Life on Mars?

Current theories say that life requires water in liquid form to be available. So far, liquid water has not been found on Mars.

However, water has been found in solid form (ice) and it is believed that that there could be liquid water might exist underground

The ALH84001 meteorite, which is believed to have originated from Mars, was found in Antarctica in December 1984 by a group of researchers for the project ANSMET. Some researchers believe that regular shapes found within it could be fossilized microorganisms.

In 1998, NASA's Mars Global Surveyor orbiter detected dark spots beneath the ice of the sand dunes at the south pole of Mars. 70% of these dark spots were found in the same place the following year.

A team of scientists from Budapest have suggested that these spots might be of biological origin. They believe they may indicate the existence of "extremophiles" which exist on Earth in spots such as volcanoes or solid ice where other creatures could not possibly live.

The European Space Agency is using Mars Express to study these spots.

Traces of methane gas were detected in the atmosphere of Mars in 2003. Methane is unstable and disappears after several years under Martian atmospheric conditions and solar radiation. Therefore, the presence of methane in the atmosphere indicates that Mars should have a source of methane which could be biological, which maintains the concentration of methane in the atmosphere. This source would have to produce minimum of 150 tons of methane each year.

In 2007, it was estimated that life on Mars could not exist less than 7.5 meters below the surface, because above that detrimental cosmic radiation would kill off DNA molecules.

NASA plans to probe further with its Mars Science Laboratory, which includes a mass spectrometer capable of measuring the difference between carbon-12 and carbon-14 to determine whether the methane is of biological or geological origin.