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No. 144 - Solar array testing

No. 144 - Solar array testing

Report for the period 28 August to 24 September 2010This report covers 28 days of Rosetta mission operations. On 3 September, the performance of the solar arrays was tested by tilting them with respect to the Sun direction, simulating deep-space conditions. Data have been acquired and are being processed; a preliminary analysis indicates that performance was nominal.

During the reporting period, mission operations were conducted using the ESA New Norcia (NNO) ground station.

Main activities during reporting period

DoY Date Pass Activity
242 30-Aug-2010 NNO 2378 Monitor
243 31-Aug-2010 NNO 2379 Monitor
246 3-Sep-2010 NNO 2382 Solar arrays performance test at 3.1 AU
250 7-Sep-2010 NNO 2386 Monitor
252 9-Sep-2010 NNO 2388 Completion of reaction control system pressure regulator switch over
254 11-Sep-2010 NNO 2390 Monitor
257 14-Sep-2010 NNO 2393 Monitor
259 16-Sep-2010 NNO 2395 Monitor
260 17-Sep-2010 NNO 2397 Monitor
263 20-Sep-2010 NNO 2400 Monitor
265 22-Sep-2010 NNO 2402 Monitor
267 24-Sep-2010 NNO 2404 Monitor

DoY = Day of year

At the end of the reporting period on 24 September, Rosetta was 627 million km from Earth (4.19 AU); the one-way signal travel time was 34 min 52 sec (2092 sec). The spacecraft's distance from the Sun was 483.5 million km (3.23 AU).


On 9 September, the procedure to switch over to the redundant reaction control system (RCS) pressure regulator was completed, unfortunately revealing that the pressurant leak is in a section of piping that is common between the two regulators and cannot be isolated. In the light of this failure, it has been decided not to repressurise the RCS for the rest of the mission. This implies that the system will be used in 'blow-down' mode. This increases operational uncertainties, but the margins remain comfortable. A precise estimation of the overall effect will be possible at the time of the first rendezvous manoeuvre in January 2011; however, the impact on the comet arrival timeline is expected to be only of the order of one week.

Payload Status
ALICE The instrument is currently OFF
CONSERT The instrument is currently OFF
COSIMA The instrument is currently OFF
GIADA The instrument is currently OFF
MIDAS The instrument is currently OFF
MIRO The instrument is currently OFF
OSIRIS The instrument is currently OFF
ROSINA The instrument is currently OFF
RPC The instrument is currently OFF
RSI The USO is ON/muted since 3 February 2010 (DoY 032/2010) 
VIRTIS The instrument is currently OFF
Lander (Philae) The instrument is currently OFF
SREM The instrument is ON with standard settings since 3 February 2010 (DoY 032/2010)

Future milestones

The spacecraft will enter a superior conjunction phase that will last from 2 to 31 October; the deepest conjunction condition will occur between 10 and 23 October and will affect the telemetry link to such an extent that dumping of the mass memory will not be attempted during this period. The detailed results of the solar arrays test will be fed into the spacecraft configuration for deep space operations and thereby incorporated into the mission planning.

After this phase, spacecraft activities will focus on the final payload checkout and preparation of the instruments for the hibernation phase. These activities will be conducted between mid-November and mid-December.

Legal disclaimer
This report is based on the ESOC mission operations report, WOR #144. Please see the copyright section of the legal disclaimer (linked from the home page for terms of use.

Last Update: 1 September 2019
22-Apr-2024 21:37 UT

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