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A highly processed Viking Orbiter image of the landing area This map indicates JPL's current best estimate as to where the Pathfinder lander landed, based on landmarks seen from the Sagan Station. The site is well within the originally specified landing area. It took more than a year to precisely determine where the Viking Landers actually landed. However because of the existence of the highly processed, twenty year old Viking surface maps, the estimate for Pathfinder was accomplished in less than a day. All of the area seen above is within the central broad flow channel of the outflow region onto Ares Vallis. The smoothness of this area underlies much of the reason that this landing site was chosen. The direction of the flood flow that swept this portion of Ares Vallis flat was southwest to northeast. This direction is easily determined from the large "sand bar" that trails "Far Knob" at the lower edge of the photograph and other similar markings. The time at which the flood event occurred (1.5 to 3 bya) can be estimated by measuring and counting the number and sizes of the craters that appear on the plain and comparing that distributional count to other regions of Mars and the Moon. A number of larger craters that were buried by the Ares Vallis flood can also be seen in the image. Evidence that the Ares Vallis flood plain may currently contain a great deal of subsurface water is derived from features such as the larger crater in the upper left of the map. The crater's rays are not the long, dry, powdery pencil-like rays characteristic of craters on the Moon. Rather, the rays are more of a mud flow, similar to other crater rays that have been found on Mars. For such rays to form, the meteoritic impact is presumed to have melted the permafrost layer, creating liquid water for a bit of time on the surface. In this instance, a sinuous valley, characteristic of either water or lava flow, proceeds from raised outer lip of the crater, downhill to a flat basin. Given the general geologic history of the flood plain, water is the more likely candidate for the liquid that flowed through this channel. A more detailed image of this section of the map is available.
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