During Apollo 17, the last mission of a human crew to the Moon in December 1972, air was reported with the soil samples taken on this occasion. A very precious scientific material studied since 2021 thanks to a cold extraction process which contributes to the understanding of the formation and evolution of our natural satellite. That’s why atmospheric scientists have high hopes for the air in the Martian soil sample capsules that the Perseverance rover is collecting.
« Air samples from Mars would tell us not only about the current climate and atmosphere, but also how they have changed over time “, explains Brandi Carrier, planetologist at NASA’s Jet Propulsion Laboratory.
Perseverance must collect 38 samples from Mars
Since arriving on Mars in February 2021, Perseverance has collected 24 samples of regolith, rocks and dust from the surface which are stored in titanium tubes. Fifteen of these tubes are stored in a compartment of the rover while the others have been placed on the ground, spaced 5 to 15 meters apart, with a geolocation device which will allow them to be found in due time. In total, Perseverance must take 38 samples plus five “control tubes” intended to document the cleanliness of the sampling system throughout the mission.
photo credit: © NASA/JPL-Caltech
The first sample tube taken by the NASA rover is atmospheric only. Furthermore, each tube also contains air from Mars which will continue to interact with the rocky materials until their eventual return to Earth. This combination is of great interest to scientists because it will make it possible to directly study the atmosphere of Mars and its interaction with the surface.
The problem of returning samples to Earth
We know that the Martian atmosphere is composed mainly of carbon dioxide, but it could contain traces of other gases (neon, argon and xenon) which can potentially shed light on the formation of the red planet and in particular the similarity of its past atmosphere with that of the early Earth. “Even scientists who don’t study Mars would be interested, because it will shed light on how planets form and evolve,” comments Justin Simon, a geochemist at NASA’s Johnson Space Center.
Researchers also hope to better understand the amount of water vapor hovering near the surface of Mars and therefore the distribution of ice on the planet and the evolution of the water cycle.
This is all obviously very promising. On condition that the samples can be brought back to Earth. However, the initial cost and complexity of the Mars Sample Return mission led NASA to review its copy. The American space agency has launched a call for projects from the private sector and selected seven companies responsible for studying more economical and rapid methods of returning samples from Mars. The plan calls for a launch in 2027 and a return of the samples to Earth in 2033.
