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No. 46 - Preparation and Entry into Passive Cruise Mode

No. 46 - Preparation and Entry into Passive Cruise Mode

Report for Period 15-29 July 2005The reporting period was dedicated to the preparation and entry into Passive Cruise Mode. This was the first time that this mode is entered operationally during the mission. The spacecraft willremain in this low activity, low bitrate mode over the next two months.

In the first week of the reporting period some outstanding maintenance activities were carried out on the on-board software parameter tables, including fine tuning of FDIR thresholds and addition of new on-board monitoring items (19 July), and the finalisation of thermal control thresholds and upload of the new TCT table in SGM EEPROM (20 July). On 21 July a confidence test was carried out to verify the TC bitrate of 250 bps, needed for the incoming passive cruise arc.

On 25 July the spacecraft was slewed to the Near Sun Hibernation Mode entry attitude and on the following day, 26 July, the Passive Cruise Mode was entered, including transition to NSHM and configuration of all subsystems for the new spacecraft mode. On 27 July, after a verification of the nominal status of the spacecraft, a test with the New Norcia ground station was carried out to verify the capability to lock on the downlink signal with narrow Phase Lock Loop bandwidth. Finally on 28th of July the spacecraft was configured to low TM and TC bitrates and TM modulation switched off at the end of the pass. This completed the activities related to entry in Passive Cruise Mode.

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 incoming passive cruise period.

A total of 7 New Norcia passes of a maximum duration of about 9 hours commanding were taken over the reporting period.

NNO Pass

Date

DOY

Main Activity

506

19.07.05

200

Monitor pass – Reset WEL and other maintenance

507

20.07.05

201

Monitor pass – update TCT lines in RAM and SGM

508

21.07.05

202

Monitor pass – test 250 bps TC bitrate

512

25.07.05

206

Slew to NSHM attitude, verify NSHM preconditions

513

26.07.05

207

Enter Passive Cruise Mode (NSHM), TM bitrate 8 kbps

514

27.07.05

208

Verify NSHM, TC link TO to 16 days, station PLL test

515

28.07.05

209

Monitor pass – TM bitrate 2 kbps, TC bitrate 250 bps

The mark of 100 million km distance from Earth was passed in the evening of Sunday 24 July.

At the end of the reporting period (DOY 210) Rosetta was at 107.3 million Km from the Earth. The one-way signal travel time was 5 min 57 sec.

Last Update: 1 September 2019
24-Apr-2024 13:42 UT

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