Feasibility of performing space surveillance tasks with a proposed space-based optical architecture

Streak detection and analysis pipeline for space-debris optical images

Apparent rotation properties of space debris extracted from photometric measurements

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO study was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive optical instrument. The SBO instrument was requested to provide statistical information on the space debris population in terms of number of objects and size distribution. The SBO instrument was considered to be a cost-efficient with 20 cm aperture and 6° field-of-view and having flexible integration requirements. It should be possible to integrate the SBO instrument easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are studied for the build-up and maintenance of a catalogue of objects. In this paper we analyse how the proposed SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude, and select an orbit close to the terminator plane. A pointing of the sensor orthogonal to the orbital plane with optimal elevation slightly in positive direction (0° and +5°) is found optimal for accessing the entire GEO regime within one day, implying a very good coverage of controlled objects in GEO, too. Simulations using ESA’s Program for Radar and Optical Observation Forecasting (PROOF) in the version 2005 and a GEO reference population extracted from DISCOS revealed that the proposed pointing scenario provides low phase angles together with low angular velocities of the objects crossing the field-of-view. Radiometric simulations show that the optimal exposure time is 1–2 s, and that spherical objects in GEO with a diameter of below 1 m can be detected. The GEO population can be covered under proper illumination nearly completely, but seasonal drops of the coverage are possible. Subsequent observations of objects are on average at least every 1.5 days, not exceeding 3 days at maximum. A single observation arc spans 3° to 5° on average. Using a simulation environment that connects PROOF to AIUB’s program system CelMech we verify the consistency of the initial orbit determination for five selected test objects on subsequent days as a function of realistic astrometric noise levels. The initial orbit determination is possible. We define requirements for a correlator process essential for catalogue build-up and maintenance. Each single observation should provide an astrometric accuracy of at least 1”–1.5” so that the initially determined orbits are consistent within a few hundred kilometres for the semi-major axis, 0.01 for the eccentricity, and 0.1° for the inclination.

Performance estimation for GEO space surveillance

PROOF — The extension of esa's MASTER Model to predict debris detections

Debris model validation and interpretation of debris measurements using ESA's proof tool

This work will discuss an ESA project “Debris Attitude Motion Measurements and Modeling” (ESA AO/1-7803/14/D/SR) dedicated to the attitude determination of large spacecraft and upper stages. Two major goals are defined for this project. First, the determination of the attitude motion vector in case of a contingency situation, when a short response time is required between the observations themselves and the attitude determination. The second goal is the long term prediction (e.g. 10 years) of the spin rate of selected targets for future potential Active Debris Removal (ADR) missions. The study should in particular fuse the results from passive optical, laser ranging and radar observations. We will discuss a highly modular software tool named ιOTA (In-Orbit Tumbling Analysis) which was 
developed during the presented activity. This tool performs short- (days) to long-term (years) propagations of the orbit and the attitude motion of spacecraft in 
Earth orbit and furthermore its post-processing modules will generate synthetic measurements, i.e. light curves, satellite laser ranging (SLR) residuals and synthet
ic radar images. Last but not least we will present results from a collaborative campaign when four priority targets have been selected for collaborative measurements with radar, SLR and light curves in order to test and validate the ΙOTA tool.

/pdf/debris-attitude-motion-measurements-and-modelling-by-3cihyprnsa.pdf

Debris Attitude Motion Measurements and Modelling by Combining Different Observation Techniques

End of 2014, ESA initiated a research project named “Debris Attitude Motion Measurements and Modeling”. The main goal of this project was to combine space debris attitude state information, obtained by different means of observation, with numerical simulations. Under the lead of AIUB, light curves and laser ranging residuals were
obtained by AIUB and IWF, while FHR conducted radar observations. In parallel, HTG developed a 6 degrees-of-freedom – orbit and attitude – propagator. This tool called
ιOTA (In-Orbit Tumbling Analysis) takes into account all relevant external and internal perturbation sources (gravity, aerodynamics, solar radiation pressure, electro-
magnetic, etc.). The final phase of the project was a critical comparison between observation data obtained for various space objects (e.g. ENVISAT, LAGEOS-2) and the corresponding simulation results. This comparison also served the purpose of software validation for ιOTA. The conversion of observation data into well-defined attitude states (i.e. rotation vector orientation and magnitude) can be quite difficult and sometimes resulting into multiple, non-unique solutions. Therefore, this comparison used an inverse approach. ιOTA is capable to convert its propagation results into synthetic observation results. This conversion takes into account the individual sensor type and relative perspective towards the observation target during the measurement campaign. This approach facilitates a direct comparison of real observation data (light curves, laser ranging residuals, and radar imaging) with the numerical propagation results. This paper presents the attitude propagation methods of ιOTA and the results of its software validation process showing a comparison between real and synthetic observation data.

J. Rosebrock

Papers

PROOF — The extension of esa's MASTER Model to predict debris detections

Debris model validation and interpretation of debris measurements using ESA's proof tool

Debris Attitude Motion Measurements and Modelling by Combining Different Observation Techniques

Debris Attitude Motion Measurements and Modeling – Observation vs. Simulation