Free Astronomy Magazine March-April 2021

P revious page. Up, Sojourner atop the “Mermaid Dune” on Sol 30. Below, 360° view of the Mars Pathfinder landing site. This page, above, type areas of rocks and soils. (A) Dark rock type, e.g. “Barnacle Bill”. Reflectance spectra typical of fresh basalt. (B) Bright rock type, e.g. “Wedge”. Reflectance spectra typical of weathered basalt. (C) Pink rock type, e.g. “Scooby Doo”. (D) Dark soil type, typically found on the wind- ward sides of rocks or in rock-free areas. (E) Disturbed soil type: the result of changes in soil texture and compaction caused by movement of the rover and retraction of the lander airbag. (F) Lamb-like soil type, with characteristics intermediate between the bright and dark soils. To the right, Sojourner analyzes “Yogi Rock” with the Alpha Pro- ton X-ray Spectrometer (APXS). This rock was the first on Mars found to be made of basalt, which suggests previous volcanic activity in the region as basalt is an igneous rock. [NASA/JPL]