Asteroid samples collected by University of Arizona researchers show surprising discovery

Some long-awaited surprises were revealed from some asteroid samples collected by the University of Arizona-led OSIRIS-REx mission. 

The deep dive into the sample of rocks and dust was years in the making as University of Arizona researchers had a chance to study something out of this world. 

The largest asteroid sample ever returned to Earth from the asteroid, Bennu. It's over 170 million miles away and it’s considered a near-Earth asteroid. 

Samples brought back to Earth revealed surprising secrets about the solar system's past.

"These samples are a scientific treasure trove. From the earliest stages of the formation of the solar system, these rocks formed before the earth existed," Dante S. Lauretta, a professor at the University of Arizona said.

The OSIRIS-REx mission sent a spacecraft to the asteroid Bennu nearly a decade ago, launching in 2016. 

It arrived at Bennu in 2018, collected samples and just last year those samples were returned to Earth. It was only about a cup's worth of rocks but they have a story to tell. 

"The biggest surprise for me is that there are salty crusts coating a subset of the particles. We're probably pretty familiar with this in Arizona. If you have hard water, and you build up those white, crusty salts that clog your shower head and your faucets, that's the same kind of process that we're seeing on these asteroid samples. You had a salty liquid and it evaporated away and left what we call evaporite minerals behind," Lauretta said.

The rock samples have been studied under atomic microscopes at the University of Arizona and the analysis of the Bennu sample unveiled intriguing insights into the asteroid's composition and clues to the history of our solar system. Bennu was possibly once part of an ocean world.

"They're the kinds of rocks that form on the sea floor at the hydrothermal events on Earth," Lauretta said. "(They are) full of clay minerals, salts, organic compounds. So we're really peering back to the beginning of our solar system and getting a good understanding of how water and organic material formed, and then ultimately was delivered to our planet to make it the habitable world that we enjoy today."

Dozens more labs in the United States and around the world will receive portions of the Bennu sample from NASA's Johnson Space Center in Houston in the coming months for further study.