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No. 214 - Mission Operations Update

No. 214 - Mission Operations Update

Report for Period 13 December to 19 December 2009The Venus Express spacecraft and instruments performed nominally during this week. The mission planning activities were focussed on the planning for the next two weeks leading up to the solar conjunction period, and for the conjunction period itself, which runs from 29 December 2009 to 22 January 2010.

During the reporting period an orbital correction manoeuvre (OCM) was successfully performed on 13 December (DoY 347). The manoeuvre constituted a phase correction, intended to keep the phasing of Venus Express in its orbit in sync with mission operations from ground.

DDOR
On 13 December 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
1496 13/12/09 347

OCM executed around 06:00 UT.
DDOR with the Cebreros and New Norcia ground stations, between 08:10 UT and 09:10 UT.
Communications pass over Cebreros

1497 14/12/09 348

Communications pass over Cebreros.
Pass shortened because of planned maintenance activities

1498 15/12/09 349

Communications pass over Cebreros.
Pass shortened because of planned maintenance activities

1499 16/12/09 350

Communications pass over Cebreros

1500 17/12/09 351

Communications pass over Cebreros.
Pass shortened

1501 18/12/09 352

Communications pass over Cebreros.
Telecommand bitrate decreased from 2000 to 1000 bps

1502 19/12/09 353

Communications pass over Cebreros

At the end of the last Cebreros pass in the reporting period (DOY 353) Venus Express was orbiting Venus at 254 million km from the Earth. The one-way signal travel time was 847 seconds.

Spacecraft

Attitude and Orbit Control System (AOCS)
The AOCS is in its nominal configuration and performing nominally. Operations continue with all four reaction wheels. The friction levels on the four reaction wheels remained stable throughout the reporting period.

From DOY 352 onwards a slight increase in the friction level on reaction wheel 1 (RW1) was observed, but it stayed well below the set limits and the maximum friction of 0.03 Nm observed in the past.

RW2 continued to show several spikes in its friction level (see status report no. 212).

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 radio science observations were made 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

  • Venus at superior conjunction on 11 January 2010. Venus Express superior conjunction operations: 29 December 2009 to 22 January 2010


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Legal disclaimer
This report is based on the ESOC mission operations report, MOR #214. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
29-Oct-2020 17:58 UT

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