How Asteroid Hunters Are Solving Earth's Greatest Mysteries: Dante Lauretta (Transcript)

Here is the full transcript of Professor Dante Lauretta’s talk titled “How Asteroid Hunters Are Solving Earth’s Greatest Mysteries” at TEDxUArizona 2024 conference.

Listen to the audio version here:

TRANSCRIPT:

Today, I want you to join me on a journey. It’s a journey to answer some of the deepest questions that we ask ourselves as the human species. Where did we come from and how did the Earth come to be a habitable world? When we go back to the dawn of the solar system and we reconstruct the events early in the stages of the formation of Earth, we recognize that it was a hot, hellish, hazardous environment, constantly bombarded by fragments from outer space.

One of those fragments was so large, it spalled off a chunk of material that accreted into our moon. And when we look at the geologic record from that era, we realize there’s no way that life as we know it would have taken hold in such an environment. And so we ask ourselves, where did the Earth get the key components for life? When we look at the Earth today, we think of it as this beautiful blue jewel in the solar system, covered in oceans, clouds and rains and rivers running across the continents.

Perfect abode for the myriad of life forms we share this planet with. And we wonder, where did that water come from that makes up our oceans? Where were the molecules that make up the air that we breathe? And most importantly, where did the carbon come from that is the central element to all life on Earth?

Asteroids as Key to Life on Earth

And when we look out into the solar system, out beyond Mars, we see a belt of asteroids, remnants from the earliest stages of planetary formation, relics that are over four and a half billion years old. Some of them stand out to us. Their surfaces are very dark, which we intuit means they may have carbon. Carbon does make things very black.

Some of them, we look at the way they absorb sunlight and we see that there are minerals on the surface, clays with water locked up in their crystal structures. And we wonder, could these have been the key that delivered these essential components to the Earth? For the past 20 years, I’ve been on a personal journey and a professional expedition to answer those questions. On September 8th, 2016, we launched a robotic spacecraft named OSIRIS-REx to a near-Earth asteroid named Bennu.

And Bennu called to us to answer these questions. Its surface was one of the darkest in the solar system. Its orbit brings it very close to our home world, so close that we actually worry that it might strike the Earth in 160 years. But we’re not talking about that today.

Today we’re interested in Bennu as this repository of the history of our solar system and holding the clues to the origin of life on Earth. We arrived at this target in 2018. And right away, when you see the shape of this asteroid, it’s not that big. It’s about 500 meters, about the size of the Empire State Building.

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Surprising Nature of Bennu’s Surface

And it has this almost spherical, what we call spinning top shape, suggesting that it’s behaving somewhat like a fluid. And as we’ll see, that’s not too far from the truth. But the first thing that leaked out to me when those resolved images came down to the Science Operations Center here on the campus of the University of Arizona was how rough and rugged the surface was.

When we analyzed our telescopic data, radar data from the Arecibo Telescope in Puerto Rico, infrared information from the Spitzer Space Telescope, it looked smooth like a beach. I even said to NASA, to the public, to my team, we’re going on vacation to Bennu Beach. It’s going to be easy. We’re going to scoop up the sample and bring it straight back to the Earth. That was certainly not the situation that we encountered.

We spent all of 2019 mapping the surface in exquisite detail in some areas down to millimeters per pixel, trying to find that one location where we might be able to collect a sample. And on October 20th, 2020, we commanded the spacecraft on the other side of the solar system, 18 minutes for the signal to travel from the Earth to receive and initiate the sequence to collect that sample. The spacecraft descended down to a region we named the Nightingale to collect that precious treasure from outer space. Here you can see a couple sequences of images from two different cameras.

The Sample Collection Process

One’s looking down at our sample collection mechanism. We call the TAGSAM, the Touch and Go Sample Acquisition Mechanism. And that was the strategy we employed. We were just going to briefly contact the surface.

The actual device that makes that contact is kind of like an air filter you would see on the carburetor of an old 57 Chevy. And quite honestly, the technology is not that much different. We brought our own gas. We had bottles of high-pressure nitrogen.

We blasted into the surface like a leaf blower, pushing rocks and dust and gravel into that filter. And what surprised us the most was how the surface responded. Through all of our testing in the laboratory on NASA’s reduced-gravity aircraft, we expected the surface to be rigid. Instead, it really responded like a fluid of rubble.

And we sank in deep, 50 centimeters, about the length of my arm. When that gas fired, the surface erupted. And then the rocket engines blasted, sending fragments of the asteroid everywhere, ultimately excavating a crater 25 feet across, about 100 times what we expected from our simulations. The good news was we got that precious sample.

Reconstructing the Sample Collection Event

The event was so dynamic that we had to reconstruct it just to understand exactly what happened when we touched the asteroid surface.

And I’ve watched this video hundreds of times. And every time I think about when we were pitching this concept to NASA, we said, this is going to be easy. It’s going to be safe. It’s going to be no problem.

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And then I can only imagine if we had showed this video to that selection board and said, this is what we’re planning to do with your billion-dollar spacecraft, right? There’s no way that mission would have got selected. But that’s why we explore, right?

We’re learning that, in fact, these near-Earth asteroids are piles of rubble. They must be relatively young to survive the age of the solar system. They had to be incorporated into a much larger asteroid. That object was shattered in a catastrophic disruption hundreds of millions of years ago, sending off thousands of fragments all around into the nearby space, many of which coalesced, reaccreted into these spinning piles of rubble.

And that is what dominates the near-Earth asteroid population today. Forces from sunlight and gravity push these asteroids into the inner solar system. These cosmic visitors to near-Earth space, allowing us to send the spacecraft out there, collect this precious sample. And I’m proud to say, on September 24th of 2023, we released a sample return capsule towards the Earth to bring that treasure home.

The Return of the Sample Capsule

And boy, what a day this was, right? The capsule hit the top of the atmosphere at 27,000 miles per hour. The surface of the capsule heated up to 5,000 degrees as friction from the atmospheric molecules imparted their energy to that device. And you might say, Dante, you’re interested in water. You’re interested in carbon. How could you survive such harsh conditions?

Well, the capsules, like a mini version of the return capsules, that the astronauts come home from outer space in, and they do just fine. They’re made out of water and carbon, just like our samples are, right?

And I’ll never forget the moment. I was in a helicopter flying across the Utah test and training range, getting ready to recover this amazing sample. And all I could get was the call-outs from the range safety officer. And I knew there was a critical event that had to happen as we crossed through 100,000 feet. The drug parachute needed to deploy. So I’m listening as intently as I can. The whirring chopper blades are making it really difficult to understand what I’m being told. And I’m, like, crossing 100,000 feet, 8,000 knots.

The Successful Recovery of the Sample

I ask the Air Force officer in the front of the helicopter, any sign of a drug parachute? She says they’re not calling drug. 60,000 feet. And I’m like, I think we’re in trouble. And then after an excruciating 360 seconds, they’re calling main chute. The main chute’s open. That capsule is coming safely down to the surface of the Earth. And I let out a holler of triumph, scaring the helicopter pilots.

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And then I broke into tears just at the amazement that our journey was complete. I got to land, get out and see that capsule. And, man, it was like seeing a friend that I hadn’t seen for seven years. It was charred and black and a little worse for wear, but it had made it.

It had left the surface of the Earth, rendezvoused with the asteroid, protected that precious sample through the return cruise to space and down to the surface. The next morning, we got it into an Air Force transport jet, landed at NASA’s Johnson Space Center. And you can see my moment of triumph there when we opened up that sample canister and we saw that beautiful TAGSAM device surrounded by a ring of black asteroid dust. And I marveled.

Analyzing the Asteroid Sample

It was the darkest material I had ever seen. It’s unfathomably dark. I still have trouble processing how does it absorb so much light? But the good news was we made it.

We achieved mission success. We got those samples and we’ve already got them into our laboratories to address those big questions. We put them into like a CAT scan, like you would go in for a medical exam, and we can X-ray their interiors and see the beautiful structures and minerals that are inside. And yes, it’s dominated by water-bearing clay minerals.

Almost 10% by weight of this rock is water. And this is the water that is the same material that was delivered to the Earth by its brethren four and a half billion years ago that makes our oceans, makes our clouds, and it makes us. We’re about 50% water. But perhaps the most exciting discovery is there in the upper kind of fluorescent image.

As we scan the sample with an ultraviolet laser, these little points of light shine back at us. Fluorescent molecules, organic compounds, some of them exactly the same kinds of materials that make up our proteins and our genetic material. And perhaps the most exciting part is to see the students here at the University of Arizona working on these materials, realizing that we’re addressing these major questions. I see that dawning recognition of just exactly what they have in front of them, and it warms my professor’s heart.

Conclusion

So we’re going to spend the next two years analyzing these materials in excruciating detail, unraveling the earliest stages of solar system formation, understanding how life might have arisen on our planet. And by figuring that out, maybe, just maybe, we’ll address the question, Are we alone in the universe? Thank you.

How Asteroid Hunters Are Solving Earth’s Greatest Mysteries: Dante Lauretta (Transcript)