Wednesday, March 24, 2010

Phoenix Lander in Springtime

With early spring at the Phoenix landing site comes the progressive sublimation of the carbon dioxide frost that has blanketed the lander and surrounding terrain throughout the winter.

During the long polar-winter night atmospheric carbon dioxide freezes onto the surface building up a layer of frost roughly 30 centimeters (about one foot) thick. In the spring this frost returns to atmosphere gas (sublimates) over the course of several months. This image, part of a seasonal frost monitoring sequence, shows some areas of bare ground are beginning to be exposed. However, extensive frost patches remain in the topographic lows, such as the troughs of the local polygonally patterned surface.

The solar arrays on the lander were clearly discernible from their distinctive bluish color in HiRISE images acquired last Martian northern summer. The enhanced color subimage [the image above] has green boxes around the backshell (top), heat shield, and lander (bottom). They are not discernible in this new image, probably because the patchy frost effectively camouflages them. (For a comparison, see PSP_008855_2485, particularly the subimage there.)

Even when the frost has completely sublimated, dust deposited during the winter may obscure them. The parachute attached to the backshell is also not apparent in this image, and we'll see if it reappears in later images. Also gone are the dark halos around the lander, backshell, and heat shield, again due to seasonal frost and/or dust. This and future images will help calibrate expectations for finding the Mars Polar Lander hardware which encountered Mars in 1999.

Photo credit: NASA/JPL/University of Arizona

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