|GeoForschungsZentrum Potsdam||Deutsches Raumfahrt-Kontrollzentrum|
CHAMP Bulletin No. 2 *
July 17, 2000, 08:00 UTC
July 18, 2000, 14:00 UTC
Further operations for commissioning CHAMP have been completed and are on schedule. After boom deployment CHAMP attained its nominal flight configuration.
Satellite bus systems
The status of the satellite sub-systems is as follows:
Power: The power supply of the satellite was at any moment of operation sufficiently secured. The solar generators produce with full capacity. The battery charging level was at any moment between 60 % and 100 %. After analyzing the first dumped data an abnormal behavior of the battery charge control was noticed, possibly an effect of the extremely powerful magnetic storm on July 15/16 , 2000, that strongly affected other satellites as well. As a preventive measure an additional protective function on thermal basis had been established. It allows full mission maintenance even at total malfunction of the battery control.
Thermal system: The temperatures of the satellite are within the predicted range and show excellent stability over the orbit.
Attitude and orbit control: In spite of the malfunction of two (of altogether six) coarse earth/sun sensors - whereas it is currently assumed that this failure was caused by collision with the rocket fairing (++ this hypothesis is disproven and the most probably cause is thermal overload during launch ascent and after fairing jettison ++ - short report will be given in one of the next newsletters; Sep 8, 2000, Ch. Reigber) - emergency functioning to be taken on by these sensors, i.e., to enable the transition into the Fine Pointing Mode, was secured by re-programming.
The Fine Pointing Mode runs presently, though nominally, with increased cold gas consumption. The reason for this are the star sensors being not optimally adjusted in terms of software. This adjustment is planned for the next days. The remaining filling level of 98 % allows for unrestricted mission.
Onboard data handling system: The onboard processor and software run correctly.
Telemetric system: The telemetric system runs correctly.
Of the seven scientific instruments, five have been successfully put into operation. The last instrument was the scalar Overhauser magnetometer. After analysing the first telemetric data, all instruments switched on hitherto show the expected accuracy and resolution.
Due to observed anomalies and for verifying the initiated counter-measures, the support by the NASA polar station tracking net was prolonged for several more days. Otherwise flight operations run nominally.
With the GPS and laser tracking data acquired hitherto, the CHAMP orbit could be recovered within sub-meter range.