No. 171 - Mission Update
DDOR
On 15 February 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 |
| 1195 | 15/02/09 | 046 |
Communications pass over Cebreros. |
| 1196 | 16/02/09 | 047 |
Communications pass over Cebreros |
| 1197 | 17/02/09 | 048 |
Communications pass over Cebreros. |
| 1198 | 18/02/09 | 049 |
Communications pass over Cebreros |
| 1199 | 19/02/09 | 050 |
Communications pass over Cebreros. |
| 1200 | 20/02/09 | 051 |
Communications pass over Cebreros |
| 1201 | 21/02/09 | 052 |
Communications pass over Cebreros |
At the end of the last Cebreros pass in the reporting period (DOY 052) Venus Express was orbiting Venus at 62.9 million km from the Earth. The one-way signal travel time was 209 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
No measurements were taken during the reporting period.
VIRTIS
VIRTIS was operated in the visual channels only.
VMC
The instrument was regularly operated as part of the routine plan.
Future Milestones
- Preparation for next gravity observation campaign with the Canberra ground station CAN43 on 15 April 2009.
- Battery Deep Discharge Test is planned for 22 April 2009.
- Start of next (outbound) quadrature phase on 29 May 2009.
- Swap of high gain antenna (HGA) from HGA2 to HGA1 on 8 June 2009.
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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #171. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.