Timeline of events during today's Venus Orbit Insertion (VOI) manoeuvre, marking arrival of ESA's Venus Express spacecraft at its destination.
VOI is a series of telecommands, engine burns and manoeuvres designed to slow the spacecraft from a velocity of 29 000 kilometres per hour relative to Venus to an entry velocity some 15 percent slower, allowing it to be captured into orbit around the planet.
VEX slew manoeuvre starts
This rotation, to last about half an hour, will re-orient the spacecraft to have the main engine facing the direction of motion, and so allow the braking manouevre.
Venus Express main engine burn starts
Venus Express main engine is due to fire for 50 minutes.
Occultation starts (loss of S-band signal)
An occultation occurs when Venus Express travels behind the planet so that the line of sight to Earth is blocked; it will lose radio contact (S-band) for almost 10 minutes. During the journey to Venus, communication has been in X-band, via the high-gain antenna HGA2. During VOI, neither of the two high-gain antennas can be used because of the spacecraft orientation. Only the low gain antenna (S-band) can carry a feeble signal to Earth to tell about the spacecraft velocity.
Controllers will closely watch for reacquisition of radio contact once the occultation ends.
|10:07||VEX main engine burn ends|
|10:10||Announcement by Flight Operations Director|
X-band transmitter on
The X-band transmitter connected to the high-gain antenna HGA2 will be switched on, and will start sending information to Earth about the health status of the spacecraft.
All times above are 'Earth Received' time - i.e. after the actual events have taken place at the spacecraft. During orbit insertion, the spacecraft will be 125 000 000 kilometres from Earth and the round-trip signal time will be 13 minutes and 32 seconds.