Big Ideas Lab - The Bennu Asteroid

Episode Date: June 2, 2026

In September 2023, a small NASA capsule streaked through Earth’s atmosphere and landed in the Utah desert, carrying 122 grams of material from the asteroid Bennu. That material has existed for more than four and a half billion years, preserving clues from the earliest moments of the solar system. At Lawrence Livermore National Laboratory, a team of scientists is now studying tiny fragments of the sample with extraordinary precision, examining isotopes and microscopic minerals to read the stories locked inside. As studies continue, they are revealing how some of the ingredients used by life on Earth are also present in ancient space rocks. Guests featured (in order of appearance): Greg Brennecka - Staff Scientist, LLNL Thomas Kruijer - Staff Scientist, LLNL -- Big Ideas Lab is a Mission.org original series. Executive Produced by Levi Hanusch. Sound Design, Music Edit and Mix by Matthew Powell. Script by Caroline Kidd Story Editing by Levi Hanusch. Audio Engineering and Editing by Matthew Powell. Narrated by Matthew Powell. Video Production by Levi Hanusch. Brought to you in partnership with Lawrence Livermore National Laboratory. Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

In a remote corner of Utah, a distant boom rolls across the desert. A capsule, only 32 inches wide, has just separated from NASA's Osiris Rex spacecraft and entered Earth's atmosphere. NASA's Osiris Rex, the first ever U.S. mission to collect a sample from an asteroid returning to Earth. After a round-trip journey of more than 2 billion miles, the capsule hits the desert. floor and the recovery team moves in carefully. Roger. Fast forward three months and the desert sand has given way to white surfaces, sealed containers, and the sound of people taking every precaution to protect what NASA spent seven years to bring home.

A scientist reaches for the sample container, slowly, because he knows it's impossible to replace. I was using a gloved hand due to contamination issues, but he was using a gloved hand due to contamination issues, but it was pretty spectacular. We really are looking at something that has changed very, very little since its inception. The object in that room was a delivery

four and a half billion years in the making. And somewhere inside it, written in chemistry, may be the story of where everything began. The next challenge, reading it. NASA partnered with a team that could measure what almost no one else on Earth could. A sample from, from the B'new Asteroor.

Welcome to the Big Ideas Lab, your exploration inside Lawrence Livermore National Laboratory. Hear untold stories, meet boundary-pushing pioneers, and get unparalleled access inside the gates. From national security challenges to computing revolutions, discover the innovations that are shaping tomorrow today. In the early 2000s,

a team of planetary scientists at NASA began planning something audacious. They would build a spacecraft, aim it at an asteroid, launch it across more than a billion miles of space, map the asteroids rugged terrain at an unprecedented centimeter level resolution, hover over the surface to collect a sample, and bring it all the way home. The mission was called Osiris Rex. The target was Benu. Any moment now, NASA will launch a space probe that will embark on a Seven-year mission. Four, three, two, one.

Osiris Rex. And lift-off of Osiris Rex in seven-year mission to boldly go to the asteroid venue and back. In September 2016, the spacecraft launched from Cape Canaveral. It would take nearly five years to reach the asteroid, map it, collect a sample, and begin the journey back. The question driving the mission is one that humanity has asked since its inception. Curiosity of where we came from and where the ingredients in our solar system came from and what they were. Where we came from as humans, where we came from as planets. Greg Brennika is a staff scientist at Lawrence Livermore National Laboratory.

One of the ways to do that is to look at samples that formed in the early solar system and analyzed it and figure out when it happened, where it happened, and what it's made from. Greg has spent his career studying meteorites, rocks from space that have landed on Earth, and the answers they may reveal about the solar system's beginning. Benu is roughly as wide as the Empire State Building is tall, a rubble pile held together by its own gravity. Never melted, never differentiated into a core, a mantle, or a crust, never weathered by Earth's wind, oceans, or atmosphere. scientifically pristine. Hazard process descended below the five meter mark.

The hazard map is go for tag. Touchdown declared. Sampling is in progress. Sample collection is complete, and the faculty burn has executed. It's a very cool way of collecting a sample, actually. So there was a spacecraft that was orbiting the asteroid. The scientist decided this is an area we want to land. It's safe, and it has the stuff that we want to collect.

So they picked an area that they knew they could get out of that wasn't near a lot of large boulders. They basically went down and essentially looks like a pogo stick. Fired the retro rockets and blasted off of the asteroid. In October of 2020, the long journey back into Earth's atmosphere began. Three years through the vacuum. But before it ever arrived, the mission was entering its next phase. Finding someone on Earth who could actually interpret the material.

I kind of like to think of this as if somebody sent you a picture of a birthday cake, you can kind of tell what that birthday cake's made of. You may have an idea about what it tastes like. You don't really know. And we can take pictures of a lot of asteroids. We can take pictures of distant planets. We can have ideas about what they're made from. But we don't really know until we get it in the laboratory and really analyze it.

You don't really know until you have that birthday cake in front of you and you can taste it. For decades, telescopes revealed spectra. Wavelanks of light reflected off asteroid surfaces. Useful. suggestive, but indirect. From Earth, scientists could see the surface, but that surface had been marked by billions of years of sunlight, radiation, and impact. The birthday cake was in the picture.

Scientists just couldn't taste it. And even when Space Rock did arrive on Earth as meteorites, there was another problem. All the meteorites we have on Earth have passed through Earth's atmosphere and have landed on Earth. and that in itself contaminates that sample. And particularly for this mission, it was really important to have an uncontaminated sample

because what they were looking at in addition to the chemical and isotopic compositions that Livermore was involved in was some of the organic biologic precursors, ingredients that may lead to the emergence of life later on. Those ingredients already exist on Earth. So if you have a meteorite that's flying through the atmosphere and lands in a bog, of course it's going to be contaminated.

Banu. It's a very primitive asteroid. Thomas Cryer is a staff scientist at Lawrence Livermore. And that means that it is not being changed or modified much over geological history, so over the billions of years since it formed. And that means that we get a very clear and true perspective of how the solar system looked like billions of years ago, even before the Earth was around. So what exists inside a preserved, primitive asteroid,

born in the outer solar system. I find this really incredible to have extraterrestrial samples. You can hold them in your hand. Livermore's case for getting to study Benu rested on a reputation built over decades. It's a competitive process to become a participating scientist that allows you to receive a sample of Benu and be part of the science team that does this work.

NASA wants you to prove to them you're eligible and are capable of doing the sophisticated analysis that you promise to do. In order to do this type of work, you need to be a leading expert in your field. You need to be able to do these very sophisticated isotopic measurements. And we are world experts here at the lab in analyzing very small samples

with very advanced analytical tools, and that specifically is related to the ability to measure isotopes in these rocks using mass spectrometers. And these isotopes then in turn tell you about where the material formed, how it forms, and when it formed. Fortunately, that expertise connects to another Lawrence Livermore mission, national security. There's a great handshake between nuclear forensics and cosmochemistry

because we are always pushing the boundary on what we can measure and getting better at it by looking at these really small samples that we see oftentimes in cosmochemistry. You want to find out where it came from. You want to find out how old it is. you want to find out what it's made from. Those are also the same types of questions that we ask in nuclear forensics. But before Benu could be measured, it had to be protected.

Not from the world beyond Earth, but from Earth itself. This is done under very clean conditions in a clean lab. It is filtered air, HEPA filters. And the reason for that is that we need to prevent any contamination from the Earth from being added to that sample. So we want to keep our environmental background levels very low. breath, a flake of skin, a particle of dust, any of it could contaminate the sample. By the time the sample reached Livermore, scientists at NASA's Johnson Space Center had already seen the complication.

Benu was not only one thing. When the sample returned back to Earth and they were able to open the canister, it became pretty obvious just with the naked eye that you could see that were slight differences in different lithologies, which is basically rock type that we're seeing in the sample. And of course this gave everyone pause and we thought, okay, well, we need to measure each individual rock type to see how different they are. Each lithology could carry a slightly different history and each one needed to be decoded. We use a technique known as mass spectrometry.

You extract information that has been retained within that sample for billions of years. It's basically locked in there and using sophisticated methods that we use at the lab and have at our disposal that allows us to measure the abundances of isotopes, individual isotopes within a rock, so of a particular element,

but we can measure the isotopes of many different elements. And we have multiple such mouse spectrometers at our disposal here at Livermore Lab. To read Benu, they were looking for tiny differences inside the atoms themselves. Isotopes are different versions of an element. What that tells us is that those different isotopes behave slightly differently in conditions like an out-eastern. space or on earth. A story that's being told by looking at the isotopic composition. So much like a very large dog is going to be able to make a different type of cut than a very small dog. If a

great dana and a chihuahua are running around a corner, the chihuahua is going to be able to make that corner earlier. So we know how those behave because we've seen it in the past. And so we can make predictions on how different isotopes behave in different environmental situations. An isotopic fingerprint. A way to read where Benu came from, and what it had been through. And when Lawrence Livermore finally measured that chemistry, all 18 isotopic systems from a fragment smaller than a coin, what they found stopped scientists in their tracks.

I guess what surprised me the most is how similar it was to the sun, and we're able to determine the composition of the sun with spectral measurements. They have fairly large uncertainties, but we can easily tell the difference between certain different types of meteorites and the sun. And what we noticed very early on is that this is indistinguishable from what we see in the sun. And that tells us that this hasn't really changed much from an ingredient standpoint over the four and a half billion years. So it really is the makeup of the sun, which is 99.9% of the solar system's mass. We have a sample of it now.

The result connected Benu to the rarest and most primitive meteorites ever found on Earth. You have meteorites falling on Earth. They fell maybe 50 years ago, maybe 100 years ago. from another body, they pass through the atmosphere, they traveled all the way to Earth, and then you have NASA taking a spacecraft to another body and returned some material by spacecraft. The composition of Benu turns out to be identical to the sun. It's also very similar to CI chondrites,

a rare class of primitive meteorites, and the most unprocessed material in any known collection on Earth. It is really a special class, and there's only very little material of that. in collections on Earth. And on top of that, the material, of course, that's returned by a spacecraft is much more pristine, because when a meteorite falls on Earth, it has to pass through the atmosphere. All while Lawrence Livermore was tracing isotopic fingerprints,

placing Benu's origin and confirming chemistry, another team was working on the same sample. Because inside Benu's dust, scientists were not only finding chemistry from the birth of the solar system. They were finding chemistry that is relevant for life. You have a lot of amino acids. You have all five of the nucleotide bases of DNA and RNA. You have the sugar backbones. These are all contained in meteorites, and we found these in the Benu samples. Our colleagues have found essentially all the components of DNA and RNA in the Benu sample. And that's just super exciting. If you talk about origins about where the ingredients for life may have come from or developed, that's pretty exciting to be able to find those in space rocks.

Not life itself, not evidence of organisms, but molecular building blocks used by life on Earth found in a rock from outer space that's never touched Earth's atmosphere. That's quite remarkable, because that means that even though, as of now, we only know for certain that life exists on Earth, at least some of the building blocks for life are also present in these mitriads. And what that exactly means, I think we don't know. yet, but it is certainly a worthwhile pursuit.

Not every answer locked away inside Benu will come from the first round of analysis. Most of the asteroid sample is sealed at NASA's Johnson Space Center, saved for scientists who will have better tools, sharper methods, and questions no one has thought to ask yet. You look at the Apollo samples that were brought back in the 1960s and 70s, and we're still uncovering secrets from those samples. We're still learning a ton about the moon, from the Apollo samples.

And when you archive samples like this, it allows people in the future to look at them with better instrumentation. I mean, we will have better instrumentation in a decade, in two decades, in five decades. There's no question. We have improved our instrumentation. We've improved methodologies.

People in high school listening to us now will have the opportunity to look at Benu's samples. And I think that's impressive in itself for us to be able to look forward enough to say, let's look at this in 20 years and see where we are. Let's look at this in 50 years and see where we are. Ben-U is not the end of this work.

At Lawrence Livermore, the team is already studying lunar samples and expanding its capabilities for the next generation of return material, including samples from Artemis. The same expertise will matter again. Clean rooms, mass spectrometers, isotope measurements, and the patients to let ancient material speak for itself. You cannot simulate or compute your way to a disobey. you need to actually measure these samples.

It's an empirical science. We do measurements and that will continue to remain important. A rock from outer space. Four and a half billion years of chemistry. A sample small enough to fit in a hand, but also old enough to carry the memory of the solar system. The measurement is what unlocked it. The understanding is what Lawrence Livermore is sending back into the world.

into the world. Thank you for tuning in to Big Ideas Lab. If you loved what you heard, please let us know by leaving a rating and review. And if you haven't already, don't forget to hit the follow or subscribe button in your podcast app to keep up with our latest episode. Thanks for listening.