by Richard Milner for Astrobiology Magazine
Moffett Field CA (SPX) Nov 04, 2011
Does Mars have water? This question has been contentious for well over a century and a half, with extreme swings in scientific opinion - from a planet criss-crossed with canals to no water at all; from trickles of briny water to a landscape as dry as a bone.
Recent missions to the Red Planet are providing information to help answer this question, but the new facts aren't flooding in like waves - they are trickling in like a coy, meandering stream, but one that is steadily growing in volume and intensity.
Debunking the "Canals" of Mars
Such a large-scale cooperative project, he was certain, could only have been conceived and executed by intelligent Martians in an effort to save their home planet from drying out.
Lowell believed that the Red Planet was once green with lush vegetation, but was now barren and desertified. Its polar ice caps, he thought, were the only remaining source of water, and the canals were a (literally) last-ditch effort to sustain the Martian civilization.
It was the brilliant and eccentric evolutionist Alfred Russel Wallace (1823-1913), Charles Darwin's junior partner in discovering the theory of natural selection, who effectively debunked Lowell's illusionary network of Martian canals.
Ever curious and intellectually and physically adventurous, Alfred Russel Wallace never allowed his specialties within natural history to keep him from poking into any and all scientific questions that interested him. In 1907, when he was 84 years old, Wallace wrote his eighteenth book, Is Mars Habitable? Here's what he had to say:
"The very immensity of this [imagined canal] system, and its constant growth and extension during fifteen years of persistent observations, have so completely taken possession of [Lowell's] mind, that...he has declared them to be "non-natural,"...therefore to necessitate the presence of highly intelligent beings who have designed and constructed them...The innumerable difficulties which [his conclusion] raises have either been ignored, or brushed aside on the flimsiest evidence.
[He] never even discussed the totally inadequate water-supply for such world-wide irrigation, or the extreme irrationality of constructing so vast a canal-system the waste from which, by evaporation, when exposed to such desert conditions as he himself describes, would use up ten times the probable supply...[It would show] complete ignorance and stupidity in these alleged very superior beings...
Six decades later, it was hoped that advances in technology would finally settle the question of water on Mars.
"Follow the Water"
In 1971, the Mariner 9 photographed almost the entire surface of Mars at close range; there were no canals, but the photos did reveal what look like dry riverbeds and alluvial channels formed by water (or at least liquid) in the past.
The Mariner flights of fifty years ago were unable to demonstrate whether Martian water exists or not, but the bleak craters and seemingly parched landscape were thought to be extremely hostile to supporting any kind of life.
today, new evidence is making it seem increasingly likely that Mars did indeed once contain lots of water - and may still have vast quantities underground. Recently released photos from NASA's High Resolution Imaging Science Experiment (HIRISE) instrument on the Mars Reconnaissance Orbiter have hinted at the presence of water on the Red Planet.
Dark, finger-like features that appear and extend down some Martian slopes during the warmest months of the year may show activity of salty water. They fade in the winter, and then recur the next spring. But so far there is no evidence of any life on the planet, simple or complex.
Jarosite Discovered on Mars
This hydrous sulfate of potassium and iron seems to be strewn over an alkaline Martian plain where sulfates and clays are plentiful. What's so interesting about jarosite? Scientists have concluded that it can only form in the presence of water, but requires dry conditions for its preservation.
University of Syracuse mineralogists, led by Suzanne Baldwin and Joseph Kula, have been able to determine the age of jarosites here on Earth and the surface conditions under which they were formed.
If and when they can ever get a sample of the Martian jarosite, their newly developed tests may tell us when, where, and under what conditions water was plentiful there. Their method utilizes trapped argon gas isotopes within the minerals that can serve as chronological markers of how long ago the rock was formed.
New Evidence of Water
The Phoenix lander also sent back unequivocal evidence of near-surface water ice. In the November 2011 Scientific American, Smith wrote, "With more water...the soil could grow asparagus."
Later this month, NASA will launch the Mars Science Laboratory, hoping to follow up on the discovery that short-lived, seasonally-varying plumes of methane gas issue from underground sources at three specific regions.
One of the most intriguing is at Nili Fossae, a large eroded fracture in the Martian surface that is partially filled by sediments. Its methane clouds could be produced by underground microbial life there, or by geothermal processes.
On Earth, methane often is a metabolic by-product of living organisms, including microbes. And now, with strong evidence for water existing on Mars, some scientists have become increasingly optimistic that the planet may indeed support some forms of life. "All in all," in Smith's current view, "the chances of finding life on Mars have never seemed better."
Mars News and Information at MarsDaily.com
Lunar Dreams and more
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
NASA Study of Clays Suggests Watery Mars Underground
Pasadena CA (JPL) Nov 03, 2011
A new NASA study suggests if life ever existed on Mars, the longest lasting habitats were most likely below the Red Planet's surface. A new interpretation of years of mineral-mapping data, from more than 350 sites on Mars examined by European and NASA orbiters, suggests Martian environments with abundant liquid water on the surface existed only during short episodes. These episodes occurre ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|