Mars Volcano Is Changing the Planet

Mars has been holding out on us. A 2026 gravity study suggests that beneath the planet's most dramatic volcanic region, something enormous is rising through the mantle and nudging Mars to spin faster.

Scientists identified a plume of unusually light material, called a negative mass anomaly, in the mantle beneath the Tharsis region. Tharsis is already the most outsized feature on Mars: a sprawling volcanic province near the equator in the planet's western hemisphere, home to the largest volcanoes in the solar system.

The research, published in the Journal of Geophysical Research: Planets, used fresh data from NASA's InSight lander combined with orbital gravity measurements to build a more complete picture of Mars's interior than previous approaches allowed. Even with an established model of the planet's structure in place, the math didn't quite add up around Tharsis. The remainder pointed underground.

The mismatch suggested a substantial negative mass anomaly in the mantle beneath the Tharsis Rise; likely extremely high-temperature buoyant material rising from depth. The best-fit anomaly sits roughly 1,200 kilometers (746 miles) below the surface. According to the researchers, this light mass will move upward and hit the Martian lithosphere, introducing melt pockets that have the potential to penetrate the crust and erupt as volcanoes.

Then there is the rotation problem. Earlier measurements comparing Viking lander data with InSight observations showed that Mars's day is shrinking by roughly 70 microseconds per year. The team says the increasing spin rate may be due to the mass anomaly, though more precise analysis is needed.

Mars has been quietly redecorating the basement while everyone was looking at the surface.

Read the full story at The Debrief, March 27, 2026