Between 3 and 4 billion years ago, Mars bubbled and burst with volcanic activity. The planet’s stationary crust and lower surface gravity meant volcanoes could build themselves up to staggering heights, like Olympus Mons which stands nearly three times higher than Mount Everest. Smaller eruptions continued in some isolated pockets as recently as 3 million years ago, but today the planet seems a much quieter place. At least that’s what we thought, until scientists discovered volcanic activity that looks like it happened in the relatively recent past, and their findings could have major implications for the search for life on the red planet.
Planetary scientists were examining a pair of fissures known as Cerberus Fossae that stretch for nearly 1000 kilometers across a volcanic plain in a region known as Elysium Planitia. They’re thought to be a relatively young geological feature since in some places the walls are almost vertical, an indication that erosion hasn’t had time to wear them down to a shallower angle. Indeed, the whole volcanic plain appears fairly new, considering the low number of impact craters compared to other regions of the planet. A rough estimate puts its age anywhere between 2.5 million and 500 thousand years old. But on closer inspection, one stretch of the region that’s just a few tens of kilometers long known as the Cerberus Fossae mantling unit seems to indicate much more recent activity.
Using visible light and infrared images from NASA’s Mars Reconnaissance and Mars Odyssey Orbiters, the researchers spotted a mysterious dark spot similar to ones on Mercury or the moon. Dark spots like this hint at explosive volcanic activity. The deposit of ash and rock sits on solidified lava flows, meaning it’s from a different time period than the other volcanic activity. In fact, it may have happened very recently, judging by how few impact craters there are in the area.
How recently? This eruption could have happened within the last 200,000 years, and perhaps even just 50,000 years ago. On a human scale that’s a long time, but geologically speaking that’s practically yesterday.
One of the scientists behind the research said that if the entire history of Mars were compressed to a single day, this eruption would have happened one second before midnight.
This opens up the possibility that maybe Mars isn’t quite as dead as it seems, in a few different ways. Maybe there’s still magma under the surface, and all it needs is the right conditions to come out. One researcher pointed to an impact crater just 10 kilometers from this newly discovered volcanic feature that appears to be from about the same time period. He speculated the impact may have been the trigger, though acknowledged it’s a longshot. It’s also possible that magma could have come into contact with ice under Mars’ surface and the expanding water vapor led to an eruption.
Heat from subsurface magma and that icy substrate could also create conditions capable of sustaining microbial life in the recent past, or perhaps even to this day. But it’s not all great news for the search for extraterrestrial life: scientists have long thought methane in Mars’ atmosphere was a potential biomarker. But volcanoes can also emit methane, so if Mars is still volcanically active, that might be a comparatively anticlimactic explanation for the methane instead.
Researchers made this discovery by studying the planet from orbit, but other probes could expand their knowledge. As it happens NASA’s InSight lander is in Elysium Planitia, and the seismometer on board has thus far detected two Marsquakes coming from Cerberus Fossae which could be due to moving magma.
Unfortunately, one InSight instrument that would have been really useful for just this situation, a heat probe known as the mole, wasn’t able to bury itself deep enough in the Martian regolith and after almost two years of troubleshooting, NASA gave up on the mole in January 2021. Perhaps a future mission with an improved mole will reveal more about how heat moves inside the red planet, or maybe we’ll get lucky and something will set off another eruption. I just hope it happens soon, and by that I mean within my lifetime and not 50,000 years from now. If you want to learn more about why the InSight lander’s mole couldn’t dent Mars’s surface by why the mission is still awesome anyway, check out my video on it here.
With the mixed news about what a volcanically active Mars could mean for the search for extraterrestrial life, are you more or less optimistic we’ll find it on Mars?