Christmas came a day earlier for a lone geologist stationed on the Red Planet.
NASA agency insight Task touched down Mars in November 2018 to look inside the planet, mapping its layers and fault lines. And on December 24, 2021, the probe made a remarkable discovery, picking up seismic waves from a large meteorite impact. Images taken from orbit made the signal even more interesting, because scientists linked the seismic discovery to the sight of a new large crater.
“It immediately became clear that this is the largest new crater we’ve ever seen,” Ingrid Dubard, lead impact sciences at Insight and a planetary scientist at Brown University, said during a press conference on Thursday (October 27).
“We thought that a crater of this size might form somewhere on the planet once every few decades, maybe once every generation,” Dubar said. “So it was very exciting to be able to witness this event, and to be lucky enough that it happened while InSight was recording the seismic data – that was a real scientific gift.”
In September, InSight scientists announced Four discoveries of meteor impactseach also associated with a new nozzle, made in 2020 and earlier in 2021.
But these were small effects: none of them produced seismic signals stronger than a magnitude 2 earthquake. InSight team members considered that they were unlikely to see signals from more powerful hits, so the Christmas Eve data for the lander was just a bolt of the blue. Those observations indicated the impact of a magnitude 4 log and produced a crater over 430 feet (130 m) wide. (InSight also observed a similar effect in September 2021, which the mission team described in scientific papers announcing these findings.)
But even as Insight scientists have been researching what the Christmas Eve effect might mean, scientists at NASA Mars Reconnaissance Orbiter (MRO)which has been studying the Red Planet since 2006, made a different discovery when they spotted a new large crater.
“When we first saw this image, we were very excited,” Lilia Pociolova, MRO’s orbital science operations leader at Malin Space Science Systems in California, said during Thursday’s briefing. “This was not what we had seen before.”
Busiulova and her colleagues spotted the new hole in data collected by the MRO Context Camera. The crater and debris rays circling the impact site filled an entire frame, 19 miles (30 kilometers) wide. “We needed to take two more pictures on the sides to capture the entire turbulence area.”
Daubar said the crater itself spans about 500 feet (150 meters), which she compared to two buildings in the city and noted that it was 10 times the size of a typical new crater on Mars. Busiulova said the new impact craters usually look like just smudges in the MRO data.
Working backward from the size of the hole, scientists have estimated that asteroid The one that collided with the red planet was between 16 feet (5 meters) and 40 feet (12 meters) wide before it met its fate. If it hit the ground, a rock this big would probably burn Earth’s atmospherebut Mars’ thin atmosphere does little to protect the surface.
Thanks to the meteorite’s size, the impact dug deep enough into the surface of Mars to shed boulder-sized chunks of rock and water ice. “Most exciting of all, we saw clearly in the high-resolution images that a large amount of water ice was affected by this effect,” Dubar said. “This was surprising because this is the warmest region on Mars, the closest to the equator, and we’ve ever seen water ice.”
She noted that since the impact likely destroyed most of the meteorite itself, it’s possible that the ice did not mean that the impactor was a comet. Instead, the team is confident that ice was sheltering beneath the surface of Mars. Now that the ice has been exposed at the surface, scientists are seeing orbital images that suggest it is disappearing, evaporating away into the atmosphere.
glimpses of the crust
The unexpected ice detection isn’t the only information the impact is giving scientists, thanks to InSight’s seismic data.
This data includes the first observations of surface waves that the InSight mission shared. When an earthquake occurs, the highest signals come from what geologists call P waves and S waves. Both types of seismic waves transmit information about the planet’s interior because of how they respond to different layers of rock.
But surface waves give scientists a way to study the crust of the Red Planet on a large scale. “The nice thing about surface waves is that they tell you about the crust not just where the probe is, but what they’re looking at as they move through a planet,” said Bruce Banerdt, InSight principal investigator at NASA’s Jet Propulsion Laboratory in California, during the press conference. “So the entire path between the event – in this case, the impact – and InSight is sampled by surface waves as they move across the planet.”
The crater from the Christmas Eve collision is located about 2,200 miles (3,500 kilometers) from the probe, so its surface waves allow scientists to peer into a long patch of Earth’s crust. (September’s impact was more distant, being about 4,700 miles or 7,500 km from Insight.)
“From the beginning of our planning, we thought we’d use surface waves to locate earthquakes, and use surface waves to examine crustal structure. But in the first three years of the mission, we didn’t see any surface waves,” Bannerdt said. Now, InSight is finally able to catch those waves, thanks to the two big effects.
While large impacts are particularly surprising events, InSight scientists also learn from less dramatic cues. A separate research also published today based on data from InSight found that Mars may still hide some molten magma after allAlthough many scientists believe that the planet is geologically dead.
That study identified InSight’s discoveries of more than 20 bogs in an area called Cerberus Fossae, where a network of fractures dominate the landscape. Researchers believe these earthquakes are a sign of molten rock under the crust.
“It is possible that what we are seeing is the last remnant of this active volcanic region, or that magma is now moving eastward to the site of the next eruption,” Simon Stahler, lead author of the new research and a seismologist at ETH Zurich in Switzerland, said in a statement. statement.
The new findings may be the last published from InSight before the grimest announcement of the mission. The landing unit operates at low power due to the accumulation of dust on the solar panels and dark sky stormThe seismometer currently monitors only eight hours every four Martian days.
InSight employees have been anticipating the end of the mission for months.
“It’s sad to think about this, but InSight has been doing great for the past four years,” Bannerdt said. “So now that we’re almost done, we’re still getting these amazing new results.” The probe captured its largest earthquake so far in May. Bannerdt said team members currently expect the job to be completed within four to eight weeks.
“What a fantastic science result to be going through,” Laurie Glaese, director of NASA’s Planetary Science Division, said of the Christmas Eve impact during the press conference. “I mean, literally coming up with a bang.”
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