Mud volcanoes on Mars hint at ancient water reservoirs

Mars’s northern lowlands are dotted with tens of thousands of what appear to be run-of-the-mill volcanoes, given the lava-like ripples and fingers that appear around them. But geologists debate whether these bumpy landforms are really frozen magma. In a select few places on Earth, mud erupts rather than molten rock. Could Martian orbiters be sending back pictures of mud volcanoes?

Absolutely not, assumed Petr Brož, a geophysicist at the Czech Academy of Sciences. The circumstances required—sediments buried in precisely the right way—were just too unlikely. Plus, would mud even slosh after hitting the frigid surface? After recreating the scenario in a lab, Brož and his team now have their answer: Muddy mixtures on Mars would flow nearly identically to the way lava flows on Earth, although for completely different reasons, they announced in Nature Geoscience this week. The finding means that the volcanic forms on Mars could be made of either rock or hardened mud, a frustration to geologists many millions of miles away.

“The" work will be much more complicated now,” Brož says. “We cannot rely on [shape] only.”

But if researchers can learn to tell the two apart, they’ll be rewarded with a host of tantalizing sites for future exploration, as mud volcanoes may also be promising places to look for life.

Brož spent a decade skeptically scrutinizing Martian photographs and trying to argue that certain features proved that the volcanic outcroppings were rocky. Eventually, he realized that to convincingly disprove the existence of mud volcanoes, he’d need to answer a simpler question: Can mud even flow on the Red Planet? To find out, he sought a little piece of Mars on Earth, and collaborators who weren’t afraid to get their hands (and expensive machines) dirty.

Brož found what he was looking for with the Open University Mars Chamber in the United Kingdom, a six-foot by three-foot cylinder reminiscent of a deep-sea submersible that could match the low air pressure of the Martian surface. Most importantly, it wasn’t reserved exclusively for high-precision research that flecks of dirt could disrupt, such as testing aerospace equipment.

“You have a huge number of vacuum chambers around the globe, but only a few of them where the head of the laboratory has enough courage to let you make crazy experiments inside,” Brož says. “I’m sure they’re still finding mud in the chamber one year later."

The researchers chilled a bed of sand to minus 20 degrees Farenheit, stuck it in the chamber, and rigged an apparatus to tip a solution of water and fine particles out over the “