Mars may be a pristine ecosystem

EARTH ASIDE, Mars is the most-studied planet in the solar system. Satellites zip around it. Rovers trundle over its surface. A helicopter may soon clatter through its skies, for a clutch of new missions are either on their way or planned to launch soon.The motive behind all this is the hope that Mars, like Earth, may support life—or may have done so in the past (see ). And, as technology spreads and rocketry gets cheaper, more people want to join the search for what would, in effect, be Biosphere 2. At first, Mars was the province of America and the Soviet Union. Japan tried and failed to explore it in 1998. Europe sent its first mission in 2003. India launched its in 2013. The United Arab Emirates joined the fray on July 20th. And China, after a failure in 2011, dispatched another attempt on July 23rd. The time is not far off when even private missions might be feasible.