Early Mars Was All Wet The delta in Jezero crater, a past lake
on Mars. Ancient rivers ferried clay-like minerals (shown in
green) into the lake, forming the delta. The clays then were
trapped by rocks (purple). CREDIT: NASA/JPL/JHUAPL/MSSS/Brown
University A lot more Martian rocks were altered by water than
scientists originally thought, suggesting that early Mars was a
very wet place. New observations made by NASA's Mars
Reconnaissance Orbiter (MRO), currently circling the planet,
have revealed evidence that vast regions of the southern
highlands of Mars were altered by water in a variety of
environments billions of years ago. Water is a key condition for
life as we know it. Though there is no firm evidence that Mars
has ever harbored life, knowing that the planet was once wet
suggests that it was at least habitable in the past. The key to
the finding is the discovery that rocks called phyllosilicates
are widespread on at least the planet's southern hemisphere. The
water present on Mars from about 4.6 billi