Design & Development Of Correlation Techniques To Maintain A Space Surveillance System Catalogue
- Paper number
IAC-07-A6.1.09
- Author
Mrs. Noelia Sanchez Ortiz, DEIMOS Space, Spain
- Coauthor
Mercedes Lerate, DEIMOS Space S.L., Spain
- Coauthor
Ms. Estrella Olmedo, DEIMOS Space S.L., Spain
- Coauthor
Mr. Guillermo Ruiz, DEIMOS Space S.L., Spain
- Coauthor
Mr. Miguel Bello Mora, DEIMOS Space S.L., Spain
- Coauthor
Dr. Heiner Klinkrad, European Space Agency/ESOC, Germany
- Year
2007
- Abstract
An increasing interest exists in a future, autonomous European Space Surveillance System (ESSS). Currently, most of the knowledge on Earth-orbiting space objects is based on information provided by the USA. This paper presents the required initial orbit determination and correlation techniques to process optical measurements. Former studies were focused on the handling of radar measurements, which will also be summarised with the aim of describing a global procedure for processing hybrid measurement types (combination of radar and optic data for catalogue maintenance). Estimation of manoeuvres will also be presented due to the importance of this aspect in the space object correlation techniques. The detection of uncatalogued objects and successful correlation of already catalogued objects involves two different tasks for the telescopes: surveying and tasking. Assumptions for both strategies are developed in the basis of previous work developed at the University of Berne. When a new object appears in the field of view, initial orbit determination must be performed. Since the initially available measurements are separated by only few seconds, the initial orbit determination is quite inaccurate due to bad mathematical conditioning of the problem. In order to improve the accuracy of the initial orbit determination, several follow-up observations of the object are required. That implies that the telescope needs to track the detected objects during a long period, and therefore the time available for surveying is reduced. If assumptions on the orbital eccentricity can be made, it is possible to recover the object after a few hours. Processing the additional follow-up measurements, separated now by a few hours, the initial orbit determination gives more accurate results and the object can be recovered after an orbital revolution. The different methods applied for short arcs (separated by a few seconds) and long arcs (separated by a few hours), as well as the selected methods for circular orbits and elliptic orbits, will be explained. Numerical results will be shown in order to evaluate their accuracy. A key point for performing efficiently the cataloguing process is the calculation of the estimated state vector covariance matrix. The covariance matrix analysis will allow an adaptive tasking-survey telescope scheduling. Moreover, the implementation of a proper batch orbit determination process by means of a Square Root Information Filter (SRIF) requires a realistic initial covariance matrix. Hybrid measurements are available from objects that can be observed by both radar and optical sensors (e.g. GTO objects). The batch orbit determination and correlation process of hybrid measurements is also based on SRIF using an extended measurement model. Both initial orbit determination methods using radar and optical measurements have to be sufficiently accurate to initialise SRIF correctly. In order to avoid filter divergence, estimated covariance must be correctly updated after processing both kinds of measurements. The implemented algorithms will be explained and their performance will be shown through realistic simulations. Techniques to detect and characterise object manoeuvres during the cataloguing process have been developed and implemented. A temporal catalogue containing the objects that did not appear at the expected position at the expected time is created during the cataloguing process. When an object with a uncatalogued orbit appears, a comparison between the new orbit and the orbits contained in the temporal catalogue of lost objects is performed. If the required ∆V to convert the lost orbit into the detected orbit seems to be feasible, a manoeuvre will be identified and the orbit will be updated in the catalogue. Otherwise, it will be decided that a new object was found. For this purpose, a procedure to estimate the ∆V-budget of the optimal manoeuvre between any two orbits has been developed. The detection and estimation feasibility of typical manoeuvres (e.g. GTO to GEO, LEO to GTO) using the developed correlation techniques for European SSS will be studied.
- Abstract document
- Manuscript document
IAC-07-A6.1.09.pdf (🔒 authorized access only).
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