On April 6, NASA’s InSight lander recorded a faint tremor that appeared to originate from the interior of Mars. If this is confirmed, it would be the first-ever "Marsquake" recorded on the Red Planet. Scientists are still examining the signals so they can be absolutely certain of the tremor's origin.
The signal was recorded by the lander’s Seismic Experiment for Interior Structure (SEIS) and while it is not powerful enough to help researchers probe the inside of the Red Planet, it shows that Mars is still active. SEIS has the chance to learn a lot about what lies beneath the lander.
"InSight's first readings carry on the science that began with NASA's Apollo missions," InSight Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory said in a statement. "We've been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology!"
The connection to the Apollo mission is an important one. Apollo astronauts left several seismographers on the Moon, which showed that our natural satellite is seismically active. The network was operated until 1977 and recorded 28 Moonquakes with magnitudes as high as 5.5 on the Richter scale. Thanks to these, scientists were able to develop a precise idea of what a typical Moonquake looks like. And the signal coming from InSight is remarkably similar. That’s what got the team excited.
"We've been waiting months for a signal like this," said Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France. "It's so exciting to finally have proof that Mars is still seismically active. We're looking forward to sharing detailed results once we've had a chance to analyze them."
The potential Marsquake is not the only signal recorded by InSight. Three other events were registered on March 14, April 10, and April 11. These were too weak to be considered quakes and their origins were very ambiguous, but there will still be follow-up studies to help us understand how they developed. These microquakes can help us determine what the crust near the lander is like, and how it is changing.
SEIS is not the first seismographer on Mars. The Viking landers also had seismometers but they were positioned on the landers and were affected by the Martian wind. SEIS is located on the ground away from InSight’s main body and is shielded as much as possible from extreme temperature changes and wind. Despite being out in the elements, instead of deep in a lab like it was on Earth, the instrument has exceeded the team's expectations in terms of sensitivity.