The SEIS (Seismic Experiment for Interior Structure) instrument on NASA’s InSight lander detected the faint seismic signal on April 6, 2019, the lander’s 128th Martian day (sol).
An artist’s impression of the InSight lander on Mars. Image credit: NASA / JPL-Caltech.
Most people are familiar with quakes on Earth, which occur on faults created by the motion of tectonic plates.
Mars and the Moon do not have tectonic plates, but they still experience quakes — in their cases, caused by a continual process of cooling and contraction that creates stress.
This stress builds over time, until it is strong enough to break the crust, causing a quake.
“The Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during NASA’s Apollo missions,” said Dr. Lori Glaze, Planetary Science Division director at NASA Headquarters.
However, the Sol 128 seismic event was too small to provide solid data on the Martian interior, which is one of InSight’s main objectives.
This image, taken March 19, 2019 by a camera on NASA’s InSight lander, shows its Wind and Thermal Shield, which covers its seismometer, the SEIS, and the Martian surface in the background. Image credit: NASA / JPL-Caltech.
“InSight’s first readings carry on the science that began with the Apollo missions,” said InSight principal investigator Dr. Bruce Banerdt, from NASA’s Jet Propulsion Laboratory.
“We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology!”
InSight’s SEIS instrument also detected three other seismic signals: on March 14 (Sol 105), April 10 (Sol 132) and April 11 (Sol 133). They were even smaller than the Sol 128 event and more ambiguous in origin. The researchers will continue to study these events to try to determine their cause.
Regardless of its cause, the Sol 128 signal is an exciting milestone for the team.
“We’ve been waiting months for a signal like this,” said Dr. Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris, 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.”
“We are delighted about this first achievement and are eager to make many similar measurements with SEIS in the years to come,” said Dr. Charles Yana, SEIS mission operations manager at CNES.
