ORBIT DETERMINATION OF SPACECRAFT IN EARTH-MOON L1 AND L2 LIBRATION POINT ORBITS

摘要

The ARTEMIS mission, part of the THEMIS extended mission is the first tofly spacecraft in the Earth-Moon Lissajous regions. In order to effectively performlunar Lissajous station-keeping maneuvers, the ARTEMIS operationsteam has provided orbit determination solutions with typical accuracies on theorder of 0.1 km in position and 0.1 cm/s in velocity. The ARTEMIS team utilizesthe Goddard Trajectory Determination System (GTDS), using a batchleast squares method, to process range and Doppler tracking measurementsfrom the NASA Deep Space Network (DSN), Berkeley Ground Station (BGS),Merritt Island (MILA) station, and United Space Network (USN). The teamhas also investigated processing of the same tracking data measurements usingthe Orbit Determination Tool Kit (ODTK) software, which uses an extendedKalman filter and recursive smoother to estimate the orbit. The orbit determinationresults from each of these methods will be presented and we will discussthe advantages and disadvantages associated with using each method inthe lunar Lissajous regions. In addition, we used the Orbit Determination ErrorAnalysis System (ODEAS) to perform covariance analyses using various trackingdata schedules. From this analysis, it was determined that 3.5 hours ofDSN TRK-2-34 range and Doppler tracking data every other day would sufficeto meet the predictive orbit knowledge accuracies in the Lissajous region.