New Clues to Life on Mars

Data obtained by the European Space Agency (ESA) probe Mars Express and the US spacecraft Mars Odyssey show that in some equatorial locations, low-atmosphere levels of water vapor and methane "significantly overlap," the ESA said in a press statement Monday.

The two substances are often connected to life since most scientists believe water is necessary for life and because methane is often produced by living organisms.

"We have a new piece in a puzzle about understanding whether there is possible life, past or present, on Mars," ESA science spokesman Roberto Loverde told AFP.

The water vapor and methane gas concentrations were found in an area with an ice layer just below the planet's surface. When all the information is put together it points to "a common underground source," such as volcanic or hydrothermal activity or, perhaps, bacterial life, which may exist in the water below the ice table, the agency said.

If the latter case is true, the bacteria would produce methane as a natural living process and the gas would be released into the atmosphere.

Still grounds for speculation

Scientists, however, are quick to warn that methane gas, which comprises just a tiny part of the Martian atmosphere, can also be produced in other ways

A water-ice methane hydrate, which could come from microbial life or other sources, could also be responsible for the findings, Michael Mumma, an atmospheric scientist at the US space agency's Goddard Space Flight Center, told the BBC.

"If you happened to warm that beyond the liquidation temperature, then you would free both methane and water together," he said.

Underground volcanic sources could also explain the presence of water vapor and methane since they would push both substances to the surface.

The ESA's findings were made by the Planetary Fourier Spectrometer (PFS), a scientific tool onboard Mars Express made to determine the make-up of the planet's atmosphere.

Data's real test still coming

While calling the data interesting, Colin Pillinger, a professor at the Open University in Milton Keynes and the chief scientist on the British-led Beagle 2 mission, told the BBC the only way to prove a correlation between water and methane would be to measure it on the Mars' surface.

The information's real test will happen when international scientists are able to get their hands on the data, according to James Garvin, NASA's Chief Scientist for Mars and the Moon.

"The message here is that exciting initial observations such as those reported by the Mars Express PFS are what catalyze new questions, observations, and ultimately testable hypotheses," he concluded.