ORLANDO • US space agency Nasa's robotic probe InSight has detected and measured what scientists believe to be a "marsquake", marking the first time a likely seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory (JPL) in California reported.
The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on Mars' surface to begin its two-year seismological mission on the red planet.
The faint rumble characterised by JPL scientists as a likely marsquake, roughly equal to a 2.5-magnitude earthquake, was recorded on April 6 - the lander's 128th Martian day, or sol.
It was detected by InSight's French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.
"We've been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology," InSight principal investigator Bruce Banerdt said in a news release.
Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.
"The high frequency level and broad band is very similar to what we get from a rupture process. So we are very confident that this is a marsquake," lead researcher for InSight's seismometer Philippe Lognonne said in an e-mail.
Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.