No. 56 - Third Passive Payload Checkout
The periodic AOCS checkout was carried out over the period 1 - 3 March, involving activation and testing of all the sensors and actuators. In order to check-out the reaction wheels the spacecraft attitude control was kept for several hours on thrusters. All activities were carried out successfully. Detailed data analysis will be completed offline.
On 23 & 24 February RPC was activated to perform troubleshooting and anomaly investigations on the ICA instrument. All planned activities, including instrument software patch and verification, were successfully completed.
The third passive payload checkout (PC2) was performed outside visibility in the period 3 - 7March. In addition the RSI passive checkout, which requires ground contact, took place on 2 March over New Norcia. All instruments (except Rosina) were activated and checked out in sequence. The data generated during the checkout were dumped over the following two ground station passes and are under analysis by the instrument teams.
Due to the increased level of activities the frequency of ground station passes has also increased from one to two passes per week. A total of 6 New Norcia passes were taken over the reporting period.
|RPC ICA Test part 1|
|RPC ICA Test part 2|
|RSI PC2, AOCS Checkout part 1|
|AOCS Checkout part 2|
|Payload PC2 downlink (HK)|
|Payload PC2 downlink (Science)|
At the end of the reporting period (DOY 069) Rosetta was at 392.7 million km from the Earth (2.62 AU; one-way signal travel time was 21m 49s). The distance to the Sun was 249.7 million km (1.67 AU).
In preparation for the Osiris observation of asteroid Steins, which will bring the Sun about 23 degrees below +X for about 37 hours, a test was carried out on DOY 053 in order to decrease the initial temperature of the –Z thrusters. The heaters of the four –Z thruster modules were switched off during the pass. The thrusters on the –X of the spacecraft decreased from about 20 degrees to the lower threshold of 7 degrees in about 1.5 hours, and the heaters switched back on by the thermal control software as expected. The thrusters on the +X side decreased from the initial 35 degrees to a steady state value of about 8 degrees, and the heater remained off.
Payload Passive Checkout 2
On DOY 060/061 the passive checkout 2 for RSI was successfully executed over the New Norcia pass, according to the defined timeline. All activities on the TTC and the ground station were executed nominally.
The payload passive checkout was executed between DOY 062 and DOY 066. All instruments were activated individually in sequence via MTL commands. All activities took place as usual outside coverage, and the following New Norcia passes used to downlink the telemetry data stored over the checkout period.
A previously unplanned scientific observation of asteroid Steins using the OSIRIS camera will be carried out in the period 11 -12 March outside coverage. This exceptional scientific operation was agreed due to its mission relevance, as it will contribute to the knowledge base on asteroid Steins characteristics. This asteroid will be visited by Rosetta in close fly-by in September 2008.
Preparation for the first Solar Conjunction continues. The spacecraft will be configured on 14 March and will remain at an angular distance from the Sun below 5 degrees between mid March and mid May 2006, with a minimum separation angle of about 0.3 degrees on 13 April.
After the Solar Conjunction the spacecraft will be configured into Near Sun Hibernation Mode for a period of about 2 months, from end May to end July 2006.
Operations for the Mars swing-by (February 2007) will start in August 2006, with another payload passive checkout (PC3), an intense tracking campaign around the Trajectory Correction Manoeuvre (DSM-2) in September, and the first payload Active Checkout (PC4) in November/December.