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| November
2000 |
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Visual evidence suggests water springs on Mars
http://www.cnn.com/2000/TECH/space/06/22/mars.water.03/
By Richard Stenger
CNN.com Writer
(CNN) -- Liquid water in the recent past likely formed distinct gullies
and deltas on
Mars, scientists said Thursday. The discovery bolstered hopes that the
red planet
could harbor simple life and someday host human colonists.
"The presence of liquid water on Mars has profound implications for the
question of
life not only in the past, but perhaps even today," NASA Associate Administrator
Ed
Weiler told reporters.
Water seepage and surface runoff could have formed
more than 100 rare landforms found along steep cliffs
"a million years ago, a thousand years ago, perhaps
yesterday," Weiler said.
Planetary geologists made the discovery by combing
through recent photos taken by the Mars Global
Surveyor spacecraft. The images show the smallest
features ever observed from martian orbit, about the
size of a sport-utility vehicle.
Water mostly in the south
"These are new landforms that have never been seen
before on Mars," principal investigator Michael Malin
said. "We see features that look like gullies formed by
flowing water and the deposits of soil and rocks transported by these flows."
Mostly in high latitudes and the southern hemisphere, the sites include
gullies and
alluvial fans within the walls or rims of pits, valleys and impact craters.
More than
90 percent occur south of the equator and most occur on slopes that face
away
from the sun.
"We were quite surprised and confused by it. It didn't fit our model of
what Mars is
like," said Malin of the Surveyor data. Malin Space Sciences operates a
camera
onboard the NASA satellite, which has orbited Mars since 1997.
Scientists have long thought Mars' surface coursed with water billions
of years ago,
based on evidence of liquid erosion and signs of ancient channels and seas.
But the
water all but disappeared as the planet cooled and its atmosphere thinned.
'Dragged kicking and screaming'
Water is known to exist today as ice in the
northern polar cap and as vapor in faint
clouds. But the presence of liquid water
near the surface could strengthen the theory
that life exists or once existed on Mars.
"If life ever did develop there, and if it
survives to the present time, then these
landforms would be great places to look,"
Weiler said.
Liquid water on Mars would also make
travel to the planet easier. Astronauts could
convert water into hydrogen and oxygen,
using both as rocket fuel and the second for breathing gas.
Ken Edgett, the co-author of the Science Magazine report, was at first
skeptical that
water formed the unusual features.
"I was dragged kicking and screaming to this conclusion," but the visual
evidence
linking groundwater discharges as the cause was too strong, he said.
The water is thought to exist about 100 to 400 meters (300 to 1,300 feet)
below the
surface. Malin estimated the volume of a typical flow at about 2,500 cubic
meters
(90,000 cubic feet), "which would fill half a dozen or so swimming pools."
Troubling questions remain
Still some troubling questions remain. Why do the discharges take place
in the
coldest areas on Mars, near the poles and on slopes facing the poles?
Malin suggested that that the groundwater could be some exotic salty brine
with
unknown physical properties.
U.S. Geological Survey scientist Kenneth Tanaka suggested in Science that
frozen
carbon dioxide, flashing into a liquid and then gas, could be the culprit.
NASA plans to launch an orbiter in 2001 that will examine the seepage sites
for
evidence of water-related minerals. The agency is considering two options
for an
unmanned mission to Mars in 2003.
The Mars Polar Lander was to search for martian water in 1999. The doomed
robot
ship was to dig beneath the surface and study the atmosphere, but went
silent as it
entered the atmosphere of the red planet.
Correspondent Miles O'Brien contributed to this report.
| November 2000
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