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No. 15 - Moving towards Cruise Phase

No. 15 - Moving towards Cruise Phase

Report for week 28 May to 4 JuneThe reporting period covered part of the transition from the payload commissioning activities to the start of the Cruise 1 phase, which will take place next week. The ALICE PAT test was finally and, after two cancellations due to different reasons in the past weeks, successfully carried out. The first pass of the extra slot requested by OSIRIS to repeat some of the measurements taken in slot 2 was also successfully carried out.

On the subsystems side two passes were dedicated to TTC commissioning. The LGA TC threshold test could not be completed due to a problem in the New Norcia station, which prevented the use of the Low Power Amplifier. Due to the relatively short distance to the Earth, the low threshold for LGA commanding could not be reached with the High Power Amplifier and the test will have to be re-scheduled to a later stage in the Cruise. On a second New Norcia pass the S-band ranging test with both transponders was successfully completed.

An important mission milestone this week was the fact that for the first time one of the daily New Norcia passes was skipped on 30 May. This means that Rosetta was left without ground contact for 42 hours. The spacecraft was prepared on the day before (reduce TM generation rate, increase TC link timeout) and was found in a perfect state when contact was re-acquired on the evening of 31 May. It is planned to gradually increase the period of non-contact during the first month of Cruise 1, to arrive at weekly passes by mid July.

The table below shows a chronology of the main activities in the reporting period:

Mission Day

Date

DOY

Main Activity

88

28/29.05.04

149/150

ALICE Performance Aliveness Test

89

29/30.05.04

150/151

Prepare to skip pass, dump ALICE PAT data

90

30/31.05.04

151/152

First skipped ground contact!

91

31.05/01.06.04

152/153

Monitoring pass

92

01/02.06.04

153/154

LGA TC threshold test

93

02/03.06.04

154/155

S-band ranging test

94

03/04.06.04

155/156

OSIRIS extra slot pass 1

At the end of the last New Norcia pass in the reporting period (DOY 156, 02:00) Rosetta was at 44.7 million km from the Earth. The one-way signal travel time was 2 minutes 29 seconds.


Science Results

Comet C/2002 T7 (LINEAR)

On 30 April Rosetta targeted the comet C/2002 T7 (LINEAR) for its first scientific observations. Data was successfully acquired by the four instruments ALICE, MIRO, VIRTIS and OSIRIS and will be fully analysed after the calibration of the instruments is completed.

OSIRIS acquired this image of the comet at a distance of about 95 million kilometres through a blue filter, showing the comet's nucleus and tenuous tail extending for over 2 million km.

 

Last Update: 1 September 2019
20-Sep-2020 18:01 UT

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