Liquid Water Likely Supports Life On Mars Today, Scientists Claim
By Leonard David
Senior Space Writer
posted: 12:20 pm ET
06 August 2003
Even on the present-day cold and dusty surface of Mars, liquid water may
be sustaining a world of Martian microbes.
Data churned out by NASA's Mars Odyssey suggests that the nearby planet
is waterfront property -- at least in the form of below surface deposits
of water ice. Odyssey scientists report that the soil very close to the
surface over much of the planet contains large amounts of ice.
Now a father and son science team argue that ice near Mars' surface
means liquid water in its "topsoil", thereby strengthening the case for
life on the red planet.
The researchers presented their findings this week at the International
Society for Optical Engineering (SPIE) meeting being held in San Diego,
Evidence for liquid water on Mars is yet another chapter in a
long-standing battle waged by Gilbert Levin, a scientist that took part
in NASA Viking lander missions in the mid-1970s. Levin believes his
experiment detected microbial life on Mars, now some 27 years ago.
Matching the two Viking landing sites on Odyssey maps of Mars water
locations, Levin said the soil sampled by the Viking 1 lander would have
contained about two percent water. The Odyssey data also shows that the
water content at the Viking 2 lander site is about 10 percent.
"The Odyssey data lend further strength to my claim that the 1976 Viking
Labeled Release results are of biological origin," Levin reported at the
SPIE meeting. Life-sustaining liquid water, he said, was in the soil
sampled by his Viking experiment.
According to recent Mars Odyssey data interpretations, up to 50 percent
water by mass can be found at the planet's polar regions and from two to
ten percent closer to the equator.
Levin is now Chief Executive Officer of Spherix in Beltsville, Maryland,
a firm engaged in biotechnology research. Along with his son, Ron Levin,
a physicist at MIT Lincoln Laboratory, and co-investigator John
Weatherwax, the researchers presented evidence that liquid water can
exist on the Martian surface.
"Since Viking, relevant discoveries have been made of organisms living
under extreme environments. Many terrestrial microbial forms are now
known that populate environmental extremes until recently though
inimical to life," Levin said.
The envelope of temperature, pressure, atmospheric composition, and
salinity has been pushed to unanticipated regions, including the
environment of Mars, Levin said. "These findings make it likely that
Martian organisms could be well adapted to the current Martian conditions."
The team provided both experimental evidence and mathematical work
showing, in their view, how water can exist in liquid phase under
Martian surface conditions. It occurs when and where the surface
temperature exceeds zero-degrees Celsius. Surface temperatures above
freezing were found at the Viking 1 landing site, and snow or frost was
seen at the second Viking location.
Theoretical and counterintuitive
A study of the physics of evaporating water by Ron Levin and Weatherwax
show that ice on the surface of Mars may melt into liquid water under
Martian solar illumination.
Other factors must be taken into account too. These include the density
of air on Mars, the planet's gravity, weaker transfer of energy by
convection, and wind factors. While they admit their work is theoretical
and can be counterintuitive, the ultimate conclusion of their study:
"There are no physical reasons prohibiting the availability of liquid
water on the surface of Mars."
Biologically significant amounts of liquid water can currently exist on
the surface of Mars, Levin and Weatherwax stated. "The previously
presumed unavailability of liquid water is not a reason to rule out the
existence of microbial life on current day Mars," the team reported.
Gilbert Levin says he regrets that, despite NASA and the European Space
Agency statements that the search for life on Mars remains their highest
priority, none of this trio of spacecraft currently voyaging to Mars
contains a life detection test. Nonetheless, he predicts these missions
will likely advance his cause by finding liquid water and an environment
that could support microorganisms.
New tools needed
Do such views about life today on Mars hold water?
More needs to be known explains James Garvin, NASA Lead Scientist for
Mars Exploration in the space agency's Office of Space Science in
Washington, D.C. "We have the tools to go look for evidence of the sorts
that Levin claims are there," he said.
Garvin points to Odyssey, and the future launches of the Mars
Reconnaissance Orbiter, and the newly selected Phoenix Scout mission.
Also, next generation instruments to be carried on a Mars science lander
late this decade can be definitive where Levin's Viking experiment could
not be, he added.
"Odyssey's findings are definitive in that the physics of hydrogen as
viewed via neutrons does not lie. Levin's experiment, good as it was did
not have the benefit of multi-temporal observations and independent
verification," Garvin said. There are three different sensors in the
Odyssey suite of instruments to support the water ice story, he said.
Water in the regolith on Mars that is bombarded by ultraviolet and
cosmic rays is not the most habitable place... given what little we
know, Garvin told /SPACE.com/. "What's needed is to design experiments
that are definitive and avoid years of controversy fomented in part by
"My view is that we cannot be certain yet," Garvin said, "except that
subsurface habitats with liquid water must have existed at some depths
and in the more modern record. Levin did not prove that with his Viking
gas-exchange measurements of the upper 20 centimeters at the Viking
Lander 1 site. But perhaps his attention to these issues has pushed
others to pursue better approaches to resolving the issue, such as
Phoenix, and other future missions."