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No. 189 - Gravity observation campaign

No. 189 - Gravity observation campaign

Report for Period 21 June to 27 June 2009The Venus Express spacecraft and instruments performed nominally during this week of quadrature operations. As part of the quadrature operations the Venus Express spacecraft is flying a tilted attitude during Earth contact with the Cebreros ground station. The 10° attitude tilt with respect to the non-quadrature Earth pointing attitude requires an extended cool-down period for the spacecraft afterwards, before resuming with science pointings. As a result, Cebreros passes - each lasting about 8 hours and nominally performed once every 24-hour orbit - are routinely skipped to allow more time for science pointings. Only four passes were performed in this reporting period as opposed to the usual seven daily passes.

With less passes available to uplink all the required commands, Venus Express is using delayed telecommand files to store and call the commands on-board at a specific time.

VeRa gravity observation campaign
The mission's ninth gravity observation campaign (GRA#9) started this week. 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#9 campaign is a set of four observations and is executed with the spacecraft's High Gain Antenna 1 (HGA1). The first observation was completed in this reporting period on 27 June.

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
1321 21/06/09 172

Communications pass over Cebreros

1322 22/06/09 173

Pass skipped

1323 23/06/09 174

Communications pass over Cebreros.
Shortened pass.
Uplink of GRA#9 commands

1324 24/06/09 175

Pass skipped

1325 25/06/09 176

Communications pass over Cebreros

1326 26/06/09 177

Pass skipped

1327 27/06/09 178

Communications pass over Cebreros.
Canberra RSI pass (GRA#9)

At the end of the last Cebreros pass in the reporting period (DOY 178) Venus Express was orbiting Venus at 130.9 million km from the Earth. The one-way signal travel time was 436 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 for gravity observation campaign #9 were carried out on 27 June.

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

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

Future Milestones

  • End of current outbound quadrature phase: 3 July 2009

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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #189. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
10-Jul-2020 01:18 UT

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