Rosetta Update - June 2, 2006

http://rosetta.esa.int/science-e/www...objectid=39332

Rosetta Enters Near Sun Hibernation Mode
European Space Agency
June 2, 2006

Report for Period 12 May - 2 June 2006

The reporting period covers three weeks of cruise, in which telemetry
stored during solar conjunction was recovered and the spacecraft
reconfigured to Near Sun Hibernation Mode (NSHM).

On 24 May the spacecraft entered Passive Cruise Mode, including
transition to NSHM, telecommunications reconfiguration to MGA with low
telemetry and telecommanding bit rates and configuration of all
subsystems for the new spacecraft mode. This completed the activities
related to entry in Passive Cruise Mode. Two more passes were taken on
25 and 26 May, to confirm the correct behaviour of the new spacecraft
mode. The spacecraft will remain in this low activity, low bit rate
mode
until 26 July.

No payload operations were carried out in the reporting period. SREM
was
kept active in the background for the entire period, and configured for
a lower data collection rate to cope with the reduced visibility
periods
and bitrates available during the passive cruise period.

A total of 7 New Norcia passes of 8 hours commanding were taken during
the reporting period. TM/TC links with the OCC have been established
for
all passes.

NNO Date DOY Main Activity
Pass

808 16.05.06 136 Monitor pass - Solar Conjunction TM Recovered
809 17.05.06 137 Monitor pass - Prepare NSHM Entry
814 22.05.06 142 Monitor pass - Prepare NSHM Entry
815 23.05.06 143 NSHM Entry - TTC reconfigured to MGA-X, TM bit rate to
148 bps, TC bit rate to 250 bps
816 24.05.06 144 NSHM monitor pass
817 25.05.06 145 NSHM monitor pass
823 31.05.06 151 NSHM monitor pass

At the end of the reporting period (DOY 153) Rosetta was at 354.0
million km from Earth (2.37 AU; one-way signal travel time was 18
minutes 58 seconds). The distance to the Sun was 209.8 million km (1.40
AU).

Spacecraft Status

Thermal
The thermal behaviour of the spacecraft is nominal and stable. Its
configuration is NSHM1 since DOY 144/2006.

As expected after NSHM entry, the temperature of the spacecraft
internal
units, such as batteries, tanks, CDMUs and reaction wheels, has
decreased by a few degrees. Apart from this mode-related adjustment of
the on-board temperatures, the spacecraft is slowly warming up as the
Sun distance is decreasing.

Power
The subsystem is in its nominal configuration and performing nominally.
All three batteries are in active configuration, at full state of
charge.

Future Milestones

The spacecraft will remain in Passive Cruise Mode until 26 July
2006. During the entire period, the spacecraft will be monitored on the
basis of weekly ground station passes.

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.