What do we expect from the Bennu asteroid sample that will reach Earth?

(CNN) — When the OSIRIS-REx spacecraft passes by Earth on Sunday, it is expected to deliver a rare cosmic gift: an original sample collected from Bennu, an asteroid close to our planet.

If all goes as planned, the spacecraft will launch a capsule containing about 250 grams of rocks and soil from the asteroid from space to the landing area in the Utah desert.

NASA will be broadcast Live sample deliveries beginning at 10 a.m. Miami time on Sunday. The capsule is expected to enter the Earth’s atmosphere at 10:42 a.m. Miami time, and travel at a speed of about 44,498 km/hour. It will land in Utah in about 13 minutes.

After launching the capsule, OSIRIS-REx will continue its journey through the solar system to observe in detail another asteroid called Apophis.

Studying the sample could help scientists understand basic details about the origins of our solar system, as asteroids are “remnants” of those early days 4.5 billion years ago. But the sample could also provide information about Bennu, which has the potential to collide with Earth in the future.

NASA has been preparing for years to return the first asteroid sample collected in space to Earth. Here are the milestones of the mission so far and what lies ahead.

The spacecraft took detailed pictures of the asteroid’s surface.
(Credit: NASA/Goddard/University of Arizona)

The cosmic journey of a spaceship

OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, has been on quite a journey over the past seven years. NASA’s spacecraft launched from Cape Canaveral in 2016 and reached Bennu’s orbit in December 2018.

OSIRIS-REx, the first American mission to be sent to a near-Earth asteroid, has made history several times. It achieved the closest orbit by a spacecraft to a planetary body (and Bennu became the smallest body ever orbited by a spacecraft).

OSIRIS-REx scanned the entire asteroid to determine the best location to collect the sample. Bennu is about 500 meters wide and consists of rocks held together by gravity.

Views of Bennu provided by the spacecraft allowed the mission team to obtain unprecedented information about the asteroid, including the discovery of ice trapped in Bennu’s rocks and carbon in a form largely associated with biology. The team also witnessed particles from the asteroid being launched into space.

The spacecraft moved closer and closer to the asteroid until on October 20, 2020 it carried out the historic TAG (Touch-and-Go) sample collection mission.

Throughout the mission, problems arose that threatened its success, such as the spacecraft’s sampling head collecting so much material that the container could not seal properly, causing valuable asteroid material to leak into space.

During the historic collection event, the OSIRIS-REx spacecraft’s sampling head plunged 0.5 meters into the asteroid’s surface. Bennu’s exterior appears to be made up of loose particles that aren’t securely bound together, based on what happened while the spacecraft was collecting a sample. If the ship had not fired its recoil engine after the rapid collection of dust and rocks, it would have fallen directly into the asteroid.

That’s when the mission team discovered that the asteroid’s surface resembled a pit of plastic balls.

Illustration of the OSIRIS-REx spacecraft as it descends to the rocky surface of asteroid Bennu.
(Credit: NASA/Goddard/University of Arizona)

The OSIRIS-REx team was able to meet and overcome these challenges, and the spacecraft is scheduled to return the largest sample collected by a NASA mission since the Apollo astronauts returned lunar rocks decades ago.

The team was also able to arrange a final flyby of Bennu in April 2021, giving them the opportunity to see how OSIRIS-REx created turbulence and changed the surface of the asteroid while collecting samples. The before-and-after images showed some interesting differences created by collecting samples and firing the spacecraft’s thrusters after it moved away from the asteroid, including the movement and rearrangement of large rocks on the asteroid’s surface.

Back to earth

Since bidding farewell to Bennu in May 2021, OSIRIS-REx has been on a return trip to Earth, orbiting the Sun twice so it can pass by our planet in time to drop off the asteroid sample.

NASA and Lockheed Martin Space have spent much of this year practicing every step of the sample recovery process.

If the spacecraft’s trajectory is on track, the sample capsule is expected to separate from OSIRIS-REx about 102,000 kilometers from Earth early Sunday. Since leaving Bennu, the spacecraft has performed numerous maneuvers and fired its thrusters to pass Earth in time to launch the capsule. The capsule will land in an area measuring 58 kilometers by 14 kilometers at the Department of Defense Test and Training Range in Utah.

Parachutes will deploy to slow the capsule so it can land at 17.7 km/h, and teams will be ready to recover the capsule as soon as it is safe to do so, said Sandra Freund, OSIRIS-REx program manager at Lockheed Martin Space. With NASA to build the spacecraft, provide flight operations, and assist in capsule recovery.

A helicopter will transport the sample in a cargo net and deliver it to a temporary clean room set up at the range in June. There, a team will prepare the sample container for transport on a C-17 plane to NASA’s Johnson Space Center in Houston on Monday. Details of the sample will be revealed via a NASA broadcast from Johnson on October 11.

Scientists will analyze rocks and soil over the next two years in a dedicated clean room inside the Johnson Space Center.

It is important to better understand how many near-Earth asteroids, such as Bennu, could collide with our planet. Better knowledge of their composition and orbits is key to predicting which asteroids may come closer to Earth and when, as well as developing methods to deflect them.

The sample will be split and sent to laboratories around the world, including OSIRIS-REx mission partners at the Canadian Space Agency and the Japan Aerospace Exploration Agency. About 70% of the sample will remain intact in the repository so that future generations, with better technology, can learn more than is possible now.

The screen will reveal information about the formation and history of our solar system, as well as the role of asteroids in the evolution of habitable planets like Earth. Scientists believe that carbonaceous asteroids such as Bennu collided with Earth early in its formation, providing elements such as water.

The sample is expected to arrive at the Department of Defense Test and Training Range in Utah, where recovery teams have been training for months.
(Credit: Keegan Barber/NASA)

“We’re looking for clues to explain why Earth is a habitable world, this rare gem of outer space that has oceans and a protective atmosphere,” explains Dante Lauretta, principal investigator for OSIRIS-REx at the University of Arizona in Tucson.

“We think that all of this material was brought back by these carbon-rich asteroids very early in the formation of our planetary system. And we think that we’re bringing back this kind of material, literally, that perhaps represents the seeds of life that were The creation of this amazing biosphere, to biological evolution and to our being here today.