No. 180 – Gravity observation campaign
VeRa gravity observation campaign
The mission's sixth gravity observation campaign (GRA#6) was performed on 20 April. The campaign is part of the Venus Express Radio Science Investigations (RSI) performed under the Venus Radio Science experiment (VeRa). For these investigations the VeRa team makes use of the radio links of the spacecraft's communications system. The gravity observation campaign is set up to measure anomalies in the planet's gravitational field by analyzing the spacecraft's radio carrier signals received on ground, simultaneously in two radio bands. The detected anomalies provide insight into the properties of the crust and lithosphere of Venus.
The GRA#6 observations were executed with the Venus Express High Gain Antenna 2 (HGA2). Three more sets of gravity observations are planned before 1 July 2009. The HGA1 - the bigger dish with a higher signal to noise ratio - can only be used in defined geometrical constellations between Sun, Earth and Venus, because of thermal considerations that constrain the spacecraft's attitude. The swap from HGA2 to HGA1 will be on 8 June 2009, allowing the last set of gravity observations to be performed with HGA1.
The 70m NASA DSN ground station at Canberra, Australia, was used for receiving the spacecraft's radio signals in the gravity observation campaign.
The table below shows a chronology of the main activities:
| MET (Day) |
Date | DOY | Main Activity |
| 1258 | 19/04/09 | 109 |
Communications pass over Cebreros |
| 1259 | 20/04/09 | 110 |
Canberra RSI pass (GRA#6). |
| 1260 | 21/04/09 | 111 |
Communications pass over Cebreros |
| 1261 | 22/04/09 | 112 |
Communications pass over Cebreros. |
| 1262 | 23/04/09 | 113 |
Communications pass over Cebreros |
| 1263 | 24/04/09 | 114 |
Communications pass over Cebreros |
| 1264 | 25/04/09 | 115 |
Communications pass over Cebreros |
At the end of the last Cebreros pass in the reporting period (DOY 115) Venus Express was orbiting Venus at 58.3 million km from the Earth. The one-way signal travel time was 194 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 measurements of gravity observation campaign #6 were made on 20 April.
VIRTIS
VIRTIS-M was operated in the visual channels only.
VMC
The instrument was regularly operated as part of the routine plan.
Future Milestones
- 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 #180. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.