Color photometry and light curve observations of space debris in GEO

Paper number

IAC-08.A6.1.4

Author

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

Coauthor

Dr. Reto Musci, Astronomical Institute University of Bern (AIUB), Switzerland

Coauthor

Mrs. Carolin Früh, Astronomical Institute University of Bern (AIUB), Switzerland

Coauthor

Dr. Martin Ploner, Astronomical Institute University of Bern (AIUB), Switzerland

Year

2008

Abstract

The ESA debris surveys at high altitudes revealed a significant population of small-size debris in GEO and GEO-like orbits. For a sub-set of the discovered objects high area-to-mass ratios were determined. The nature and the origin of most of this debris are currently unknown. There are several ways to identify possible progenitors or parent objects. Studies of the dynamical properties of the objects are one way; another possibility is to acquire more information on the sizes, shapes and possibly the material of the debris pieces. Non-resolving observation techniques like color photometry, light curves, and spectrometry are the only ground-based optical methods applicable for objects at the given distances.
 
Objects are searched for and discovered by performing dedicated survey campaigns with the ESA 1-meter telescope (ESASDT) in Tenerife, Canary Islands. Observations are then shared in a network of observing sites, which acquire further observations allowing to determine and maintain orbits and to provide ephemerides to other observation techniques and partners, especially in the context of the Inter-Agency Space Debris coordination Committee (IADC). 

Currently these ephemerides are in particular used to acquire light curves and color photometry observations with AIUB’s 1-meter ZIMLAT telescope in Zimmerwald, Switzerland. Color observations may help inferring the material type of the debris and thus may provide information on the potential parent objects of the debris. Light curves are used to estimate rotation or tumbling rates. Finally empirical characteristics of light curves may help to identify object classes or even individual objects and thus may provide crucial information when trying to correlate new observations with the existing catalogue of objects.

Multi-color observations of small-size space debris including high area-to-mass ratio debris were obtained with ZIMLAT. We will discuss the techniques used to obtain colors for objects with considerable brightness variations over short time intervals. The colors of the small-size debris are compared with measurements from large ‘known’ debris objects like abandoned upper stages. 

Light curves of a variety of space debris were obtained over different time spans. Large debris objects show distinct signatures and periods in their light curves. These features seem to be stable over long time intervals and may thus be used to identify the objects. The observed small-size debris, on the other hand, show highly variable light curves with strongly changing amplitudes and periods, indicating complex shapes and scattering properties. 

Abstract document

IAC-08.A6.1.4.pdf

Manuscript document

IAC-08.A6.1.4.pdf (🔒 authorized access only).

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