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UA analysis of OSIRIS-REx samples matches hypotheses about asteroid Bennu

By Nicholas Gerbis
Published: Monday, December 25, 2023 - 10:05am

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The UA-led OSIRIS-REx mission returned samples from the asteroid Bennu to Earth in late September.

Analysis of their contents is now underway.

So far, their composition has largely matched predictions: Two years of remote surveys by the spacecraft suggested Bennu held abundant water locked up in claylike minerals, and that’s what the team has found, along with lots of carbon, nitrogen, sulfur and phosphorus.

Of the 70 grams of sample confirmed so far, the university's Kuiper-Arizona Laboratory for Astromaterials Analysis has just 200 milligrams (about one-fifth the weight of a large paperclip) to work with.

Chris Richards/University Communications (UA)
UA scientists have 200 milligrams of the asteroid Bennu sample for analysis. The small particles pictured here in a concavity slide are observed under an optical microscope.

NASA's Johnson Space Center in Houston will likely make around one-quarter of the full sample available to science team members around the globe. The rest will be preserved for external researchers and future generations, not unlike moon rocks from the Apollo landings.

Much of the lab’s sample consists of particles that weigh a billionth or trillionth of a gram and are almost invisible to the naked eye. The team uses electron microscopes to study them at the atomic scale and a nanoscale secondary ion mass spectrometer to look at isotopes that could hold clues as to the particles’ origins.

Because the samples were collected at the source, they offer an unprecedented record of the formation processes at play in the solar system 4.5 billion years ago.

The team also hopes to uncover the origins of Bennu, which scientists believe broke off of a much larger carbon-rich asteroid about 700 million to 2 billion years ago.

Chris Richards/University Communications (UA)
UA scientists have received a small portion of the asteroid Bennu sample and analysis has begun in their lab. Here, doctoral student Lucas Smith loads Bennu sample into an electron microscope for analysis.

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Chris Richards/University Communications (UA).
Discussing sample analysis measurements in the lab: doctoral students Zoë Wilbur, Lucas Smith and Iunn Ong (front to back).
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