No. 192 - Start of Earth Occultation Season #7
VeRa Earth occultation season #7
The first three observations of the seventh season of Earth occultation experiments have been successfully performed during the reporting period. These experiments effectively represent a sounding of the Venusian atmosphere and ionosphere. The measurements are made just before and after the spacecraft passes behind the disk of Venus as seen from Earth (occultation).
The occultation measurements are 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 spacecraft's High Gain Antenna is pointed toward the Earth before the approach to occultation and a dual signal is sent in the S-band and X-band. Just before and after the occultation, the transmitted signal passes through the ionosphere and atmosphere of Venus. The effect that this has on the received signal gives valuable information on the composition and characteristics of the atmosphere as a function of altitude.
The 35m ESA deep space antenna at New Norcia (NNO), Australia, was used for receiving the spacecraft's radio signals on ground.
The table below shows a chronology of the main activities:
| MET (Day) |
Date | DOY | Main Activity |
| 1342 | 12/07/09 | 193 |
Communications pass over Cebreros |
| 1343 | 13/07/09 | 194 |
Communications pass over Cebreros. |
| 1344 | 14/07/09 | 195 |
Communications pass over Cebreros. |
| 1345 | 15/07/09 | 196 |
Communications pass over Cebreros |
| 1346 | 16/07/09 | 197 |
Communications pass over Cebreros. |
| 1347 | 17/07/09 | 198 |
Communications pass over Cebreros. |
| 1348 | 18/07/09 | 199 | Communications pass over Cebreros. RSI occultation measurements with NNO |
At the end of the last Cebreros pass in the reporting period (DOY 199) Venus Express was orbiting Venus at 154.96 million km from the Earth. The one-way signal travel time was 516 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
Three occultation experiments took place on DOY 197, 198, and 199.
VIRTIS
VIRTIS-M was operated in the visual channels only.
VMC
The instrument was regularly operated as part of the routine plan.
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This report is based on the ESOC mission operations report, MOR #192. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.