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No. 233 - Orbital Correction Manoeuvres

No. 233 - Orbital Correction Manoeuvres

Report for the period 27 March to 23 April 2011 (week 13 - week 16)The reporting period, covering four weeks of Venus Express mission operations, was devoted to routine science activities.

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

MET
(Day)

Date
(DD-MON-YYYY)

DOY

Main Activity

MET = Mission elapsed time; DOY = Day of year

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.

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.
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.

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.

Last Update: 1 September 2019
9-Mar-2021 11:26 UT

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