Apparent rotation properties of space debris extracted from photometric measurements

Over the past 60 years, satellite technology has demonstrated its usefulness successfully. However, this usefulness is at stake from a future point of view, due to the well-admitted orbital/space debris threat. This article thoroughly reviews all aspects of space debris issue including causes, amount and sizes of orbital debris, potential threats, counter-strategies with their latest status and related legal issues to highlight the criticality and urgency of the problem. This review elaborates the fact that despite all the worries and threats, the efforts to confront this challenge are considerably insufficient until today. This bitter reality demands for at-least curtailing the number of future launches to ensure the long-term sustainability of space, until the improvement in debris situation. However, contradictory to this necessity, large satellite constellations have been proposed that can drastically increase the existing orbital population in coming years. This approach will certainly not help in improving the space environment in the future; instead, it can worsen the space environment situation as recent studies shows. Also, space resources (i.e. orbital slots and frequencies) are limited to accommodate many more satellite projects from commercial and government organization in the future. So, there is a serious question of how the space industry can move forward to maintain a balance in controlling the future number of the satellite while accommodating many commercial or government space entities. This article also identifies two optimized approaches as a way forward for future satellite projects that can also enhance the effectiveness of space technology in the future.

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Orbital Debris Threat for Space Sustainability and Way Forward (Review Article)

Analysis of the attitude and geometry of space targets with the inverse synthetic aperture radar (ISAR) technique is a significant and difficult task. Most of the existing methods hardly consider the radar observation geometry in the determination of target attitude. This paper proposes a novel approach to estimating the three-dimensional attitude and reconstructing typical component geometry of space targets from an ISAR image sequence. The approach bridges range-Doppler images and target attitude parameters with the accommodation of target trajectory information and the ISAR geometric projection model. By exploring the shape feature within the ISAR sequence, the target attitude and the rectangular component size are estimated through solving an optimization with prior shape constraints. Comparative experiments illustrate the advantages of the proposed method in both feature association and reconstruction feasibility. Moreover, considering practical circumstances, a further analysis is made of the robustness of the proposed algorithm after the attitude estimation experiment.

Attitude Estimation and Geometry Reconstruction of Satellite Targets Based on ISAR Image Sequence Interpretation

Prospects of de-tumbling large space debris using a two-satellite electromagnetic formation

Space debris is a major threat to the satellite infrastructure A collision with even small particle, eg 1 cm of size, can cause a catastrophic event when the parent body, spacecraft or upper stage, will break up into hundreds of trackable fragments Space debris research helps to discover, monitor and characterize these objects, identify their origin and support their active removal Surveys with optical telescopes aim to discover new objects for cataloguing and to increase the accuracy of space debris population models The follow-up observations are performed to improve their orbits or to investigate their physical characteristics We will present the space debris population, its orbital and physical characteristics and we will discuss the role which the optical telescopes play in space debris research We will also discuss the adopted astronomical techniques like astrometry, photometry and spectroscopy used in the space debris domain

Space Debris -- Optical Measurements

Our paper will discuss the photometry observation techniques currently in use by the Astronomical Institute of the University of Bern (AIUB) and at the Zimmerwald observatory. We present the processing of light curves with the aim to determine apparent spin periods of observed objects and to reconstruct their folded phase functions. We will summarize spin rates for 397 objects extracted from 1991 light curves which were acquired with the ZIMLAT telescope during the last ten years. More than dozen of defunct spacecraft showed a periodic change of the apparent spin rates over time. These cases will be briefly discussed.

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Extensive light curve database of Astronomical Institute of the University of Bern

Slovakia became the 9th ESA European Cooperative State in 2015 and the first calls to action for the Plan for European Cooperating State (PECS) were announced shortly after. The Department of Astronomy and Astrophysics, a part of the Faculty of Mathematics, Physics and Informatics of Comenius University in Bratislava, Slovakia (FMPI CU), won the call and an activity with a main goal to transform a 0.7-m Newton telescope (AGO70) dedicated to amateur astronomical observations to a professional optical system for regular support of the space debris tracking and research has started. The transformation includes the necessary hardware and software modifications to the existing solution. The presented activity has been performed in cooperation with the Astronomical Institute of University of Bern (AIUB). The AGO70 has been installed at the FMPI's Astronomical and Geophysical Observatory in Modra, Slovakia (AGO) in fall 2016. There are several predefined objectives to be accomplished within the activity. First, it was imperative to adapt the low-level telescope control for the needs of space debris tracking. Second, the image processing software must have been developed in a modular way. The observation planning has been formulated according to the AGO70 system's hardware limitations with focus on GEO, GTO and GNSS like orbits. To verify the system's capabilities, the whole activity is concluded with an observation campaign measuring AIUB's HAMR (High-Area-to-Mass-Ratio) objects and public TLE objects. The quality of the system's output is monitored by the AIUB via its state-of-the-art epoch bias and astrometric accuracy analysis routines.

Slovakian Optical Sensor for HAMR Objects Cataloguing and Research

Since 2007 the Astronomical Institute of the University of Bern (AIUB) is using its 1-meter telescope ZIMLAT situated at the Zimmerwald observatory, Switzerland to collect light curves of space debris objects including defunct 
spacecraft, upper stages and fragments. The last two and half years, 2014,
2015 and 2016, can be considered as the most productive for the Zimmerwald light curve acquisition. Several different photometric campaigns have been 
performed which were focused on Low Earth Orbit (LEO) targets suitable for future Active Debris Removal (ADR) missions, on regular monitoring of large defunct spacecraft in LEO and in the GLONASS constellation, and on new 
objects discovered during the Zimmerwald and ESA Geosynchronous Earth Orbit (GEO) surveys. From each lightcurve we extracted some information about the attitude motion. This information includes a general characterization 
of the attitude behaviour, like “stable” or “tumbling” state, and, if applicable
, also the determination of the apparent spin period and the reconstruction of the phase. Our paper will discuss the photometry observation techniques currently in use at the Zimmerwald observatory and the processing of the light curves with the aim to determine apparent spin periods and to reconstruct the
irphases. Spin rates for objects acquired with the ZIMLAT telescope during the last two years will be discussed and the morphology of their reconstructed phases will be briefly presented.

Light curve database of Astronomical Institute of the University of Bern

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Michal Hamara

Papers

Apparent rotation properties of space debris extracted from photometric measurements

Extensive light curve database of Astronomical Institute of the University of Bern

Slovakian Optical Sensor for HAMR Objects Cataloguing and Research

Light curve database of Astronomical Institute of the University of Bern

Color Indices of Selected Objects Situated on the MEO and GEO Orbits Obtained by two Telescopes Observations