Credit NASA. Caption:This mosaic is a section of west Chryse where, after a month long search for a landing site, a suitable region was certified as safe for the Viking 1 landing. The largest ellipse incudes a region 137 miles long and 62 miles wide, representing an area of 99% landing probability. The smaller ellipse represents a 50% landing probablity. Teh exact target was at 22.4 degrees North 47.5 degrees West and the Lander missed that target by only 18 miles to the west and 4 miles to the North. Chrsye Planitia was once fed by massive floods of water from the highlands surrounding the basin, as evidenced by the ghosts of large, ancient river channels - some of which can be seen in this picture. The landing site, near the lowest part of the basin, is approximately two miles below the Mars mean elevation - based on surface pressure (6.1 mb mean, 7.7 mb at site). from orbit the area is lunar-mare-like, and the site - though strewn with rocks - does offer characteristics that agree with that concept.