Strategy For Detection Of Eccentric Objects Near The Geosynchronous Region

Paper number

IAC-07-A6.1.04

Author

Dr. Toshifumi Yanagisawa, Japan Aerospace Exploration Agency (JAXA), Japan

Year

2007

Abstract

Detection of eccentric objects with orbital period near 24 hours is a very important issue. However, extremely narrow fields-of-view of optical telescopes hinders us from identifying eccentric objects. A new observation strategy to systematically detect these objects and determine their orbits precisely with one telescope is outlined in this presentation. Basically, one specific geosynchronous (GEO) location (not one specific celestial position) is observed on two nights. Objects which pass through that location in the first night must pass through that location again in the second night. By identifying the same objects from two nights of data, rough orbits for those objects are determined. A third night is needed for precise orbital determination.
The current observation strategy for NASA is to observe a few celestial positions for one night and detect as many objects (in, near, or crossing GEO) as possible. These objects have different motions from the celestial motion which limits the observable time for each object to about five minutes. From a five-minute orbital arc, it is difficult to determine the precise orbit of an object. Therefore, circular orbits are assumed for all detections. This assumption makes it possible to calculate their semi-major axes, inclinations, and the right ascensions of ascending node (RAAN). Various applications, such as the average distributions of GEO objects, and identifications of some groups in the RAAN-inclination phase space, are possible using these data. More precise orbit determinations are needed for other applications, such as long-term tracking and impact hazard analysis. A reliable orbital determination requires at least three observations to create a long arc. However, narrow fields-of-view of optical telescopes makes it difficult to re-acquiring the same objects after a few hours, especially in the case of eccentric orbits. To get a long arc, a telescope has to follow one target for a long period of time. Determining precise orbits of many GEO-crossing objects demands a lot of time, and is not an efficient use of telescope time. The proposed new observation strategy has the ability to cope with this situation to determine precise orbital elements of many objects in relatively short observation time. An application of this strategy to the observation for Titan fragments is also discussed.

Abstract document

IAC-07-A6.1.04.pdf

Manuscript document

IAC-07-A6.1.04.pdf (🔒 authorized access only).

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