Sojourner. Mars Pathfinder mosaic image of the robotic Sojourner vehicle on the surface of Mars analyzing the rock known as 'Barnacle Bill' (at upper left). 'Barnacle Bill' was the first rock to be studied by Sojourner with its Alpha Proton X- Ray Spectrometer (APXS). The APXS determines the chemical composition of rocks & soil by bombarding them with alpha particle radiation and monitoring the spray of particles released in response. All elements except hydrogen can be detected during the 10 hours the APXS takes to complete an analy- sis. Image taken by the Imager for Mars Pathfinder (IMP) on the third Martian day (Sol 3) spent on Mars since it landed on 4 July 1997.
Sojourner on the surface of Mars. Photography. Britannica ImageQuest. Encyclopædia Britannica, Inc., 25 May 2016.
http://quest.eb.com/search/132_1247906/1/132_1247906/cite. Accessed 24 Aug 2016.
Mars mission BBC documentaries
Books on space flight