No. 21 - Targeting for Venus Orbit Insertion
A Trajectory Correction Manoeuvre of about 13 cm s-1 has been executed in the evening of 29 March to reduce the pericenter altitude at Venus arrival by a bit more than 100 kilometres. The latest calibration of the nominal TCM gives the following results (uncertainties are 1-sigma):
- magnitude error = -1.2 mm/s (-0.9% +/- 2.1%)
- direction error = 0.8 deg +/- 0.3 deg
Performance of the ground segment has been nominal in the reporting period and the configuration of all critical systems for the orbit insertion is now under "freeze".
DDOR measurements with ESA and DSN ground stations are continuously conducted.
The table below shows a chronology of the main activities in the reporting period:
| MET (Day) | Date | DOY | Main Activity |
| 136 | 24/03/06 | 083 | SC monitoring and S-TX2 Switch ON |
| 137 | 25/03/06 | 084 | SC monitoring |
| 138 | 26/03/06 | 085 | SC monitoring |
| 139 | 27/03/06 | 086 | SC monitoring |
| 140 | 28/03/06 | 087 | SC monitoring and possibly last WOL before VOI |
| 141 | 29/03/06 | 088 | Trajectory Correction Manoeuvre (VOI-13d) |
| 142 | 30/03/06 | 089 | SC monitoring |
At the end of the last Cebreros pass in the reporting period (DOY 089, 13:00) Venus Express was at 104 million km from the Earth, 105.9 million km from the Sun, and 4.8 million km from Venus. The one-way signal travel time was 347 seconds.
Payload Activities
ASPERA
The instrument is off.
MAG
The instrument is off.
PFS
The instrument is off.
SPICAV
The instrument is off.
VeRA
The USO is kept powered but muted.
VIRTIS
The instrument is off.
VMC
The instrument is off.
Special Events
The Cebreros pass of DoY 089 has been fully conducted with automated operations as scheduled by the Station Computer (STC) based on input from the Venus Express Mission Planning System. Operations included ground station configuration for Venus Express, TM reception, uplink sweep, Doppler and Ranging measurements, and end of pass activities. This is a first for the ESA deep space missions and stations. It will hopefully constitute the first of a long series.
Future Milestones
Next week, operations for the Venus capture manoeuvre will begin and as from DoY 094 a dual station coverage will be guaranteed by the ESA deep space network. This coverage will be augmented by tracking passes with DSN stations.
At the end of next reporting period, DoY 096, the commands for the capture burn will be finalised and prepared for uplink the day after.
An opportunity for a Trajectory Correction Manoeuvre is foreseen on DoY 095 but it is very unlikely that it will be used.
The current nominal times for the events during Venus Orbit Insertion on Tuesday 11 April 2006 (DoY 101) are:
| Event | Spacecraft Time (UTC) |
Ground Receive Time (UTC) |
| VOI LSP start | 07:08:16 | 07:15:01 |
| VOI main engine start | 07:10:46 | 07:17:31 |
| Pericentre passage | 07:36:37 | |
| Eclipse start | 07:37:53 | |
| Occultation start | 07:38:37 | 07:45:23 |
| Occultation end | 07:48:25 | 07:55:10 |
| Eclipse end | 07:55:13 | |
| VOI burn end | 08:00:39 | 08:07:25 |