ESA Science & Technology - No. 233 - Orbital Correction Manoeuvres

Tests to verify the status of the VIRTIS-M cooler were carried out on 3 and 15 April 2011. The cooler failed some time ago, and tests are performed occasionally to verify that the status has not changed. Each test lasted about 40 minutes; the cooler was commanded to operate with the helium pump at various rotation speeds during a time when the instrument did not have visibility and was not being operated for science acquisition. The tests confirmed no improvement in the condition of the VIRTIS-M instrument cooler.

Summary of main activities

During the reporting period, routine mission operations were conducted using the ESA Cebreros ground station (CEB). Orbital Correction Manoeuvres (OCM) were performed on 27 March 2011 (pericentre) and 28 March 2011 (apocentre). The burns are pericenter are used to change the distance of the orbit apocentre, and vice versa. Delta Differential One-way Ranging (DDOR) was performed on 19 April 2011, using the ESA New Norcia (NNO) ground station.

Bad weather at the Cebreros ground station caused the data downlink on 4 April 2011 to be interrupted. When the data and telemetry are downlinked, the reception is verified before the information is deleted on the spacecraft. When severe local rain disrupts the X-band downlink, as was experienced here, the data are retained on the spacecraft and downlinked later in the pass or on a subsequent pass. For this case, these science data were downloaded during subsequent communications passes.

A time correlation was performed during this reporting period. This synchronizes the light-weight clock on-board the spacecraft with the very accurate - but heavy - atomic clocks on Earth.

At the end of the reporting period on 23 April 2011, Venus Express was 208.5 million kilometres from Earth. The one-way signal travel time was 695 seconds.

At the end of the reporting period, the final oxidizer mass was estimated to be 33.910 kilograms, and the final fuel mass estimate was 21.150 kilograms.

Payload Activities

Future Milestones

Atmospheric Drag Experiment (ADE) #5 will start on 23 May 2011. Superior solar conjunction will start on 6 August 2011.

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This report is based on four ESOC mission operations reports, MOR #281 through MOR #284. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.