Curiosity Rover Discloses That Mars Lost its Atmosphere 4 Billion Years Ago, But May Have Supported Life

A first detailed analysis of the data provided by Curiosity rover's samples of the Martian atmosphere suggests that the Red Planet eventually lost its atmosphere due to a mysterious catastrophic event.

Curiosity's Sample Analysis at Mars (SAM) has measured the abundance of different gases as well as isotopes in the Martian atmosphere.

SAM checked the ratios of various isotopes right from heavier to lighter isotopes of  carbon and oxygen in the carbon dioxide that makes up most of the Martian atmosphere. Isotopes are variants of same chemical element that have different atomic weights.

The measurements revealed that the present Martian atmosphere is made of heavy isotopes of carbon and oxygen when compared to the earlier proportions discovered in the raw materials that formed Mars. This offers clue as to why Mars lost its air and why it keeps thinning.

"As atmosphere was lost, the signature of the process was embedded in the isotopic ratio," said Paul Mahaffy of NASA Goddard Space Flight Center, Greenbelt, who is the principal investigator for SAM and lead author of one of the two papers about Curiosity.

Certain other factors such as persistent presence of water on the planet's surface long ago, provide clues that previously Mars had a thicker atmosphere.  The enhancement of heavier isotopes in carbon dioxide gas indicates a process of loss from the top of the atmosphere.

Curiosity simultaneously measured the same pattern in isotopes of hydrogen, carbon and oxygen. Prior to this, the enrichment of heavier isotopes was measured on Mars and in gas bubbles that were present in Mars meteorites. Measurements of these meteorites offer clues about the Martian atmospheric loss. The team assumes that some 4 billion years ago the Martian atmosphere was torn apart due to a catastrophic event.

The rate at which Mars is currently losing its atmosphere will be measured by MAVEN mission that will launch in November of this year.

"Getting the same result with two very different techniques increased our confidence that there's no unknown systematic error underlying the measurements," said Chris Webster of NASA's Jet Propulsion Laboratory, Pasadena, Calif. He is the lead scientist for the tunable laser spectrometer and the lead author for one of the two papers. "The accuracy in these new measurements improves the basis for understanding the atmosphere's history."

The finding was published in the journal Science.