Probe Checkout at Earth 2

(From Issue 30, September 1992)

The upcoming Earth 2 activities include a Probe Mission Sequence Test (MST) and an abbreviated Probe Checkout. As defined by the Probe Engineering Team, the normal Probe checkout consists of a systems functional test (SFT) and an MST. The SFT provides a complete functional test at the subsystem level, while the MST thoroughly tests the actual Probe mission sequence, including the operation of the data and command processor and the Neutral Mass Spectrometer (NMS) valves. To date, only the SFT has been performed in flight, once eight days after launch and again at Earth 1. Dr. Hasso Nieman, Principal Investigator for the NMS, requested that the MST be performed periodically to cycle the NMSÕ valves to ensure its proper operation as the Probe descends through the Jovian atmosphere on December 7, 1995.

A full checkout of the Probe is planned prior to its release in July 1995. However, if the High-Gain Antenna (HGA) is not deployed by that time, in order to reduce the data playback time an abbreviated procedure will check only what is mandatory and could be corrected prior to release. This abbreviated checkout will also be verified at Earth 2. If the HGA is not successfully deployed, the activities at Earth 2 will provide a final thorough test of the Probe, including its scientific instruments. Consequently, the Probe Engineering Team and the Probe Science Team are eagerly anticipating the challenge of the Probe activities at Earth 2.