Life on the Red Planet?
The Surface of Mars Revisited
NASA scientists
studying image
data
from the Mars Global Surveyor spacecraft
report that there may be current sources
of liquid water at or near the surface of
the red planet.
Gullies or valleys
formed by flowing water appear to be
recent additions to the martian surface
and may still be forming today. These new
landforms have never been seen before on
Mars.
Twenty eight years
ago the Mariner 9 spacecraft (a
predecessor to the Viking spacecraft)
found evidence of channels and valleys to
suggest that billions of years ago the
planet had water flowing across its
surface. Ever since that time NASA
scientists have been interested to learn
where the water went. The Global Surveyor
pictures suggest that some of water went
underground, and quite possibly is still
there. The presence of liquid water has
profound implications for the possibility
of life (as we know it) on the martian
surface not only in the past, but perhaps
even today. If life ever did develop
there, and if it survives to the present
time, then these landforms would be great
places to look.
Since the
atmospheric pressure at the surface of
Mars is about 100 times less than that on
Earth, liquid water would immediately
begin to boil. Then how did these gullies
form ? NASA scientists believe that the
process must have involved repeated
outbursts of water and debris, similar to
flash floods. When water evaporates it
cools the ground below it. This would
cause the water left behind to freeze. The
result over time would lead the formation
of an 'ice dam.' Ultimately, the dam would
break and send a flood of liquified water
across the surface. Nearly all the gullies
observed occur between latitudes 30 and 70
degrees south usually on slopes that get
the least amount of sunlight during each
martian day. If these gullies were on
Earth they would be at latitudes between
Sydney, Australia and much of the
Antarctic coast.
The location of the
gullies on the martian planet may justify
observations made by mass spectrometers on
board the NASA Viking landers. Viking 1
landed on Mars on July 20, 1976 on the
western slope of Chryse Planitia (the
Plains of Gold) at a latitute of 22.3
degrees north. Viking 2 touched down
September 3, 1976 at Utopia Planitia at a
latitude of 48 degrees North. The landers'
gas chromatography-mass spectrometers each
found no sign of organic chemistry at
either landing site, but they did provide
a precise and definitive analysis of the
composition of the Martian atmosphere and
found previously undetected trace
elements. The three biology experiments
discovered unexpected enigmatic activity
in the Martian soil, but provided no clear
evidence for the presence of living
microorganisms in soil near the landing
sites. Did the landers study the wrong
hemisphere ?
The bulk of the
water supply on Mars is believed to be
about 100 to 400 meters below the planet
surface. If water is available in
substantial volumes in certain areas of
the planet, it would make it easier for
human visitors to access and use it for
drinking and for use in portable energy
sources. NASA is in the process of
evaluating two options for a 2003 mission
to Mars to study the formations
further.
The NASA findings
appear in the June 30 issue of
Science
magazine.