Spaceship finds hard evidence of water on Mars

 
San Francisco: A high-resolution camera mounted on a spaceship orbiting Mars has found evidence that water once ran under the planet's surface. The geological features could be probed for fossil evidence for past life or used to point to other regions of the planet where running water — and maybe life — can be found today.
The pictures were taken by the Mars Reconnaissance Orbiter which was launched by the National Aeronautics and Space Administration (NASA) in August 2005 and began sending data back from the planet in November last year.
They show discoloured rocky ridges in the Candor Chasma, part of a massive canyoned region at the equator called the Valles Marineris, the largest geological rift in the solar system. The ridges are evidence of chemical changes caused by a fluid as it flowed down a fissure in the rock.
The changes cemented the rock together making it stronger, so erosion left strengthened ridges. Chris Okubo, a geologist at the University of Arizona's Lunar and Planetary Laboratory, studies similar geological evidence for ancient flowing water on the earth. "When I started to look at some of the HiRISE images of Mars we started to see the exact same features along the fractures. HiRISE [the High Resolution Science Experiment] is a camera on the orbiter with a resolution of about 30 cm.
"It is hard to say how long ago the fluids were there — hundreds of millions or perhaps a billion years ago," said Dr. Okubo. "But the fact that we see evidence for chemical reactions between the fluids and the rock means that the fluids were sitting there for quite a long time... that's perhaps good if you want to look for any habitable areas that might support any biological activity." He suggested that the regions of altered rock would be a good place to look for fossilised simple organisms and that landers might find water flowing underground. In December 2006, NASA scientists, using images from another orbiter, Mars Global Surveyor, found evidence for water flowing on the surface in the last five years. They compared images of the side of a crater taken in 2001 and 2005. The second showed gullies apparently caused by water bursting out of the crater wall.

(The Hindu, 17th February 2007)