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No. 47 - Cruise Mode

No. 47 - Cruise Mode

Report for Period 29 July to 20 August 2005The reporting period was originally dedicated to spacecraft monitoring in Passive Cruise Mode.However, an unexpected fuel over-consumption of 20 grams and a delta-V of 2.5 mm per second weredetected off-line on data acquired during DOY 216. On DOY 220, a short pass was taken onshort-notice to confirm the delta-V.

Spacecraft telemetry indicated that the fuel consumption had gone back to normal, and that the acceleration had disappeared. Telemetry downlinked on DOY 223 finally showed anomalous spacecraft dynamics between DOY 213 and 216. Therefore, the decision was taken on DOY 224 to return the spacecraft to Active Cruise Mode as soon as possible.

The system transition to Active Cruise Mode took place successfully on DOY 230. The transition was completed on DOY 231, when the telecommunications were reconfigured to HGA-X and maximum TM/TC bit rates. All telemetry acquired during Passive Cruise Mode was successfully recovered on DOY 231.

Since DOY 216, no anomaly could be detected in the spacecraft dynamics and RCS behaviour. Since DOY 231, the spacecraft is being monitored on a weekly basis.

No payload operations were carried out in the reporting period. SREM was kept active in the background for the entire period, and configured for a lower data collection rate to cope with the reduced visibility periods and bitrates available during the passive cruise period.

A total of 8 New Norcia passes of a max duration of about 10 hours commanding were taken over the reporting period, 4 of which scheduled on short notice to support investigation of the spacecraft anomaly in Near Sun Hibernation Mode (NSHM) and anticipated transition to Active Cruise Mode.

NNO Pass

Date

DOY

Main Activity

522

04.08.05

216

Monitor pass

526

08.08.05

220

Unplanned tracking pass

529

11.08.05

223

Monitor pass - recover NSHM housekeeping telemetry acquired between DOY 213 and 216.

530

12.08.05

224

Unplanned monitor pass - recover NSHM memory cell acquisition telemetry acquired between DOY 213 and 216

534

16.08.05

228

Unplanned pass: prepare anticipated NSHM exit

536

18.08.05

230

Monitor NSHM exit

537

19.08.05

231

Unplanned monitor pass.  Recover NSHM telemetry

544

25.08.05

238

Monitor pass

At the end of the reporting period (DOY 238) Rosetta was at 152 million km from the Earth. The one-way signal travel time was 8 minutes 7 seconds.

Last Update: 1 September 2019
19-May-2024 20:34 UT

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