The European Space Agency's Mars Express orbiter is to monitor the 13min entry, descent and landing of NASA's Phoenix Mars lander. ESA's French Guiana ground station will support the US mission's launch.

During its descent through the Martian atmosphere Phoenix will transmit information to two of NASA's spacecraft already orbiting Mars but the US agency has requested that Mars Express, which has been in orbit around the planet since December 2003, also monitor the entry, descent and landing. Phoenix's launch is planned for 4 August.

Expected to arrive in the second quarter of 2008, Phoenix will investigate the Martian environment in the northern polar region and search the subsurface for conditions favourable to past or present life. The Phoenix lander does not have a rover.

Mars Express will optimise its orbit so that Phoenix is continuously in view during the entry, descent and landing.

ESA says: "Mars Express has been selected since, in principle, its elliptical orbit makes it possible for the spacecraft to have a continuous view of the lander and to communicate with it for longer periods of time."

The orbiter will use its Mars Express Lander Communications system to listen to the lander, not only during EDL, but potentially for the remainder of the anticipated 90-day mission. The system was originally designed to communicate with Mars Express' Beagle 2 lander, which was lost during its entry, descent and landing phase in December 2003.

The final orbit adjustment required for Mars Express to monitor Phoenix will be determined a few weeks after the lander's launch. Final adjustments will be made in April next year, just before the vehicle's entry, descent and landing.

Source: Flight International