Mars’ atmosphere, once as thick as if not thicker than Earth’s today, is leaking into space.
About 0.25 lbs of Mars’ atmosphere (0.11 kg) is pushed away every second by the incessant solar wind, the speedy stream of charged particles routinely blasted from the sun which pervade the solar system and even reach beyond Pluto.
But for a rare two days last December, a few of that wind went away. Its sudden and dramatic disappearance, causing the atmosphere on Mars’ sun-facing side to swell by nearly 4 times its usual size — from its usual 497 miles (800 km) to over 1,864 miles (3,000 km). The peculiar event was recorded by a NASA orbiter named MAVEN (short for Mars Atmosphere and Volatile Evolution) which has been observing each Mars’s atmosphere and its response to the sun‘s behavior since 2014. MAVEN’s data showed other elements of the Martian system, including the tear drop-shaped magnetosphere, the bow shock and the ionosphere expanded similarly.
“We’re really off the charts here,” Jasper Halekas, a professor of physics and astronomy on the University of Iowa and a member of the MAVEN team, said on Monday (Dec. 11) on the AGU conference being held this week in California and online. “That is something that we have not seen at Mars before with MAVEN.”
Related: Lost in Space: How Mars’ Atmosphere Evaporated Away
The atypical episode — the primary in nearly a decade of MAVEN’s profession — occurred after a fast-moving region of a solar wind overtook its slower counterpart and swept up the latter’s material, forsaking a sparse region. The emptied storm reached Mars on Dec. 25, 2022, giving scientists an exciting front-row seat to observe the planet’s atmosphere balloon out, the way in which it may need been if it were circling a less ‘windy’ star.
“This was a Christmas present for us,” said Halekas, who’s leading a brand new study reporting this event. “Nature arrange this perfect science experiment.”
With MAVEN’s data of the unexpected dynamics on Mars, Halekas and his colleagues studied how extreme solar events — and their absence — influence the planet’s atmosphere, an insight priceless to understanding its evolution. The findings even have implications for our understanding of Earth-like planets outside our solar system and the way they interact with their host stars, the team shared on Monday.
“We could look under the hood at what physics is occurring, how the dynamics are working and really get a way of those details,” said MAVEN team member Skylar Shaver of the Laboratory for Atmospheric and Space Physics in Boulder.
Two days after the almost-vacant storm passed Mars, the atmosphere across the Red Planet settled all the way down to its original state once more, but not before bouncing a little bit like a jiggling plate of Jell-O. An analogous storm struck Earth in 1999, when our planet’s atmosphere grew to 5 times its normal size. But there aren’t often orbiting spacecraft positioned in addition to MAVEN is now to review such events, the Latest Atlas reported.
Shannon Curry, the principal investigator for the MAVEN mission, suspects events like this were common during Mars’ early evolution 3 to 4 billion years ago, when our sun was more fiery than it’s now and maybe blasted out storms once every week and even day-after-day. Such extreme events were likely answerable for parching the Red Planet, a world scientists presume once hosted liquid water and offered conditions friendly toward life. Extrapolating the most recent MAVEN data to review Mars’ evolution through time could make clear how much its atmosphere eroded away and how briskly the planet dried up, Curry said.
Curry added events like this will occur multiple times in the following two years because the sun’s activity climbs to its peak, expected to occur in July 2025 if not late next yr.