No. 10 - First Earth Pointing of Payload
Towards the end of the foreseen Earth pointing period an unplanned slew was executed to move the Sun into the +Z hemisphere as the temperature of the -Z thrusters was reaching its highest allowed limits due to Sun illumination. This manoeuvre resulted in cancelling the ALICE PAT test planned for the following pass.
The second slot of OSIRIS commissioning took the rest of the reporting period. All planned activities were executed successfully, except for the Earth-Moon imaging which had to be postponed as a precautionary measure after the high thruster temperatures observed during the MIRO Earth pointing period. This however did not affect the achievement of the OSIRIS commissioning objectives.
On the subsystem side no special activity was performed. Close monitoring of the thermal environment continues, and the experience with the Earth pointing attitude has resulted in a further restriction on the range of allowed attitudes. The Sun is now allowed in a range from -4 to +50 degrees from the +X axis in the X/Z plan, at least until after perihelion is reached on 25 May.
The table below shows a chronology of the main activities in the reporting period:
|
Mission Day |
Date |
DOY |
Main Activity |
|
53 |
23/24.04.04 |
114/115 | MIRO Earth pointing |
|
54 |
24/25.04.04 |
115/116 | MIRO/VIRTIS Earth pointing |
|
55 |
25/26.04.04 |
116/117 | OSIRIS commissioning slot 2 - pass 1 |
|
56 |
26/27.04.04 |
117/118 | OSIRIS commissioning slot 2 - pass 2 |
|
57 |
27/28.04.04 |
118/119 | OSIRIS commissioning slot 2 - pass 3 |
|
58 |
28/29.04.04 |
119/120 | OSIRIS commissioning slot 2 - pass 4 |
|
59 |
29/30.04.04 |
120/121 | OSIRIS commissioning slot 2 - pass 5 |
At the end of the last New Norcia pass in the reporting period (DOY 121, 02:30) Rosetta was at 23.5 million km from the Earth. The one-way signal travel time was 1 minute and 18 seconds.