Scientists Surprised by Samples Recovered From Ancient Asteroid

Noor Al-Sibai
Wed, December 13, 2023 


Technical Difficulties

NASA scientists are hard at work sifting through samples from an asteroid dating to the dawn of our Solar System, and what they've found so far has been fascinating.

As the journal Nature reports in a news brief, there has been some very peculiar asteroid dust gleaned from the US space agency's first sample return mission to the asteroid Bennu — but researchers haven't been able to test it all yet, because two of the screws in its high-tech canister still won't budge.

After touching down at the end of September, the OSIRIS-REx capsule that collected dust samples from the ancient Bennu has proved to be a problem because two of the canister's 35 screws are stuck. Though scientists have been able to extract more than 70 grams of space dust so far, there's more in there that they can't access.

"It’s kind of like Schrödinger’s sample," joked Dante Lauretta, a University of Arizona planetary scientist who heads OSIRIS-REx's scientific analysis, in an interview with Nature. "We don’t know what’s in there."

Sing the Blues

As frustrating as the Fort Knox-esque canister conundrum has been, what has been analyzed so far has offered some pretty incredible results — though they too have left scientists with more questions than answers.

During a meeting of the American Geophysical Union held in San Francisco on December 11, Lauretta said that the Bennu samples he and his team have done early analyses on are unique even to the naked eye. Most of the material is black in color, but some has a bluish sheen to it — while other, smaller fragments are light in color and reflective in a way that makes them pop against the other pebbles brought back by OSIRIS-REx.

Those lighter-colored bits are magnesium, phosphate, and sodium per the early analysis, and that bright and brittle outer layer chips off to reveal darker rock beneath it, the UA planetary scientist explained. Wilder still: that combination is thought to be rare in asteroids, making it something of a "head-scratcher," per Lauretta.

Also among the findings from the early Bennu analyses are what could be the building blocks of life: organic compounds containing carbon-carbon or carbon-hydrogen bonds. Meteorites found on Earth have had similar compounds, and as Nature explains, those carbon-rich minerals may have contributed to life on our planet.

Despite the technical difficulties, the Bennu samples are a big deal because, as Lauretta puts it, they represent the first time NASA has been able to physically handle such ancient materials.

"This alone makes the whole mission worthwhile," the scientist said. "We now have abundant pristine material."

'What is that material?': Potentially hazardous asteroid Bennu stumps scientists with its odd makeup

Sharmila Kuthunur
Wed, December 13, 2023

A view of the outside of the OSIRIS-REx sample collector. Sample material from asteroid Bennu can be seen on the middle right. Scientists have found evidence of both carbon and water in initial analysis of this material. The bulk of the sample is located inside.

Tasked with finding clues about origins of life on Earth, NASA's OSIRIS-REx spacecraft scooped up pieces of a rugged, rubble-pile asteroid named Bennu in late 2020 and delivered them to Earth about two months ago. On Monday (Dec. 11), scientists got their first detailed description of some of that extraterrestrial collection.

"We definitely have hydrated, organic-rich remnants from the early solar system, which is exactly what we were hoping when we first conceived this mission almost 20 years ago," Dante Lauretta, the mission's principal investigator, said at the American Geophysical Union (AGU) conference being held this week in California and online. "I fully expect the cosmochemistry community is going to go to town on this."

Lauretta, a professor of planetary science and cosmochemistry at the University of Arizona, said the bits of the 3-billion-year-old asteroid that have been retrieved so far are from the outer lid of the sample capsule and are rich in carbon and organic molecules. All the particles are very dark in color and consist of centimeter- and millimeter-sized "hummocky boulders" that have a rough "cauliflower-like texture", said Lauretta. "They cling to everything we touch them with."

The OSIRIS-Rex spacecraft was designed to be in contact with Bennu for six seconds, but it ended up plunging 1.6 feet (0.5 meters) into the asteroid's surface for 17 seconds instead. A victim of its own success, the probe dug out so much material that particles began leaking out of the sample collector's head — but they were still protected inside its outer lid. On Monday, Lauretta blamed a 1.3-inch (3.5 cm) stone that appeared to have jammed open a small flap on the head and let the material escape into the lid.

Two faulty fasteners continue to prevent technicians from removing the lid to access and catalog the bulk of the collected sample that's still trapped within the head. While they wait for new tools to be approved for use on the precious rocks, they are using tweezers to pick tiny rocks through the partially open flap, totaling the collected material to 70.3 grams (0.07 kg) — higher than the predicted 60 grams (0.06 kg).

Some of that material was shipped for spectral analysis at the NASA-supported Reflectance Experiment Laboratory (RELAB) facility in Rhode Island, while another batch was sent to the Natural History Museum in London. Initial findings using spectroscopy, a scientific technique that reveals a material's makeup by studying how it reflects different wavelengths of light, show a dominant spectral signature in blue. This azure hue is currently unexplained but may mean the space rocks contain even more water than scientists initially predicted, Lauretta said, adding that more results will be shared at a scientific meeting next spring.

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The material also hosts high amounts of magnesium, sodium and phosphorus, a combination that so far puzzles the team.

"I've been looking at meteorites for a long time and I've never come across anything like that," said Lauretta. "It's a head-scratcher right now. What is this material?

Barringer Crater may have been formed by a cosmic 'curveball,' asteroid simulations show

Deepa Jain
Wed, December 13, 2023 

Aerial view of Barringer crater (meteor impact) in Arizona.


Loosely-bound clumpy asteroids with curveball-like spins may have scooped out some of Earth's most distinctly shaped craters, including Arizona's bowl-like Barringer Crater, a study published Nov. 22 in the journal Physical Review E suggests. Craters carved by fast-spinning space rocks tend to be wider and shallower than those formed from their slower-spinning counterparts, the study authors found — a potentially counterintuitive finding if you've ever seen a curveball slam hard against a player's bat in a game of baseball.

Impact craters ― pock-marks created by space rocks ― scar the surface of most of the solar system's rocky bodies, from Jupiter's moon Io to our own home planet. But these traces of past celestial encounters have a bewildering diversity of shapes.

Take those on Earth. Some, like Arizona's 49,000-year-old Barringer Crater, resemble a bowl jammed in the ground. Others have more complicated architectures with one or more peaks around or even inside the crater.

Geologists have previously unearthed many factors responsible for this diversity, like an asteroid's velocity upon impact. But in the new study, researchers zeroed in on two typically overlooked parameters.

One was the asteroid's spin, or how quickly it rotates while whizzing through the atmosphere. Rotating objects have more energy than non-rotating ones. So it may seem intuitive that a spinning asteroid would gouge out a deeper crater than a non-spinning one.

Related: World's 1st mountaintop impact crater discovered in northeastern China

But what if the incoming impactors — whether comets, asteroids or smaller meteoroids — were made up of thousands of smaller bits glommed together through gravity? Recent NASA missions, like the OSIRIS-REx mission that collected samples from asteroid Bennu, have confirmed that not all asteroids are monoliths; many, especially the gargantuan ones that are a kilometer (half-a-mile) in size or larger, are actually clumps of smaller rocks glued together by gravity.

Studying the spin and clumpiness of asteroids will help scientists "better understand how the different types of crater are formed, [and] how the material from the impactor spread[s] after collision has taken place," study co-author Erick Franklin, a researcher at Brazil's University of Campinas, said in an email to Live Science.

To investigate both factors, the researchers ran many simulations. They created virtual asteroid-like projectiles, each "the size of a grapefruit", Franklin said. Every projectile itself was a cluster of two thousand mite-sized spheres. The researchers then virtually dropped each of these "asteroids" on a grainy layer meant to resemble a planet's surface. In some models, the projectile's spin ranged between that of a super slow-spin splitter and an off-the-charts high-spin curveball.

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The researchers found that rapidly rotating asteroids did gouge out narrow, deep gorges ― but only when the asteroid's tiny constituent spheres were tightly bound together. Fast spinning "rubble-piles" — asteroids like Bennu with weakly-bound components — produced wide, shallow holes. "Roughly speaking, the more the grains forming the projectile spread radially at the impact, the shallower and wider the crater will be," Franklin noted.

That's because part of the asteroid's energy is used to break the bonds holding its components together. This scatters the fragments, but leaves each with less energy, so they don't burrow as deeply into the ground as when the asteroid doesn't rotate. In addition to Barringer Crater, another potential curveball-created crater is the saucer-shaped Flynn Creek crater in Gainesboro, Tennessee, Franklin said.