This image, and many like it, are one way NASA's Phoenix Mars Lander is
measuring trace amounts of water vapor in the atmosphere over far-northern
Mars. Phoenix's Surface Stereo Imager (SSI) uses solar filters, or filters
designed to image the sun, to make these images. The camera is aimed at
the sky for long exposures.
SSI took this image as a test on June 9, 2008, which was the Phoenix
mission's 15th Martian day, or sol, since landing, at 5:20 p.m. local
solar time. The camera was pointed about 38 degrees above the horizon. The
white dots in the sky are detector dark current that will be removed
during image processing and analysis.
The Phoenix Mission is led by the University of Arizona, Tucson, on behalf
of NASA. Project management of the mission is by NASA’s Jet Propulsion
Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin
Space