Mars Atmosphere
July 18, 2013

Curiosity Offers Insights Into How Mars Lost Its Atmosphere

[ Watch the Video: Searching for Mars' Missing Atmosphere ]

Lee Rannals for - Your Universe Online

NASA's Curiosity rover has helped bring in some new insights about how Mars lost its original atmosphere.

Scientists believe the original Martian atmosphere was much thicker than it is today, leading many to wonder how it became so thin. The Mars Curiosity laboratory has provided some clues into this mystery, which scientists recently reported about in the journal Science.

"The beauty of these measurements lies in the fact that these are the first really high-precision measurements of the composition of Mars' atmosphere," said Sushil Atreya, professor of atmospheric, oceanic and space sciences at the University of Michigan.

Curiosity's Sample Analysis at Mars (SAM) instrument measured the abundances of different gases and isotopes in samples of Martian air. Isotopes are variations of the same chemical elements that contain different numbers of neutrons. SAM analyzed the ratios of heavier to lighter isotopes of carbon and oxygen in the carbon dioxide that makes up most of Mars' atmosphere today. These measurements showed that heavy isotopes of carbon and oxygen were more abundant in today's atmosphere compared with the proportions in the raw material that formed the planet.

The measurements provide supporting evidence for the loss of much of Mars' original atmosphere as well as clues as to how the loss occurred. The findings suggest that Mars' atmosphere escaped from the top, rather than due to the lower atmosphere interacting with the ground.

"The isotope data are unambiguous and robust, having been independently confirmed by the quadrupole mass spectrometer and the tunable laser spectrometer, two of the SAM suite instruments," Atreya said. "These data are clear evidence of a substantially more massive atmosphere, hence a warmer, wetter Mars in the past than the cold, arid planet we find today."

Curiosity's measurements did not directly measure the current rate of atmospheric escape, but NASA's next planned Mars mission will be able to.

"The current pace of the loss is exactly what the MAVEN mission now scheduled to launch in November of this year is designed to determine," said Paul Mahaffy of NASA Goddard Space Flight Center, Greenbelt, Md.

MAVEN's assembly was completed back in February, and then underwent environmental testing at Lockheed Martian Space Systems facilities. This mission is scheduled to launch in November of this year and will be able to examine in greater detail how Mars lost its atmosphere.