NASA’s Insight mission has detected the first signs of seismic activity on Mars months after its November landing.
On April 6th, after months of patiently waiting on Mars’ surface –NASA’s Insight lander registered the first unmistakable signs of seismic activity on the Red Planet–NASA and ESA announced yesterday.
The quake–detected by Insight’s dome shielded seismometer (SEIS) is so small that it would not have been detected on Earth amid the background noise from waves and wind.
The silent environment of Mars allowed the lander’s sensitive seismometer to pick up the signal, which resembles similar surface ripples detected travelling through the moon’s surface after moonquakes.
The French space agency Cnes, which operates the Seismic Experiment for Interior Structure (SEIS), said it had detected “a weak but distinct seismic signal” from the probe.
Philippe Lognonné, a planetary seismologist at Paris Diderot University who leads the mission’s seismometer experiment, adds that scientists were unable to detect any waves tied to the small quake that had passed through the Martian interior and were thus unable to estimate its exact location and strength.
Lognonné adds that the discovery was still extremely gratifying: “It is the first quake. All the time, we were waiting for this.”
Bruce Banerdt, InSight’s principal investigator and a geophysicist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, says that the detection is a milestone for the $816-million lander–kicking off a new field of “martian seismology.”
The observation confirms theories that Mars is seismologically active–despite lacking plate tectonics, the force that drives most earthquakes.
More about InSight.
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The InSight team estimated the lander might see one or so marsquake a month, but that number could possibly be much higher or lower. SEIS was deployed in February after the researchers waited for the tell-tale signs of seismic activity.
The team was able to determine that the seismometer was working well, as it was picking up background vibrations–microseisms–in the Martian surface that was induced by wind.
But despite this, Mars was stubborn in delivering quakes.
The team now believes the delay in detection was because SEIS needed time to settle on the planet’s surface. Week after week, background noise during martian nights has dropped–allowing the 6 April detection
Three other signals–detected on 14 March, 10 April, and 11 April–may well turn out to be other marsquakes, but the 6 April quake is the only event to rise above minimum requirements set by the mission for detection. Plus, it was the only one of the four that was observed by both the primary seismometer and a smaller, less sensitive sensor.
Yosio Nakamura, a planetary seismologist at the University of Texas in Austin who worked on Apollo seismology, told Science that the quake was reminiscent of what the seismometer that Apollo 11 brought to the moon revealed during its 3 weeks of operation.
The quakes that device recorded remained mysterious until NASA’s Apollo 15 team established a network of three seismometers and scientists realized that some of what Apollo 11 recorded had actually been quakes from the moon’s deep interior.
Nakamura says: “With a seismometer of better quality and better analysis techniques than what we had 50 years ago, I hope they can do better than what we did with the Apollo 11 data.
“This may take a while, but we can wait.”
Lognonné believes that there is a good chance that this marsquake detection is just the beginning of such observations. During the course of the lander’s 2-year primary mission continues, he expects Insight will track larger and larger quakes–which will ultimately allow the team to peer beneath the planet’s surface.
Lognonné concludes “We’re starting to have many small quakes. By the end of the mission, we’ll have a super big quake.”