NASA to check for unlikely winter survival of Phoenix Mars Lander
Tue Jan 12, 2010 at 08:43 UTC
Beginning Jan. 18, NASA's Mars Odyssey orbiter will listen for possible, though improbable, radio transmissions from the Phoenix Mars Lander, which completed five months of studying an arctic Martian site in November 2008.
The solar-powered lander operated two months longer than its three-month prime mission during summer on northern Mars before the seasonal ebb of sunshine ended its work. Since then, Phoenix's landing site has gone through autumn, winter and part of spring. The lander's hardware was not designed to survive the temperature extremes and ice-coating load of an arctic Martian winter.
In the extremely unlikely case that Phoenix survived the winter, it is expected to follow instructions programmed on its computer. If systems still operate, once its solar panels generate enough electricity to establish a positive energy balance, the lander would periodically try to communicate with any available Mars relay orbiters in an attempt to reestablish contact with Earth. During each communications attempt, the lander would alternately use each of its two radios and each of its two antennas.
Odyssey will pass over the Phoenix landing site approximately 10 times each day during three consecutive days of listening this month and two longer listening campaigns in February and March.
High resolution image
With early spring at the Phoenix landing site comes progressive sublimation of 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.
In HiRISE images acquired during the last Martian summer, the solar arrays on the lander were clearly discernable from their distinctive bluish color. For example, see the subimage PSP_008855_2485 from June 16, 2008.
The springtime image here has green boxes around the backshell (top), heat shield, and lander (bottom). The solar arrays are not discernable in this new image, probably because the patchy frost effectively camouflages them. 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, dust or both. This and future images will help calibrate expectations for finding the Mars Polar Lander hardware, which encountered Mars in 1999.
This image covers a swath of ground about 300 meters (about 1,000 feet) wide, at 68.2 degrees north latitude, 234.3 degrees east longitude. It is one product from HiRISE observation ESP_016160_2485. Other image products from this observation are available at http://hirise.lpl.arizona.edu/phoenix-spring.php.
Credit: NASA/JPL-Caltech/University of Arizona
The amount of sunshine at Phoenix's site is currently about the same as when the lander last communicated, on Nov. 2, 2008, with the sun above the horizon about 17 hours each day. The listening attempts will continue until after the sun is above the horizon for the full 24.7 hours of the Martian day at the lander's high-latitude site. During the later attempts in February or March, Odyssey will transmit radio signals that could potentially be heard by Phoenix, as well as passively listening.
If Odyssey does hear from Phoenix, the orbiter will attempt to lock onto the signal and gain information about the lander's status. The initial task would be to determine what capabilities Phoenix retains, information that NASA would consider in decisions about any further steps.
| Source: Jet Propulsion Laboratory | |
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