       
  • A robust object-based shadow detection method for cloud-free high
           resolution satellite images over urban areas and water bodies
    • Authors: Nurollah Tatar; Mohammad Saadatseresht; Hossein Arefi; Ahmad Hadavand
      Pages: 2787 - 2800
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Nurollah Tatar, Mohammad Saadatseresht, Hossein Arefi, Ahmad Hadavand
      Unwanted contrast in high resolution satellite images such as shadow areas directly affects the result of further processing in urban remote sensing images. Detecting and finding the precise position of shadows is critical in different remote sensing processing chains such as change detection, image classification and digital elevation model generation from stereo images. The spectral similarity between shadow areas, water bodies, and some dark asphalt roads makes the development of robust shadow detection algorithms challenging. In addition, most of the existing methods work on pixel-level and neglect the contextual information contained in neighboring pixels. In this paper, a new object-based shadow detection framework is introduced. In the proposed method a pixel-level shadow mask is built by extending established thresholding methods with a new C4 index which enables to solve the ambiguity of shadow and water bodies. Then the pixel-based results are further processed in an object-based majority analysis to detect the final shadow objects. Four different high resolution satellite images are used to validate this new approach. The result shows the superiority of the proposed method over some state-of-the-art shadow detection method with an average of 96% in F-measure.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.011
       
  • A novel method for destriping of OCM-2 data and radiometric performance
           analysis for improved ocean color data products
    • Authors: Rakesh Kumar Singh; Palanisamy Shanmugam
      Pages: 2801 - 2819
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Rakesh Kumar Singh, Palanisamy Shanmugam
      Despite the capability of Ocean Color Monitor aboard Oceansat-2 satellite to provide frequent, high-spatial resolution, visible and near-infrared images for scientific research on coastal zones and climate data records over the global ocean, the generation of science quality ocean color products from OCM-2 data has been hampered by serious vertical striping artifacts and poor calibration of detectors. These along-track stripes are the results of variations in the relative response of the individual detectors of the OCM-2 CCD array. The random unsystematic stripes and bandings on the scene edges affect both visual interpretation and radiometric integrity of remotely sensed data, contribute to confusion in the aerosol correction process, and multiply and propagate into higher level ocean color products generated by atmospheric correction and bio-optical algorithms. Despite a number of destriping algorithms reported in the literature, complete removal of stripes without residual effects and signal distortion in both low- and high-level products is still challenging. Here, a new operational algorithm has been developed that employs an inverted gaussian function to estimate error fraction parameters, which are uncorrelated and vary in spatial, spectral and temporal domains. The algorithm is tested on a large number of OCM-2 scenes from Arabian Sea and Bay of Bengal waters contaminated with severe stripes. The destriping effectiveness of this approach is then evaluated by means of various qualitative and quantitative analyses, and by comparison with the results of the previously reported method. Clearly, the present method is more effective in terms of removing the stripe noise while preserving the radiometric integrity of the destriped OCM-2 data. Furthermore, a preliminary time-dependent calibration of the OCM-2 sensor is performed with several match-up in-situ data to evaluate its radiometric performance for ocean color applications. OCM-2 derived water-leaving radiance products obtained after calibration show a good consistency with in-situ and MODIS-Aqua observations, with errors less than the validated uncertainties of ±5% and ±35% endorsed for the remote-sensing measurements of water-leaving radiance and retrieval of chlorophyll concentrations respectively. The calibration results show a declining trend in detector sensitivity of the OCM-2 sensor, with a maximum effect in the shortwave spectrum, which provides evidence of sensor degradation and its profound effect on the striping artifacts in the OCM-2 data products.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.021
       
  • Essential features of long-term changes of areas and diameters of sunspot
           groups in solar activity cycles 12–24
    • Authors: V.M. Efimenko; V.G. Lozitsky
      Pages: 2820 - 2826
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): V.M. Efimenko, V.G. Lozitsky
      We analyze the Greenwich catalog data on areas of sunspot groups of last thirteen solar cycles. Various parameters of sunspots are considered, namely: average monthly smoothed areas, maximum area for each year and equivalent diameters of groups of sunspots. The first parameter shows an exceptional power of the 19th cycle of solar activity, which appears here more contrastively than in the numbers of spots (that is, in Wolf’s numbers). It was found that in the maximum areas of sunspot groups for a year there is a unique phenomenon: a short and high jump in the 18th cycle (in 1946–1947) that has no analogues in other cycles. We also studied the integral distributions for equivalent diameters and found the following: (a) the average value of the index of power-law approximation is 5.4 for the last 13 cycles and (b) there is reliable evidence of Hale's double cycle (about 44 years). Since this indicator reflects the dispersion of sunspot group diameters, the results obtained show that the convective zone of the Sun generates embryos of active regions in different statistical regimes which change with a cycle of about 44 years.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.012
       
  • The influence of non-Gaussian distribution functions on the time-dependent
           perpendicular transport of energetic particles
    • Authors: J. Lasuik; A. Shalchi
      Pages: 2827 - 2836
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): J. Lasuik, A. Shalchi
      In the current paper we explore the influence of the assumed particle statistics on the transport of energetic particles across a mean magnetic field. In previous work the assumption of a Gaussian distribution function was standard, although there have been known cases for which the transport is non-Gaussian. In the present work we combine a kappa distribution with the ordinary differential equation provided by the so-called unified non-linear transport theory. We then compute running perpendicular diffusion coefficients for different values of κ and turbulence configurations. We show that changing the parameter κ slightly increases or decreases the perpendicular diffusion coefficient depending on the considered turbulence configuration. Since these changes are small, we conclude that the assumed statistics is less significant in particle transport theory. The results obtained in the current paper support to use a Gaussian distribution function as usually done in particle transport theory.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.014
       
  • Reliability-based trajectory optimization using nonintrusive polynomial
           chaos for Mars entry mission
    • Authors: Yuechen Huang; Haiyang Li
      Pages: 2854 - 2869
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Yuechen Huang, Haiyang Li
      This paper presents the reliability-based sequential optimization (RBSO) method to settle the trajectory optimization problem with parametric uncertainties in entry dynamics for Mars entry mission. First, the deterministic entry trajectory optimization model is reviewed, and then the reliability-based optimization model is formulated. In addition, the modified sequential optimization method, in which the nonintrusive polynomial chaos expansion (PCE) method and the most probable point (MPP) searching method are employed, is proposed to solve the reliability-based optimization problem efficiently. The nonintrusive PCE method contributes to the transformation between the stochastic optimization (SO) and the deterministic optimization (DO) and to the approximation of trajectory solution efficiently. The MPP method, which is used for assessing the reliability of constraints satisfaction only up to the necessary level, is employed to further improve the computational efficiency. The cycle including SO, reliability assessment and constraints update is repeated in the RBSO until the reliability requirements of constraints satisfaction are satisfied. Finally, the RBSO is compared with the traditional DO and the traditional sequential optimization based on Monte Carlo (MC) simulation in a specific Mars entry mission to demonstrate the effectiveness and the efficiency of the proposed method.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.009
       
  • Interstellar hydrogen bonding
    • Authors: Emmanuel E. Etim; Prasanta Gorai; Ankan Das; Sandip K. Chakrabarti; Elangannan Arunan
      Pages: 2870 - 2880
      Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11
      Author(s): Emmanuel E. Etim, Prasanta Gorai, Ankan Das, Sandip K. Chakrabarti, Elangannan Arunan
      This paper reports the first extensive study of the existence and effects of interstellar hydrogen bonding. The reactions that occur on the surface of the interstellar dust grains are the dominant processes by which interstellar molecules are formed. Water molecules constitute about 70% of the interstellar ice. These water molecules serve as the platform for hydrogen bonding. High level quantum chemical simulations for the hydrogen bond interaction between 20 interstellar molecules (known and possible) and water are carried out using different ab-intio methods. It is evident that if the formation of these species is mainly governed by the ice phase reactions, there is a direct correlation between the binding energies of these complexes and the gas phase abundances of these interstellar molecules. Interstellar hydrogen bonding may cause lower gas abundance of the complex organic molecules (COMs) at the low temperature. From these results, ketenes whose less stable isomers that are more strongly bonded to the surface of the interstellar dust grains have been observed are proposed as suitable candidates for astronomical observations.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.003
       
  • A modern robust approach to remotely estimate chlorophyll in coastal and
           inland zones
    • Authors: Palanisamy Shanmugam; Xianqiang He; Rakesh Kumar Singh; Theenathayalan Varunan
      Pages: 2491 - 2509
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Palanisamy Shanmugam, Xianqiang He, Rakesh Kumar Singh, Theenathayalan Varunan
      The chlorophyll concentration of a water body is an important proxy for representing the phytoplankton biomass. Its estimation from multi or hyper-spectral remote sensing data in natural waters is generally achieved by using (i) the waveband ratioing in two or more bands in the blue-green or (ii) by using a combination of the radiance peak position and magnitude in the red-near-infrared (NIR) spectrum. The blue-green ratio algorithms have been extensively used with satellite ocean color data to investigate chlorophyll distributions in open ocean and clear waters and the application of red-NIR algorithms is often restricted to turbid productive water bodies. These issues present the greatest obstacles to our ability to formulate a modern robust method suitable for quantitative assessments of the chlorophyll concentration in a diverse range of water types. The present study is focused to investigate the normalized water-leaving radiance spectra in the visible and NIR region and propose a robust algorithm (Generalized ABI, GABI algorithm) for chlorophyll concentration retrieval based on Algal Bloom index (ABI) which separates phytoplankton signals from other constituents in the water column. The GABI algorithm is validated using independent in-situ data from various regional to global waters and its performance is further evaluated by comparison with the blue-green waveband ratios and red-NIR algorithms. The results revealed that GABI yields significantly more accurate chlorophyll concentrations (with uncertainties less than 13.5%) and remains more stable in different waters types when compared with the blue-green waveband ratios and red-NIR algorithms. The performance of GABI is further demonstrated using HICO images from nearshore turbid productive waters and MERIS and MODIS-Aqua images from coastal and offshore waters of the Arabian Sea, Bay of Bengal and East China Sea.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.024
       
  • Manifold structure preservative for hyperspectral target detection
    • Authors: Maryam Imani
      Pages: 2510 - 2520
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Maryam Imani
      A nonparametric method termed as manifold structure preservative (MSP) is proposed in this paper for hyperspectral target detection. MSP transforms the feature space of data to maximize the separation between target and background signals. Moreover, it minimizes the reconstruction error of targets and preserves the topological structure of data in the projected feature space. MSP does not need to consider any distribution for target and background data. So, it can achieve accurate results in real scenarios due to avoiding unreliable assumptions. The proposed MSP detector is compared to several popular detectors and the experiments on a synthetic data and two real hyperspectral images indicate the superior ability of it in target detection.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.027
       
  • Effect of removing the common mode errors on linear regression analysis of
           noise amplitudes in position time series of a regional GPS network & a
           case study of GPS stations in Southern California
    • Authors: Weiping Jiang; Jun Ma; Zhao Li; Xiaohui Zhou; Boye Zhou
      Pages: 2521 - 2530
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Weiping Jiang, Jun Ma, Zhao Li, Xiaohui Zhou, Boye Zhou
      The analysis of the correlations between the noise in different components of GPS stations has positive significance to those trying to obtain more accurate uncertainty of velocity with respect to station motion. Previous research into noise in GPS position time series focused mainly on single component evaluation, which affects the acquisition of precise station positions, the velocity field, and its uncertainty. In this study, before and after removing the common-mode error (CME), we performed one-dimensional linear regression analysis of the noise amplitude vectors in different components of 126 GPS stations with a combination of white noise, flicker noise, and random walking noise in Southern California. The results show that, on the one hand, there are above-moderate degrees of correlation between the white noise amplitude vectors in all components of the stations before and after removal of the CME, while the correlations between flicker noise amplitude vectors in horizontal and vertical components are enhanced from un-correlated to moderately correlated by removing the CME. On the other hand, the significance tests show that, all of the obtained linear regression equations, which represent a unique function of the noise amplitude in any two components, are of practical value after removing the CME. According to the noise amplitude estimates in two components and the linear regression equations, more accurate noise amplitudes can be acquired in the two components.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.031
       
  • Observation of a 27-day solar signature in noctilucent cloud altitude
    • Authors: Merlin C. Köhnke; Christian von Savigny; Charles E. Robert
      Pages: 2531 - 2539
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Merlin C. Köhnke, Christian von Savigny, Charles E. Robert
      Previous studies have identified solar 27-day signatures in several parameters in the Mesosphere/Lower thermosphere region, including temperature and Noctilucent cloud (NLC) occurrence frequency. In this study we report on a solar 27-day signature in NLC altitude with peak-to-peak variations of about 400 m. We use SCIAMACHY limb-scatter observations from 2002 to 2012 to detect NLCs. The superposed epoch analysis method is applied to extract solar 27-day signatures. A 27-day signature in NLC altitude can be identified in both hemispheres in the SCIAMACHY dataset, but the signature is more pronounced in the northern hemisphere. The solar signature in NLC altitude is found to be in phase with solar activity and temperature for latitudes ≳ 70 ° N. We provide a qualitative explanation for the positive correlation between solar activity and NLC altitude based on published model simulations.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.035
       
  • Equatorial secondary cosmic ray observatory to study space weather and
           terrestrial events
    • Authors: Geeta Vichare; Ankush Bhaskar; Gauri Datar; Anil Raghav; K.U. Nair; C. Selvaraj; M. Ananthi; A.K. Sinha; M. Paranjape; T. Gawade; C.P. Anil Kumar; C. Panneerselvam; S. Sathishkumar; S. Gurubaran
      Pages: 2555 - 2568
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Geeta Vichare, Ankush Bhaskar, Gauri Datar, Anil Raghav, K.U. Nair, C. Selvaraj, M. Ananthi, A.K. Sinha, M. Paranjape, T. Gawade, C.P. Anil Kumar, C. Panneerselvam, S. Sathishkumar, S. Gurubaran
      Recently, equatorial secondary cosmic ray observatory has been established at Equatorial Geophysical Research Laboratory (EGRL), Tirunelveli, (Geographic Coordinates: 8.71°N, 77.76°E), to study secondary cosmic rays (SCR) produced due to the interaction of primary cosmic rays with the Earth’s atmosphere. EGRL is a regional center of Indian Institute of Geomagnetism (IIG), located near the equator in the Southern part of India. Two NaI(Tl) scintillation detectors are installed inside the temperature controlled environment. One detector is cylindrical in shape of size 7.62 cm × 7.62 cm and another one is rectangular cuboid of 10.16 cm × 10.16 cm × 40.64 cm size. Besides NaI(Tl) detectors, various other research facilities such as the Geomagnetic observatory, Medium Frequency Radar System, Digital Ionosonde, All-sky airglow imager, Atmospheric electricity laboratory to measure the near-Earth atmospheric electric fields are also available at EGRL. With the accessibility of multi- instrument facilities, the objective is set to understand the relationship between SCR and various atmospheric and ionospheric processes, during space weather and terrestrial events. For gamma-ray spectroscopy, it is important to test the performance of the NaI(Tl) scintillation detectors and to calibrate the gamma-ray spectrum in terms of energy. The present article describes the details of the experimental setup installed near the equator to study cosmic rays, along with the performance testing and calibration of the detectors under various conditions. A systematic shift in the gain is observed with varying temperature of the detector system. It is found that the detector’s response to the variations in the temperature is not just linear or non-linear type, but it depends on the history of the variation, indicating temperature hysteresis effects on NaI detector and PMT system. This signifies the importance of isothermal environment while studying SCR flux using NaI(Tl) detectors, especially for the experiments conducted during daytime such as solar eclipses etc.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.006
       
  • A comparative study of ionospheric IRIEup and ISP assimilative models
           during some intense and severe geomagnetic storms
    • Authors: M. Pietrella; A. Pignalberi; M. Pezzopane; A. Pignatelli; A. Azzarone; R. Rizzi
      Pages: 2569 - 2584
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): M. Pietrella, A. Pignalberi, M. Pezzopane, A. Pignatelli, A. Azzarone, R. Rizzi
      Three-dimensional (3-D) electron density matrices, computed in the Mediterranean area by the IRI climatological model and IRIEup and ISP nowcasting models, during some intense and severe geomagnetic-ionospheric storms, were ingested by the ray tracing software tool IONORT, to synthesize quasi-vertical ionograms. IRIEup model was run in different operational modes: (1) assimilating validated autoscaled electron density profiles only from a limited area which, in our case, is the Mediterranean sector (IRIEup_re(V) mode); (2) assimilating electron density profiles from a larger region including several stations spread across Europe: (a) without taking care of validating the autoscaled data in the assimilation process (IRIEup(NV)); (b) validating carefully the autoscaled electron density profiles before their assimilation (IRIEup(V)). The comparative analysis was carried out comparing IRI, IRIEup_re(V), ISP, IRIEup(NV), and IRIEup(V) foF2 synthesized values, with corresponding foF2 measurements autoscaled by ARTIST, and then validated, at the truth sites of Roquetes (40.80°N, 0.50°E, Spain), San Vito (40.60°N, 17.80°E, Italy), Athens (38.00°N, 23.50°E, Greece), and Nicosia, (35.03°N, 33.16°E, Cyprus). The outcomes demonstrate that: (1) IRIEup_re(V), performs better than ISP in the western Mediterranean (around Roquetes); (2) ISP performs slightly better than IRIEup_re(V) in the central part of Mediterranean (around Athens and San Vito); (3) ISP performance is better than the IRIEup_re(V) one in the eastern Mediterranean (around Nicosia); (4) IRIEup(NV) performance is worse than the IRIEup(V) one; (5) in the central Mediterranean area, IRIEup(V) performance is better than the IRIEup_re(V) one, and it is practically the same for the western and eastern sectors. Concerning the overall performance, nowcasting models proved to be considerably more reliable than the climatological IRI model to represent the ionosphere behaviour during geomagnetic-ionospheric storm conditions; ISP and IRIEup(V) provided the best performance, but neither of them has clearly prevailed over the other one.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.026
       
  • Solar activity variations of equatorial spread F occurrence and sustenance
           during different seasons over Indian longitudes: Empirical model and
           causative mechanisms
    • Authors: M.K. Madhav Haridas; G. Manju; T. Arunamani
      Pages: 2585 - 2592
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): M.K. Madhav Haridas, G. Manju, T. Arunamani
      A comprehensive analysis using nearly two decades of ionosonde data is carried out on the seasonal and solar cycle variations of Equatorial Spread F (ESF) irregularities over magnetic equatorial location Trivandrum (8.5°N, 77°E). The corresponding Rayleigh Taylor (RT) instability growth rates (γ) are also estimated. A seasonal pattern of ESF occurrence and the corresponding γ is established for low solar (LSA), medium solar (MSA) and high solar (HSA) activity periods. For LSA, it is seen that the γ maximizes during post sunset time with comparable magnitudes for autumnal equinox (AE), vernal equinox (VE) and winter solstice (WS), while for summer solstice (SS) it maximizes in the post-midnight period. Concurrent responses are seen in the ESF occurrence pattern. For MSA, γ maximizes during post-sunset for VE followed by WS and AE while SS maximises during post-midnight period. The ESF occurrence for MSA is highest for VE (80%), followed by AE (70%), WS (60%) and SS (50%). In case of HSA, maximum γ occurs for VE followed by AE, WS and SS. The concurrent ESF occurrence maximizes for VE and AE (90%), WS and SS at 70%. The solar cycle variation of γ is examined. γ shows a linear variation with F10.7 cm flux. Further, ESF percentage occurrence and duration show an exponential and linear variation respectively with γ. An empirical model on the solar activity dependence of ESF occurrence and sustenance time over Indian longitudes is arrived at using the database spanning two solar cycles for the first time.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.040
       
  • A new inversion algorithm for HF sky-wave backscatter ionograms
    • Authors: Jing Feng; Binbin Ni; Peng Lou; Na Wei; Longquan Yang; Wen Liu; Zhengyu Zhao; Xue Li
      Pages: 2593 - 2608
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Jing Feng, Binbin Ni, Peng Lou, Na Wei, Longquan Yang, Wen Liu, Zhengyu Zhao, Xue Li
      HF sky-wave backscatter sounding system is capable of measuring the large-scale, two-dimensional (2-D) distributions of ionospheric electron density. The leading edge (LE) of a backscatter ionogram (BSI) is widely used for ionospheric inversion since it is hardly affected by any factors other than ionospheric electron density. Traditional BSI inversion methods have failed to distinguish LEs associated with different ionospheric layers, and simply utilize the minimum group path of each operating frequency, which generally corresponds to the LE associated with the F2 layer. Consequently, while the inversion results can provide accurate profiles of the F region below the F2 peak, the diagnostics may not be so effective for other ionospheric layers. In order to resolve this issue, we present a new BSI inversion method using LEs associated with different layers, which can further improve the accuracy of electron density distribution, especially the profile of the ionospheric layers below the F2 region. The efficiency of the algorithm is evaluated by computing the mean and the standard deviation of the differences between inverted parameter values and true values obtained from both vertical and oblique incidence sounding. Test results clearly manifest that the method we have developed outputs more accurate electron density profiles due to improvements to acquire the profiles of the layers below the F2 region. Our study can further improve the current BSI inversion methods on the reconstruction of 2-D electron density distribution in a vertical plane aligned with the direction of sounding.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.002
       
  • Accurate approximation of in-ecliptic trajectories for E-sail with
           constant pitch angle
    • Authors: Mingying Huo; Giovanni Mengali; Alessandro A. Quarta
      Pages: 2617 - 2627
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Mingying Huo, Giovanni Mengali, Alessandro A. Quarta
      Propellantless continuous-thrust propulsion systems, such as electric solar wind sails, may be successfully used for new space missions, especially those requiring high-energy orbit transfers. When the mass-to-thrust ratio is sufficiently large, the spacecraft trajectory is characterized by long flight times with a number of revolutions around the Sun. The corresponding mission analysis, especially when addressed within an optimal context, requires a significant amount of simulation effort. Analytical trajectories are therefore useful aids in a preliminary phase of mission design, even though exact solution are very difficult to obtain. The aim of this paper is to present an accurate, analytical, approximation of the spacecraft trajectory generated by an electric solar wind sail with a constant pitch angle, using the latest mathematical model of the thrust vector. Assuming a heliocentric circular parking orbit and a two-dimensional scenario, the simulation results show that the proposed equations are able to accurately describe the actual spacecraft trajectory for a long time interval when the propulsive acceleration magnitude is sufficiently small.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.034
       
  • Improving orbit prediction accuracy through supervised machine learning
    • Authors: Hao Peng; Xiaoli Bai
      Pages: 2628 - 2646
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Hao Peng, Xiaoli Bai
      Due to the lack of information such as the space environment condition and resident space objects’ (RSOs’) body characteristics, current orbit predictions that are solely grounded on physics-based models may fail to achieve required accuracy for collision avoidance and have led to satellite collisions already. This paper presents a methodology to predict RSOs’ trajectories with higher accuracy than that of the current methods. Inspired by the machine learning (ML) theory through which the models are learned based on large amounts of observed data and the prediction is conducted without explicitly modeling space objects and space environment, the proposed ML approach integrates physics-based orbit prediction algorithms with a learning-based process that focuses on reducing the prediction errors. Using a simulation-based space catalog environment as the test bed, the paper demonstrates three types of generalization capability for the proposed ML approach: (1) the ML model can be used to improve the same RSO’s orbit information that is not available during the learning process but shares the same time interval as the training data; (2) the ML model can be used to improve predictions of the same RSO at future epochs; and (3) the ML model based on a RSO can be applied to other RSOs that share some common features.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.03.001
       
  • A robust star identification algorithm with star shortlisting
    • Authors: Deval Samirbhai Mehta; Shoushun Chen; Kay Soon Low
      Pages: 2647 - 2660
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Deval Samirbhai Mehta, Shoushun Chen, Kay Soon Low
      A star tracker provides the most accurate attitude solution in terms of arc seconds compared to the other existing attitude sensors. When no prior attitude information is available, it operates in “Lost-In-Space (LIS)” mode. Star pattern recognition, also known as star identification algorithm, forms the most crucial part of a star tracker in the LIS mode. Recognition reliability and speed are the two most important parameters of a star pattern recognition technique. In this paper, a novel star identification algorithm with star ID shortlisting is proposed. Firstly, the star IDs are shortlisted based on worst-case patch mismatch, and later stars are identified in the image by an initial match confirmed with a running sequential angular match technique. The proposed idea is tested on 16,200 simulated star images having magnitude uncertainty, noise stars, positional deviation, and varying size of the field of view. The proposed idea is also benchmarked with the state-of-the-art star pattern recognition techniques. Finally, the real-time performance of the proposed technique is tested on the 3104 real star images captured by a star tracker SST-20S currently mounted on a satellite. The proposed technique can achieve an identification accuracy of 98% and takes only 8.2 ms for identification on real images. Simulation and real-time results depict that the proposed technique is highly robust and achieves a high speed of identification suitable for actual space applications.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.029
       
  • Robust model predictive control for satellite formation keeping with
           eccentricity/inclination vector separation
    • Authors: Yeerang Lim; Youeyun Jung; Hyochoong Bang
      Pages: 2661 - 2672
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Yeerang Lim, Youeyun Jung, Hyochoong Bang
      This study presents model predictive formation control based on an eccentricity/inclination vector separation strategy. Alternative collision avoidance can be accomplished by using eccentricity/inclination vectors and adding a simple goal function term for optimization process. Real-time control is also achievable with model predictive controller based on convex formulation. Constraint-tightening approach is address as well improve robustness of the controller, and simulation results are presented to verify performance enhancement for the proposed approach.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.036
       
  • Development and verification of an innovative photomultiplier calibration
           system with a 10-fold increase in photometer resolution
    • Authors: Shyh-Biau Jiang; Tse-Liang Yeh; Li-Wu Chen; Jann-Yenq Liu; Ming-Hsuan Yu; Yu-Qin Huang; Chen-Kiang Chiang; Chung-Jen Chou
      Pages: 2673 - 2679
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): Shyh-Biau Jiang, Tse-Liang Yeh, Li-Wu Chen, Jann-Yenq Liu, Ming-Hsuan Yu, Yu-Qin Huang, Chen-Kiang Chiang, Chung-Jen Chou
      In this study, we construct a photomultiplier calibration system. This calibration system can help scientists measuring and establishing the characteristic curve of the photon count versus light intensity. The system uses an innovative 10-fold optical attenuator to enable an optical power meter to calibrate photomultiplier tubes which have the resolution being much greater than that of the optical power meter. A simulation is firstly conducted to validate the feasibility of the system, and then the system construction, including optical design, circuit design, and software algorithm, is realized. The simulation generally agrees with measurement data of the constructed system, which are further used to establish the characteristic curve of the photon count versus light intensity.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.039
       
  • The SEVAN Worldwide network of particle detectors: 10 years of
           operation
    • Authors: A. Chilingarian; V. Babayan; T. Karapetyan; B. Mailyan; B. Sargsyan; M. Zazyan
      Pages: 2680 - 2696
      Abstract: Publication date: 15 May 2018
      Source:Advances in Space Research, Volume 61, Issue 10
      Author(s): A. Chilingarian, V. Babayan, T. Karapetyan, B. Mailyan, B. Sargsyan, M. Zazyan
      The Space Environment Viewing and Analysis Network (SEVAN) aims to improve the fundamental research on particle acceleration in the vicinity of the sun, on space weather effects and on high-energy physics in the atmosphere and lightning initiation. This new type of a particle detector setup simultaneously measures fluxes of most species of secondary cosmic rays, thus being a powerful integrated device for exploration of solar modulation effects and electron acceleration in the thunderstorm atmosphere. The SEVAN modules are operating at the Aragats Space Environmental Center (ASEC) in Armenia, in Croatia, Bulgaria, Slovakia, the Czech Republic (from 2017) and in India. In this paper, we present the most interesting results of the SEVAN network operation during the last decade. We present this review on the occasion of the 10th anniversary of the International Heliophysical Year in 2007.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.02.030
       
  • List of Referees
    • Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12


      PubDate: 2018-05-17T17:15:51Z
       
  • Cumulative Author Index for Volume XX - ISSUE 12 OF EACH VOLUME ONLY
    • Abstract: Publication date: 15 June 2018
      Source:Advances in Space Research, Volume 61, Issue 12


      PubDate: 2018-05-17T17:15:51Z
       
  • List of Referees
    • Abstract: Publication date: 1 June 2018
      Source:Advances in Space Research, Volume 61, Issue 11


      PubDate: 2018-05-17T17:15:51Z
       
  • THESEUS: a key space mission concept for Multi-Messenger Astrophysics
    • Authors: G. Stratta; R. Ciolfi; L. Amati; E. Bozzo; G. Ghirlanda; E. Maiorano; L. Nicastro; A. Rossi; S. Vinciguerra; F. Frontera; D. Götz; C. Guidorzi; P. O’Brien; J.P. Osborne; N. Tanvir; M. Branchesi; E. Brocato; M.G. Dainotti; M. De Pasquale; A. Grado; J. Greiner; F. Longo; U. Maio; D. Mereghetti; R. Mignani; S. Piranomonte; L. Rezzolla; R. Salvaterra; R. Starling; R. Willingale; M. Böer; A. Bulgarelli; J. Caruana; S. Colafrancesco; M. Colpi; S. Covino; P. D’Avanzo; V. D’Elia; A. Drago; F. Fuschino; B. Gendre; R. Hudec; P. Jonker; C. Labanti; D. Malesani; C.G. Mundell; E. Palazzi; B. Patricelli; M. Razzano; R. Campana; P. Rosati; T. Rodic; D. Szécsi; A. Stamerra; M. Putten; S. Vergani; B. Zhang; M. Bernardini
      Abstract: Publication date: Available online 17 May 2018
      Source:Advances in Space Research
      Author(s): G. Stratta, R. Ciolfi, L. Amati, E. Bozzo, G. Ghirlanda, E. Maiorano, L. Nicastro, A. Rossi, S. Vinciguerra, F. Frontera, D. Götz, C. Guidorzi, P. O’Brien, J.P. Osborne, N. Tanvir, M. Branchesi, E. Brocato, M.G. Dainotti, M. De Pasquale, A. Grado, J. Greiner, F. Longo, U. Maio, D. Mereghetti, R. Mignani, S. Piranomonte, L. Rezzolla, R. Salvaterra, R. Starling, R. Willingale, M. Böer, A. Bulgarelli, J. Caruana, S. Colafrancesco, M. Colpi, S. Covino, P. D’Avanzo, V. D’Elia, A. Drago, F. Fuschino, B. Gendre, R. Hudec, P. Jonker, C. Labanti, D. Malesani, C.G. Mundell, E. Palazzi, B. Patricelli, M. Razzano, R. Campana, P. Rosati, T. Rodic, D. Szécsi, A. Stamerra, M. Putten, S. Vergani, B. Zhang, M. Bernardini
      The recent discovery of the electromagnetic counterpart of the gravitational wave source GW170817, has demonstrated the huge informative power of multi-messenger observations. During the next decade the nascent field of multi-messenger astronomy will mature significantly. Around 2030, third generation gravitational wave detectors will be roughly ten times more sensitive than the current ones. At the same time, neutrino detectors currently upgrading to multi km3 telescopes, will include a 10 km3 facility in the Southern hemisphere that is expected to be operational around 2030. In this review, we describe the most promising high frequency gravitational wave and neutrino sources that will be detected in the next two decades. In this context, we show the important role of the Transient High Energy Sky and Early Universe Surveyor (THESEUS), a mission concept proposed to ESA by a large international collaboration in response to the call for the Cosmic Vision Programme M5 missions. THESEUS aims at providing a substantial advancement in early Universe science as well as playing a fundamental role in multi–messenger and time–domain astrophysics, operating in strong synergy with future gravitational wave and neutrino detectors as well as major ground- and space-based telescopes. This review is an extension of the THESEUS white paper (Amati et al., 2012), also in light of the discovery of GW170817/GRB170817A that was announced on October 16th, 2017.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.04.013
       
  • Formation of Multiple Landers for Asteroid Detumbling
    • Authors: Michael C.F. Bazzocchi; M. Reza Emami
      Abstract: Publication date: Available online 17 May 2018
      Source:Advances in Space Research
      Author(s): Michael C.F. Bazzocchi, M. Reza Emami
      This work develops a method for ascertaining the landing locations and thruster orientations of a formation of multiple spacecraft on an irregular asteroid for discrete time optimal detumbling control, as a prerequisite to asteroid redirection. Asteroid geometries are known to be extremely irregular, especially for small asteroids, which are the typical targets for redirection missions. The method entails the modelling of asteroids as convex polyhedra with triangular facets, and computing the mass and inertial properties through the divergence theorem and Green’s theorem. Given the asteroid geometry, mass, and inertial properties, the feasible lander locations and thruster orientations are determined. The model ensures full attitude control of the asteroid, using multiple spacecraft with fixed-orientation, low-thrust modules, through measures imposed on the location and orientation of each thruster. A linear control scheme is employed to assess the time and fuel requirements of the asteroid detumbling maneuver, given feasible spacecraft formation configurations and thruster orientations. The method then assesses the detumbling time performance of each formation configuration to determine the discrete optimal landed formation configuration for a given asteroid. Simulations are performed to demonstrate the method using an irregular asteroid with characteristics derived from available asteroid data. Extensions of the method are further discussed in light of the results.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.05.011
       
  • DME pulse interference mitigation for airborne BDS and flight test results
    • Authors: Jiu-yuan Guo; Xiao-lin Zhang
      Abstract: Publication date: Available online 17 May 2018
      Source:Advances in Space Research
      Author(s): Jiu-yuan Guo, Xiao-lin Zhang
      BeiDou Navigation Satellite System (BDS) B2 signal works in the aeronautical radio navigation services (ARNS) band. It suffers high-power pulse interference, particularly from distance measuring equipment (DME), which will affect signal acquisition, signal tracking, as well as positioning of airborne BDS receiver. Regarding the problem, a DME pulse interference mitigation algorithm based on FLOC-TDE (Fractional Lower Order Covariance-Time Delay Estimation) is proposed in this paper, which can effectively mitigate DME pulse and retain useful BDS satellite signals. We firstly analyzed the live data collected from COMAC (Commercial Aircraft Corporation of China Ltd) Airborne BDS First Flight Project. And then, experiments on COMAC airborne BDS experiment platform were performed. The proposed algorithm, time domain pulse blanking algorithm and non- mitigation algorithm were compared in the experiments. The values of correlation peak to secondary peak ratio (CPSP) and the correlation peak to mean peak ratio (CPMP), and carrier-to-noise ratio ( C / N 0 ) using the proposed algorithm were the biggest. The results verify that the proposed algorithm can mitigate DME pulse interference, improve acquisition and tracking performance of airborne BDS receiver, which can ensure the system integrity.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.05.012
       
  • Exploring Small Bodies: Nano- and microlander options derived from the
           Mobile Asteroid Surface Scout
    • Authors: Caroline Lange; Tra-Mi Ho; Christian D. Grimm; Jan T. Grundmann; Christian Ziach; Roy Lichtenheldt
      Abstract: Publication date: Available online 17 May 2018
      Source:Advances in Space Research
      Author(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.

      PubDate: 2018-05-17T17:15:51Z
      DOI: 10.1016/j.asr.2018.05.013
       
 
 
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