The Aerobraking Phase
During the two part Aerobraking phase, the MGS spacecraft skimmed through
the Martian atmosphere and used the drag force on the extended solar panels
to slowly reduce the eliptical orbit from 44 hours down to 16 hours.
The second part eventually converted the long, eliptical orbit into a 2 hour circular,
polar orbit for Mapping operations. TES regularly collected data throughout
the MGS aerobraking event to assist the earthbound spacecraft engineers
as they guided MGS through this dangerous dance. The TES dataset proved
to be so valuable that it was collected for every Mars mission that
launched during the TES lifetime: the Mars 2001 Odyssey, the 2003 Mars Rovers,
and the 2005 Mars Reconnisance Orbiter.
SEP 19, 1997
These images represent the Martian surface temperature
as measured by the TES. The purple areas are the coldest,
about -200°F (140K), while the red areas are the warmest at about
30°F (270K). Click on the image for a larger version.
The two image panels shown above represent two points along each MGS
Aerobraking orbit (see figure
- The left panel is approximately centered on the south pole and was obtained
when TES was approaching the farthest point away from Mars in the orbit.
The warm, sunlit day side is to the right of the pole, and the cool, night
side is to the left of the pole. The shape of image results from observing
the full disk of Mars.
- The right panel was obtained when TES was approaching the closest point to
Mars in the orbit. The equator is centered horizonally in this view,
and the north and south polar regions are off the image at the top and bottom
respectively. Unlike the left panel, the image shape results from the
circular shape of the TES field of view (like a telescope); the right
image only shows a partial view of the full disk of Mars.
The progression of Mars seasons through time are dramatically displayed by
observing the changes in the left panels from the earliest to the latest orbits.
When MGS first arrived at Mars (Sept 1997, Orbit 5
the season was northern hemisphere fall/southern hemisphere spring.
Stepping forward through the images shows the temperatures dropping
in the north, and simultaneously rising in the south. The carbon dioxide
ice cap that developed during the previous winter, slowly sublimates and
shrinks as we complete this phase of aerobraking (Feb 1998,