Water flowed 'recently' on Mars
2006 12 07

From: news.bbc.co.uk

Nasa says it has found "compelling" evidence that liquid water flowed recently on the surface of Mars.
The finding adds further weight to the idea that Mars might harbour the right conditions for life.

The appearance of gullies, revealed in orbital images from a Nasa probe, suggests that water could have flowed on the surface in the last few years.

But some scientists think these fresh gullies could also have been cut by liquid carbon dioxide (CO2).

The latest research emerged when Nasa's Mars Global Surveyor (MGS) spacecraft spotted gullies and trenches that scientists believed were geologically young and carved by fast-moving water coursing down cliffs and steep crater walls.

Scientists at the San Diego-based Malin Space Science Systems, who operate a camera aboard MGS decided to retake photos of thousands of gullies in search of evidence for recent water activity.

Two gullies that were originally photographed in 1999 and 2001, and imaged again in 2004 and 2005, showed changes consistent with water flowing down the crater walls, according to the study.

In both cases, scientists found bright, light-coloured deposits in the gullies that were not present in the original photos. They concluded that the deposits - possibly mud, salt or frost - were left there when water recently cascaded through the channels.

Other scientists think it possible that gullies like this were caused not by water but by liquid carbon dioxide.

One of the reasons for favouring CO2 was that computer models of the Martian crust indicated water could exist only at depths of several kilometres. Liquid carbon dioxide, on the other hand, could persist much nearer the surface where temperatures can drop as low as -107C.

Prospects for life

Oded Aharonson, an assistant professor of planetary science at the California Institute of Technology (Caltech) said that while the interpretation of recent water activity on Mars was "compelling," it was just one possible explanation.

Aharonson said further study was needed to determine whether the deposits could have been left there by the flow of dust rather than water.

Deciding what was responsible for the features is a pressing question that has important consequences for the likelihood of life on Mars. Scientists have proposed that reservoirs of liquid water could exist beneath the Martian surface, providing a habitat for microbial life.

"This underscores the importance of searching for life on Mars, either present or past," said Bruce Jakosky, an astrobiologist at the University of Colorado at Boulder, who had no role in the study. "It's one more reason to think that life could be there."

Mars Global Surveyor abruptly lost radio contact with Earth last month. Attempts to locate the spacecraft, which has mapped the Red Planet since 1996, have failed, and scientists fear it is lost.

Nasa's Mars rovers, which landed in 2004, have sent scientists back equally strong evidence that liquid water flowed on the surface in ancient times, based on observations of alterations in ancient rocks.

"We're now realising Mars is more active than we previously thought, and that the mid-latitude section seems to be where all the action is," said Arizona State University scientist Phil Christensen, who was not part of the current research.

Details of the work appear in the journal Science.

Article from: http://news.bbc.co.uk/2/hi/science/nature/6214834.stm



Related Articles


Latest News from our Front Page

Norway Joins the Race to Develop Killer Robots
2014 10 24
Norway is a large exporter of weapons, which makes the resolution of the debate about creating killer robots an important issue for everyone.  One could debate the overall merits or failings of robotic systems, but an area that clearly has become a point for concern on all sides is the emergence of "killer robots." According to robotics pioneer, David Hanson, ...
Gene That Once Aided Survival in the Arctic Found to Have Negative Impact on Health Today
2014 10 23
In individuals living in the Arctic, researchers have discovered a gene variant that arose thousands of years ago and most likely provided an evolutionary advantage for processing high-fat diets or for surviving in a cold environment; however, the variant also seems to increase the risk of hypoglycemia, or low blood sugar, and infant mortality in today’s northern populations. {snip} “Our work ...
The Ebola hoax: questions, answers, and the false belief in the “One It”
2014 10 23
“The Reality Manufacturing Company doesn’t just sell ‘fake paintings’ that are easy to spot. No. They also sell images that are geared to mesh with people’s deeply held instincts and thereby produce rigid false beliefs. People are sure that if they gave up such beliefs, their world would fall apart and blow away in the wind.” ...
New Controversial Theory Suggests "Hobbits" Were Not Human - Who Were These Mysterious Beings?
2014 10 23
The origin of the Hobbit species remains a challenging subject to scientists. The Hobbit’s discovery confirmed the view that the Earth was once populated by many species of human, but new research the Hobbit’s were not human at all! So, who were these mysterious beings? Where did they come from? The idea that our species, Homo sapiens, was the only species of human on ...
Right into enemy hands? ISIS shows off new weapons allegedly airdropped by US (VIDEO)
2014 10 23
Islamic State has published a new video in which a jihadist shows off brand-new American hardware, which was purportedly intended for the Kurds they are fighting in the Syrian border town of Kobani. The undated video, posted by the unofficial IS mouthpiece “a3maq news”, sees a jihadist showing several boxes of munitions with English-language markings, with a parachute spread out on ...
More News »