After seven years and nearly 4 billion miles, mission returns with sample of asteroid that may offer secrets of the universe.

After seven years hurtling through the solar system, NASA's OSIRIS-REx space mission ended in a resounding success as its precious cargo tore through Earth's atmosphere to touch down in the Utah desert.

Launched on Sept. 8, 2016, the initially $800 million Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer, or OSIRIS-Rex, spacecraft set off on its journey to a near-Earth asteroid named Bennu to collect a sample of rocks and dust from its surface.

Near-Earth, however, is entirely relative. Orbiting the Sun roughly 74.6 million miles away, Bennu has been of intense interest to scientists for a number of reasons. For a start, it is thought to be an untouched time capsule from the very beginning of the universe, providing not only clues to the origins of our home planet but also all life that it supports.

Despite the potential answers to our very inception, it also carries a possibility of being our end, as NASA has described Bennu as the "most dangerous rock" in our solar system due to it having a small chance of colliding with Earth within the next 300 years.

Among many of the possible choices for sampling, Bennu ultimately held a more attractive composition. Relatively rich in carbon-based material, asteroids like Bennu may have brought water and organic material to Earth and helped kick off life.

With the capsule touching down on Sept. 24, 2023, the list was long for research centers to receive a piece of this dusty pie.

Tools for the job

Originally, OSIRIS-REx was named a finalist for NASA's New Frontiers mission class in 2009. Along with missions to study Venus (Surface and Atmosphere Geochemical Explorer or SAGE) and the Moon (MoonRise) in 2011, OSIRIS-REx was ultimately chosen as the winning proposal.

The New Frontiers program consisted of a series of medium-class spacecraft missions intended to help humanity better understand the solar system. OSIRIS-REx was the third mission chosen for that program, with previous selectees being New Horizons, which flew by the dwarf planet Pluto in 2015 and by an object called 2014 MU69 in 2019, which is still continuing its mission out in the solar system, as well as the Juno mission, which arrived in orbit around Jupiter in 2016 and is still operational there.

Launched in 2016, OSIRIS-REx was equipped with various instruments the space agency determined most suitable for the information they hoped to learn at Bennu and when a sample returned to Earth. The five instruments onboard the spacecraft studied, mapped, and analyzed the asteroid in unprecedented detail. These included:

• OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) – By measuring visible and near-infrared light, OVIRS hunted for organics and other minerals.

• OSIRIS-REx Thermal Emission Spectrometer (OTES) – Using thermal infrared, OTES took Bennu's temperature and mapped mineral and chemical quantities. Together, OVIRS and OTES mapped Bennu over a range of wavelengths to select the best site to sample the asteroid.

• OSIRIS-REx Camera Suite (OCAMS) – Consisting of a three-camera suite to map Bennu, the largest, called PolyCam, acquired the first images of Bennu, taking them from 1.2 million miles (two million kilometers) out, capturing images in high-resolution of the potential sample site. MapCam hunted for satellite and dust plumes around the asteroid, mapped them in color, and took photographs to create a topographical map of the 500-meter rock. SamCam documented the collection of the sample and its eventual capture.

• OSIRIS-REx Laser Altimeter (OLA) – By scanning the entire surface of Bennu, OLA sent back data to create highly accurate 3D models of the asteroid's surface.

• Regolith X-ray Imaging Spectrometer (RExIS) – Studying X-ray emissions of Bennu was intended to help with the creation of a map showing the abundance of different elements on the surface. Unlike other imaging instruments, RExIS examined the composition of the asteroid at the level of individual atomic elements.

Mission accomplished

After traveling nearly 4 billion miles, the capsule containing the extraterrestrial sample of Bennu was released from the OSIRIS-REx spacecraft as it passed by Earth the morning of Sept. 24, where it entered the atmosphere at around 27,000 miles per hour.

Reported practically by the minute as it touched down, a specialized recovery team led by Lockheed Martin – who designed, built, and flew the mission for NASA – and representatives from NASA's Goddard Space Flight Center, NASA Johnson Space Center, and the University of Arizona, were there to secure and retrieve the capsule.

"The landing was safe, recovery was a huge success, and we're thrilled that the next phase of this mission can now begin," said Kyle Griffin, vice president and general manager of Commercial Civil Space at Lockheed Martin. "This particular sample return is monumental – scientists are about to open a time capsule with some of the earliest history of our solar system inside."

After approaching the capsule landing area in helicopters, the recovery team carefully searched for any hazardous material, sampled the neighboring soil, wrapped the 100-pound capsule in protective material, and attached it for transport via helicopter to an on-site cleanroom at the range.

There, the sample was processed for shipment on a military aircraft to curation team members at NASA Johnson in Houston, Texas, who made it available for study.

While the capsule landed safely toward the end of Sept., it would not be until closer to the end of Nov. that research centers could get their hands on a part of the sample.

Natural History Museum

The Bennu sample made its way to the Natural Museum in London, where scientists were eagerly waiting for a chance to examine the origins of the universe.

There, a team of researchers has begun studying the black, rocky powder in extraordinary detail. Exposing the material to a whole host of experiments and tests, the hope is a glimpse at the earliest preserved material in the cosmos, which may unlock answers to age-old questions.

"We're really lucky," said Ashley King, a meteorite researcher at the Natural History Museum, who will be part of the team studying the pieces of Bennu. "We're one of the first people to get our hands on Bennu samples."

"And here at the museum we have a team of researchers that are going to start studying these samples to understand their mineralogy and chemical composition," she added.

This is exciting because Bennu is thought to have coalesced from material that formed during the birth of the solar system some 4.56 billion years ago.

Now, what makes a sample collected from a rock so far away different from, say, a meteorite that crashes down on Earth? Well, for starters, it has not been exposed to Earth's atmosphere. And due to painstaking efforts to isolate the material as securely as possible so as not to contaminate it, this allows the closest simulation of if one were to test the material out in the vacuum of space millions of miles away.

When OSIRIS-REx first made contact with Bennu, it blasted a jet of nitrogen gas onto the surface to kick up little bits of the rocky layer into a container before backing off and sealing the tube shut. It is this capsule that the spacecraft then sent back down to Earth.

Once the capsule returned safely to Earth, scientists opened it in a sealed nitrogen environment with no oxygen and very low humidity. After they assessed that the mission had indeed been a success and did a stock take of the material, the scientists removed a small sample and sealed it in a stainless-steel tube.

It was this sample they then sent to the Natural History Museum, where it is now stored in yet another nitrogen environment to await study.

The sample doesn't look like much, maybe a teaspoon (roughly 100 milligrams) of fine jet-black dust within a glass vial.

"The sample, we believe, comes from the sort of asteroid that we think might be responsible for bringing water to Earth," said Helena Bates, a researcher at the Natural History Museum who will also be studying the sample in minute detail. "So, when Earth formed it was quite a dry environment, and we think that water was delivered from an extraterrestrial source at some point during Earth's later evolution. We think that Bennu could be representative of the type of asteroid that delivered water to Earth."

This means that Bates and her colleagues are keen to peer into the tiny grains to see if they contain any extraterrestrial water and then compare it to the water we have on Earth. This could give them clues as to the origin of the life-sustaining substance.

Dream made real

Along with potential water, the team will be searching for possible organic content.

"We're going to be looking at the organic content," said Bates. "When I say organics, I don't mean life, but carbon-bearing molecules. We're obviously made up of organic molecules built into life. But we find organic material in some meteorite samples that are similar to Bennu. So we're going to be looking at the organic complement of this sample, trying to see if maybe these samples from Bennu - or samples like the samples from Bennu - could have acted like a stock cube for life and were delivered to Earth."

For others at the Natural History Museum, it is more than just excitement to know, but the gratification of seeing a dream made real.

"It's almost unbelievably exciting,' said Sara Russell, who has been involved in the OSIRIS-REx mission from the very beginning. "It's almost like a dream to have the sample back, because we've been thinking about it for so long."

Part of a team made up of hundreds of scientists all over the world, each one adding their own expertise and knowledge to make the earliest musings into reality, this mission was simply a part of a grander collective.

"There has been so much planning," said Rusell. "And we've spent years talking about what the sample might be like and speculating. To actually have a bit of the sample here at our museum and to be able to analyse it in our own labs is really a dream come true."

In the end, excitement toward future possibilities replaces fulfillment, and Russell expects that this mission will only be the start and hopes it will inspire a new generation to begin exploring space and creating new, extraterrestrial natural history collections.

"It's almost like a second era of voyages of exploration," finished Russell. "We're starting to explore the solar system around us and bring back materials from space. I see this as being the next era of natural history collections."

CORRECTION: This article has been updated to correctly state the total distance of the entire mission.