Destination Mars

For a planet so close to ours, Mars has proved strangely inhospitable to earthly visitors. Of the 33 missions to the Red Planet since 1960, 22 have crashed, broken up en route or otherwise failed before they could complete their research. Undaunted, earthlings are launching yet another assault on Mars this month, when no fewer than three spacecraft — two from NASA, one from the European Space Agency (esa) — will take flight. If they deliver on even part of their promise, the missions could go a long way toward explaining the history, geology and — most intriguing — biology of...