The High Resolution Imaging Science Experiment, or HiRISE, run from the University of Arizona, is releasing two views of the Phoenix Mars Lander, the 2008 NASA mission also run from the UA, which show the lander shrouded in dry-ice frost on Mars.
The HiRISE camera aboard NASA's Mars Reconnaissance Orbiter captured one image of the Phoenix lander on July 30, 2009, and the other on Aug. 22, 2009. That's when the sun began rising over the northern polar plains at the end of the northern hemisphere winter, the imaging team said.
The new images are available at the HiRISE Web site.
"We decided to try imaging the site despite the low light levels," said. HiRISE team members Ingrid Spitale of the UA Lunar and Planetary Laboratory.
"The power of the HiRISE camera helped us see it even under these poor light conditions,"said Michael Mellon of the University of Colorado in Boulder, a member of both the HIRISE and the Phoenix Mars Lander science teams.
The HiRISE team targeted their camera at the known location of the lander to get the new images and compared them to a HiRISE image of the frost-free lander taken in June 2008.
That enabled them to identify the hardware disguised by frost, despite the fact that their views were hindered by poor lighting and also by atmospheric haze, which often obscures the surface at this location and season.
Carbon dioxide frost completely blankets the surface in both images. The amount of carbon dioxide frost builds as late winter transitions to early spring, so the layer of frost is thicker in the Aug. 22 image. The first day of spring on Mars was Oct. 26.
HiRISE scientists noted that brightness doesn't necessarily indicate the amount of frost seen in the images because of the way the images are processed to produce optimal contrast. Even the darker areas in the frost-covered images are still brighter than typical soil that surrounds the lander in the frost-free image.
Other factors that affect the relative brightness include the size of the individual grains of carbon dioxide ice, the amount of dust mixed with the ice, the amount of sunlight hitting the surface, and different lighting angles and slopes, Spitale and Mellon said.
Studying the changes will help scientists understand the nature of the seasonal frost and winter weather patterns in this area of Mars.
Scientists predicted that the ice layer would reach maximum thickness in September 2009, but don't have images to confirm that because HiRISE camera operations were suspended when Mars Reconnaissance Orbiter entered an extended safe mode on Aug. 26, following a series of four spacecraft anomalies.
The Phoenix Mars Lander ceased communications last November, after successfully completing its mission and returning unprecedented primary science data to Earth. Launched Aug. 4, 2007, Phoenix safely touched down on Mars on May 25, 2008, at a site farther north than where any previous spacecraft had landed. During the first quarter of 2010, teams at JPL will listen to see if Phoenix is still able to communicate with Earth. Springtime thaw images may also be available.
HiRISE is run from the Lunar and Planetary Laboratory's HiROC, or HiRise Operations Center, on the UA campus. Planetary sciences professor Alfred McEwen is HiRISE principal investigator. Planetary sciences professor Peter Smith, also of the Lunar and Planetary Laboratory, is principal investigator for the Phoenix Mars Lander mission.
Mars Reconnaissance Orbiter is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, for the NASA Science Mission Directorate. Lockheed Martin Space Systems, based in Denver, is the prime contractor and built the spacecraft. Ball Aerospace and Technologies Corp., of Boulder, Colo., built the HiRISE camera.