Rosetta Status Report, 28-06-2004

Testing Availability of MGA-S Antenna
28 Jun 2004 14:15

Report for Week 18 to 25 June 2004
The reporting period covers the third week of Cruise 1. The main activity
was a first check for availability of the MGA-S antenna, in order to select
it in case of Survival Mode.

The test, executed on 20 June, had to be carried out with the 70m dish of
DSN due to the orbital geometry and the attitude constraints of the
spacecraft, which put the MGA in a very marginal condition from a link
budget point of view. The test successfully confirmed the availability of
MGA-S, and the antenna was then selected in the on-board software on 24 June
for use in case of Survival Mode triggering.

In support of the investigations on the Star Tracker acquisition behaviour
identified last week after having enabled the "dust settings" (see report
no. 17) a test has been proposed on the spacecraft and planned for 3 July.
To prepare for this test, Star Tracker B has been patched to the dust
settings on 24 June and put into tracking mode.

As planned, on 24 June the GSEP pointing bias has been reset to 60 degrees
above +X.

Three New Norcia ground station passes were skipped, as planned, on 19, 22
and 23 June. On 18 June a short TM monitoring pass was taken only to check
correct entry into GSEP.

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

Mission Day
Date
DOY
Main Activity

109
18/19.06.04
170/171 Reduced ground contact (only GSEP entry TM check)

110
19/20.06.04
171/172 Skipped ground contact

111
20/21.06.04
172/173 DSN 70m test with MGA-S + monitoring over NNO

112
21/22.06.04
173/174 Monitoring, re-enabling of TCT lines 35/36 (CAM)

113
22/23.06.04
174/175 Skipped ground contact

114
23/24.06.04
175/176 Skipped ground contact

115
24/25.06.04
176/177 Prepare STR B for dust settings test; select MGA for Survival Mode
communications; set TC link timeout for weekly contact.



At the end of the last New Norcia pass in the reporting period (DOY 177)
Rosetta was at 57.1 million kilometres from the Earth. The one-way signal
travel time was 3 minutes 10 seconds.



--
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Jacques :-)

www.spacepatches.info