People got very excited in 2004 when NASA’s rover Opportunity
discovered evidence that Mars had once been wet. Where there is
water, there may be life. After more than 40 years of human
exploration, culminating in the ongoing Mars Exploration Rover
mission, scientists are planning still more missions to study
the planet. The Phoenix, an interagency scientific probe led by
the Lunar and Planetary Laboratory at the University of Arizona,
is scheduled to land in late May on Mars’s frigid northern
arctic, where it will search for soils and ice that might be
suitable for microbial life (see “Mission to Mars,”
November/December 2007). The next decade might see a Mars Sample
Return mission, which would use robotic systems to collect
samples of Martian rocks, soils, and atmosphere and return them
to Earth. We could then analyze the samples to see if they
contain any traces of life, whether extinct or still active.
Such a discovery would be of tremendous scientific significance.
What could be more fascinating than dis