The OSIRIS-REx Asteroid Observed Bouganda: Discovery of the Bigst Treasure in the Earth’s History

This bounty of materials comes from the outer surface of OSIRIS-REx’s sample canister. The biggest treasure trove will be revealed soon, when mission curators open the canister. In the meantime, they have been picking their way through the material coating the outside of the canister, taking pictures and classifying the dust. Only 1.5 grams have been formally catalogued so far, of an anticipated 250-plus grams brought back by OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer).

The boulders that dominate Bennu are similar to the rocks in the Bennu sample. The mission’s principal investigator, Dante Lauretta at the University of Arizona in Tucson, calls it his “favourite grain” so far. Scientists had suspected that there could be light- and dark- coloured rocks on Bennu. The light colours might represent areas altered by water early in Bennu’s history.

Once the canister was unsealed, researchers immediately saw black asteroid dust and slightly larger particles. Those got sent to labs for analysis — and the results have scientists excited.

The first picture of the asteroid material that NASA has shared is a small portion of it locked inside a sample collection device.

The principal investigator for the OSIRIS-REx mission says that they’re already thrilled with the results.

In 2020 the asteroid was briefly tagged with some rocks by a device called the Touch-and-Go Sample Acquisition Mechanism.

Workers rushed the canister to a laboratory at the Johnson Space Center. There, workers opened it up inside of special cabinets, so the pristine asteroid samples wouldn’t get contaminated with Earth stuff.

The TAGSAM collection device was taken out of the locking mechanism that kept it in place, and they saw more dust and larger rocks that had escaped through a Mylar flap.

All of the rocks have been gathered and documented in the Astromaterials lab. But Lauretta says he was absolutely captivated by one image showing the bounty.

He said he spent the weekend staring at the picture for hours and hours, getting more excited as the day went on.

Bennu, a new baby: from the first OSIRIS-REx spacecraft to the most Earth-sized objects to return from outer space

Lauretta says that Benjamin has a salt-and-pepper kind of texture, with bright grains and dark grains. I felt like I was running around on a small Bennu when I was zooming in on the images.

Researchers haven’t yet found out how much of Bennu they captured. When OSIRIS-REx extended its robotic arm in 2020 it came away with so much material that it overflowed the collecting mechanism.

“It looks fragile, friable, so it could be delicate,” says Lauretta. “You can’t have a favorite child, so all of them look amazing, but that one I really want to understand what’s going on.”

Bennu also contains organic material made of carbon and hydrogen. On Earth, organic compounds are found in living organisms — but also in the absence of life. The organic patches in theBennu samples light up like a holiday tree when they are exposed to ultraviolet light. “This thing’s loaded with organics,” says Daniel Glavin, an astrobiologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. This material is amazing.

The clay samples from Bennu look like tiny fibres in electron microscopy images. Water locked inside the clay minerals may have been ancient water from the Solar System. The early Earth may have had some water carried by asteroids.

There are hexagonal crystals that are very sulfur-rich. Sulfur compounds play a key role in determining the rate at which rocks melt and are involved in biologically interesting chemical reactions. The Bennu samples also contain iron-rich minerals with large flat surfaces, which might have helped catalyse chemical reactions early in the asteroid’s history.

It will be the most material to return from outer space since Apollo astronauts brought Moon rocks to Earth in the 1960s and 1970s. Japan’s two Hayabusa missions, which both flew to asteroids and came back with samples, together brought back a teaspoon of material at most.