No. 229 - Start of outbound quadrature phase
An outbound quadrature phase began on 30 December 2010. Quadrature phases are periods of about five weeks during which the Sun-spacecraft-Earth angle is between 75° and 95°. They occur twice in every synodic period [see note 1] of Venus (584 days, or about 19 months), with an inbound quadrature phase ending 9 weeks before an inferior conjunction [see note 2] of Venus and an outbound quadrature phase starting 9 weeks after an inferior conjunction. This outbound quadrature phase started nine weeks after the inferior conjunction that occurred on 30 October 2010.
Summary of main activities
During the reporting period, routine mission operations were conducted using the ESA Cebreros ground station (CEB). The beginning of transmission for a number of Cebreros communications passes was delayed at the request of the Venus Express Science Operations Centre (VSOC). The delayed start of the communication passes allowed the Venus Monitoring Camera (VMC) team to take images with optimal angles to track cloud movements. A number of Cebreros communications passes were shortened, either at the request of VSOC or due to scheduled maintenance of the ground station. Delta differential one-way ranging (DDOR) was performed on 7 December 2010. A tracking test was performed using the Perth ground station (PER) on 9 December 2010. An orbital correction manoeuvre (OCM) was performed on 12 December 2010.
| Main activities during reporting period | |||
|
MET |
Date |
DOY |
Main Activity |
|
MET = Mission elapsed time; DOY = Day of year | |||
| 1853 | 5-Dec-2010 | 339 | CEB communications pass. |
| 1854 | 6-Dec-2010 | 340 | CEB communications pass. Later BOT at VSOC request. Telemetry bit rate set to 91 kbps before CEB pass. |
| 1855 | 7-Dec-2010 | 341 | CEB communications pass. DDOR before communications pass. |
| 1856 | 8-Dec-2010 | 342 | CEB communications pass. Later BOT at VSOC request. |
| 1857 | 9-Dec-2010 | 343 | CEB communications pass. PER tracking test before communications pass. |
| 1858 | 10-Dec-2010 | 344 | CEB communications pass. Later BOT at VSOC request. |
| 1859 | 11-Dec-2010 | 345 | CEB communications pass. |
| 1860 | 12-Dec-2010 | 346 | CEB communications pass. OCM performed. |
| 1861 | 13-Dec-2010 | 347 | CEB communications pass. Telemetry bit rate set to 76 kbps before CEB pass. |
| 1862 | 14-Dec-2010 | 348 | CEB communications pass. Shortened due to CEB maintenance. |
| 1863 | 15-Dec-2010 | 349 | CEB communications pass. Shortened due to CEB maintenance. |
| 1864 | 16-Dec-2010 | 350 | CEB communications pass. |
| 1865 | 17-Dec-2010 | 351 | CEB communications pass. |
| 1866 | 18-Dec-2010 | 352 | CEB communications pass. |
| 1867 | 19-Dec-2010 | 353 | CEB communications pass. Telemetry bit rate set to 57 kbps before CEB pass. |
| 1868 | 20-Dec-2010 | 354 | CEB communications pass. |
| 1869 | 21-Dec-2010 | 355 | CEB communications pass. |
| 1870 | 22-Dec-2010 | 356 | CEB communications pass. |
| 1871 | 23-Dec-2010 | 357 | CEB communications pass. |
| 1872 | 24-Dec-2010 | 358 | CEB communications pass. |
| 1873 | 25-Dec-2010 | 359 | CEB communications pass. |
| 1874 | 26-Dec-2010 | 360 | CEB communications pass. |
| 1875 | 27-Dec-2010 | 361 | CEB communications pass. |
| 1876 | 28-Dec-2010 | 362 | CEB communications pass. |
| 1877 | 29-Dec-2010 | 363 | CEB communications pass. |
| 1878 | 30-Dec-2010 | 364 | CEB communications pass. Telemetry bit rate set to 45 kbps before CEB pass. Quadrature entry. Shortened pass at VSOC request. |
| 1879 | 31-Dec-2010 | 365 | CEB communications pass. |
| 1880 | 1-Jan-2011 | 1 | CEB communications pass. |
At the end of the reporting period on 1 January 2011, Venus Express was at 93 million kilometres from Earth. The one-way signal travel time was 310 seconds.
At the end of the reporting period, the final oxidizer mass was estimated to be 34.732 kilograms, and the final fuel mass estimate was 21.687 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 | No operations. |
| VIRTIS | The instrument was regularly operated as part of the routine plan. |
Future Milestones
The swap from using the small high-gain antenna (HGA2) for Earth communications to HGA1 will be performed on 12 January 2011. Earth occultation season #10 will start on 17 January 2011. The spacecraft will exit outbound quadrature on 6 February 2011.
Occultation #10 will start in January 2011.
Notes
- The synodic period is the time between two successive identical configurations as seen from the Earth.
- A conjunction is the alignment of two Solar System bodies (in this case Venus and the Sun) so that they have the same longitude as seen from Earth. An inferior conjunction occurs when Venus is between the Sun and the Earth; superior conjunction refers to when Venus is on the opposite side of the Sun from Earth.
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This report is based on four ESOC mission operations reports, MOR #265 through MOR #268. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.