Dan sez: "But the Tharsis has been inactive for quite a long period..."

I'm not sure that anyone completely understands the Tharsis Bulge and its active history. There are some indication it may once have been a polar terrain. If so, no wonder there was so much water to discharge. There are plenty of arguments that allow activity on Tharsis today. It would be very interesting, I think, if that activity were primarily venting and collapse rather than firey volcanic lava flows and whatnot. That would indicate that Tharsis may be cooling, that its heat source has possibly withdrawn or turned off. Current activity would be confined to relatively rare escape of volatiles and collapse of the surface into interior voids. That there are such voids and that they are extensive is certain. That volatiles could cycle and circulate through Tharsis should be self evident. That MOC could capture at least one venting event should not be surprising. In fact, I suspect that MOC has captured hundreds of images of rather extensive venting and outgassing in many areas. Remember "Dan's Smoker?"

Given past experience, I wouldn't be surprised if Malin makes an announcement in a few months.

And the press will have a field day. But some of the initial indications and discoveries were on hand almost five years ago.

What does a currently active Mars mean in the vast, eternal scheme?

Cheers, B R Felix