Feasibility of performing space surveillance tasks with a proposed space-based optical architecture
Introduction
Since 2007 the European Space Agency (ESA) focuses it’s 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.
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) instrumentation 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 architecture, and the key results of the performance assessment have been published, see reports by Flohrer et al., 2005, Flohrer et al., 2006, Vanwijck and Flohrer, 2008, Wokke et al., 2006.
Other concepts for space-based optical observations have been discussed before the SBO proposal, see, e.g., the work of Krag et al. (2001) or Lobb et al. (1993). An orbital telescope observing the debris environment in GEO (Oswald et al., 2004) played an essential role in the scope of the proposed ROGER project (Robotic Geostationary Orbit Restorer). Furthermore the observation of space debris is sometimes investigated as a secondary application of space-based observations of Near-Earth Objects (NEOs), see, e.g., papers by Mottola et al., 2008, Wallace et al., 2004. It was also shown how tasked space-based observations of satellites could be extracted from other missions, such as from the Canadian MOST (Scott et al., 2006).
The space-based visible (SBV) instrument onboard the Midcourse Space Experiment (MSX) satellite acquired space-based optical observations between 1996 and 2008 (Gaposchkin et al., 2000, Harrison and Chow, 1996). Those observations substantially contributed to cataloguing objects in high altitudes by USSTRATCOM (Miller and Schick, 1999). The upcoming constellation of space-based space surveillance satellites (SBSS) can be seen as the successor of the SBV and is reported to have capabilities for quick tasking due to slewable telescopes mounted on each satellite. SBSS is also expected to provide higher resolution data. Reported to be of a similar design as the SBV the future Canadian SAPPHIRE mission will be capable to provide observations of GEO objects from a sun-synchronous dusk-dawn orbit (Maskell and Oram, 2008).
In this paper we analyse how space-based optical observations, in particular acquired by the proposed SBO architecture, could contribute to the space surveillance task survey and tracking.
In Section 2 we re-visit the key findings of the previous SBO-related work, in particular the observation strategy, the sensor design, and the assessed performance for the observation of small-sized space debris objects. We analyse possible efficient observation strategies in Section 3. A detailed discussion focuses on the assumption that the SBO instrumentation is a secondary payload placed onboard an Earth-observation satellite in a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude. In Section 4 the radiometric performance of the SBO instrument and the selected observation scenario is analysed. We derive the detectable object diameters. The coverage of a reference population, and assessment of the covered arc lengths of individual objects is discussed in Section 5. This discussion is of particular interest for the simulation of the orbit determination, correlation, and cataloguing, which is addressed in Section 6. Assuming realistic noise levels known from the SBO design we simulate first orbit determination (surveys) for sample objects and derive requirements for a correlation process.
Section snippets
SBO architecture and observation concepts
The aim of the SBO study (see Flohrer et al., 2005, Flohrer et al., 2006, Wokke et al., 2006) was to analyse how the knowledge on small-sized space debris population can be improved through using passive optical observations. The SBO study team formulated the user requirements and the derived observation and processing strategy. An instrument architecture fulfilling the observational requirements was developed, and the according ground support system architecture was described. The study team
SSA-related observation strategies with the SBO architecture
We will now discuss how the SBO instrument could contribute to SSA-related tasks. First we have to identify efficient operation scenarios. The SBO observation scenario is not applicable, as sampling a space debris population statistically while striving to cover smallest objects in the cm-regime is not a primary task of SSA. Instead, the definition of an appropriate observation strategy is driven by the needs of SSA, in particular by the build-up and maintenance of a catalogue of orbital
Radiometric performance of the SBO observing high altitudes
The expected detection limits and accordingly the observation frequency depend on the SNR detection threshold of the on-board object detection algorithm. In order to study the detection threshold the radiometric performance of the SBO sensor operating a survey only strategy can be assessed using analytical formulations (Schildknecht, 2007). Those formulations are in line with the formulations used in the ESA Program for Radar and Optical Observation Forecasting (PROOF) (Krag et al., 2000).
The
Coverage of reference populations
In this section we discuss the core performance parameters for space surveillance, that are the coverage of a reference population, and the reacquisition period and covered arc lengths of individual objects. We use the simulation scenario already introduced in Table 1.
Table 2 together with Fig. 7 outline the covered catalogue fraction during the analysed observation batches of 10 days and also allow to draw conclusion about the overall population coverage during the year. Nearly complete
Simulated orbit determination
We use a simulation environment that connects PROOF through its plug-in functionality to AIUB’s program system CelMech (Beutler, 2005). We use a non-published extended version of the CelMech module ORBDET that allows first orbit determination from a space-based sensor. PROOF outputs via the plug-in function the observation epoch, the sensor coordinates, and the observation vector. In ORBDET we simulate the equatorial coordinates of the observation and add normally-distributed astrometric noise.
Conclusion
We discussed the space surveillance capabilities of a proposed passive, small, and comparably simple space-based optical intrumentation of 6° field-of-view and with 20 cm aperture diameter fix-mounted onboard a earth observation satellite orbiting in an 800 km altitude sun-synchronous orbit. The orbit was assumed 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°) allows accessing the entire GEO
References (24)
- et al.
Survey and chase: a new method of observations for the Michigan Orbital DEbris Survey Telescope (MODEST)
Acta Astronaut.
(2009) - et al.
Proposed strategies for optical observations in a future European Space Surveillance Network
Adv. Space Res.
(2008) - et al.
Proof – the extension of ESA’s master model to predict debris detections
Acta Astronaut.
(2000) - et al.
Development of concepts for detection and characterisation of debris in Earth orbit using passive optical instruments
Adv. Space Res.
(1993) - et al.
Orbit improvement for GTO objects using follow-up observations
Adv. Space Res.
(2005) - et al.
Concept for an orbital telescope observing the debris environment in GEO
Adv. Space Res.
(2004) Methods of Celestial Mechanics
(2005)- DeMars, K., Jah, M. Passive multi-target tracking with application to orbit determination for geosynchronous objects,...
- DeMars, K., Jah, M., Schuhmacher, P.W. The use of short-arc angle and angle-rate data for deep-space initial orbit...
- Flohrer, T., Schildknecht, T., Jehn, R., Oswald, M. Performance of a proposed instrument for space-based optical...
Space-based optical observation of space debris
Space-based space surveillance with the space-based visible
J. Guid. Control Dynam.
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