28 May 1999
Vol 284, Issue 5419

About The Cover

Cover image expansion

COVER The topography of Mars revealed by Mars Orbiter Laser Altimeter measurements taken through 15 April 1999 from Mars Global Surveyor. Shading was obtained by "illuminating" the topography from the northeast. The upper image shows the Hellas impact basin (dark blue, ~2300 km across), and the lower image shows Tharsis volcanic province and Valles Marineris. See page 1495 [Graphics: G. A. Neumann, Massachusetts Institute of Technology and NASA/Goddard Space Flight Center]