No. 69 - Start of First Payload Active Checkout
05 December 2006 13:12Report for Period 17 November to 1 December 2006
The reporting period covers two weeks of active cruise, during which the first payload Active Checkout (PC4) started.
The campaign started on 22 November with the execution of the passive checkout sequence for the Radio Science Investigation instrument (RSI). Checkout operations for all other instruments started on 23 November with a joint non-interactive set of operations involving all instruments except ROSINA and OSIRIS.
The two navigation cameras were also operated as part of this slot. These operations were executed outside ground coverage. The data acquired during this non-interactive slot were dumped to ground on 27 November. From 28 November until 1 December, all passes have been dedicated to the Lander Philae interactive checkout.
The Rosetta Plasma Consortium (RPC) and SREM remain active in the background throughout the campaign. The other instruments are active for execution of their checkout sequences.
All checkout operations have been executed smoothly, with the exception of the Noisy Channel test of the RPC's Ion and Electron Sensor on 26 November. The sensor is in good condition, however, and a repetition of the test within the next few days is under definition.
In addition, the RPC time synchronisation failed upon two consecutive power-on of the instrument on 25 and 26 November, resulting in more than one day of data remaining unsynchronised. This was the first time that such an incident occurred for any of the instruments. Initial investigations are pointing to tight timing of data handling commands within the RPC power-on OBCP.
Manual workarounds are being defined to avoid that the problem reoccurs during the Active Checkout campaign.
A total of 6 New Norcia passes of 4 to 12 hours commanding were taken during the reporting period, one of which is for tracking only. In addition one Delta-DOR measurement was performed with the New Norcia/Cebreros baseline. 5 tracking passes of 4 hours and 1 delta-DOR track have been taken with DSN.
At the end of the reporting period (DOY 335) Rosetta was at 298.2 million km from Earth (1.99 AU; one-way signal travel time was 16 minutes 34 seconds). The distance to the Sun was 164.2 million km (1.10 AU).
The first interactive PC4 activities took place between DOY 332 and 335. This slot was dedicated to Philae checkout operations. All operations ran nominally.
SREM and RPC remain active continuously throughout the Active Checkout scenario, with the exception of occasional RPC switch-off when required by other instruments.
All operations performed as expected.