* Astronomy

Images for September 22-28, 2005

oSouth Polar Details (Released 22 September 2005)
oDevilish Details (Released 23 September 2005)
oPits on Ascraeus (Released 24 September 2005)
oLoire Dust Devil (Released 25 September 2005)
oHigh Latitude Polygons (Released 26 September 2005)
oMars at Ls 288 Degrees (Released 27 September 2005)
oGully in the North (Released 28 September 2005)

MARS GLOBAL SURVEYOR IMAGES September 8-14, 2005

oAram Chaos Rocks (Released 8 September 2005)
oMOC Imaging Resumes (Released 9 September 2005)
oInverted Valley (Released 10 September 2005)
oFlows of Ascraeus (Released 11 September 2005)
oCelebrating 8 Years at Mars: Repeated Weather Events (Released 12 September 2005)
oMars at Ls 288 Degrees (Released 13 September 2005)
oLonely Butte (Released 14 September 2005)

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image acquired on 6 July 2005 shows an isolated water ice cloud extending more than 30 kilometres above the Martian surface.



Clouds such as this are common in late spring over the terrain located southwest of the Arsia Mons volcano. Arsia Mons is the dark, oval feature near the limb nearest the cloud.
The other slightly darker, nearly circular feature is the volcano, Pavonis Mons, and the other dark circular feature near the right of the picture is Ascraeus Mons.

Illumination is from the left/lower left.

NASA has been forced to switch off the scientific instruments on board its Mars Global Surveyor (MGS) spacecraft, just a week before the fly by of the suspected crash site of the Mars Polar Lander, a US mission to the red planet that was lost in 1999.

Mission managers are hoping to get the craft up and running again in time as they will not have the opportunity to fly over the site again for two years.
After 10 September, the crash site near the pole will be plunged into darkness, making it impossible to photograph from orbit.
Pictures of the site are important because elements of the 1999 mission have been recycled for Phoenix, a new Mars mission scheduled to launch in 2007. Images of the crash could help engineers decide whether or not to modify any of the systems for the 2007 flight.

The MGS had to be put into safe-mode after it started to switch between its main onboard computer and its backup for no apparent reason.
Safe mode switches off the scientific instruments, and turns the craft so that its solar panels directly face the sun, for maximum battery recharging. It also limits its communication with Earth to that possible with its low gain antenna.

NASA says that the MGS unexpectedly switched to its back-up computer on 30 July. The main computer was rebooted, but left in safe mode and the back-up machine was left in charge. In late August, it switched back to the main computer, again without warning. This plunged the whole craft into safe mode, and engineers have been working to restore normal function since then.
Both computers have now been rebooted, and the back-up machine is running in contingency mode. The engineers hope to have the main computer into contingency mode soon too, which will switch communications back to the main antenna.

"It's getting to be a fairly old spacecraft and it's been having a number of issues; none of them are considered life-threatening. The spacecraft's operating fine; they can command and communicate with it. The poor engineers will work hard over the weekend and we'll be back on track early next week" - Professor Phil Christensen, principal investigator on MGS's thermal emission spectrometer instrument.

The MGS mission was originally designed to run until January 2001.