Hi -

I simply wanted to move this discussion back to the top, so I've reposted my comment here.

IF (and that's a big if) there were hotspots on Mars, a fracture surrounding a large impact crater might be a good place to look, just as on Earth one looks for oil pools in fractures around impact craters.

My ASSUMPTION is that gravitational compression would lead to heat, and even though the fractures may be filled in by wind blown soils, they still might leak internal heat.

You know, if some of you folks would simply understand that CAPS is the best method of dealing with the impact hazard, it would allow me to give some thought to manned Mars mission architectures.