Martian Atmosphere Destroyed Billions of Years Ago

CNN’s Elizabeth Landau highlights new findings by NASA’s Mars rover Curiousity:

Two new studies in the journal Science this week suggest that the Martian atmosphere hasn’t changed much in terms of chemical composition in the past 4 billion years. It’s much thinner than our planet’s atmosphere, and the mix of ingredients isn’t friendly to living organisms that are known to us.

On the plus side, scientists are excited that the atmospheric analyses from instruments on board the Mars rover Curiosity square with what has been seen from meteorites that have landed on Earth from Mars.

“In a sense our measurements confirm that those meteorites are from Mars,” said Chris Webster, program manager of the Planetary Science Instruments Office at NASA’s Jet Propulsion Laboratory, who led one of the studies.

The main gas in Mars’ atmosphere is carbon dioxide, at a whopping 96%, according to the scientists. Earth’s atmosphere is mostly nitrogen, at 78%.

The Martian atmosphere also has very low oxygen content — 0.1% — especially compared with our own atmosphere, which has 19%.

More bad news for those who are eager to find life on the Red Planet: The rover has not detected methane so far, Webster said. This colorless gas is released by organisms as they digest nutrients, so it is an indicator of life, although it can also be produced in geological processes.

Because of the harsh environment on Mars, the assumption is that any life that might be there is below the surface, and that it’s microbial.

“By definition, if we don’t detect methane, it means the probability that that’s happening today is reduced significantly,” he said.

Still, the hunt for methane will continue as Curiosity, the most technologically advanced rover to explore Mars, continues its journey.