SPACE.com
has learned that NASA has discovered evidence of water
on the Red
Planet’s
surface. The finding, made by the Mars Global Surveyor
spacecraft, fuels hopes that there may be life on
Mars.
Sources close to the agency’s Mars program said the
discovery involves evidence of seasonal deposits that
could be associated with springs on the planet’s
surface.
NASA plans to make the blockbuster announcement
during a press conference scheduled for June 29, sources
said.
The discovery,
if confirmed, would mark the achievement of a primary
goal in NASA’s program to explore Mars.
NASA’s ambitious
plans for Mars focus on gaining an understanding of the
potential for either past or present life on the
planet.
The program also aims to improve science’s understanding
of Mars’
climate
and its resources.
Key to all three themes is water: Where and when it
may have flowed in the past, where it might lurk today
and in which forms and what quantities. The water has
been found in a region called the Candor Chasm, part of
a large canyon known as Valles Marineris, according to
other news reports. The 3,700-mile (6,000-kilometer)
long canyon sits along Mars' equator.
NASA scientists
on the Mars Global
Surveyor
team declined to comment, pending the press conference
and subsequent publication in the journal Science
of a paper on the discovery.
Ed Weiler, NASA
associate administrator for space science, told the
National Academy of Sciences’ Space Studies Board on
June 14 that the Mars
program
needs a clear-cut vision. The real reason to go is to
find out if life is there or not, he said.
|
Mars was most likely warm and wet about 3.7
billion years ago. But as the planet cooled, the
water froze. Remnants exist as ice caps at the
poles (as shown here). IMAGE:
NASA
|
"To meet that long-term mission requires that you
follow the water. Without water there is not life…there
was not life," Weiler said. "By following the water, it
all fits together. So for the first time, we have a
really good, clear, long-term vision for
Mars."
Water most
likely flowed in the distant past on Mars, carving
channels and other features clearly
visible
on its surface. But other than in the form of clouds and
ice, liquid water cannot exist on the planet’s surface
today, thanks to the thinness of its atmosphere.
Scientists have hypothesized that vast stores of
water could still persist beneath the surface of
Mars.
In a 1997 Mars Global Surveyor image, shown above,
scientists proposed that water could have seeped from
the walls of this unnamed crater in the planet’s
southern hemisphere, and perhaps even pooled at the
bottom of the impact basin.
At the time NASA originally released the image, it
urged caution about adopting any one hypothesis
explaining its details. Although the labeled version
shown here lists water-related sources for the crater’s
features, NASA stressed they could also be explained by
the flow of lava.
NASA has suggested that certain Martian
features, as seen in this 1997 image, may indicate fluid
seepage.
Finding water on Mars will likely put spurs into
future mission planning: The American space agency will
in upcoming weeks announce whether it will send an
orbiter or lander spacecraft to Mars in 2003. (In 2001,
it plans to send only an orbiter to the planet.)
"It's not like people don’t suspect there's water on
Mars. We certainly know there was probably water in the
past in fairly good quantities with all these older
features," said Jack Farmer, an astrobiologist in the
Department of Geology at Arizona State University,
Tempe.
"But actually finding a place where water might make
it to the surface, or at least some expression of it,
such as gases emitted into the atmosphere…that would be
a big deal," he added.
Although the labeled features in this image could
be explained by the presence of water, they could also
be volcanic in
origin.
The finding of upwelling water could mean striking
biological pay dirt, Farmer said.
"In that situation, where you have water coming up
from depth, into the surface, you might be replenishing
the ground ice there on a fairly regular basis. Even if
you never got liquid water to the surface you might be
able to sequester organic materials, prebiotic chemistry
or life, whatever, in the ground ice inventory, which
you could access then by shallow drilling," Farmer
said.
By finding liquid water near the surface, or actually
part of the surface environment, "you could really move
the whole question of searching for life ahead
significantly, I think," Farmer said. "You could do some
sort of shallow drilling program in a robotic sense,
well in advance of any human missions," he said.
The original version of this story was posted at 8:03
p.m., June 20.
