No. 214 - Mission Operations Update
During the reporting period an orbital correction manoeuvre (OCM) was successfully performed on 13 December (DoY 347). The manoeuvre constituted a phase correction, intended to keep the phasing of Venus Express in its orbit in sync with mission operations from ground.
DDOR
On 13 December delta differential one-way ranging (DDOR) was performed using the New Norcia and Cebreros ground stations to track the spacecraft. These measurements are performed monthly to support the accurate determination of the ephemeris for the planet Venus that is maintained by NASA's Solar System Dynamics Group.
The DDOR measurement principle uses a technique to highly accurately determine the position of a transmitter in space and relies on observing the time delay between reception of the signal from the transmitter by two ground stations at different positions on Earth. In this case the Venus Express spacecraft is the transmitter and the two ground stations are New Norcia in western Australia and Cebreros in Avila, Spain.
The table below shows a chronology of the main activities:
| MET (Day) |
Date | DOY | Main Activity |
| 1496 | 13/12/09 | 347 |
OCM executed around 06:00 UT. |
| 1497 | 14/12/09 | 348 |
Communications pass over Cebreros. |
| 1498 | 15/12/09 | 349 |
Communications pass over Cebreros. |
| 1499 | 16/12/09 | 350 |
Communications pass over Cebreros |
| 1500 | 17/12/09 | 351 |
Communications pass over Cebreros. |
| 1501 | 18/12/09 | 352 |
Communications pass over Cebreros. |
| 1502 | 19/12/09 | 353 |
Communications pass over Cebreros |
At the end of the last Cebreros pass in the reporting period (DOY 353) Venus Express was orbiting Venus at 254 million km from the Earth. The one-way signal travel time was 847 seconds.
Spacecraft
Attitude and Orbit Control System (AOCS)
The AOCS is in its nominal configuration and performing nominally. Operations continue with all four reaction wheels. The friction levels on the four reaction wheels remained stable throughout the reporting period.
From DOY 352 onwards a slight increase in the friction level on reaction wheel 1 (RW1) was observed, but it stayed well below the set limits and the maximum friction of 0.03 Nm observed in the past.
RW2 continued to show several spikes in its friction level (see status report no. 212).
Payload Activities
ASPERA
The instrument was regularly operated as part of the routine plan.
MAG
The instrument was regularly operated as part of the routine plan.
PFS
The instrument was not operated during the reporting period.
SPICAV
The instrument was regularly operated as part of the routine plan.
VeRA
No radio science observations were made during the reporting period.
VIRTIS
VIRTIS-M was operated in the visual channels only.
VMC
The instrument was regularly operated as part of the routine plan.
Future Milestones
- Venus at superior conjunction on 11 January 2010. Venus Express superior conjunction operations: 29 December 2009 to 22 January 2010
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This report is based on the ESOC mission operations report, MOR #214. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.