NASA’s Mars rover Curiosity is now helping scientists understand how much of its original atmosphere the red planet may have lost. The data could help researchers predict whether Mars was ever habitable.

Using its on-board Sample Analysis at Mars (SAM) instruments, Curiosity has analyzed samples of the Martian atmosphere during its weeks stationed at the “Rocknest” site. NASA states that its findings show the loss of the atmosphere has been a significant factor in the evolution of the planet.

More specifically, the samples show a 5% increase in the heavier isotopes of carbon in atmospheric carbon dioxide compared to estimates of what the ratio would have been when Mars formed. This suggests to NASA researchers that the top of the Martian atmosphere may have been lost, depleting lighter isotopes. The findings match previous estimates of the composition of the atmosphere made from studies of meteorites from Mars, and more investigation into the loss of the upper atmosphere will be undertaken by NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) in 2014.

“With these first atmospheric measurements we already can see the power of having a complex chemical laboratory like SAM on the surface of Mars,” said Paul Mahaffy, SAM Principal Investigator at NASA’s Goddard Space Flight Center. “Both atmospheric and solid sample analyses are crucial for understanding Mars’ habitability.”

Curiosity project scientists were also hoping to find evidence of methane gas on Mars, but found little to none. The compound is a chemical precursor for carbon-based life. The rover’s Tunable Laser Spectrometer (TLS), pictured above, provided the most sensitive measurement for Methane yet and placed an upper limit of a few parts methane per billion parts Martian atmosphere, with a large enough error range for the amount to possibly be zero.

“Methane is clearly not an abundant gas at the Gale Crater site, if it is there at all,” said Chris Webster, SAM TLS lead at NASA’s Jet Propulsion Laboratory. “At this point in the mission we’re just excited to be searching for it. “While we determine upper limits on low values, atmospheric variability in the Martian atmosphere could yet hold surprises for us.”

Curiosity’s SAM is is set to analyze the chemical composition of its first sample of Martian soil in the coming weeks. Researchers will be looking for organic compounds that could suggest past environmental conditions favorable for microbial life.