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No. 188 - Quadrature Operations

No. 188 - Quadrature Operations

Report for Period 14 June to 20 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 three 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.

DDOR
On 19 June delta differential one-way ranging (DDOR) was performed using the New Norcia and Cebreros ground stations to track the spacecraft. These measurements are performed monthly to support the accurate determination of the ephemeris for the planet Venus that is maintained by NASA's Solar System Dynamics Group.

The DDOR measurement principle uses a technique to highly accurately determine the position of a transmitter in space and relies on observing the time delay between reception of the signal from the transmitter by two ground stations at different positions on Earth. In this case the Venus Express spacecraft is the transmitter and the two ground stations are New Norcia in western Australia and Cebreros in Avila, Spain.

The table below shows a chronology of the main activities:

MET
(Day)
Date DOY Main Activity
1314 14/06/09 165

Pass skipped

1315 15/06/09 166

Communications pass over Cebreros

1316 16/06/09 167

Pass skipped

1317 17/06/09 168

Communications pass over Cebreros

1318 18/06/09 169

Pass skipped

1319 19/06/09 170

Communications pass over Cebreros.
First hour of the Cebreros pass used for DDOR observation, together with New Norcia

1320 20/06/09 171

Pass skipped

At the end of the last Cebreros pass in the reporting period (DOY 171) Venus Express was orbiting Venus at 122.7 million km from the Earth. The one-way signal travel time was 409 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
No measurements were taken during the reporting period.

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 #188. 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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