I have just heard some more news about Sunday’s Phobos flyby from Mars Express Project Scientist Olivier Witasse. He says, “We are now entering a new phase for the Phobos flybys. The dayside encounter phase means that remote sensing can proceed at full speed!”
The MARSIS, SPICAM, OMEGA, ASPERA experiments will all be working, as will, of course, the camera (HRSC). The Sunday flyby will take place at an altitude of 107 km, and provide the opportunity for high-resolution imaging. It is a delicate operation.
The camera is fixed in position on the spacecraft and cannot move independently. So, to keep tracking Phobos the whole spacecraft will have to turn. Because of the large MARSIS antenna, which measures 40 metres end-to-end, the spacecraft is usually only turned at a rate of once every 40 minutes. On Sunday, the team will exceed this a little to keep Phobos centred in the camera. But the tracking does means that we will all have to be patient before seeing the images.
The spacecraft cannot point in two directions at once. It cannot track Phobos and keep pointing its high gain antenna to Earth. So the images will be stored onboard and then downlinked at the next available ground station pass. “The images will arrive on the ground on Monday,” says Witasse. The data will then pass straight to the camera team, who will begin the processing.
Witasse suggests that images may be available by Wednesday, once the processing is complete. Watch the blog for updates to this schedule. -- Stuart