NASA's Historic Journey to Bennu Is All for One Unprecedented Sample

In 2016, a team of scientists bid goodbye to the spacecraft OSIRIS-REx as it began its two-year journey to Bennu, a mysterious asteroid orbiting the Sun. On Monday around 12 p.m. Eastern, the spacecraft finally approached the asteroid, kicking off a long and delicate process.

Scientists from NASA, the University of Arizona, and Lockheed Martin intend to bring back the first asteroid sample to Earth, and because of Bennu’s ancient origins, hope the samples will teach us about Earth’s history.

Erin Morton, communications lead for the University of Arizona’s Lunar and Planetary Laboratory, tells Inverse that the team has been waiting for today with bated breath. While it only launched two years ago, it’s been nearly ten years since Bennu was chosen as a NASA target.

The goal of OSIRIS, whose journey is illustrated in the video above, is to collect samples from the quarter-mile-wide carbonaceous meteorite, which should reveal two stories: How organic molecules attached to carbon have changed since the beginning of our solar system, and how we might be able convert elements on Bennu into fuel for deep space missions.

A “Pristine Sample”

Carbon is a crucial element to life on Earth because it serves as the chemical “backbone” that other organic molecules can attach to. Scientists believe that Bennu is rich in carbon and, by extension, carbon-based organic molecules as well.

Importantly, Bennu hasn’t really changed that much since the formation of the solar system 4.6 billion years ago, making it a “pristine sample from the beginning of our solar system,” according to Morton.

bennu asteroid
The size of Bennu, the asteroid that scientists hope to bring back samples from by 2023

“Bennu as an asteroid, and as a carbonaceous asteroid, we believe is like a time capsule from the beginning of the solar system,” Morton says. “The makeup of Bennu hasn’t changed. There’s been no weathering. Because of that, we want to go and look and see what carbon looked like at the very beginning.”

Missions Into Deeper Space

While OSIRIS could yield important insight into our solar system’s past, the scientific teams behind it also have the future in mind. The samples from Bennu may play a role in a grander design for space exploration, Morton says.

“We’re also going to need to find fuel and other resources on asteroids, kind of like way stations that we can mine and use for further travel,” she says. “One of the ideas is that carbonaceous asteroids we think have clays and bound up in that is hydrogen and oxygen, which you can heat up and create water from. With water, you can create fuel — rocket fuel.”

What Happened Monday?

On Monday, OSIRIS performed a carefully calculated “right-hand turn” directly above Bennu’s pole and begin its precarious journey closer to the asteroid’s surface — but it hasn’t touched down yet. For now, it will circle 7 to 19 kilometers above Bennu’s surface, looking for the right place to land and collect its precious samples.

nasa osiris
OSIRIS will collect samples once it creates a 3D map of Bennu and finds the best place to land. 

Sandy Freund, the OSIRIS-REx mission operations program manager at Lockheed Martin, tells Inverse she’s been waiting for this moment for two years:

“I have been working on this mission for many years and since launch in 2016, we have all been waiting for this moment,” she says. “We have done so many things in the past two years, but I am thrilled to be in this next phase of the mission — to officially be at Bennu.”

Once OSIRIS finds the right place to touch down, which Morton says could take between one and 1.5 years, the craft will collect its samples and begin the long journey home. The samples are expected to return to Earth by 2023. Then, the plan is to study 15 percent of them. The remaining 75 percent will be stored at NASA’s Johnson Space Center for future generations to use in experiments that we haven’t even dreamed up yet.

“This is when the work starts,” Morton adds. “We’ve just been waiting to get there. Now we’re here.”