No. 211 - Mission Operations Update
02 Dec 2009 12:08
Report for Period 22 November to 28 November 2009
The Venus Express spacecraft and instruments performed nominally during this week.
The table below shows a chronology of the main activities:
At the end of the last Cebreros pass in the reporting period (DOY 332) Venus Express was orbiting Venus at 249.7 million km from the Earth. The one-way signal travel time was 833.1 seconds.
Attitude and Orbit Control System (AOCS)
The friction level on reaction wheel 1 (RW1) remained stable up to DOY 329, when new ASPERA scanner operations were introduced. During these scanner operations there are more pointings, requiring more frequent spacecraft slews. The net effect was a slightly raised friction level on RW1 due to higher wheel speeds. The friction level, however, is still within set limits and has had no negative effect on the spacecraft attitude control.
The new scanner operations also resulted in several spikes being observed in RW2's friction level on DOY 329. RW2 in addition continues to show spikes in its friction level, mainly during the Earth pointing communication periods. The latter behaviour has been correlated to higher bearing temperatures. Both types of spikes are small, but their influence on the spacecraft's attitude is being closely monitored.