The first direct geophysical data of the Martian surface is in. In a suite of studies detailing the first 10 months of observations made by NASA's Mars InSight lander, scientists have announced it's a seismically active planet with signs of tectonic plate activity, much like that seen on Earth.
Together, the studies confirm an initial detection by Insight made on April 6, 2019, when the lander picked up a weird signal coming from deep within Mars' interior. It was a seismic rumbling, akin to an earthquake of the kind that regularly shake the Earth — but this planet-shaking spasm was on Mars.
Now dubbed a "Marsquake," InSight confirms that not only does the Red Planet have seismic activity, its quakes can also closely resemble those recorded here on Earth. But that's not all scientists have managed to glean from these initial observations.
“Before the launch and the landing of the mission, it was only in theoretical papers that we do have marsquakes but now we do know that we have them,” Philippe Lognonné, professor at Institut de Physique du Globe de Paris, and a co-investigator of the mission, said during a press briefing to discuss the findings.
The lander’s initial findings are published Monday in a series of studies in the journal Nature Geoscience.
The top ten findings from InSight, from the Inverse point of view:
- 1. Marsquakes are real: Mars does experience seismic activity, clocking in at between the Moon and the Earth in terms of the frequency and strength of the events.
- 2. 235 Martian days saw 174 seismic events: The measurements were taken up to September, 2019. But there could be many more, the data suggest.
- 3. Majority of marsquakes resemble those seen on the Moon:150 of the recorded quakes appear to be high-frequency events similar to ground-shaking activity recorded during the Apollo missions.
- 4. Mars may have tectonic activity: Three of the marsquakes showed wave patterns akin to those seen on Earth during seismic events spurred by tectonic activity, hinting that the Red Planet may have similar processes at work beneath its surface.
- 5. Marsquakes and Martian weather may be linked: Mars' famous dust and wind storms appear to have a seismic signature, the data suggest.
- 6. Marsquakes run deep: Quakes tended to occur at a much greater depth than seismic activity on our own planet.
- 7. Marsquakes tend to be small scale: Scientists expected to observe more strong quakes on Mars. Just 20 of those observed were magnitude 3 or 4 on the Richter scale.
- 8. Mars' magnetic field may be much stronger than we thought: Measurements taken from the lander's immediate surroundings suggest the planet's magnetic field is 10 times stronger than predicted.
- 9. Mars gets eerily calm in the early evening: InSight tracked the planet's wind activity, finding that the early evening is surprisingly calm on the Martian surface (although seismic activity continued through this period).
- 10. Mars' 'seismic noise' is extremely quiet: The data suggest Mars' seismic activity is extremely quiet at night, at about 500 times quieter than ground vibrations observed in the quietest locations on Earth.
"Understanding these processes is part of a bigger question about the planet itself," Nicholas Schmerr, assistant professor at University of Maryland and an author on one of the studies, said in a statement.
"Can it support life, or did it ever? Life exists at the edge, where the equilibrium is off. Think of areas on Earth such as the thermal vents at the deep ocean ridges where chemistry provides the energy for life rather than the sun. If it turns out there is liquid magma on Mars, and if we can pinpoint where the planet is most geologically active, it might guide future missions searching for the potential for life."
A first good look at Mars' interior?
InSight, which stands for Interior Exploration using Seismic Investigations, launched in May, 2018. It landed at the planet’s Elysium Planitia, a crater, in November, 2018. Elysium Planitia is just north of Mars’ equator, and has a flat surface, allowing the lander to conduct its measurements by probing deep into Mars’ interior.
The lander is designed to study the interior structure of Mars to look for the fingerprints of the ancient processes that formed the planet, and the Solar System.
During the mission’s first 10 months on Mars, it detected 174 confirmed seismic events, including 20 that were of magnitude 3 to 4, the scientists report.
But unlike on Earth, the quakes on Mars are much deeper, running around 30 to 50 kilometers beneath the surface, according to the researchers. On Earth, earthquakes are about 5 to 10 kilometers deep.
So to feel a quake on Mars, you would need to be standing directly above the quake with your feet planted on the ground.
The team were hoping to observe more strong marsquakes, of the 3 to 4 magnitude, but these were unexpectedly scarce, especially when compared to the number of smaller tremors.
“The patterns are not at all clear,” Bruce Banerdt, InSight’s principal investigator on one of papers, and research scientist at NASA’s Jet Propulsion Laboratory, said during the press briefing. “We have been seeing an increase in the very smallest events and we don’t understand that at all yet.”
“The larger quakes seem to be less frequent than we had expected given the number of smaller quakes that we have seen. That’s something that’s puzzling to us right now,” he said.
Larger quakes would allow the scientists to peer deeper into the planet's interior and work out its structure, but the smaller quakes may still reveal these details — albeit at a slower pace.
“I’m confident that we’ll be able to pull out the information that we’re after,” Banerdt said. “It may take us a little longer than we’d hoped, but I’m confident that we’re on track.”
“I check my email every morning to see what our team has seen in the last day of data, waiting to see whether these big quakes come along,” he said. “If we don’t get these larger quakes, it will be a disappointment.”
InSight's initial observations also measured Mars' magnetic field through the magnetometer instrument, the first to land on the planet. Shockingly, scientists discovered a steady magnetic field that is 10 times stronger than previously predicted through satellite observations.
Right now, it is too soon to draw any conclusions as to why there is such a discrepancy, the scientists say.
"There are variations that we're excited to try and understand better," Catherine Johnson, co-investigator of the InSight mission and researcher at NASA's JPL, said during the call.
One of the other intriguing observations made by InSight is Mars' wind and weather pattern and how much it varies over the course of a day. InSight reveals that the Martian wind picks up overnight between midnight and the early morning hours. When the Sun rises on the Red Planet's surface, it heats the wind, resulting in convective currents that build up through the daytime, peaking in the afternoon.
At that point, atmospheric pressure drops, giving rise to towering columns of wind and Mars' infamous dust devils
But all the turbulence of the day subsides as the planet progresses into evening, when things get eerily quiet on the surface. As a result of all the daytime noise — InSight picks up all that wind and weather as seismic activity — the marsquakes seen so far have been recorded during this evening peace, although the researchers say more likely take place through the day.
"What is so spectacular about this data is that it gives us this beautifully poetic picture of what a day is actually like on another planet," Vedran Lekic, associate professor at University of Maryland and an author on one of the studies, said in a statement.
Mystery lies within:
Mars is the perfect sized planet to conduct these types of measurements since it is neither too big nor too small, the scientists on the new studies say. That means the record of its formation is likely still preserved deep within the Red Planet.
InSight has already spent more than a year on Mars, and the mission is expected to last for another year. That is good news for the researchers, because the initial data have uncovered more mysteries than they have answers, they say.
“There are definitely some very odd and mysterious patterns that someday we’ll probably understand, but don’t really understand today,” Banerdt said. “Right now we’ve got a lot more data than we have conclusions.”