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Water Discovery Gives Boost to Astrobiology
Special Report: Continuing Coverage of the Mars Water Discovery
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The latest news from Astronomy Now and Spaceflight Now
WATER DISCOVERY GIVES NEW IMPETUS TO MARS EXPRESS
The latest evidence that liquid water has flowed on Mars very
recently, makes the European Space Agency's upcoming Mars Express
mission even more relevant, officials said Friday.
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
June 22, 2000
The new images show the smallest features ever observed from martian orbit -- the size of an SUV. NASA scientists compare the features to those left by flash floods on Earth.
"We see features that look like gullies formed by flowing water and the deposits of soil and rocks transported by these flows. The features appear to be so young that they might be forming today. We think we are seeing evidence of a ground water supply, similar to an aquifer," said Dr. Michael Malin, principal investigator for the Mars Orbiter Camera on the Mars Global Surveyor spacecraft at Malin Space Science Systems (MSSS), San Diego, CA. "These are new landforms that have never been seen before on Mars."
The findings will be published in the June 30 issue of Science magazine.
"Twenty-eight years ago the Mariner 9 spacecraft found evidence -- in the form of channels and valleys -- that billions of years ago the planet had water flowing across its surface," said Dr. Ken Edgett, staff scientist at MSSS and co-author of the paper in Science. "Ever since that time, Mars science has focused on the question, 'Where did the water go?' The new pictures from Global Surveyor tell us part of the answer -- some of that water went under ground, and quite possibly it's still there."
"For two decades scientists have debated whether liquid water might have existed on the surface of Mars just a few billion years ago," said Dr. Ed Weiler, Associate Administrator for Space Science, NASA Headquarters. "With today's discovery, we're no longer talking about a distant time. The debate has moved to present-day Mars. The presence of liquid water on Mars has profound implications for the question of life 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."
The gullies observed in the images are on cliffs -- usually in crater or valley walls -- and are made up of a deep channel with a collapsed region at its upper end (an "alcove") and at the other end an area of accumulated debris (an "apron") that appears to have been transported down the slope. Relative to the rest of the martian surface, the gullies appear to be extremely young, meaning they may have formed in the recent past.
"They could be a few million years old, but we cannot rule out that some of them are so recent as to have formed yesterday," Malin said.
Because the atmospheric pressure at the surface of Mars is about 100 times less than it is at sea level on Earth, liquid water would immediately begin to boil when exposed at the martian surface. Investigators believe that this boiling would be violent and explosive. So how can these gullies form? Malin explained that the process must involve repeated outbursts of water and debris, similar to flash floods on Earth.
"We've come up with a model to explain these features and why the water would flow down the gullies instead of just boiling off the surface. When water evaporates it cools the ground -- that would cause the water behind the initial seepage site to freeze. This would result in pressure building up behind an 'ice dam.' Ultimately, the dam would break and send a flood down the gully," said Edgett.
The occurrence of gullies is quite rare: only a few hundred locations have been seen in the many tens of thousands of places surveyed by the orbiter camera. Most are in the martian southern hemisphere, but a few are in the north. "What is odd about these gullies is that they occur where you might not expect them -- in some of the coldest places on the planet," Malin indicated. "Nearly all occur between latitudes 30 degrees and 70 degrees, and 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 roughly between New Orleans, Louisiana, and Point Barrow, Alaska, in the northern hemisphere; and Sydney, Australia, to much of the Antarctic coast in the south.
The water supply is believed to be about 100 to 400 meters (300 to 1300 feet) below the surface, and limited to specific regions across the planet. Each flow that came down each gully may have had a volume of water of, roughly, 2500 cubic meters (about 90,000 cubic feet) -- about enough water to sustain 100 average households for a month or fill seven community-sized swimming pools. The process that starts the water flowing remains a mystery, but the team believes it is not the result of volcanic heating.
"I think one of the most interesting and significant aspects of this discovery is what it could mean if human explorers ever go to Mars," said Malin. "If water is available in substantial volumes in areas other than the poles, it would make it easier for human crews to access and use it -- for drinking, to create breathable air, and to extract oxygen and hydrogen for rocket fuel or to be stored for use in portable energy sources."
"This latest discovery by the Mars Global Surveyor is a true 'watershed'--that is, a revolution that pushes the history of water on Mars into the present," said Dr. Jim Garvin, Mars Program Scientist, NASA Headquarters. "To follow up on this discovery we will continue the search with Mars Global Surveyor and its rich array of remote sensing instruments, and in 2001, NASA will launch a scientific orbiter with a high spatial resolution middle- infrared imaging system that will examine the seepage sites in search of evidence of water-related minerals.
"Furthermore, NASA is in the process of evaluating two options for a 2003 mission to Mars, both of which could provide independent information concerning the remarkable sites identified by Malin and Edgett."
JPL manages the Mars Global Surveyor Mission for NASA's Office of Space Science, Washington, DC. Malin Space Science Systems built and operates the camera system. JPL is a division of the California Institute of Technology, Pasadena, CA.
JPL's industrial partner is Lockheed Martin Astronautics, Denver, CO, which developed and operates the spacecraft.
The Mars Global Surveyor images are available at:
http://www.msss.com/mars_images/moc/june2000/
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
June 21, 2000
Panelists will be:
NASA Television is broadcast on GE-2, transponder 9C located at 85 degrees West longitude, with vertical polarization. Frequency is on 3880.0 MHz, with audio on 6.8 MHz.
SPACE.com
June 21, 2000
NASA to Announce Evidence of Water on Mars
SPACE.com has learned that the Mars Global Surveyor has found evidence of water on the Red Planet’s surface. The finding, which involves evidence of seasonal deposits that could be associated with surface springs, has significant implications for the possibility of life on Mars.
NEWSALERT: Wednesday, June 21, 2000 @ 0750 GMT
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June 21, 2000 - Issue #260
A Biospherics news release
July 21, 1998
In recent years, all arguments against the LR experiment had been eliminated except the claim that there was no life-requiring liquid water on the surface of the Red Planet. Last February, in discussing Mars against the background of startling new findings of life in hostile Earth environments, Dr. Wesley Huntress, NASA's Associate Administrator for Space Science, said: "We used to think that life was fragile, but wherever liquid water and chemical energy are found, there is life. There is no exception. Life may be a cosmic imperative."
Dr. Levin described a dynamic daily cycle on Mars in which the extreme cold of the Martian atmosphere greatly restricts its ability to hold water vapor. Thus, the scant water vapor on Mars is forced down to the surface, where it is deposited in frozen form. As the sun rises, the ice melts, but its evaporation is restricted by the low vapor capacity of the overlying cold atmosphere. Levin cited Pathfinder's results to show that the atmosphere immediately above the surface warms considerably, equaling a spring day on Earth, but, just a couple of feet above the surface, temperatures are sub-freezing. The warmed surface layer of air absorbs water vapor until saturated. No more water can then evaporate from the surface, and the ice remaining there melts into liquid water. As the sun mounts, the temperature of the atmosphere above the surface warms sufficiently to permit any remaining water and ice to evaporate. However, during this daily cycle, the soil has been moistened with enough water to sustain microorganisms.
Dr. Levin explained: "Based on Viking and Pathfinder data, and consistent with the principles of thermodynamics of the triple point of water, a model has been created for a diurnal water cycle on Mars. The model predicts the presence of several tenths of a percent to one percent water moisture in the topmost layer of the surface material over large regions of Mars. Images taken by the Viking Lander cameras show nightly deposits of surface water frost, even snow, verifying the prediction of the model. Terrestrial experiments in natural environments, including the Death Valley sand dunes of California, demonstrated that the amount of soil water moisture predicted by the model is sufficient to sustain survival and growth of common soil microorganisms." Levin states: "This model removes the final constraint preventing acceptance of the biological interpretation of the Viking LR Mars data as having detected living microorganisms in the soil of Mars. It comes at a time when a growing body of evidence from the Earth and space are supporting the presence of life not only on Mars, but on many celestial bodies." As a result, Levin pressed for early Mars biology missions, none of which is currently planned by NASA, to verify and study life forms, and for caution in current plans for returning a Mars sample to Earth.
Under its motto, "Technologies for Information and Health," Biospherics' mission is to provide guidance and products to improve the quality of life. In addition to its BioTechnology unit, the Company offers telecommunications and database management information, and proprietary environmental, food and medical innovations.
For more information, visit the Biospherics Web site
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