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.
AZPM's Christopher Conover sat down with OSIRIS-REx Principal Investigator Dr. Dante Lauretta to talk about the first results from the study of the samples from the asteroid Bennu.
To learn more about the OSIRIS-REx mission you can watch AZPM's documentary OSIRIS-REx: To Bennu and Back.
Dante Lauretta The paper in Nature, and we got the cover, by the way, so that's quite prestigious for us, is showing that we have a complete sequence of salt crystals that evaporated as a large liquid body on an ancient ocean world evaporated away and left these crystals behind. So we can see the composition of the water changing as different minerals precipitate out, and these have never been seen before in any meteorites ever analyzed on Earth. The companion paper follows up on that and shows that that fluid was not just water, but had abundant ammonia, which people might be familiar with from glass cleaner or fertilizer. And ammonia, like when you salt your sidewalk to melt the ice, it reduces the melting point of water ice, so that liquid could have stayed around for a much longer time at much lower temperatures, and it enabled the formation of a huge suite of organic molecules, including 14 of the amino acids that make all the proteins for life on Earth and all the letters of the genetic code. So basically, the building blocks of life were in an ocean in the ancient solar system before the Earth even existed. And the samples that OSIRIS-REx returned have recorded that history.
Christopher Conover Somebody is going to hear what you just said, and said 'They found life on Bennu?' I don't think that's what you said.
Dante Lauretta We don't have life. We have pre-life. We have the building blocks of life, all the ingredients. Think of it like a Lego kit that was delivered to the early Earth. Something had to come along and assemble it all into the first living organism. And we still don't know how that happened. That's a huge mystery. But we know all the pieces were available, and they were delivered to the Earth from outer space by these carbon-rich asteroids.
Christopher Conover You said at the beginning of this that this was from another, for lack of a better term, a planet. Do we know where Bennu existed before it became an asteroid? Are we getting closer to answering that?
Dante Lauretta We have some good clues to that because Bennu is in near-Earth space. It crosses the orbit of our planet, and it's not going to survive in that configuration for very long. It's either going to hit the Earth or it's going to fall into the Sun or hit one of the other planets. When we trace its orbit back, we can see that it came from the main asteroid belt, which is a population of objects that orbit the Sun between Mars and Jupiter. And in fact, we can see that there is a shattered world out there. There are thousands and thousands of fragments that look like they were all part of one much larger body that was probably struck by another asteroid and catastrophically disrupted. And Bennu is just a random grab sample from that event.
Christopher Conover Science does not end with the publication of the first paper, the first big paper. What's next for this? And as you said, these samples were sent all around the world. It's not just here at the University of Arizona.
Dante Lauretta That's right. This is the first of a huge wave of publications, we're going to be cranking out dozens of papers over the next year, building on these exciting results, exploring different aspects of this history, and increasing our knowledge of the inventory of the organic material that was delivered to the earth by these kinds of bodies.
Christopher Conover Is this the first time that we found this much organic material, or these types of organic material, somewhere out in space?
Dante Lauretta What we were able to do with the OSIRIS-REx mission is definitively say these were from outer space. We've had hints of these detections in meteorites before, but they were always suspect because bacteria love these rocks. They colonize them, they start to eat these compounds, and they change the chemistry. So, there's been, yeah, hints that meteorites might have contained the letters of the genetic code, but because we went to the asteroid and we brought it back and we kept it clean and pristine, we can say with high confidence these absolutely came from outer space.
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