Christmas has come a day early for a lone geologist stationed on the Red Planet.
from NASA Insight the mission has landed March in November 2018 to peer into the planet’s interior, mapping its layers and fault lines. And on December 24, 2021, the lander made a remarkable detection, picking up seismic waves from a large meteoroid impact. Photos taken from orbit made the signal even more intriguing, as scientists linked seismic detection to the sight of a large, cool crater.
“It was immediately clear that this was the largest new crater we had ever seen,” said Ingrid Daubar, InSight’s impact science manager and planetary scientist at Brown University, during the interview. a press conference held on Thursday 27 October.
“We thought a crater of this size might form somewhere on the planet once every few decades, maybe once in a generation,” Daubar said. “So it was very exciting to be able to witness this event and have the chance to have this happen while InSight was recording seismic data – it was a real science gift.”
Related: NASA’s Mars InSight lander takes dusty ‘final selfie’ as power dims
In September, InSight scientists announced four detections of meteor impactseach also linked to a new crater, which were made in 2020 and earlier in 2021.
But these were small impacts: none produced stronger seismic signals than a magnitude 2 quake. InSight team members had deemed it unlikely that they would see signals from more powerful strikes, so the lander’s Christmas Eve data was a thunderclap. These observations indicated an impact that reached magnitude 4 and produced a crater over 130 meters (430 ft) wide. (InSight also observed a similar impact in September 2021, which the mission team described in the scientific papers announcing these findings.)
But even as InSight scientists researched what the Christmas Eve impact might mean, NASA scientists Mars Reconnaissance Orbiter (MRO)who has been studying the Red Planet since 2006, made a different discovery when they spotted a large, cool impact crater.
“When we first saw this image, we were extremely excited,” said Liliya Posiolova, orbital science operations manager for MRO at Malin Space Science Systems in California, during Thursday’s briefing. “It was nothing like we’ve seen before.”
Posiolova and her colleagues first spotted the new crater in data collected by MRO’s pop-up camera. The crater and rays of debris surrounding the impact site filled an entire frame 19 miles (30 kilometers) wide. “We needed to take two more images from the sides to capture the entire disturbance area.”
Daubar said the crater itself extends about 500 feet (150 m), which she compared to two city blocks and noted that it was 10 times larger than a typical new crater on March. Posiolova said new impact craters generally look like simple specks in MRO data.
Based on the size of the crater, the scientists estimated that the asteroid that slammed into the Red Planet was between 16ft (5m) and 40ft (12m) wide before it knew its fate. If it had hit the Earth, a rock of this size would probably have burned up. earth’s atmospherebut Mars’ thin atmosphere does little to protect the surface.
Thanks to the size of the meteor, the impact dug deep enough into the Martian surface to blast boulder-sized chunks of rock and water ice. “Most exciting of all is that we clearly saw in the high resolution images that a large amount of water ice had been exposed by this impact,” Daubar said. “It was surprising because it’s the hottest place on Mars, the closest to the equator, we’ve never seen water ice.”
She noted that because the impact would likely have destroyed most of the meteoroid itself, the ice probably doesn’t mean the impactor was a comet. Instead, the team is convinced that ice was sheltering beneath the surface of Mars. Now that the ice is exposed on the surface, scientists are seeing orbital images suggesting it is disappearing, vaporizing in the atmosphere.
Insights into the crust
The unexpected discovery of ice isn’t the only information the impact is giving scientists, thanks to seismic data from InSight.
These data include the first observations of surface waves shared by the InSight mission. When an earthquake occurs, the strongest signals come from what geologists call P waves and S waves. These two types of seismic waves transmit information about the interior of the planet due to the how they react to different layers of rock.
But surface waves give scientists a way to study the Red Planet’s crust on a large scale. “The nice thing about surface waves is that they tell you about the crust, not just where the lander is, but they look at the crust as they move across a planet,” said Bruce Banerdt, InSight principal investigator at NASA’s Jet Propulsion Laboratory in California, said at the press conference. “So the whole path between the event – in this case, the impact – and InSight is sampled by surface waves as they travel across the planet.”
The crater from the Christmas Eve impact is located about 2,200 miles (3,500 km) from the lander, so its surface waves allow scientists to peer down a long strip of crust. (The September impact was more distant, nearly 4,700 miles or 7,500 km from InSight.)
“Early on in our planning, we thought we were going to use surface waves to locate earthquakes, use surface waves to probe the structure of the crust,” Banerdt said. “But during the first three years of the mission, we saw no surface waves.” Now InSight has finally caught those waves, thanks to the two big impacts.
While large impacts are particularly striking events, InSight scientists are also learning from far less dramatic signals. Separate research also published today based on InSight data reveals that Mars may still be hiding molten magma after alldespite the belief of many scientists that the planet is geologically dead.
This study identified InSight detections of more than 20 Marchquakes in a region called Cerberus Fossae, where a network of fractures dominates the landscape. Researchers believe these earthquakes are the signature of molten rock just below the crust.
“It’s possible that what we’re seeing are the last remnants of this once active volcanic region, or that magma is currently moving east toward the next eruption location,” said Simon Staehler, lead author of the news. researcher and seismologist at ETH Zurich in Switzerland, said in a statement.
Impact results are described in of them papers published Thursday in the journal Science; research on magma is described in a paper published Thursday in the journal Nature Astronomy.
The new findings could be the last published by InSight before a darker mission announcement. The lander is running out of power due to dust accumulating on its solar panels and a sky darkened by stormand the seismometer currently only observes eight hours every four Martian days.
InSight staff have been anticipating the end of the mission for months now.
“It’s a sad thing to contemplate, but InSight has worked wonders for the past four years,” Banerdt said. “Even now that we’re winding down, we’re still getting these amazing new results.” The lander caught its biggest March quake yet in May; Banerdt said team members currently expect the mission to be complete in four to eight weeks.
“What an impressive synthetic science result to end,” Lori Glaze, director of NASA’s Planetary Science Division, said of the Christmas Eve impact during the press conference. “I mean, literally going out with a bang.”
#NASAs #sick #Mars #lander #feels #shockwaves #ice #meteoroid #impact