Mars may look dry and dusty from the outside, but it has a surprisingly vibrant inner life, according to new findings from NASA's quake-hunting InSight mission.
The lander, which touched down on the red planet 15 months ago, has detected plenty of seismic activity, an unexpectedly strong local magnetic field and around 10,000 whirlwinds passing over the Martian surface.
The findings, published Monday in a suite of six papers in the journals Nature Geoscience and Nature Communications, will help scientists unlock the secrets of Mars' interior and understand why it looks so different from Earth.
"What these results really are showing us is that Mars is an active planet today," said Bruce Banerdt, the mission's principal investigator, based at NASA's Jet Propulsion Laboratory in La Canada-Flintridge, Calif., and a co-author of the new studies.
InSight is situated in a roughly 27-yard-wide impact crater in western Elysium Planitia, a volcanic plain whose surface material ranges in age from 3.7 billion to just 2.5 million years old. About 1,000 miles away lies Cerberus Fossae, a volcanic region full of faults, evidence of old lava flows and signs that liquid water once ran on the surface.
"Anything that's been active in the last couple million years could be active today, especially at depth," Banerdt said.
The lander is equipped with a dome-covered seismometer to measure quakes in Mars' upper layers. The quake-sensing instrument also comes with a small entourage of magnetic pressure, wind and temperature sensors to filter out the "noise" generated by storms and other phenomena.
The seismometer picked up 174 marsquakes through Sept. 30, including more than 20 measuring magnitude 3 to magnitude 4. These shakers wouldn't necessarily have felt like magnitude 3 or 4 temblors on Earth because they originated far deeper than such quakes typically do on this planet. Still, if you were standing in the right spot, you might pick it up, said Suzanne Smrekar, the mission's deputy principal investigator.
"You'd have to be very close to feel a quake like that in California," said Smrekar, who is based at JPL.
In general, tectonic activity on Mars is caused by the upper layers of the planet deforming and cracking as its interior cools and shrinks. But there are many different potential causes of individual marsquakes, and scientists said they'd need to catch more of them -- particularly the larger-magnitude ones -- to figure out the cause of any single event. So far, the larger quakes seem to be less frequent than scientists expected, and no "big ones" over magnitude 4 have appeared.