Water
Mars once
had more Water
than Earth
P
erhaps about 4.3 billion years ago, Mars would have had enough water to cover its entire surface
in a liquid layer about 137 metres (450 feet) deep. More likely, the water would have formed
an ocean occupying almost half of Mars’ northern hemisphere, in some regions reaching depths
greater than a 1,6 kilometres (a mile).
A primitive ocean on Mars held more water than Earth’s Arctic
Ocean, according to NASA scientists who, using ground-based
observatories, measured water signatures in the Red Planet’s
atmosphere.
Scientists have been searching for answers to why this vast
water supply left the surface. Details of the observations and
computations appeared in a recent Science magazine.
“Our study provides a solid estimate of how much water Mars
once had, by determining how much water was lost to space,”
said Geronimo Villanueva, a scientist at NASA’s Goddard Space
Flight Center in Greenbelt, Maryland, and lead author of the new
paper. “With this work, we can better understand the history of
water on Mars.”
The new estimates are based on detailed observations made
at the European Southern Observatory’s Very Large Telescope
in Chile, and the W.M. Keck Observatory and NASA Infrared
Telescope Facility in Hawaii. With these powerful instruments, the
researchers distinguished the chemical signatures of two slightly
different forms of water in Mars’ atmosphere. One is the familiar
H2O. The other is HDO, a naturally occurring variation in which
one hydrogen is replaced by a heavier form, called deuterium.