On-Orbit Observations of Conjuncting Space Objects Prior to the Time of Closest Approach
- PDF / 2,194,435 Bytes
- 20 Pages / 439.37 x 666.142 pts Page_size
- 15 Downloads / 201 Views
Open Access
On-Orbit Observations of Conjuncting Space Objects Prior to the Time of Closest Approach Robert Lauchie Scott 1
& Stefan
Thorsteinson 1 & Viqar Abbasi 2
Accepted: 11 September 2020/ # The Author(s) 2020
Abstract Conjunction assessment of space objects in Low Earth Orbit (LEO) generally uses information collected by ground-based space surveillance sensors. These sensors track both the primary object (normally an active satellite) and the secondary object (typically space debris). The tracking data is used to update both objects’ orbits for collision risk assessment. The primary satellite’s involvement in this process is that of a satellite in jeopardy - the primary satellite does not usually contribute tracking data on the secondary as they are typically unequipped to do so. In this paper, an examination how an at-risk LEO primary satellite could obtain optical tracking data on a secondary object prior to the Time of Closest Approach (TCA) and assess its own collision risk without the need for additional ground-based space surveillance data is performed. This analysis was made possible by using in-situ optical measurements of space objects conjuncting with the Canadian NEOSSat Space Situational Awareness R&D microsatellite. By taking advantage of the near “constant-bearing, decreasing range” observing geometry formed during a LEO conjunction, NEOSSat can collect astrometric and photometric measurements of the secondary object in the time prior to TCA, or in the multiple half-orbits preceding TCA. This paper begins by describing the in-situ phenomenology of optically observed conjunctions in terms of the observing approach, geometry and detected astrometric and photometric characteristics. It was found that conjuncting objects are detectable to magnitude 16 and astrometric observations can be used for position covariances in the computation of probability of collision. Illustrative examples are provided. In orbits prior to TCA, in-track positioning error is improved by a factor of two or more by processing space-based This article belongs to the Special Topic Section: Advanced Maui Optical and Space Surveillance Technologies (AMOS 2018 & 2019) Guest Editors: James M. Frith, Lauchie Scott, Islam Hussein An earlier version of this article was first presented at the 20th Advanced Maui Optical and Space Surveillance Technologies Conference, held in Wailea, Maui, Hawaii, September 17-20, 2019.
* Robert Lauchie Scott Lauchie.Scott@drdc–rddc.gc.ca
1
Defence R&D Canada Ottawa, 3701 Carling Avenue, Ottawa, ON K1A 0Z4, Canada
2
Canadian Space Agency, 6767 Route d’Aeroport, St. Hubert, QC J3Y 8Y9, Canada
The Journal of the Astronautical Sciences
observations on a filtered position estimate of the secondary. However, cross-track positioning knowledge is negligibly improved due to the inherent astrometric measurement precision of the NEOSSat sensor and the oblique observing geometry during conjunction observations. A short analysis of object detectability where star trackers could be used to perform simil
Data Loading...
