How NASA Captured Asteroid Dust to Find the Origins of Life

The sample of the space rock Bennu that OSIRIS-REx collected could unlock an ancient existential mystery

The OSIRIS-REx sample return capsule (foreground) landed in the Utah desert on September 24, carrying samples collected from the near-Earth asteroid Bennu (background).  Emily Lankiewicz

Capturing a piece of an asteroid and bringing it to Earth is even more difficult than it is time-consuming. NASA’s OSIRIS-REx spacecraft launched on September 8, 2016, and began orbiting the skyscraper-sized asteroid Bennu on December 31, 2018. On October 20, 2020, it made a brief landing on Bennu’s surface to collect samples of the ancient rock. Just more than six months later, part of the spacecraft began its journey home to Earth. And earlier this fall, that sample collection cannister landed, via parachute, at a Department of Defense proving ground in Utah about 80 miles west of Salt Lake City. The contents of that canister are older than Earth itself. Scientists will be studying them for decades in the hope of unlocking the mystery of how life on Earth began—but they’ve already learned enough to get them excited.

On the latest episode of the Smithsonian podcast “There’s More to That,” I spoke with Linda Shiner, the former editor of Air & Space magazine, about the challenges and triumphs of the OSIRIS-REx mission, and what scientists hope it will teach us about how life on Earth began.

A transcript is below. To subscribe to “There’s More to That” and to listen to past episodes on J. Robert Oppenheimerthe OceanGate Titan disaster, Killers of the Flower Moon and more, find us on Apple PodcastsSpotify or wherever you get your podcasts.

[Clip from NASA teleconference from Johnson Space Center, Houston, Texas, October 11, 2023]

Shaneequa Vereen, NASA public affairs officer: Hello and welcome to today’s media telecon. Today we are discussing the initial findings of NASA’s OSIRIS-Rex asteroid sample after its reveal earlier today.

Chris Klimek: Earlier this fall, a space capsule landed in the Utah desert. It may sound like something out of “The X-Files,” but this was actually a planned landing 20 years in the making.

Dante Lauretta, OSIRIS-REx principal investigator: It’s great to be here at NASA’s Johnson Space Center, where since September 25, when the OSIRIS-REx samples arrived, we have been systematically and methodically getting into the science canister and ultimately to the sample collection device—the actual piece of spacecraft hardware that touched the surface of asteroid Bennu and collected material back in 2020.

Klimek: As Earth makes its yearlong journey around the sun, it occasionally passes a small companion nearby: an asteroid about a third of a mile in diameter named Bennu. Bennu was born around the same time as the rest of our solar system, so scientists are hopeful that by studying the asteroid, we’ll get some clues about how life on Earth came to be. So in 2016, after years of preparation, a NASA spacecraft left Earth and headed toward Bennu. It arrived there in 2018 and spent two years mapping the asteroid’s surface until it was finally time to land. It grabbed a sample of dust and rocks from Bennu’s surface in 2020. More than two years later, that sample has now arrived. Dante Lauretta, the chief scientist on this mission, says he’s already excited about the early findings from the sample.

Lauretta: We have verified that Bennu is dominated by water-bearing clay minerals. We have found iron minerals in the form of iron sulfides and iron oxides, which themselves are indicative of formation in a water-rich environment. And, perhaps most exciting, the sample contains about 4.7 percent by weight carbon, which is obviously the essential element for all life on Earth, and central to our astrobiology investigation.

Klimek: So what does this all mean? How do you land a spacecraft on an asteroid anyway? And why is NASA so excited about a tiny piece of space rock?

From Smithsonian magazine and PRX Productions, this is “There’s More to That,” the show where we can let ourselves feel a little delighted about four-and-a-half-billion-year-old dust particles from space. This episode is all about a mission named OSIRIS-REx. I’m Chris Klimek. Let’s get ready for launch.

I worked for Smithsonian’s Air & Space magazine for seven years, covering lots of NASA missions, including the launch of OSIRIS-REx back in 2016. So when the sample collection capsule landed back on Earth, I knew exactly who to call. Linda Shiner was the editor of Air & Space and my former boss. We fell right back into our old banter.

Klimek: You can have a free copy of Smithsonian magazine if you can decode the acronym OSIRIS-REx without looking it up.

Linda Shiner: And that’s a question for me?

Klimek (narration): In Linda’s defense, the acronym is a mouthful. OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer. You probably would’ve guessed that, right?

Shiner: Dante Lauretta, who is the principal scientist on the mission, is the guy who came up with that. He said at the press conference that we could blame him. So we will blame him for it.

Klimek: So we’re going to crank this all the way back. At the end of September, a canister with some rock samples parachuted into the Utah desert. Why is that significant?

Shiner: It’s the first time that that much of an asteroid has come back to Earth. It’s not the first mission to explore an asteroid, but it is the first NASA mission that returned samples from an asteroid. And the reason that NASA wants those samples is that they can’t take their labs into space. They can take little instruments into space to take pictures of asteroids and comets and planets, and to analyze them by separating the colors reflected from them with a machine called a spectrograph. But to do a real thorough analysis, they need to get pieces of these things back to Earth, to subject them to tests in a laboratory.

Klimek: What are they hoping they will learn by studying these little pieces of Bennu, the big asteroid?

Shiner: The big question is: “Where did life come from on Earth?” And all of NASA’s exploration, almost all in the planetary system, has been directed toward that. All of the Mars rovers are looking for the same thing. They’re on Mars performing tests with their own little laboratories in the rovers, which of course are much less powerful than the labs on Earth, in order to find out what the material of Mars is and whether there was water on Mars. And this is a comparative study for Mars. Mars is a dead planet, we think. We haven’t confirmed that there is no microbial life there, but we believe that it is. Earth is not. Earth is teeming with life. And the question is: How, among these inner planets, was Earth the only one who could begin life and sustain life? And they believe that those answers are contained in the primordial ingredients from which the planets and the asteroids and even the sun was made. And that’s why they’re looking at the asteroid, Bennu.

Klimek: Thank you. So this is a piece of matter that is in a laboratory on Earth, but it’s older than any substance on Earth.

Shiner: Older than any substance on Earth, and never subjected to the forces that Earth has been subjected to. So not squeezed like Earth. Not under the pressures and the heat of Earth. So Bennu has no core like the planets have. It’s really a rubble pile. And that was one of the surprises that the spacecraft gifted to the scientists. They didn’t think that Bennu was as loosely connected, all the pieces of Bennu, as it was. And so there was an arm on the spacecraft that reached out to touch Bennu and to take a sample. And that arm touched it and kept going and going and going. And one of the scientists said if they hadn’t had power on the spacecraft to withdraw, that asteroid would’ve eaten their spacecraft.

Klimek: Wow. So how can studying this sample offer clues as to how life on Earth may have began?

Shiner: It’s a test of a theory, and the theory is that life needed something from the solar system in order to begin. And this goes back to the 1950s with something called spark discharge experiments. You may have read about this in your high school science book. I remember it from high school biology. These scientists tried to imagine what the atmosphere of Earth was like, and they introduced a spark. This is very Frankenstein-like. Their thought was: This is the lightning. Lightning was in the primordial Earth’s atmosphere. And yeah, I remember that ammonia was one of the substances in the atmosphere.

And when they subjected that spark to it, they thought that they would get amino acids or at least some organic materials that could have developed into life, but they did not. And all of those discharge experiments were not successful in producing the organics or the basics of chemicals that would lead to life in any abundance that they could explain. And so the thought was, well, Earth didn’t have all of the stuff it needed to make life. And that must have come from this incredibly violent era of collisions where asteroids and comets struck planets.

Klimek (narration): Like planets, asteroids and comets also orbit the sun. But their compositions are quite different. It all comes down to what they’re made of. Comets are made of ice and dust, while asteroids like Bennu are mostly rock.

Shiner: And the ones that struck our planet brought water. And that’s one of the major discoveries of Bennu: that it has clay-like materials, and clay forms in the presence of water. So this is instructing the scientists that these materials were brought to Earth by asteroids like Bennu, and therefore we have to understand the composition of Bennu in order to understand how life could have started on this planet.

Klimek: Wow. So that’s the main purpose of this mission there. I read there was also a small likelihood that Bennu could strike Earth toward the end of the 21st century.

Shiner: Yes. That’s one of the S’s in OSIRIS. The last “S” in OSIRIS stands for “security.” Yes. It’s a near-Earth asteroid. So most of the asteroids, because of the mechanics of the composition of the early solar system, they orbit between Mars and Jupiter. But Bennu is very, very close, and it sometimes comes inside the orbit of Earth. So it crosses Earth’s orbit. By studying the celestial mechanics of both Earth and the asteroids, astronomers know which asteroids are likely to cross Earth’s orbit at the time at the place that Earth is there in that orbit. And Bennu is one of those, but it’s a hundred years out. And the likelihood—I think I read that it was the same likelihood as a professional golfer getting a hole in one. That would make me afraid if it were happening next year.

Klimek: I mean, we’ve heard of golfers having a hole in one, right? That’s not some inconceivable scenario.

Shiner: Yeah. It can happen, is the point. And if you’ll allow me, I can take you back all the way to the beginning when I think this great interest in asteroids started at NASA and on Earth. And that’s way back in 1994: A comet named Shoemaker-Levy impacted Jupiter, and we had about a year’s notice of this. All of the astronomers on Earth had pointed their telescopes toward Jupiter to see this impact. It was the first time we’d ever seen an impact in real time. And the Hubble Space Telescope was in orbit, and the Galileo Telescope was on its way to Jupiter. And from every point of view imaginable, we saw this comet slam into Jupiter. And the giant Jupiter, you would think he would just swallow that comet and there would be no effect. But there were effects in its atmosphere for years.

And it was one of those “there but for the grace of God” moments, because these scientists and everybody else who was seeing these pictures thought, That could have been us. And from that moment forward, planetary defense became very important. As a matter of fact, four years later, Congress said, “NASA, go find those asteroids. Go find the comets. Go find any object that could possibly slam into Earth.”

Klimek: 1998 was also the year we had an incoming asteroid movie and an incoming comet movie in theaters at the same time. So clearly some screenwriters a couple years before were reading the paper and thought, “Ah, this is scary.”

Shiner: Yeah, that’s right.

Klimek: How does attempting to intercept and land on an asteroid differ from trying to do that with a planet? Is it simply the size of the objects, or are there other factors?

Shiner: Size is an enormous factor. They’re flight operators, just like in a mission control, just like NASA has mission control for astronauts.

Klimek (narration): OSIRIS-Rex’s flight path and sample collection was precisely planned and orchestrated by a team of navigation engineers. They directed the OSIRIS-REx mission from their base on Earth using a combination of computer code and onboard cameras, much like a remotely piloted drone or rover. They were able to monitor the spacecraft using a network of radio transmission stations known as the Deep Space Network.

Shiner: So they’re controlling this spacecraft, and there’s very little gravity on an asteroid. And so being able to keep the spacecraft there in orbit and also to match the rotation rate the asteroid is spinning … the spacecraft, in order to reach out and touch the asteroid, has to mimic its rate of rotation. Now, this isn’t the first time, by the way, we’ve touched an asteroid. The very first time was in 1996. We sent a probe. The probe was called NEAR Shoemaker, not to be confused with Shoemaker-Levy the comet, but named for the same guy, Eugene Shoemaker, very famous in the planetary field.

That probe went to the asteroid Eros, and it landed on it [in February 2001]. That was an incredibly big deal. And there have been landings since that time on asteroids, on comets. And we have brought samples back, not from an asteroid, but we did bring a sample back from a comet, in a real precursor to this mission. That mission was called Stardust, and it flew through the tail of comet Wild 2.

I remember in Air & Space magazine, our headline was, “Bring Me the Tail of Wild 2.” And that’s exactly what Stardust did: It held up an arm, it looked like a little catcher’s mitt, and it was filled with aerogel, and it put it in the tail of that comet and brought it back in a capsule that looks very much like the sample return capsule of OSIRIS-REx. And it landed in, I think also in Utah. And one of the scientists who’s leading the study of life-making chemicals in OSIRIS-REx studied that sample and found an amino acid for the first time. So everybody’s extremely excited that not only will there be amino acids … as a matter of fact, this scientist said he would be surprised if they didn’t find amino acids in the Bennu sample.

And part of what they’re being able to understand from studying these things is the machinery that guided the formation of the solar system. So the Stardust probe, for example, that looked at the comet, they always believed that the comets existed where they exist now: … They’re icy, so they’re very far away from the sun. They’re at the far reaches of the solar system. Studies of that comet make scientists believe that the comets could have been formed closer to the sun, because there’s evidence of melting. So they were subjected to very high temperatures and pressures, and they somehow migrated to the outer solar system.

It’s the same with Bennu’s parent body. So Bennu, one of those rocks that we think could possibly collide with Earth, is itself the victim of a collision. It was broken off from its parent. The parent body was in a farther orbit. It was much farther from the sun and somehow migrated closer to the sun. And those are mechanisms that aren’t perfectly understood yet, but that these samples from Bennu would be able to help [scientists] understand.

Klimek: So it arrives at its destination and has to physically collect the sample somehow. But first it has to match the orbit?

Shiner: Yes, it caught up with the asteroid and flew in formation with it and orbited it from various distances and mapped the entire surface of the asteroid. They found a landing spot called Nightingale. They thought that it was fairly smooth, but with the vision that they had at the time, there was a monster rock in the way that the arm of OSIRIS-REx had to navigate around. It almost magically avoided this boulder and got itself down to the rubble pile that is Bennu and grabbed a sample and backed away.

Klimek: I think this is something that people don’t really grasp when they read about space missions: these navigation problems that’ll be familiar to anybody who turned the steering wheel to go around a pothole or something, except this is happening astronomical distances away, and you’re trying to make these decisions based on limited information.

Shiner: And even more surprising than that, so it launched in 2016. At that point, your technology is frozen. You can’t use any of the advances that we have between 2016 and 2023. You’ve already built the spacecraft, so its autonomous operations are being conducted by seven-year-old technology, which is old! I mean, how long have you had your recent iPhone? And all of that code had to be written for it in advance. So it is a miracle to me. I just can’t imagine how they made it.

Klimek: So tell us about the actual sample collection: physically scraping a little bit of Bennu off and bringing it home.

Shiner: They have something like an air filter on the arm, which is pretty wonderful. And so there’s this disc. It’s like a clock. It has thickness to it, the disc does. And inside this disc is sort of a filtration or a blowing system, a reverse vacuum. And when the spacecraft disc comes in contact with Bennu, it huffs at it. It blows a little bit of nitrogen onto it, and the nitrogen poofs out this cloud of dust and rocks, and those enter the collection device. And then it pulls back, and it closes the lid to capture whatever it has poofed off the surface. But the lid didn’t close, because it had been so successful in creating this cloud that a rock got caught on the lid. So they quickly brought it back. They saw the stuff spilling out, and they brought it back into the canister and shut the canister.

And when they opened it, you could see that the lid had been propped open. You could see the rock that was there, and all of this black dust and rubble had gathered on the outside of it because of that. And actually it’s taken them a longer time at the conservation facility—which, by the way, was built brand new for this mission—but it took them much longer than they expected because they’re very carefully brushing that dust and capturing it and putting it in containers so that at the end of all of this, they’ll be able to look at this 260 grams [about half a pound], I think, of material and separate it and classify it and divide it for all of the scientists around the world to examine.

Chris: How did the sample of Bennu make it back here to Earth?

Shiner: OSIRIS-REx has something called a sample return canister, and it looks a little bit like a cupcake. The sample was placed back in a cylinder with the cap somewhat closed, and that was retracted into a sample return canister. And that canister lives inside the spacecraft. The spacecraft winged its way back. It left Bennu and worked its way back to Earth, and it dropped the sample return canister. OSIRIS-REx didn’t come back through the atmosphere. It dropped the canister, and it’s gone on to study another Earth-crossing asteroid, Apophis, and the sample return canister entered the atmosphere and it came in over California, is what I’m remembering. And, of course, it goes through what spacecraft do when they go through the atmosphere. It heated. It has an aero shell that protected it on its return, and I think it was at 5,000 feet the parachutes were supposed to open.

What I recall is that the drogue chute was never seen, and the parachutes opened a little bit later than expected, which is why nobody was breathing in all of Utah for several minutes. So the parachutes brought it down, and then there was a very interesting question. We saw the capsule, and there was a lot of TV coverage that NASA provided. We saw a fellow who was working at the Dugway Proving Ground walk up to it, and he was checking to make sure there was no unexploded ordnance, because the Dugway Proving Ground is just that: It’s a proving ground. They drop bombs there. And one of the reporters who was on the press call after this video said, “You mean this thing came all the way back from an asteroid and it could have landed on something and blown itself up?” And apparently that was a very small chance. A smaller chance than getting a hole in one, I think.

Klimek: OK, good. Yikes.

Shiner: They’re very, very careful to keep materials from Earth from contaminating the capsule. And so it was hoisted by a helicopter and taken to a clean room there in Utah, and then there were tests done, and then there was a nitrogen purge. So, nitrogen inert gas can’t react with things. They filled the capsule with this inert gas, and then they put that on a NASA aircraft and flew it to the Johnson Space Center, where they took it from the NASA aircraft and put it in a clean room there at the Johnson Space Center, and they removed the canister. The canister was put into what they call a glove box. You can reach it only with gloved hands, so the conservators there can put their hands into these gloves working in these nitrogen-filled glove boxes so that there’s no possibility of Earth contamination, and they’ll be able to remove the sample for study.

Klimek: Is this purely about just protecting the integrity of the samples from Earth contamination, or is there any actual potential danger of introducing something dangerous that was native to Bennu?

Shiner: I think they’re not expecting any little green men.

Klimek: OK.

Shiner: I think it is all about Earth contamination, and that is because we have samples from asteroids: They’re meteorites. They’ve been landing on Earth since there was Earth.

Klimek (narration): Meteors are tiny chunks of asteroids or comets that fall to Earth. When they enter our atmosphere, they burn and give us shooting stars. If that bit of burning rock survives the trip and makes it all the way to the ground, we call them meteorites.

Shiner: And some of them have taught scientists really amazing things. If you want to see them, there’s a beautiful collection on display at the Smithsonian National Museum of Natural History. I just was there a couple of days ago looking at the meteorites. One of them is called the Murchison meteorite. It landed in Australia—it’s probably the most studied meteorite in the world, and it has given scientists that belief that the amino acids and building blocks of proteins that are the building blocks of RNA and DNA, the things that make life possible, that those came from asteroids.

Klimek: Wow. What are some of the hypotheses that they’re testing at this early stage?

Shiner: One is whether or not life on Earth could have started with some of the materials from asteroids. And so they’re looking for samples of organic materials, materials that have carbon in them, since carbon is present in all of life. And here’s a really kind of fascinating thing. Between biotic materials (that is, organic living materials) and prebiotic (the same chemicals, but they’re not used in living processes) … they all have something called either right- or left-handedness. It’s called chirality. On Earth—this is so weird—all of the organic materials used in living processes are left-handed. They’re shaped—

Klimek: What?

Shiner: Yes. The way that the molecules are constructed, they’re not symmetrical. So you can’t place one on the other and have it be symmetrical.

Klimek: OK. And what we mean by left-handed is they’re asymmetrical?

Shiner: That’s right. It’s asymmetrical toward the left. The materials that have the same type of composition but are prebiotic, are not used in life processes, are right-handed. Why is that?

Klimek: I’m asking you. Do we know?

Shiner: No.

Klimek: OK.

Shiner: But asteroids will be able to help us understand these things, and we’ll be able to confirm that, yep, all of these right-handed substances are right-handed on the asteroids, too. Or they’re left-handed on the asteroids. There will be a lot of discoveries through Bennu.

Klimek: Linda Shiner is the longtime editor of Air & Space / Smithsonian magazine. Thank you so much for talking with us today, Linda.

Shiner: My pleasure.

Klimek: We have a bonus for you for this week’s “dinner party fact.” Linda was able to share a little bit of a conversation with one of the lead OSIRIS-REx investigators.

Shiner: His name is Jason Dworkin, and he runs the astro materials lab at Goddard spacecraft center.

Klimek: In case you were wondering, the official name for this lab is the Astrobiology Analytical Laboratory at NASA Goddard Space Flight Center. Anyway, Linda asked Jason how the samples of Bennu will travel to the different labs around the country, and beyond, for analysis.

Shiner: Will you take it in a briefcase that’s handcuffed to your wrist to carry it across the country?

Jason Dworkin: No, we don’t do that.

Klimek (narration): The answer Jason gave her was extremely unexpected, though.

Dworkin: They’ll either be hand-carried—you take it on an airplane in a pouch with a letter saying “Don’t open this” from the curator—or it’ll be mailed insured.

Shiner: It will be mailed?

Dworkin: Yes.

Shiner: You would take something that had come back ...

Dworkin: It happens all the time.

Shiner: … from billions of miles away and—

Dworkin: Other samples are mailed all the time.

Shiner: Really?

Dworkin: The U.S. Postal Service is a remarkable organization.

Shiner: Well, they’re going to be delighted to hear you say that. But what if they lost some?

Dworkin: That hasn’t happened. Genesis Curation has a system that they’ve been using for decades. They’ve mailed moon rocks and all kinds of things. You have to sign for it.

Shiner: Sure. OK.

Dworkin: For registered mail.

Shiner: I’m glad to hear that.

Klimek: “There’s More to That” is a production of Smithsonian magazine and PRX Productions. From the magazine, our team is me, Debra Rosenberg and Brian Wolly. From PRX, our team is Jessica Miller, Genevieve Sponsler, Adriana Rozas Rivera, Ry Dorsey and Edwin Ochoa. The executive producer of PRX Productions is Jocelyn Gonzales. Episode artwork is by Emily Lankiewicz. Fact-checking by Stephanie Abramson. Music is from APM Music.

I’m Chris Klimek. Thanks for listening.

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