The Curiosity rover sits on the surface of Mars on 12 May 2019.
With its suite of science instruments, the car-sized Curiosity rover tin can sample both the surface and the atmosphere of Mars, helping search for signs of past and present habitability. Credit: NASA/JPL-Caltech/MSSS
Source: Journal of Geophysical Research: Planets

The Martian atmosphere is sparse and cold and consists mostly of carbon dioxide. Although certainly unsuitable for humans, Martian air could hold clues to whether other life-forms live—or once lived—on the Red Planet. At present Trainer et al. report the first measurements of the five major components of the Martian atmosphere captured over several seasonal cycles.

The researchers made the new measurements over nigh three Martian years (about 5 Earth years) using the Sample Analysis at Mars (SAM) musical instrument suite on NASA's Curiosity rover. In that time, Curiosity explored a xvi-kilometer stretch of Gale Crater, located near the equator. Four or v times per season (like World, Mars has a winter, spring, summer, and fall), SAM nerveless an air sample to examine the atmosphere's limerick.

On average, the data revealed, the equatorial Martian atmosphere consists of 95% carbon dioxide, 2.59% nitrogen, 1.94% argon, 0.161% oxygen, and 0.058% carbon monoxide. Still, throughout the yr, some of these concentrations vary widely because of seasonal freezing of carbon dioxide at the planet'south poles, which periodically removes much of this gas from the atmosphere.

Seasonal polar freezing—and subsequent thawing—of carbon dioxide also causes atmospheric pressure level to rise and autumn throughout the year. SAM measurements showed that nitrogen and argon concentrations at the equator reflect these seasonal pressure changes, simply with a time filibuster. This result suggests that seasonal pressure level changes drive movement of air across the planet faster than the gases in the air can mix to reverberate each season's limerick.

The researchers besides found unexpected patterns in seasonal and twelvemonth-to-year oxygen concentrations that cannot be explained by any known atmospheric or surface processes on Mars. The authors suggest that these variations could be due to chemical reactions in surface rocks but note that farther enquiry is needed to solve this mystery.

The new findings provide a clearer motion picture of seasonal atmospheric compositions on Mars, which could assistance in the ongoing search for signs of past or present life on the planet. (Journal of Geophysical Enquiry: Planets, https://doi.org/10.1029/2019JE006175, 2019)

—Sarah Stanley, Freelance Writer

Citation:

Stanley, S. (2019), Curiosity rover reveals oxygen mystery in Martian atmosphere, Eos, 100, https://doi.org/10.1029/2019EO136720. Published on 25 Nov 2019.

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