status reports 23-May-2013 22:37:21

No. 194 - Earth Occultation Season #7

05 August 2009

Report for Period 26 July to 1 August 2009

The Venus Express spacecraft and instruments performed nominally during this week. The seventh Earth occultation season is ongoing, with three observations performed in this reporting period. An orbit control manoeuvre (OCM) was carried out in the night of 25-26 July between 23:06 and 02:07 UT. This manoeuvre constitutes a phase correction to keep the phasing of Venus Express in its orbit in sync with mission operations from ground.

VeRa Earth occultation season #7
The mission's seventh season of Earth occultation experiments started on 16 July 2009 (DOY 197). 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 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
1356 26/07/09 207

Orbit control manoeuvre.
Communications pass over Cebreros

1357 27/07/09 208

Communications pass over Cebreros.
RSI occultation measurements with NNO

1358 28/07/09 209

Communications pass over Cebreros

1359 29/07/09 210

Communications pass over Cebreros.
RSI occultation measurements with NNO

1360 30/07/09 211

Communications pass over Cebreros

1361 31/07/09 212

Communications pass over Cebreros.
RSI occultation measurements with NNO

1362 01/08/09 213

Communications pass over Cebreros

At the end of the last Cebreros pass in the reporting period (DOY 213) Venus Express was orbiting Venus at 169.9 million km from the Earth. The one-way signal travel time was 566 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 on DOY 208, 210 and 212.

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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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #194. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 19 October 2009

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