2020 – 2023: Touchdown! And Goodbye


This week, we have been recapping noteworthy OSIRIS-REx mission events each day so you can catch up on anything you may have missed so far on NASA’s first mission to collect a sample from an asteroid. 

(Post #4 in a series of four) 

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At 1:50 p.m. EDT on Oct. 20, 2020, NASA’s OSIRIS-REx spacecraft fired its thrusters to nudge itself out of orbit around Bennu. It extended the shoulder, then elbow, then wrist of its 11-foot (3.35-meter) sampling arm and transited across Bennu while descending about half a mile (805 meters) toward the surface. After about a four-hour autonomous descent to a 26-foot- (8-meter-) wide spot on Bennu, past menacing boulders that could tip the spacecraft or the sample head and thwart the sample grab, OSIRIS-REx contacted the surface. It then fired a burst of nitrogen gas that stirred up dust and rocks, which were captured by the sample-collection head. Finally, OSIRIS-REx fired its thrusters and safely backed away from Bennu, allowing a captivated global audience to breathe a collective sigh of relief.  

Before departing Bennu, OSIRIS-REx conducted one last flyby of the sample site, “Nightingale,” so scientists could see how the spacecraft’s contact with Bennu’s surface altered the site. They saw something astonishing: Even though the spacecraft barely touched the surface, it left a sizeable crater and scattered many rocks. Scientists ran hundreds of computer simulations to understand how this could have happened, given they had expected the spacecraft to leave only a small divot in the surface.  

That’s when they learned that the particles making up Bennu’s exterior are loosely packed and lightly bound to each other, which means they act more like a fluid than a solid. Had it not fired its thrusters to back away immediately after grabbing a sample, OSIRIS-REx would have sunk into Bennu. 

On May 10, 2021, the spacecraft departed Bennu and headed back toward Earth to drop off the sample-return capsule. When it arrives here on Sept. 24, 2023, OSIRIS-REx will release its sample capsule to land on Earth in the Utah desert, but the spacecraft will not land itself. With the sample delivered, the spacecraft will set off on a new mission, OSIRIS-APEX (OSIRIS-Apophis Explorer), to explore asteroid Apophis. 

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Learn more: 

NASA’s OSIRIS-REx Spacecraft Collects Significant Amount of Asteroid 

NASA’s OSIRIS-REx Spacecraft Heads for Earth with Asteroid Sample 

Surprise – Again! Asteroid Bennu Reveals its Surface is Like a Plastic Ball Pit 

— Lonnie Shekhtman 

2019 – 2020: Choosing a Touchdown Site from a Sea of Hazards 

This week, we are recapping noteworthy OSIRIS-REx mission events each day so you can catch up on anything you may have missed so far in NASA’s first mission to collect a sample from an asteroid.   

(Post #3 in a series of four) 

Pictured here are the four candidate sample collection sites on asteroid Bennu selected by NASA’s OSIRIS-REx mission. Site Nightingale (top left) is located on Bennu’s northern hemisphere. Sites Kingfisher (top right) and Osprey (bottom left) are located on Bennu’s equatorial region. Site Sandpiper (bottom right) is located on Bennu’s southern hemisphere. Nightingale was chosen as the sample collection site. CREDITS: NASA/Goddard/University of Arizona

Given Bennu’s unexpectedly rough terrain, NASA’s OSIRIS-REx team took extra time to evaluate potential sample collection areas. They looked for flat surfaces between numerous rugged boulders. They also looked for regions with fine grains on the surface that the spacecraft could easily ingest. Through their own analyses and a public mapping campaign, the mission team first identified more than 50 sites, whittled those down to 16, and then to the final four candidates. The spacecraft then spent a month investigating each of the four sites and sending home images so scientists could further evaluate them.  

A spot dubbed “Nightingale” by the team, set in a small crater, rose to the top of the list in December 2019. The size of a few parking spaces, Nightingale was the most promising location to meet both safety and sample-availability considerations. But it wasn’t perfect. The area was only about one-tenth the size the mission team had planned for. This put pressure on OSIRIS-REx navigation engineers to program the spacecraft to dodge boulders, such as a building-size one, nicknamed “Mount Doom,” during its 2020 autonomous navigation to a small spot on the surface. 

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Learn more: 

NASA Mission Selects Final Four Site Candidates for Asteroid Sample Return 

X Marks the Spot: NASA Selects Site for Asteroid Sample Collection 

Coming up tomorrow: “Touchdown! And Goodbye.” 

  — Lonnie Shekhtman 

2018: Arrival at Bennu — A World Full of Surprises 

This week, we are recapping noteworthy OSIRIS-REx mission events each day so you can catch up on anything you may have missed so far in NASA’s first mission to collect a sample from an asteroid.  

(Post #2 in a series of four)

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After traveling 1.2 billion miles (2 billion kilometers) to Bennu, NASA’s OSIRIS-REx spacecraft arrived in December 2018 and began orbiting the asteroid. Until the spacecraft got to Bennu, we could only see the asteroid as a pixelated blob through Earth telescopes and radar measurements. Still, scientists had an idea of what they would find at Bennu by using years of radar and thermal measurements and computer models to predict its mass, shape, and surface features.  

On the left, a compilation of radar images of asteroid Bennu. On the right, a shape model based on radar imaging and visible light curves. CREDITS: Michael C. Nolan / Arecibo Observatory / CC BY-NC-ND 3.0

In early 2019, OSIRIS-REx began to study Bennu in detail. The spacecraft zigzagged Bennu in a trajectory that looked like a child’s sweeping crayon sketch. The first closeup images of the asteroid revealed surprises that would require scientists to update some of the fundamental assumptions used in their predictive computer models.  

Instead of there being a smooth, sandy beach on the surface that the mission team had expected to see, Bennu was littered with boulders and was spewing rock particles into space. It became clear that safely navigating to the surface would be an unexpected challenge. The mission team would spend most of the next year mapping Bennu in detail and looking for a relatively smooth area with the fewest hazards and the most opportunity to gather scientifically interesting samples. 

Learn more:

NASA’s OSIRIS-REx Spacecraft Arrives at Asteroid Bennu 

NASA’s OSIRIS-REx Spacecraft Enters Close Orbit Around Bennu, Breaking Record 

NASA Mission Reveals Asteroid Has Big Surprises 

Coming up tomorrow: “Choosing a Touchdown Site from a Sea of Hazards.” 

 — Lonnie Shekhtman 

2016: NASA’s OSIRIS-REx Launches from Earth

This week, we are recapping noteworthy OSIRIS-REx mission events each day so you can catch up on anything you may have missed so far in NASA’s first mission to collect a sample from an asteroid.  

(Post #1 in a series of four) 

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NASA’s first mission to sample an asteroid, OSIRIS-REx, launched on Sept. 8, 2016, at 7:05 p.m. EDT from Cape Canaveral Space Force Station in Florida. About the size of an S.U.V., OSIRIS-REx would travel for two years to a near-Earth asteroid originally designated 1999 RQ36. The name “Bennu,” referencing an ancient Egyptian deity, was picked in 2013 by nine-year-old Michael Puzio, from North Carolina, who won a naming competition.  

NASA chose to go to Bennu because the asteroid possesses several key characteristics that make it perfect for a sample return mission. Here are all the reasons why 

Scientists around the globe have been waiting for years for the spacecraft to deliver a sample from Bennu to Earth. Among the many questions they’ve been waiting to explore by analyzing pieces of Bennu is: Did asteroids deliver molecules that played a role in the origin of life on Earth, and potentially on other planets and moons? 

Learn more: 

NASA’s OSIRIS-REx Speeds Toward Asteroid Rendezvous 

Why Bennu? 10 Reasons 

Coming up tomorrow:Arrival at Bennu — A World Full of Surprises.” 

— Lonnie Shekhtman 

NASA Prepares for Historic Asteroid Sample Delivery on Sept. 24

After seven years in space, including a nail-biting touchdown on Bennu in 2020 to gather up dust and rocks, NASA’s intrepid OSIRIS-REx spacecraft is about to face one of its biggest challenges yet: deliver an asteroid sample to Earth while protecting it from heat, vibrations, and earthly contaminants.   

“Once the sample capsule touches down, our team will be racing against the clock to recover it and get it to the safety of a temporary clean room,” said Mike Moreau, deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. 

Learn more here.

Welcome to the OSIRIS-REx Blog


Welcome to the OSIRIS-REx blog. Here you will find updates on NASA’s first mission to collect an asteroid sample for analysis in labs around the globe.

NASA’s OSIRIS-REx spacecraft is cruising back to Earth now with samples it collected at the rocky surface of asteroid Bennu on Oct. 20, 2020. The spacecraft will deliver these samples on Sept. 24, 2023, thereby expanding NASA’s legacy of bold missions to collect extraterrestrial samples of rocks and regolith – missions that started in 1969 when Apollo 11 landed on the Moon’s surface.

We invite you to check back here regularly to learn how NASA is preparing for the sample return event. You’ll learn how the asteroid sample will make it to Earth’s surface and meet the scientists and engineers who will collect the sample capsule in the Utah desert, where it will land. We’ll also give you a behind-the-scenes peek at the extensive rehearsals necessary to transport, open, and store this pristine cache of rocks and dust that can reveal the history of our solar system.  

– The OSIRIS-REx Team

If you want to learn more about the OSIRIS-REx launch in 2016, see the posts below.