Mars Changed Forever By 'Catastrophic' Event
Scientists say the latest data has told them a lot but more analysis is needed before humans can step onto the red planet.
Mars rover Curiosity has been analysing the atmosphere
The atmosphere of Mars was destroyed four billion years ago by a mysterious "catastrophic" event, scientists have said.
Data returned by the Curiosity rover suggests there was a major upheaval, caused by volcanic eruptions or a massive collision.
The rover, which landed a year ago, has returned its first measurements of the make-up of gases in the Martian atmosphere. The results are published as part of two papers in the journal Science.
Dr Chris Webster, from Nasa's Jet Propulsion Laboratory in Pasadena, said the data allows for direct comparisons with the Earth's climate.
He said: "As Mars became a planet and its magma solidified, catastrophic outgassing occurred while volatiles were delivered by impact of comets and other small bodies.
"Our Curiosity measurements are - for the first time - accurate enough to make direct comparisons with measurements done on Earth on meteorites using sophisticated large instrumentation that gives high accuracy results."
His team believes a major event that destroyed the atmosphere must have happened around four billion years ago.
The results also show that reservoirs of carbon dioxide and water were established afterwards, and largely remain.
Dr Paul Mahaffy from Nasa's Goddard Space Flight Centre, who was the lead author on the other paper, said further analysis was needed before humans could be put on Mars.
"From a practical standpoint we need to know the composition (of the atmosphere) today and how it is changing, so that we can prepare for the eventual arrival of human explorers," he explained.
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