No. 49 - AOCS and Payload Passive Checkouts
10 October 2005 10:20Report for Period 16 September to 7 October 2005
The reporting period covers three weeks of passive cruise for Rosetta, in which the periodic passive payload checkout and the AOCS checkout were executed.
The AOCS checkout was carried out on 28 and 29 September, partially during coverage of the New Norcia station. All units were exercised except for the reaction wheels, in order to avoid long duration attitude control via thrusters, which are still under close observation after the problem experienced in August in Near Sun Hibernation Mode. All activities were executed successfully.
Several on-board memories were dumped and checked out over the entire reporting period, to confirm that no permanent corruption had been caused by the solar flare experienced on 8 September (see also status report no. 48). Health and consistency of al the checked memories could be confirmed.
On the payload side, a test on the RPC-IES experiment was executed on 20 September but failed due to an incorrect operation request that missed a telecommand in the sequence. On 21 September a complex troubleshooting activity on the Lander Data Processing Unit 1 (DPU1) was executed and successfully achieved the reactivation of the unit.
The Radio Science Investigation (RSI) passive checkout 1 was carried out over New Norcia on 29 September.
The second in-flight passive payload checkout (PC-1) was executed outside coverage between 1 and 4 October. All instruments were activated in sequence (with the exception of Rosina) and executed a set of pre-defined tests. Data from the checkout were dumped during the new Norcia passes on 5 and 6 October and the analysis of the results by the PI teams is on-going.
A total of 5 New Norcia passes of maximum 10 hours commanding duration were taken over the reporting period. In addition Rosetta supported a tracking campaign for the validation of the new ESA deep space ground station in Cebreros, Spain. Three passes were successfully conducted on 26, 27 and 28 September. All functions, including telemetry, telecommanding and tracking were validated, together with the relevant interfaces to the Mission Control Centre.
At the end of the reporting period (DOY 280) Rosetta was at 226.2 million km from Earth (1.51 AU; one-way signal travel time was 12 minutes and 34 seconds). The distance to the Sun was 252.4 million km (1.69 AU)