Could Martian atmospheric samples teach us more about the red planet than surface samples?

NASA is actively working to return surface samples from Mars in the next few years, which they hope will help us better understand whether ancient life once existed on the red planet's surface billions of years ago. But what about atmospheric samples? Could these provide scientists with better information pertaining to the history of Mars?

This is what a recent study presented at the 55th Lunar and Planetary Science Conference hopes to address as a team of international researchers investigated the significance of returning atmospheric samples from Mars and how these could teach us about the formation and evolution of the red planet.

Here, Universe Today discusses this research with the study's lead author, Dr. Edward Young, who is a professor in the Department of Earth, Planetary, and Space Sciences at UCLA, and study co-author, Dr. Timothy Swindle, who is a Professor Emeritus in the Lunar & Planetary Laboratory at the University of Arizona, regarding the motivation behind the study, how atmospheric samples would be obtained, current or proposed missions, follow-up studies, and whether they think life ever existed on the red planet. Therefore, what was the motivation for the study?

Dr. Young tells Universe Today, "We learn a lot about the origin of a planet from its atmosphere as well as its rocks. In particular, isotope ratios of certain elements can constrain the processes leading to the formation of the planet."

Dr. Swindle follows this with, "There are two basic types of motivation. One is that we're planning on bringing all these rock samples, and we're going to be interested in knowing how they've interacted with the atmosphere, but we can't figure that out without knowing the composition of the atmosphere in detail.

"So, we need an atmospheric sample to know what the rocks might have been exchanging elements and isotopes with. But we'd also like to have a sample of the Martian atmosphere to answer some basic questions about processes that have occurred, or are occurring, on Mars.

"For example, Martian meteorites contain trapped atmospheric noble gases, like krypton and xenon. But it appears that there are at least two different 'atmospheric' components in those meteorites."

For the study, the researchers proposed several benefits of returning a Mars atmospheric sample to Earth, including atmospheric samples being among the NASA Perseverance (Percy) rover sample tubes, gaining insight into potential solar gar within the Martian interior, evolutionary trends in atmospheric compositions, nitrogen cycling, and sources of methane on Mars.

For the Percy atmospheric sample, also known as Sample No.1 "Roubion," the study notes how this sample was obtained after Percy tried to collect a rock core sample but ended up collecting atmospheric gases instead.

Additionally, the study proposes the lack of leakage the sample tube will experience while awaiting its return to Earth and the gases present within the sample are ideal for analysis once returned to Earth, as well. But aside from the Percy rover sample, how else could a Martian atmosphere sample be obtained?

"At least two other ideas for collecting a sample of Martian atmosphere have been suggested," Dr. Swindle tells Universe Today. "One is to fly a spacecraft through the Martian atmosphere, collect a sample as it goes through, then return it to Earth. The other is to have a sample return cannister (it doesn't have to be any bigger than a Perseverance tube) that has valves and a (Martian) air compressor.