Mars Probes
Viking found no direct life signs, but
- surface features strongly suggest liquid H2O was flowing in the past
- Fig. 23-22 c shows dry flow channels meandering into a lowland desert
- look very similar to dry riverbeds on Earth
- Evidence for subsurface water surrounding large crater
- Fig. 6.6 shows a closeup of 18 km splash crater Yuty
- overlapping lobes quite dissimilar to any craters on the Moon or Mercury
- Moon’s craters showed radial “rays” from ballistic debris
- flow filled in crater just South of Yuty
- most likely flowing mud
- subsurface ice melted by impact, mixed with regolith to form mud
- Fig. 23-22 a shows more dry river channels
- Ages estimated at 1-3 billion years from crater counts