No. 164 - Quadrature Operations
VIRTIS continues to be operated in the visual channels only. Radio Science Investigation (RSI) occultation measurements were taken during three ground station passes in the reporting period.
DDOR
On 28 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 |
| 1146 | 28/12/08 | 363 |
Communications pass over Cebreros. |
| 1147 | 29/12/08 | 364 |
Communications pass over Cebreros. |
| 1148 | 30/12/08 | 365 |
Skipped communications pass over Cebreros |
| 1149 | 31/12/08 | 366 |
Communications pass over Cebreros. |
| 1150 | 01/01/09 | 001 |
Communications pass over Cebreros. |
| 1151 | 02/01/09 | 002 |
Skipped communications pass over Cebreros. |
| 1152 | 03/01/09 | 003 |
Communications pass over Cebreros. |
At the end of the last Cebreros pass in the reporting period (DOY 003) Venus Express was orbiting Venus at 115.13 million km from the Earth. The one-way signal travel time was 383.8 seconds.
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
RSI occultation measurements were taken during the reporting period on DOY 364, 366 and 001 with the New Norcia ground station.
VIRTIS
The instrument was regularly operated as part of the routine plan.
VIRTIS is operated in the visual channels only.
VMC
The instrument was regularly operated as part of the routine plan.
Future Milestones
- VIRTIS cooler test on 10 January 2009.
- High gain antenna swap from HGA1 to HGA2 on 13 January 2009.
- The quadrature phase will end on 25 January 2009.
- Commissioning of the Reaction Control Subsystem B on 12 February 2009.
- Battery Deep Discharge Test is planned for 22 April 2009.
- Start of next (outbound) quadrature phase on 29 May 2009.
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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #164. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.