Bennu asteroid: Hummocky boulders with cauliflower-like texture in canister stump scientists

Over a month after NASA unveiled the sample collected from asteroid Bennu, scientists have finally been able to take a closer look at the rock from outer space and they are stumped. Earlier this week, at a meeting of the American Geophysical Union (AGU), researchers said that they have found that the sample contains a surprisingly rich array of carbon-bearing molecules.

‘Cauliflower-like texture’

“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,” said Dante Lauretta, the mission’s principal investigator and professor of planetary science and cosmochemistry at the University of Arizona, during the AGU.

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He added, “I fully expect the cosmochemistry community is going to go to town on this.” Lauretta, as per Live Science, also spoke about how they have been able to retrieve only bits of the 3-billion-year-old asteroid from the outer lid of the sample capsule and described it as rich in carbon and organic molecules.

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The scientists have only been able to take a small part of the sample since the probe dug out so much material that particles began leaking out of the sample collector’s head, but the ones inside its outer lid were protected.

Therefore, while the researchers wait for approval to use new tools for use on the precious rocks, they are using tweezers to pick tiny rocks through the partially open flap and have collected 70.3 grams.

The team believes the container still holds an additional 30 grams to 70 grams of rock which will be extracted next year.

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So far, they have found that the particles are very dark in colour and consist of centimetre- and millimetre-sized “hummocky boulders” that have a rough “cauliflower-like texture,” said Lauretta, adding that they “cling to everything we touch them with.”

‘Largest pristine reservoir’

Speaking at the conference, Lauretta also described the material as the “largest pristine reservoir of this material on Earth.” It is believed that the diversity of organic compounds that the extraterrestrial rock contains would help researchers understand the billions of years old complex space-based chemistry and if the origins of life on Earth can be traced back to it being hit by these asteroids.

According to Lauretta, an initial analysis at the Carnegie Institution for Science suggests that the sample contains up to 4.7 per cent carbon by mass. Researchers also observed metre-long veins of white minerals which were initially thought to be calcium carbonate or limestone.

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However, once placed under an electron microscope, the white material looked more like skin, according to the principal investigator. Researchers also shined a light on the white material and it reflected, which does not happen with calcium carbonate.

The team later not only found the signs of carbon and organic molecules but also magnesium, sodium, and phosphate. “I’ve been looking at meteorites for a long time and I’ve never come across anything like that,” said the University of Arizona professor.

He added, “It’s a head-scratcher right now. What is this material?” The researcher also highlighted an important early result based on the initial findings which indicate that overall composition closely resembles the ratio of elements seen in the Sun.

(With inputs from agencies)