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No. 22 - Final Preparations for Orbit Insertion

No. 22 - Final Preparations for Orbit Insertion

Report for period 31 March to 06 April 2006 The Venus approach phase is proceeding according to plan with all activities conducted successfully. The last week has been dedicated to the spacecraft preparation for the capture burn to take place on 11 April. The fuel and oxidiser tanks have been pressurised and the helium tank is being warmed-up to properly sustain the main engine burn.

The last orbit determination performed during the reporting period has confirmed a good targeting and will be now used to produce the parameters to be commanded for the burn.

Performance of the ground segment has been nominal in the reporting period and the configuration of all critical systems for the orbit insertion is still under freeze. The spacecraft is now monitored almost 24 hours a day with the additional support of the New Norcia station and occasional tracking passes from DSN stations.

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
143 31/03/06 090 SC monitoring
144 01/04/06 091 SC monitoring
145 02/04/06 092 SC monitoring
146 03/04/06 093 SC monitoring
147 04/04/06 094 Tanks pressurisation and start of dual station coverage
148 05/04/06 095 Helium tank warm-up
149 06/04/06 096 Switch to Short MTL

At the end of the last Cebreros pass in the reporting period (DOY 096, 13:00) Venus Express was at 114.5 million km from the Earth, 107.3 million km from the Sun, and 2 million km from Venus. The one-way signal travel time was 382 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.

Ground Facilities

Cebreros is regularly used for operations and as from DoY 094 also New Norcia is used daily to track the spacecraft. The tracking time is then also augmented by tracking passes offered by the DSN network with the stations in Goldstone and Canberra. The DDOR campaign continues as foreseen.

Future Milestones

On DoY 097 the essential commands for the VOI burn will be uplinked to the spacecraft with an execution time of DoY 101 between 07:00 and 08:00 UTC. The spacecraft will be then continuously monitored for the next days till DoY 100 when the mass memory will be switched OFF and the FDIR settings will be changed for the VOI phase. These activities are not essential for the burn itself but are performed in order to minimise the risk of autonomous actions taken by the spacecraft that could hamper the execution of the burn.

With the capture burn the spacecraft will be inserted in a highly elliptical orbit around Venus with a period of about 9 days, an apocentre of about 350 000 km and a pericenter below 400 km. The first science observations of the planet will be done during this orbit together with additional changes of velocity required to control the next pericenter and to lower the apocenter altitude.

The overall phase of the orbit insertion phase will last till the beginning of May when Venus Express will finally be on the designed operational orbit.

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 07:07:59 07:14:44
VOI main engine start 07:10:29 07:17:14
Pericentre passage 07:36:37
Eclipse start 07:37:45
Occultation start 07:38:27 07:45:12
Occultation end 07:48:33 07:55:18
Eclipse end 07:55:13
VOI burn end 08:00:42 08:07:28

Due to the sensitivity to the predicted minimum altitude, the expected occultation start and end times may still change by up to a few seconds until the final estimates are made on Monday.

Last Update: 1 September 2019
9-Mar-2021 11:21 UT

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