Combination of Light Curve Measurements and Orbit Determination for Space Debris Identification

Paper number

IAC-11,A6,1,14,x9389

Author

Mrs. Carolin Früh, University of New Mexico, United States

Coauthor

Prof. Thomas Schildknecht, Astronomical Institute University of Bern (AIUB), Switzerland

Year

2011

Abstract

Since the first satellite Sputnik was launched 1957, the number of space resident objects has increased constantly.  The majority of those objects are so called space debris; objects with no intended use any more. Whereas in low earth orbit regime a natural cleaning mechanism exists, which removes space debris through dissipative drag forces,  no such mechanism exits in the geostationary orbital regime. With the increasing density of space resident objects, error ellipsoids of propagated catalogue orbits may overlap. This is especially true for objects, whose physical properties are unknown and whose orbits may therefore be hard to model, which leads to large residuals between the propagated ephemerides and the actual observations. 

The Astronomical Institute of the University of Bern, Switzerland, has maintained a catalogue of space resident objects in geostationary and geostationary transfer orbits for over ten years now. Besides position measurements for orbit determination, also light curve measurements are performed regularly with the ZIMLAT telescope, located at Zimmerwald, Switzerland. 

The paper investigates the combination of information extracted from optical light curve measurements and information from orbit determination for a small subset of space debris objects. The analysis focuses on the potential gain for the object characterization, which differs from the known approach to support object identification in the sense, that an orbital element catalogue is combined with light curve measurements, which serve as so called finger prints of objects on an empirical basis. 

When determining orbits a value for the area-to-mass ratio can be estimated. Different values for the area-to-mass ratio may result from orbit determinations over different fit spans of observations over time. The orbits can be propagated and ephemerides can be calculated. These ephemerides can be compared to further observations of the same object, which serve as a ground truth. The residuals, which are found in this comparison, are a measure for the extend to which the parameters estimated in the orbit determination are still a good approximation for the orbit after some time. Light curves are independent from the orbit determination and parameter estimation process, and provide an independent source of information.  The main objective of this work is to analyze if this information may helb understanding the temporal variation of the area-to-mass ratio as determined from the orbits.

Abstract document

IAC-11,A6,1,14,x9389.brief.pdf

Manuscript document

IAC-11,A6,1,14,x9389.pdf (🔒 authorized access only).

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