Strange New Worlds

Published Jun 25, 2024

Jess talks with NASA OSIRIS-REx mission lead planetary scientist and cosmochemist Dr. Dante Lauretta about collecting samples from the asteroid Bennu that are now helping us understand the very origins of the universe.


We’ve all heard the term “moonshot” which has entered popular vernacular as a way to describe attempting the impossible. Of course, when scientists in the mid-20th century took the original moonshot at the urging of President John F. Kennedy, they were truly voyaging into the unknown. Humans did accomplish the impossible, and we’ve always looked to the stars to dream those impossible dreams.

Just last year, an intrepid team leading the OSIRIS-Rex mission for NASA scored another impossible win for science and retrieved samples from an asteroid hurtling through space. When it comes to redefining the word “impossible,” it doesn’t get any better than this.

I’m your host Jess Phoenix, and this is science.

Jess: Joining me today is Dr. Dante Lauretta, principal investigator for NASA's OSIRIS-REx mission, which successfully retrieved geologic samples from the asteroid Bennu in 2023. He is Regents Professor of Planetary Science and Cosmochemistry at the University of Arizona's Lunar and Planetary Laboratory, and he's now director of the University of Arizona's Astrobiology Center. Basically, he's who you call when you want to know what rocks that aren't on Earth are made of. Dante, thank you so much for joining me today to talk space rocks. Can you start by telling me what led you to study the least accessible rocks in the solar system?

Dante: Yeah, thanks, Jess. It's really great to be here, and I'm excited to share this story. I was always an explorer. I grew up in the middle of the Arizona desert with no television and not even running water. We had to haul our own water from miles away with a big 500-gallon tank, and I just fell in love with the natural history, the geology, the unique flora and fauna that we have in the Sonoran Desert, and also the people who came before me. I would find Native American structures, petroglyph walls, old mining operations. And so I started to think about the past and who was here before me and then who was here before them. And how far back can you take that question? At some point, there was nobody. Nothing was alive on our planet.

I really became fascinated with that whole concept of the formation of the Earth, other planets in our solar system, and did they ever have life? And how does this phenomena...which we all kind of take for granted, it's all around us right now, but when you really think about it, it's amazing, and it's a huge mystery. How did the origin of life occur on Earth? And especially when we know the early history of our planet was very violent. There was huge impacts. One was so large, it spun off our moon. The planetary surface was a magma ocean. It was a very inhospitable world, yet somehow water became oceans, molecules became our atmosphere, and organics transitioned from something that was not alive to something that was alive. And as I dug into that question, it became obvious that some of the answers probably resided within asteroids.

Jess: I know a lot about initiating research projects on Earth. How does one go about initiating a research project that requires space work?

Dante: I was really fortunate when I got to the University of Arizona in 2001 to have a very invested mentor, Dr. Michael Drake. He was the director of the Lunar and Planetary Laboratory and the individual who hired me, and we really clicked. He was about 25 years older than me, so we had this fantastic mentor-mentee relationship. We were interested in similar problems.

And in 2004, the University of Arizona partnered with Lockheed Martin, had won a contract for a Phoenix Mars lander. And they were targeting the polar regions of Mars, and they were going to dig down and find the ice. And so Lockheed came back to Arizona and said, "We want to partner with you on an asteroid sample return mission." And they approached Mike to be the principal investigator. And Mike immediately called me, and he said, "I want you to come in as my deputy." And that kicked off a seven-year odyssey to convince NASA to fly the mission.

And Mike knew if we were going to be able to convince NASA to fly this mission, it had to target these carbon-rich objects, and it had to address these fundamental origins questions. And I was the individual that he brought in to lead that part of the science investigation. We spent 7 years writing and getting rejected and revising our proposal until the year 2011 when we finally won the contract to fly the spacecraft. That was in May, and, unfortunately, Mike passed away in September of that year, creating a huge hole in my life, because I love this man, and he really had brought me up into the professional ranks that I have achieved. And I took over as the principal investigator of OSIRIS-REx and have been leading it now for the past 13 years.

Jess: I was going to ask you about that specifically, about how working on a project with objectives so far in the future that people actually die over the course of the project. And then how does that change how you perceive the impact of your research? I mean, it can take literal lifetimes for these things to come to fruition.

Dante: Yeah, I celebrated my 20-year anniversary on OSIRIS-REx this February. And absolutely, part of it, you just don't think about how long of a timeline you've signed up for because there's a lot of immediate tasks in front of you and you've got to get them done.

As a teenager, I was really into cars, and I didn't have a very good car. So I kind of had to learn how to fix it to keep it running. And it felt a lot like being in the garage with your buddies, except instead of a $400 1976 Plymouth Duster, I had a $400 million robotic asteroid explorer sitting next to me there. But I became really good friends with the engineering technicians that were assembling the spacecraft. I got to see OSIRIS-REx come into being. And it was just this phenomenal experience of seeing what seemed impossible take shape. And, of course, you get it on that rocket, and there's nothing like launch day. Your whole career is now invested in a giant pile of explosives that's sending your vehicle off into outer space for seven years. And then you arrive at the asteroid, and you really are a team of adventurers, right? You did your best to plan the expedition. You brought all the tools you think you would need.

The only thing you can fix or change is your software, which we had to do quite a lot of. But you're exploring this fantastic world that nobody's ever seen before. And then, of course, the bringing the sample back down through the atmosphere. That was a nail-biting experience just last year. And now we're exploring that same world but at a whole new scale with our electron microscopes, in some cases down to the atoms that make up the minerals of this asteroid. So it's been a phenomenal journey. One I document in my memoir, "The Asteroid Hunter," I invite our listeners to join me on some of the details there.

Jess: Yes, I actually need to read it. So thank you for giving me something to read when I'm traveling in the next few weeks…good recommendation. I'd love it if you could tell me what made the asteroid that was selected, Bennu. Why was this one so appealing?

Dante: Yeah, we chose Bennu as the target of the mission back in 2005, so now almost 20 years ago. It was discovered in 1999, and right away, it got scientists' interest because it's in a very Earth-like orbit and in fact has a substantial probability of impacting the Earth about 160 years in the future. So it shot up to the top of the planetary defense list as a key object of interest. And that made it accessible. So it's kind of two sides of the same coin. We were looking for an asteroid in an Earth-like orbit because you need to launch off the planet, rendezvous and spend a substantial amount of time, a couple of years, we were at Bennu, and then leave and come back to the Earth. And if you try to do that with an object in the main asteroid belt, which is in between Mars and Jupiter, it's much more expensive, both in time and in energy. It would take several decades to lead a sample return mission out to the asteroid belt.

So the orbit was a big part of our selection criteria. And then we got to think about how big of an object do we want to go to, because there were several hundred asteroids that fit the orbital criteria. Many of them are really small, like 10 meters. And we thought that would just be really hard to operate around and try to get a sample. It's probably just a solid boulder. So you'd have to break it or shatter it or some kind of chip it away. So we said, "Let's go to something reasonably large," and we chose the value of 200 meters or bigger.

Because when we look at the asteroid population, objects that are smaller than that tend to rotate really rapidly, like sometimes more than once per minute, and that also would imply they're a coherent object. And then when you get to bigger and bigger objects, Bennu's about 500 meters across, they're rotating relatively slowly. Bennu's rotational period is 4.3 hours. So there was a few dozen asteroids that kind of fit all of those constraints, the orbital constraints, the size constraints, and the rotation constraints. And then, finally, science got to come in and say, "Hey, we're interested in the origin of life, the origin of habitability, oceans, atmospheres. We need to go to a carbon-rich, water-rich asteroid." And there was only five that we thought had high confidence of meeting that criterion.

And Bennu was very well characterized. Especially in 2005, we had a custom astronomical campaign using every major telescope you can imagine, Hubble, Spitzer, Arecibo, Goldstone, tons of glass all over the world was on this thing. So we had a really great knowledge base, and we were able to use that for our operational planning. And so it kind of reduced risk in that manner. So carbon-rich, relatively large, slow rotator, Earth-like orbit all led to Bennu as the prime target for the mission.

Jess: I was hoping you could take us to the day that you were physically there when OSIRIS-REx touched back down on Earth after all of these decades of planning and execution. Could you describe the scene for me? Because I was watching live, the world was watching, and you and a select group of other people really knew how much was at stake, I mean, the decades that went into it, the millions of dollars, people's lives, and all the knowledge you hope to get. So just give us that experience. Kind of let us ride on your coattails through it.

Dante: Yeah, that was September 24th of 2023. And I woke up in a Holiday Inn at the Dugway Proving Ground, which is part of the U.S. Department of Defense's Utah Test and Training Range, which is just southwest of Salt Lake City. And this is the largest continuously controlled airspace in the continental United States. The military uses it for all kinds of testing and training scenarios. And that's why we chose it, because we had the flight path that was coming in over California, across Nevada, and then into Utah for touchdown in the Utah desert. I woke up really early in the morning, like 1:30 a.m., because we had spacecraft operational activities, particularly to command the release of the capsule targeting the Earth.

We were about a quarter of the distance between the Earth and the moon when that capsule was released. And this is a dumb capsule. It has no guidance capability whatsoever. You use the spacecraft to line it up, targeting Utah from tens of thousands of kilometers away from the Earth. And then you give it a little bit of a spin to spin, stabilize it through the atmosphere. And that was a little bit of a nail-biting moment because it wasn't guaranteed we would release the capsule because we had to guarantee safety, safety of the people in Utah, safety of the military assets. If we were off track at all, we would have had to have waved off, and it would have been two years to loop around the sun and come back to the Earth to try again.

So it was an anxious moment. After almost 20 years of my life, we had to get that capsule released. I wear a fitness tracker, and my heart rate was 120 BPM when I woke up, which is like over twice my normal baseline. That's like when I'm really running or on my bike or, you know, moving fast. So I knew that I could just feel the anxiety of the day and just this career's worth of effort that was at stake here. So the spacecraft commanding went according to plan. We got the batteries powered up. These batteries are responsible for releasing the parachute system, and we hadn't talked to them for seven years because they were passivated. They had this layer to prevent any voltage or current from flowing. So it was like, "Okay, are the batteries still there? They've been sitting in space for seven years. Who knows what's happened?" But they came online, and then we saw a successful release of the capsule.

Everybody was in pretty good mood. The operations had gone according to plan that day. And we drove out to the Michael Army Airfield where there was a huge crowd that had gathered. There was all these high-level officials from NASA, from the military, from government, the university, Lockheed Martin. Lots of international partners from Japan, from Canada, from Europe were all there. So this big crowd of VIPs, my family, my wife and my two sons, were there to celebrate with me. And I get into a helicopter, and we fly out to a staging area, and we're waiting to hear the callouts. There's a range control officer that's giving us the information, "Capsule spotted over California, coming in at 27,500 miles per hour." We crossed the entire state of California in two seconds, right? And then over Nevada and then into Utah. And as soon as we got into Utah airspace, the helicopters take off. There was four choppers.

I'm in the helicopter, and there's a critical altitude crossing of 100,000 feet where a small parachute called a drogue chute is supposed to deploy because you're transitioning from supersonic flight to subsonic, but dropping below the speed of sound, and the capsule is not stable in that low velocity. So the drogue comes out to kind of stabilize it. And I'm hearing 100,000-foot altitude crossing. And I tapped the officer in the front seat, and I was like, "Drogue?" And she said, "They're not calling drogue." And I'm like, "Oh, man." My memory goes back to a disaster in 2004, a NASA mission called Genesis, which was collecting particles of solar wind whose parachute failed to deploy, and it cratered into the Utah desert. And there's a little memorial there that we visited at UTTR to that capsule.

So I was thinking, "Okay, this is a disaster. All of this work is going to come down into a shattered remnant of our beautiful spacecraft. And I'm going to have to deal with it on live TV. I'm going to have to keep my cool when all I'm going to want to do is cry." And we go through 60,000 feet, and there's no drogue. And I'm like, "Okay, this is it." And then all of a sudden, they say, "Main Chute spotted." And I was like, "Well, that's not according to plan." I said, "But thank goodness that this thing finally opened up. It came in really low in altitude, but it was enough to slow it down and land this capsule." So I just broke into tears in the helicopter. All this stress that I didn't even know I was carrying for the past 20 years just released. And I was like, "We did it." I mean, when we first talked about this in 2004, it seemed like magic, "Like, really, I can pick an asteroid, any asteroid in the solar system, and I'll get samples back in my laboratory. No way. There's no way that's feasible." Sure enough, on that day, the dream came true.

Jess: That is absolutely wild. And what a catharsis, because I do remember one of the most striking images that I took from watching you all do that was you were running to it, you know, with your arms in the air like, you know, you just won the Super Bowl. And that was really cool, because I think, for so many years, people have thought that scientists are boring, usually old guys in lab coats that never leave the lab, and they're very dry and don't get emotional. But you and your team really helped show the world the essence of yourself that you put into this work. And so I wanted to thank you for being so expressive, because that really helps the world understand what we as scientists go through.

Dante: And we're very passionate. We're artists, right? And our art is expressed in a different way, because we are expressing the human condition, our curiosity, our wonder at the universe, the amazement that we all feel when we truly appreciate natural systems and what they represent, how old they are and how complex they are and how fortunate we are to be here, to be able to appreciate, to learn, and to share that knowledge. And I thank you because, you know, I mentioned it before, but you were one of my inspirations when I got to writing my book. Yours was one of the ones I pulled off the shelf to say, "Okay, how do people tell these stories?" And yours was one of my favorite. Ms. Adventure, if you guys haven't read it, I would highly recommend it. Jess has done some crazy stuff, and she tells the stories really well. I was with you there through many of those wild, wild rides that you took us on in that book.

Jess: All the amazing research we do and all the cool discoveries and the failures that we learn from, none of it matters if we can't tell the stories. I do want to go a little ultra nerdy here. And you mentioned it, you kind of teased it before, about what the samples from a carbonaceous asteroid can tell us about the origins of our universe. And so geek out. Tell me about the mineralogy, the geology, you know, anything that you've learned so far. Like, lay it on us.

Dante: The sample is awesome. I mean, we are having so much fun analyzing this material. It's exactly what we hope for, and it's full of surprises. So it's dominated by a class of minerals called phyllosilicates, more commonly known as clay minerals. We're seeing lots of a material called serpentine and also another clay called saponite. We have lots of carbonates. This is carbon in mineral form. A lot of people are familiar with it. If you live in an area with hard water and you get those white crusts that clog up your showerheads and your faucets, those are carbonates. You have carbonated water or soda water, right? Carbon dioxide in the water. And you have typically calcium, which makes it hard. And then calcium and the carbonate bond, and that forms a mineral called calcite. We're seeing a lot of calcite.

It turns out it's very rich in carbon. About 4.7% by weight of the sample is carbon. Only 10% is in those carbonate minerals. The other 90% are in organic molecules. We're seeing all the nucleobases that are used in DNA and in RNA. So the letters of the genetic code are in this asteroid. The other major biomolecule are proteins. And we use 20 amino acids commonly in biology on Earth. If you take protein supplements, you can usually see which amino acids are in there. We have 13 of the 20 amino acids so far have been detected in the Bennu samples. We're seeing these really intriguing structures we call nanoglobules. They're little spheres. They're fluorescent. So if you put it under UV light and you have a fluorescence microscope, they light up, and they look like little bright specks throughout this dark matrix. And then we zoom in. They're sometimes hollow. Sometimes they have minerals inside of them. Maybe even fluid is trapped inside of them. So there probably were, like, oil droplets in this hydrothermal system on this ancient asteroid.

And then the big surprise so far has been we did find white-encrusted stones that I thought was going to be those carbonates, but they turned out to be magnesium and sodium-rich phosphates. And phosphorus, which makes up the phosphate mineral, is also a key element in biology. It makes up the backbone of DNA and RNA. It makes up a key component of cell membranes. And when you get to animals, it makes bones and teeth. So that's also really interesting for early life studies. We put all of that together, and we think about environments on Earth or elsewhere in the solar system where you get the same kind of minerals. It looks a lot like what's forming at the alkaline hydrothermal vents at the mid-ocean ridge on Earth. And we're seeing very similar mineralogy coming out of the plumes of an icy satellite called Enceladus around Saturn. So I think we have an ancient hydrothermal system from an icy ocean world, probably formed in the outer solar system, because you needed to get the carbon dioxide ice. And we're seeing a lot of ammonia, which is a very volatile element. So you had to form this thing probably around Saturn. And then it had to migrate into the main asteroid belt, get shattered. Bennu was just a scoop of all of the fragments that broke off in that catastrophic disruption and then has migrated into the inner solar system where we were able to retrieve it and start to piece this very complex history together.

Jess: Okay, so I have to say that is one of the most mind-blowingly cool things that I've ever heard, like, without a doubt. And I've heard some cool stuff over the years. The way you describe it really touches on what makes studying things like Bennu so important for our understanding of the origins of life on Earth, what the solar system was like when these things formed. So if you can get a little bit specific, even more than you already have, about what this understanding of conditions were like on Bennu when it was formed, how does that help us with our efforts to piece together our understanding of Earth itself?

Dante: Well, it's clear that water and key organics and nitrogen were delivered to the Earth by these kinds of objects. So they are responsible for our planet being a habitable world, as opposed to just, no offense, you know, a volcanic-encrusted object, right? So...

Jess: None taken, none taken.

Dante: ...these kind of transitioned us over from being a dry, pretty inhospitable place to this beautiful paradise that we enjoy and live in and thrive in and, hopefully, we'll take care of so future generations can do the same thing. And the other thing it implies is that these components of habitability and prebiotic chemistry were ubiquitous across the solar system. The Earth wasn't the only place that they were delivered to. Venus would have had a substantial inventory. And there's strong evidence that Venus had oceans early in its history. Mars would have had the same kind of inventory. Definitely icy satellites, dwarf planets, things like Ceres, Europa, Enceladus, Titan, all of them would have had the chance for the origin of life to occur.

So you start to ask the question, did it? Is there life today on Mars? We know Mars went through massive climate change, but life could have migrated to the subsurface where we find organisms on Earth today. What about Venus? Venus is now a hot, hellish pizza oven kind of surface temperature. But if you get in the upper atmosphere, it's similar to the conditions at the surface of the Earth. So maybe life migrated up. What about Ceres? What about Europa? Enceladus, where we know we have oceans under those ice caps. There's hydrothermal vents... Let's try that again. There's hydrothermal vents and plumes erupting into space. One of them makes the E ring of Saturn. So the hydrothermal chemistry we're seeing on the mid-ocean ridge on Earth and we saw occurring in Bennu's ancient history is happening today in the outer solar system.

I'm optimistic that there's some form of life out there because every one of those objects had the chance. And the question is, what are the odds? What does it take to go from this clay-rich, organic object into something that's alive? And to me, that is the most profound scientific mystery we're facing because we have no idea. We can't make that happen in the laboratory, and that's why we're driving into the astrobiology investigations that we are.

Jess: We're wrapping up here. And one of the things I really like to ask all of my guests, it's actually a two-part question, and it's because we are the Union of Concerned Scientists. So, Dante, why are you concerned?

Dante: Well, I'm concerned because I don't think we really take the time to appreciate how lucky we are to be alive, to be aware, and to exist on this beautiful planet. I mean, we really have this gem that has, you know, led through a very complex and turbulent history so that we could be here today. And I don't think people take the time to step back from the hecticness of their everyday lives. And I know people are facing all kinds of hardships and challenges out there. But, you know, it just changes your perspective when you realize space is a really big place. It's a really harsh environment.

We haven't seen anything like the Earth in our exoplanets yet. And we're looking for them, and we'll probably find something like it. But we need to take care of this place. We need to take care of each other, right? And, you know, human beings are very special in our ability to communicate, our ability to remember the past, to predict the future, to develop these amazing technologies. But they come at a price, and we need to understand that. We're smart. We can solve any challenge if we just join together with a common vision, respect each other, respect our home world. And I'm concerned that that is just not sunk in to most people on this planet, and we need to work hard to communicate those messages.

Jess: That is profound. And I completely agree. And so we don't end on kind of a downer because what you've done is so uplifting. What are you doing about that concern?

Dante: Well, I'm getting out there, and I'm communicating, first of all, just the sense of adventure and what we are capable of. As I said, OSIRIS-REx seemed impossible when we first started talking about it 20 years ago. But we had to bring together a very diverse team, not just, you know, diverse in profession, right, because you needed scientists, you need engineers, you needed managers, you needed business people, but ages, backgrounds, because you're solving really complex problems, and there's strength in that diversity. So you really come to appreciate people think differently than you do, people look differently than you do, they have different backgrounds, but when you unite on this common vision, there is nothing that is impossible. We can do amazing things when we join together, when we unify, and when we work towards a common goal. And that lesson translates across all aspects of our lives, right? It's not just space exploration. It's all these grand challenges that we're facing in health care and immigration, environmental concerns. All of those can be solved when we unify, agree, and move forward together.

Thanks to Omari Spears and our intern Josie Spanier for production help. The full-length video version of this interview is available on the UCS YouTube Channel. Ad astra, science space cadets!