OSIRIS-REx is bringing back an asteroid sample. What now?

In 2017, Beck Strauss drove the scariest 200 miles of their life: a road trip from Massachusetts to New Jersey with moon rocks in the back seat. Strauss had “never imagined in a million years” getting to work with rocks from the Moon, they say, let alone ferrying them down Interstate 95. But they ultimately navigated the highways of the Eastern Seaboard without issue. “I obeyed so many traffic laws, oh my gosh!”

That road trip was an essential part of a research project that Strauss, a former NASA/NIST research scientist who studies the Moon’s magnetic field, was working on at Rutgers University. The so-called “lunar dynamo” may once have been as strong as Earth’s, and they hoped to examine the rocks for further evidence of that early magnetism and the possible timing of its decline. That meant that even once Strauss arrived safely in New Jersey, the challenge of protecting the rocks wasn’t complete. If the moon rocks were formed during a period of relatively strong lunar magnetism, they should show evidence of magnetization. But how to investigate that when the rocks were already inside a much stronger magnetic field—Earth’s?

“Magnetizable rocks work a little bit like magnetic recording media,” like a VHS or cassette tape, Strauss explains. When a ferromagnetic mineral is exposed to a magnetic field, the atoms within it, which group into similarly oriented “magnetic domains,” can gradually move to align with that force. The stronger the force, the greater the number of domains that will align. But those domains remain sensitive over time, Strauss says. If researchers aren’t careful, they can “overprint” the pattern of domains left by an older magnetic force, “like recording over something you wanted to save.” Even the magnetic field from a laptop or a phone in a passing pocket can erase the very faint record of a 4-billion-year-old lunar magnetic field.

At Rutgers, Strauss carried the rocks into a room shielded with an alloy that blocks magnetic fields, much like the briefcase used to transport them. Researchers working inside the room had to take care not to expose the rocks to electronics or metallic objects like keys and jewelry. Strauss even had to avoid wearing a favorite bracelet while doing lunar magnetism research since it had nickel in it, which can carry a slight magnetic charge.

Questions about how to preserve extraterrestrial samples like Strauss’ stretch back to the era of the Apollo missions, when astronauts first brought back moon rocks. These days, scientists doing “astromaterials curation” work focus on storing, protecting, and sharing space specimens as carefully as possible. But the stakes of their work are about to get much higher, because after some daring missions to snatch material from asteroids, an unprecedented amount of space dust is headed our way.

Until now, astromaterials curation has mostly focused on caring for moon rocks astronauts have ferried back to Earth and meteorites that arrive under their own steam. But meteorites have passed through Earth’s atmosphere, which alters them chemically in fundamental ways, limiting the data that can be gleaned from them. Plus, despite advances in our ability to spot and hunt down these incoming shooting stars, they still often sit exposed to the elements for months or years, growing rusty and eroded.

Now a spate of asteroid missions is changing the game. In 2010 and 2020, the Japanese spacecraft Hayabusa and Hayabusa2 delivered to Earth capsules with tiny amounts of “raw” material from the asteroids Itokawa and Ryugu. And last year, NASA’s OSIRIS-REx managed to grab a fistful of rocks and dust when it touched down briefly on the asteroid Bennu. Although NASA won’t know exactly how much material is in the OSIRIS-REx capsule until it returns in September 2023, astromaterials curator Nicole Lunning says she expects an amount “at least 10 times more than” Hayabusa2 retrieved—or a minimum of 60 grams of material. (Mission principal investigator Daunte Lauretta has predicted even higher numbers, suggesting at a news conference in 2020 that the capsule may contain “hundreds of grams of material in the sample collector head—probably over a kilogram, easily.”). That material will provide a rare opportunity for a broad range of scientists to study raw space rock unaltered by its journey through Earth’s atmosphere. 

Lunning is helping her lab at NASA’s Johnson Space Center (JSC) in Houston come up with protocols to protect these space goodies from oxygen, humidity, biological threats, and magnetism, and to keep them as undisturbed as possible. The cargo is so precious, and the protocols so elaborate, that they have been running rehearsals to get ready for the big arrival. Using parts identical to those sent to the asteroid, they’ve practiced opening a multilayer capsule Lunning compares to Russian nesting dolls, carrying dummy material. To prevent the space rocks from chemically transforming, they plan to open and, at least for awhile, store the real capsule and its contents inside a specialized “glove box.” The apparatus incorporates arm-length gloves into a sealed container, allowing users outside to hold and manipulate items inside. It will be filled with dry nitrogen, since once the already nonreactive gas has been rid of water vapor, it prevents both problems with humidity and contact with oxygen or other chemicals that could alter the sample.

Lunning and her colleagues will also need to protect the valuable space rubble from any unwelcome visitors. The asteroids visited by both Hayabusa spacecraft and OSIRIS-REx are carbonaceous, meaning they are likely to contain the type of organic materials that hungry Earth microbes like to nibble. (The “organic” material like JSC scientists hope to find on Bennu isn’t necessarily associated with biology, as it often is on Earth. A substance is organic if it contains carbon linked with other elements like hydrogen, oxygen, or nitrogen. Together, they can create the long chains and complex structures needed for the chemical reactions that take place inside cells. That means that finding organics on Bennu could provide insight into how similar materials may have kickstarted the evolution of life on Earth.) 

To prevent any microbes from hitching a ride to an astro-buffet, researchers at JSC will cover their hair and clothes and will wash their tools in hot “ultrapure” water—water with its ions removed, which Lunning calls “surprisingly corrosive.” Then they’ll dry those tools in a nitrogen atmosphere before bagging them in Teflon.

The Teflon is part of the final element of Lunning’s curation plan. “Plastics off-gas materials like formaldehyde, and that can lead to misleading data,” Lunning says. She and the team will ensure OSIRIS-REx’s treasure only comes in contact with certain nonreactive types of stainless steel, aluminum, and Teflon during their work. That way, if they find surprising molecules in their samples, they can be sure those are actually from space and not careless contamination.

After the initial opening and imaging of the full OSIRIS-REx sample, Lunning and the JSC team will prepare to share the riches. NASA has agreed to reserve a certain percentage of the Bennu material for the Japanese and the Canadian space agencies, and will transport it in sealed, nitrogen-filled boxes. After that, curators will prepare a catalogue of Bennu sample types to send out to planetary scientists like Enrica Bonato, who can apply to use small amounts in their research. 

Bonato is helping design a lab in Berlin that will handle OSIRIS-REx material using similar protocols to those Lunning is developing. Bonato studies carbonaceous asteroids like Bennu, and until now she has been using a mix of remote sensing data and meteorite fragments in her research. These arrive via express delivery in the mail and are stored in specialized desiccator containers with silica gel beads that help control humidity. Bonato says the thrill of receiving meteorite bits in the mail hasn’t diminished. But she and her colleagues are especially excited to work for the first time with raw asteroid material that has never touched the Earth’s atmosphere—however it might arrive.

Carbonaceous asteroids present an exciting prospect for study in part because they are rich in minerals containing water. That means they could be helpful in understanding how water arrived on Earth. Bennu is also immensely old; it’s estimated to have formed in the first 10 million years of our solar system. Since then, it’s changed very little, meaning it can tell us a lot about how planets nearby formed and what forces and elements were present in our portion of the galaxy. “Studying meteorites and now starting to study pieces of asteroids, we can start to understand the process of the formation of our solar system,” Bonato says.

She also hopes she might find evidence of some of the amino acids that are essential to the emergence of basic life forms, which would lend support to the theory that those building blocks arrived on Earth by hitchhiking on a similar rock. But she doesn’t expect to find actual life. Since Bennu has no atmosphere to protect it from sterilizing radiation, Bonato says her facility is only concerned about protecting the samples from Earth’s environment, rather than the other way around. But if humans begin bringing material back from Mars, which does have an atmosphere, that will have to be a consideration, since the red planet could potentially be home to microbes that don’t play well with our ecosystems.

Still, any amino acids or other organics in the sample will be extremely fragile and vulnerable. “They’re very sensitive to any change, both water and heating processes,” she says. “Being able to look at them in this pristine material is very precious. It’s a mind-blowing step for us.”

Even after Lunning and her colleagues have shared the riches with Bonato and other scientists worldwide, a large portion of the Bennu sample will be held at Johnson Space Center, saved for future scientists. Long-term storage of the things we bring back from space is an important part of astromaterials curation, she stresses. Just as Strauss was able to work with the Apollo moon rocks a few years ago, Lunning and her team anticipate that scientists will want to examine samples from OSIRIS-REx for decades to come. “We’ll be saving parts with that in mind,” she says. “In 10, 15, 50 years—we want to make sure there’s material available for those things,” including for research using technology that might not exist yet.

Lunning’s team is also responsible for making sure researchers from different areas of space science can share the Bennu samples without issue. The key there, Strauss says, is for scientists across disciplines to talk with each other about what they need. Cutting into a moon rock with a circular saw, as a geologist might need to do, is the “kiss of death” for Strauss’ magnetism work, they point out, since the heat from friction and circular motion overwrites any magnetic record that might be present. Even glue can be weakly magnetic, meaning that if other scientists mount a thin section of rock for examination under a microscope and use the wrong adhesive, it could disrupt Strauss’ entire study.

Meanwhile, Strauss and their colleagues try to make special note if their work has involved heating of any kind. Magnetic analysis often requires baking samples at a high temperature, but that can cause chemical alterations that would throw off a geologist’s calculations. “What we’re saying to other researchers is, ‘We want to be able to make sure you can continue to use these samples when we’re done with them,’” they say.

Strauss points out that, although the Apollo missions brought back more than 800 pounds of moon rocks, the fields of astromaterials curation and lunar magnetism were brand new, meaning that the needs of the scientists who would later study all that rock weren’t taken into account. Strauss hopes that with the incoming trove of asteroid material, early-career scientists will be invited to participate in discussions about how to treat the samples, strategizing so the most people get the most insight over the longest time. That means being “open to collaboration with people who work on completely different experimental questions, open to input from folks with totally different priorities,” they say. “It ends up benefitting the whole scientific community.”