Newswise – New research shows that fluctuations in atmospheric pressure that pull gases up from the subsurface could be responsible for the release of subsurface methane into the Martian atmosphere; Knowing when and where to look for methane can help the Curiosity rover search for signs of life.

“Understanding methane variations on Mars was highlighted by NASA’s Curiosity team as an important next step in figuring out where it comes from,” said John Ortiz, a graduate student at Los Alamos National Laboratory who led the research team. “There are several challenges associated with achieving this goal, and a major one is knowing at what time of a given sol (Martian day) Curiosity is best suited to conduct an atmospheric sampling experiment.”

The paper was published the week of January 22 in the Journal of Geophysical Research: Planets.

A primary focus of NASA’s Mars missions, including Curiosity and Perseverance, is detecting and understanding past or present signs of life, such as methane. However, because the source of methane on Mars is likely underground, short-term fluctuations in atmospheric methane levels pose a research challenge.

To better understand methane levels on Mars, Ortiz and his team used high-performance computing clusters to simulate how methane travels through networks of underground fractures and is released into the atmosphere, where it then mixes within the atmospheric column. They also modeled how methane is adsorbed on the pores of rocks. This is a temperature-dependent process that can contribute to fluctuations in methane levels.

Their simulations predicted pulses of methane from Earth’s surface into the atmosphere just before sunrise on Mars in the planet’s just-ended northern summer season. This confirms previous rover data suggesting that methane levels fluctuate not only seasonally but also daily.

This valuable data will be incorporated into the Curiosity rover’s ongoing sampling campaign.

“Our work suggests several important time windows for Curiosity’s data collection. “We believe these offer the best chance of constraining the timing of methane fluctuations and (hopefully) later bringing us closer to understanding the origin of methane on Mars,” Ortiz said.

Paper: “Subsurface methane fluctuations on Mars driven by barometric pumping and the evolution of the planetary boundary layer.” Journal of Geophysical Research: Planets. DOI: 10.1029/2023JE008043

financing: This research was supported by a Center for Space and Earth Science student grant funded by the Laboratory Directed Research and Development program under project number 20210528CR.

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