Heads Up, Rovers!
We currently have three satellites orbiting Mars - NASA's Mars Reconnaissance Orbiter and Odyssey, plus Europe's Mars Express - and two operational rovers - NASA's Opportunity and Curiosity. Should Mars be the scene of a cometary smash-up, wouldn't that be bad news for the rovers?
Barring a direct hit over Gale Crater or Endeavour Crater (Curiosity and Opportunity's homes, respectively), both rovers should survive the impact, with varying results.
An amazing climate experiment it may be, but Opportunity, a solar powered robot, would suffer if the atmosphere became thick with light-obscuring dust after impact. Mars' newest arrival, Curiosity, however, should carry on just fine as the larger robot is nuclear powered, drawing its power from a radioisotope thermoelectric generator (RTG).
So we'd not only have eyes in orbit, we'd also have two tenacious observers on the ground capable of carrying out "event science" right at time of impact.
ANALYSIS: Mars Gets Hit By Cosmic Buckshot
But this wouldn't only satisfy our macabre fascination with seeing a real doomsday scenario play out on our cosmic doorstep, it might also motivate manned exploration of Mars.