No. 159 - Mission Update
Highlights of the week's activities:
- VIRTIS continues to be operated in the visual channels only.
- Cebreros was not used during the reporting period, as the ground station is under maintenance until 1 December 2008.
- An orbit control manoeuvre (OCM) was executed an DOY 328.
- The speed direction of all reaction wheels (RW) was inversed on DOY 328, to support the investigation of anomalous friction observed at RW#1.
- Radio Science Investigation (RSI) occultation measurements were taken on DOY 330, 332 and 334.
- On DOY 332 delta differential one-way ranging (DDOR) was performed using ESA's New Norcia and NASA's DSS-54 (MAD-54) ground stations to track the spacecraft.
The table below shows a chronology of the main activities:
| MET (Day) | Date | DOY | Main Activity |
| 1111 | 23/11/08 | 328 |
Communications pass over New Norcia. |
| 1112 | 24/11/08 | 329 |
Communications pass over New Norcia |
| 1113 | 25/11/08 | 330 |
Combined communications and RSI occultation measurements pass over New Norcia |
| 1114 | 26/11/08 | 331 |
Communications pass over New Norcia |
| 1115 | 27/11/08 | 332 |
Combined communications and RSI occultation measurements pass over New Norcia. |
| 1116 | 28/11/08 | 333 |
Communications pass over New Norcia. |
| 1117 | 29/11/08 | 334 |
Combined communications and RSI occultation measurements pass over New Norcia |
At the end of the last Cebreros pass in the reporting period (DOY 334) Venus Express was orbiting Venus at 152.5 million km from the Earth. The one-way signal travel time was 508 seconds.
Orbit Control Manoeuvre
An OCM with a magnitude of 638.1 mms-1 was executed on DOY 328. The result of the manoeuvre was as expected, with the apocentre altitude reduced by 120 km (<0.2%) and the orbital period reduced by 120 seconds.
DDOR
Delta differential one-way ranging (DDOR) 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.
DDOR was performed on 27 November 2008 with the Venus Express spacecraft acting as the transmitter. The two ground stations used for the DDOR measurements were New Norcia in western Australia and DSS-54 in Madrid (MAD-54), Spain.
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 330, 332 and 334 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
- High gain antenna (HGA1) S-band carrier power test is planned for 15 December 2008
- Next quadrature phase will start on 19 December 2008
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This report is based on the ESOC mission operations report, MOR #159. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.