Mars shows signs of geologically recent volcanic activity, and scientists find to their surprise that there may well be another volcanic blast in the Red Planet’s future.
“We would be very lucky to see it, but it would be a massive event,” says Gerhard Neukum of Berlin’s Free University, lead author of the study in Thursday’s journal Nature.
Images taken by the European Space Agency’s Mars Express orbiter suggest that there have been lava flows from intense volcanic activity within the last 2 million years.
To geologists, that’s yesterday, Neukum says.
Although Mars is littered with volcanoes, most notably Olympus Mons, the largest one in the solar system, geologists generally regard them today as duds. But Neukum’s team reports that the new images indicate that some volcanoes are merely dormant, not dead.
The team bases its claim on crater counts from within the calderas – collapsed volcanic domes – of several large Martian volcanoes. Crater counts are a standard method used by scientists to estimate the age of a planetary feature, with the number of craters increasing over time.
Calderas on the summits of Olympus Mons and Arsia Mons, another volcano, look comparatively recent, the team has found. Lava flows on the lower flanks of Olympus Mons appear to date from 2.4 million years ago.
The images add to recent evidence of volcanic activity at other Martian sites that are only 10 million years old. And what’s more, they suggest that this is a global phenomenon, says planetologist Victoria Hamilton of the University of Hawaii in Honolulu, who was not a member of the study team.
But she is more cautious about the chances of seeing a volcano erupt on Mars any time soon. “I doubt we’re likely to see it in our lifetime, if that’s what people are wondering,” she says. “These could be the last burps of dying volcanoes on Mars just as much as they could be signs of active, continuing volcanism as we think of it on Earth.”
For perspective, Hamilton notes that Venus appears to have had many more volcanic eruptions than Mars within the last 300 million years, and no active volcanoes have been observed on that planet.
The images also indicate that ice glaciers likely hide under dust on the northern rim of Olympus Mons. Nearby are valleys that appear plowed by glaciers. “The images showing glacial flow are quite convincing and I believe this is significant,” says Melissa Lane, a Mars expert at the Planetary Science Institute in Tucson, Ariz.
Taken together, the volcanoes and ice paint a picture of Martian hydrothermal activity stretching back billions of years, Neukum says. Some of the volcanoes appear perhaps 3.8 billion years old, whereas Mars itself is about 4.5 billion years old.