Alpha Proton X-Ray Spectrometer (APXS)
An instrument on the Sojourner rover used to analyze the elemental composition of Martian rocks and soil. It operated by bombarding samples with radiation and measuring emitted particles.
Source: mars.nasa.gov
APODs including "Alpha Proton X-Ray Spectrometer (APXS)"
Barnacle Bill And Sojourner
08/07/1997
Deployed on a pop-up mast to its full height, the Sagan Memorial Station's IMP camera now stands about 5 feet above the surface of Ares Vallis - on Mars. This is one of the first images from its new vantage point, showing the rover Sojourner near a rock named Barnacle Bill. This particularly interesting rock, with a variety of surface textures, appears to be about 8 to 10 inches high. Sojourner performed an analysis of Barnacle Bill by successfuly maneuvering to place its Alpha Proton X-Ray Spectrometer (APXS) instrument against the rock. The APXS, located at the rear of the rover, is not visible in this picture. Sojourner's next destination is ... a rock named Yogi. Results describing the composition of Barnacle Bill, the martian soil and a color panorama of the landing site will be presented at a Pathfinder press briefing today scheduled for 11:00 AM Pacific Daylight Time.