Eyjafjallajokull has reminded us who is in charge. For all of our efforts to manage Planet Earth, it only takes one minor hiccup from the blue marble itself to send us scrambling for our collective mommies. Witness how European commerce, transportation and overall confidence in our global society is withering under the spreading plume of volcanic pumice and ash.
Earth itself can absorb such minor irritations as a 7.9 quake, a tsunami, or an eruption of an unpronounceable Icelandic volcano, but the creatures that scurry around on the crust may not fare as well. We need only look to the dinosaurs for proof.
All in all, Mars exploration is suddenly looking pragmatic.