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No. 201 - End of Earth Occultation Season #7

No. 201 - End of Earth Occultation Season #7

Report for Period 13 September to 19 September 2009The Venus Express spacecraft and instruments performed nominally during this week. The seventh Earth occultation season concluded this week, with the last five observations in the series carried out in this reporting period.

VeRa Earth occultation season #7
The mission's seventh season of Earth occultation experiments, which started on 16 July 2009 (DOY 197), has concluded with the last experiment in the series carried out on 18 September 2009 (DOY 261). These experiments effectively represented a sounding of the Venusian atmosphere and ionosphere. The measurements were 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 radio 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
1405 13/09/09 256

Communications pass over Cebreros.
RSI occultation measurements with NNO

1406 14/09/09 257

Communications pass over Cebreros

1407 15/09/09 258

Communications pass over Cebreros.
RSI occultation measurements with NNO

1408 16/09/09 259

Communications pass over Cebreros.
RSI occultation measurements with NNO

1409 17/09/09 260

Communications pass over Cebreros.
RSI occultation measurements with NNO

1410 18/09/09 261

Communications pass over Cebreros.
RSI occultation measurements with NNO

1411 19/09/09 262

Communications pass over Cebreros

At the end of the last Cebreros pass in the reporting period (DOY 262) Venus Express was orbiting Venus at 214.1 million km from the Earth. The one-way signal travel time was 713 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 performed daily except on DOY 257 and 262. The five measurements in this reporting period concluded the Earth occultation season #7.

VIRTIS
VIRTIS-M was operated in the visual channels only.

VMC
The instrument was regularly operated as part of the routine plan.


Future Milestones

  • Atmospheric drag measurements: 12 to 17 October 2009
  • Superior conjunction: 29 December 2009 to 22 January 2010


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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #201. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
18-Oct-2019 09:15 UT

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