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.
|Main activities during reporting period|
|1965||27-Mar-2011||86||CEB communications pass. OCM at pericentre.|
|1966||28-Mar-2011||87||CEB communications pass. OCM at apocentre.|
|1967||29-Mar-2011||88||CEB communications pass.|
|1968||30-Mar-2011||89||CEB communications pass.|
|1969||31-Mar-2011||90||CEB communications pass. Telemetry bit rate set to 114 kbps.|
|1970||1-Apr-2011||91||CEB communications pass.|
|1971||2-Apr-2011||92||CEB communications pass.|
|1972||3-Apr-2011||93||CEB communications pass. VIRTIS-M cooler tests.|
|1973||4-Apr-2011||94||CEB communications pass. Pass affected by bad weather.|
|1974||5-Apr-2011||95||CEB communications pass. Shortened pass for Mars Express.|
|1975||6-Apr-2011||96||CEB communications pass.|
|1976||7-Apr-2011||97||CEB communications pass.|
|1977||8-Apr-2011||98||CEB communications pass. New time correlation.|
|1978||9-Apr-2011||99||CEB communications pass.|
|1979||10-Apr-2011||100||CEB communications pass.|
|1980||11-Apr-2011||101||CEB communications pass.|
|1981||12-Apr-2011||102||CEB communications pass. Shortened pass for maintenance.|
|1982||13-Apr-2011||103||CEB communications pass. Shortened pass for maintenance.|
|1983||14-Apr-2011||104||CEB communications pass.|
|1984||15-Apr-2011||105||CEB communications pass. VIRTIS-M cooler tests|
|1985||16-Apr-2011||106||CEB communications pass.|
|1986||17-Apr-2011||107||CEB communications pass.|
|1987||18-Apr-2011||108||CEB communications pass.|
|1988||19-Apr-2011||109||CEB communications pass. NNO DDOR executed before communications pass.|
|1989||20-Apr-2011||110||CEB communications pass.|
|1990||21-Apr-2011||111||CEB communications pass.|
|1991||22-Apr-2011||112||CEB communications pass.|
|1992||23-Apr-2011||113||CEB communications pass.|
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.
|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.|
|SPICAV||The instrument was regularly operated as part of the routine plan.|
|VMC||The instrument was regularly operated as part of the routine plan.|
|VeRa||The instrument was not operated.|
|VIRTIS||The instrument was regularly operated as part of the routine plan. Virtis-M cooler test was performed.|
Atmospheric Drag Experiment (ADE) #5 will start on 23 May 2011. Superior solar conjunction will start on 6 August 2011.