No. 2 - SPC Report April 2003
The 6-week in-flight validation of the software update for the Articulation and Attitude Control System (AACS) was successfully carried out in February/March. The 4-week validation of the software update for the Command and Data Subsystem (CDS) is progressing nominally and should be concluded in early May. This latest version of the CDS software includes the capability for redundant recording of the Huygens data set on each of the two Solid-State Recorders (SSR). This Huygens-specific capability was successfully tested in-flight on 9 - 12 April. It provides the capability for recording four identical copies of the Huygens data set on Cassini SSR4s as per the Huygens mission requirements.
Probe Relay Sequence development (NASA/JPL activity)
The development of the Probe Relay Sequence is nominal. A full in-flight verification (mission rehearsal) is planned in early March 2004. All elements of the Probe mission (except the Probe release itself!) will then be exercised, including the JPL and ESOC ground segments.
Revised Huygens mission implementation: status report
All Probe on-board flight software patches and the patches required for DISR and GCMS for the pre-heating option have been fully developed and validated on the EM Probe at ESOC. The Probe on-board software modification also includes a newly developed capability to send instrument telecommands whilst in mission mode (during the entry/descent phase). This telecommand capability was required by the ACP as it does not have its own flight software patch capability. The development of the HASI patch has been delayed due to late contract negotiations between ASI and Galileo Avionics. No patch is required for SSP and DWE. Full validation of the pre-heating option is awaiting the availability of the HASI patch, which is expected in late June. The pre-heating/no pre-heating decision has been postponed to July. However a plan is being developed to verify the loading (and the unloading) capability on the flight Probe of all patches required for the pre-heating option during the first week of December 2003.
Probe Relay Test#5 (conducted in November 2002 using the Madrid 32-m DSN station)
The analysis of the PRT#5 test showed that the degradation of the data set due to the large signal fluctuations experienced on the up-linked signal was too significant for the test to meet all its objectives. However, the analysis of PRT#5 data, combined with a re-analysis of PRT#4 data set and some further link modelling, should still allow quantifying potential science data losses if the pre-heating option is not implemented.
Probe in-flight checkout
The 11th and the 12th in-flight checkouts are planned respectively on 3 May and on 15 September.