NASA’s InSight lander has detected Mars quakes that mostly come from one region: Cerberus Fossae.
Scientists assessing those quakes discovered evidence that there’s molten lava deep within Mars.
Present-day magma on Mars would change scientists’ understanding of the planet’s history and interior.
Scientists have long thought Mars was dead — in the geological sense.
Sure, the planet is peppered with volcanoes and there are ancient lava flows in some places. But the cold, barren world seemed to have lost its volcanic fervor long ago.
But now, using a seismometer on NASA’s InSight lander, scientists have discovered the first evidence of molten lava deep below the Martian surface.
The presence of active lava could change scientists’ understanding of Mars’s history—from its formation, to the period when it may have hosted microbial life, to the loss of its atmosphere and the cold rock it is today. That informs how scientists understand rocky planets beyond our solar system, too, including those that could host their own life.
A series of Mars quakes clued the scientists in to the potential lava hotspot. Unexpectedly, most large quakes were coming from that one spot.
“We found something that was really not consistent with anything we believed was true,” Anna Mittelholz, a planetary scientist on the team of researchers behind the discovery, told Insider.
Mittelholz recalled the words of her team’s lead researcher, in reference to shaking up scientists’ beliefs: “Oh no, we broke Mars.”
The biggest Mars quakes point to an underground chamber of magma
InSight has detected more than 1,300 Mars quakes since landing on the red planet in 2018. To scientists’ surprise, the most powerful tremors all came from one region full of rifts, called Cerberus Fossae.
In a paper published in Nature Astronomy on Thursday, researchers analyzed 20 of those big quakes. Seismic waves carry information about every bit of Mars they travel through on their way to InSight. The researchers discovered that certain seismic waves were moving much more slowly than they expected.
“The only answer that seemed to make sense with this observation is that the region has to be hot,” Mittelholz said.
That indicates the presence of molten lava, or “magma,” deep below the Cerberus Fossae surface. That magma moving or cooling is probably what creates those quakes, according to Mittelholz, since the rumblings originate 14 to 50 kilometers below the Martian surface, where the scientists suspect the chamber of magma is.
“It is possible that what we are seeing are the last remnants of this once active volcanic region or that the magma is right now moving eastward to the next location of eruption,” Simon Stähler, who led the study, said in a press release.
The movement is also probably causing smaller, surface-level quakes, by breaking up and moving around the planet’s crust in that region.
“We are pretty confident that there is some volcanic activity going on down there. It’s very hard to explain the data in any other way. So locally, I would say it’s pretty definitive. I think the bigger question is: What would we expect globally ?” Mittelholz said.
InSight carries the only seismometer ever placed on Mars. It’s just one station in one location, and it can’t detect smaller quakes that happen far away or on the other side of the planet. So scientists have limited information about Mars’s seismic activity and any other potential hotspots for quakes or magma. To get the global picture of Mars quakes and volcanic activity, NASA would need to send more seismometers to the red planet.
This volcanic, quake-prone region of Mars is a mystery
Spacecraft orbiting Mars have imaged plenty of fault lines along its surface — regions where there’s clear disruption from subsurface tremors — so scientists expected InSight to detect quakes from many different places.
Mars has surprised them, though. Almost all the quakes so far have come from Cerberus Fossae.
“I think it will take some figuring out what this actually means and why that’s the case. What is so special about Cerberus Fossae? I wouldn’t say it’s what we expected to see,” Mittelholz said.
InSight is running out of power, as dust builds up on its solar panels. Its mission on Mars will likely end before January 2023. Then there will be no seismometer on Mars to gather new information about the planet’s deep structures.
“I think that this InSight data set will be there for awhile. There’s been so much data coming all the time that it’s actually been hard to fully take all the information that’s in it,” Mittelholz said, adding, “So I think that a lot of studies will result, even after InSight is not operating anymore.”
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