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No. 190 - End of Quadrature Phase

No. 190 - End of Quadrature Phase

Report for Period 28 June to 4 July 2009The Venus Express spacecraft and instruments performed nominally during the last week of quadrature operations. The spacecraft remained in quadrature configuration until 3 July, DOY 185. As part of the quadrature operations the Venus Express spacecraft flew 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 - were 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, delayed telecommand files were used during the quadrature operations 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) was completed 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 was a set of three observations and was executed with the spacecraft's High Gain Antenna 1 (HGA1). The first observation was completed already in the previous 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:

Date DOY Main Activity
1328 28/06/09 179

Pass skipped

1329 29/06/09 180

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

1330 30/06/09 181

Pass skipped

1331 01/07/09 182

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

1332 02/07/09 183

Pass skipped

1333 03/07/09 184

Communications pass over Cebreros.
End of quadrature.

1334 04/07/09 185

Communications pass over Cebreros.

At the end of the last Cebreros pass in the reporting period (DOY 185) Venus Express was orbiting Venus at 139.51 million km from the Earth. The one-way signal travel time was 465 seconds.

Payload Activities

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

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

The instrument was not operated during the reporting period.

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

RSI measurements for gravity observation campaign #9 were carried out on 29 June and 1 July.

VIRTIS-M was operated in the visual channels only.

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

Legal disclaimer
This report is based on the ESOC mission operations report, MOR #190. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
23-Feb-2024 19:38 UT

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