A marsquake recorded on the Red Planet on April 6 is the first tremor ever seen on that world. A four-decade long search to detect the first quakes on Mars has come to an end, giving birth to a new discipline — Martian seismology .
The Seismic Experiment for Interior Structure (SEIS) probe, carried to Mars with the InSight spacecraft, detected the tremor. This dome-shaped instrument is capable of sensing quakes deep within the surface of the planet, as well as tremors caused by weather or asteroid impacts.
“We’ve been waiting months for a signal like this. 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,” said Philippe Lognonne, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France.
The cause of this Marsquake is unknown, although the event could be the result of stress caused by heating and cooling of the Martian surface. Different materials can reflect or alter the speed of seismic waves, allowing geologists a chance to determine the underlying structure of a planet. Unfortunately, the event was too small to reveal details of the Martian crust.
The SEIS probe, part of the science payload of the InSight lander, is operated by the French space agency, The National Centre for Space Studies (CNES).
Shaking Things Up
More than four decades ago, a pair of spacecraft, NASA’s Viking landers, touched down on Mars. One of the goals of this dual mission was to detect quakes happening on Mars, although the vehicles did not detect any seismic activity on the planet during that earlier mission.
“Of all the events recorded, only one candidate potentially linked to an earthquake was detected during the course of the ground 80. Unfortunately, at that time, no meteorological data was collected by the weather station, preventing any validation: the seismologists could not be certain that the captured vibration train was really connected to a seismic phenomenon, and not to the whims of the winds,” SEIS engineers report.
Following 40 years of canceled missions, InSight landed a seismometer on Mars for the first time since Viking, on November 26, 2018.
Seismometers placed on the Moon by the Apollo astronauts have had a long history of successes, punctuated by some disappointments. The first probe placed on the Moon by the Apollo 11 astronauts lasted just 30 days before falling silent. The first true moonquakes were not recognized for what they were, but artificial quakes, caused by lunar landers impacting the Moon, taught scientists how to recognize natural seismic activity there. Between 1969 and 1977, these instruments recorded over 10,000 quakes taking place beneath the lunar surface. This study has assisted researchers in learning more about the geology of the Moon, as well as the formation of our planetary companion.
This is No Place Like Home
Unlike the Earth, the Martian crust is nearly silent, allowing SEIS to pick up small tremors. Here on Earth, a similar quake would be lost among vibrations caused by ocean waves and tiny tremors that frequently occur in regions like California. The shifting of continental plates are the main cause of earthquakes on our home planet, but the Moon and Mars do not experience this geological phenomenon. On those worlds, heating and cooling of those bodies results in stresses, which can build up, cracking the crust.
“We worked hard to develop the most sensitive silicon sensors on Earth to send to Mars as part of SEIS. Up to now we didn’t know if even that was going to be good enough. But it looks like Mars, although very much quieter than Earth, is giving us seismic signals we are able to clearly detect. Our first investigation of the interior of another planet is now under way,” said Tom Pike of Imperial College London.
By studying quakes on Mars, researchers hope to learn more about how that planet — as well as our own — formed billions of years ago.