NASA's OSIRIS-REx spacecraft will visit asteroid Apophis

An artist's depiction of the OSIRIS-REx spacecraft studying the asteroid Apophis. (Image credit: Heather Roper)

Apophis, get ready for your close-up.

NASA's asteroid-sampling OSIRIS-REx mission, on its way back to Earth from its visit to asteroid Bennu, will take a trip to another space rock. The probe is set to spend 18 months studying the infamous near-Earth asteroid Apophis, watching the rock during a close, but very safe, approach it will make to planet Earth in 2029.

The mission will also acquire a new moniker when it is officially redirected to Apophis in October, 2023. Instead of being called OSIRIS-REx, which stands for the Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, the mission will become OSIRIS-APEX, which is short for OSIRIS-Apophis Explorer.

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These NASA radar images show the asteroid Apophis on March 8, 9 and 10 as it passed within 10.6 million miles (17 million kilometers) of Earth in a 2021 flyby. (Image credit: NASA/JPL-Caltech and NSF/AUI/GBO)

The spacecraft will provide scientists a rare opportunity to examine a potentially hazardous asteroid up close. To clarify, while the asteroid falls under the classification of potentially hazardous asteroid because of its large size and ability to make close approaches to Earth, Apophis does not pose a threat to Earth. 

Previously, scientists thought Aphophis might pose a small threat to Earth during a flyby in 2068, but newer observations ruled out that threat, as described in a reassessment of its risk last year. Still, with the asteroid only coming to within a tenth of the Earth-moon distance in 2029, this flyby will be an opportunity for researchers to see Apophis up close.

"People in Europe and Africa will be able to see it with the naked eye, that's how close it will get. We were stoked to find out the mission was extended," Dani DellaGiustina, who will become the principal investigator of OSIRIS-APEX after the probe's current mission ends, said in a statement.

DellaGiustina, who is a researcher at the University of Arizona, is now deputy principal investigator of OSIRIS-REx. The mission's current principal investigator Dante Lauretta (also a researcher at the University of Arizona) will remain in his role until the mission shifts to its new objective, the statement noted.

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NASA and its partners are on a long-term quest to catalogue the number of asteroids in our solar system and their size, assessing the percentage of those objects that may pose a possible threat to Earth, however small. Decades of searching have found no imminent asteroid threats to Earth; the risk posed by Apophis was downgraded after it made a close flyby of Earth on March 5, 2021 and scientists refined its orbital predictions based on fresh observations.

While OSIRIS-REx is best known for snagging a sample from asteroid Bennu, this successor mission will instead stick in orbit around Apophis for 18 months with no touchdowns at all. 

To do this requires the team to redirect the spacecraft. It will also split the team apart, with one group covering the analysis of Bennu's sample and leaving the rest of the team tasked with keeping the spacecraft healthy and able to finish out a few more years in space. The spacecraft launched in 2016 and will be 13 years old, almost double its first mission's lifetime, by the time it studies the close approach of Apophis in 2029.

Related: Defending Earth against dangerous asteroids: Q&A with NASA's Lindley Johnson

A mosaic image of the asteroid Bennu created using data from NASA's OSIRIS-REx mission to sample the space rock. (Image credit: NASA/Goddard/University of Arizona)

The spacecraft's extended mission will add another $200 million to the mission's current cost cap of $800 million, for a total cost of $1 billion, though it will allow scientists to study Aphophis without launching a separate, second spacecraft.

Most of the instruments on the spacecraft are healthy, save for the low-energy laser transmitter of the Canadian OSIRIS-REx Laser Altimeter (OLA) that stopped working in 2020 after its primary mission was concluded, according to SpaceQ. (The high-energy laser transmitter was still functioning well at that time.) 

But with the remaining roster of tools available, the mission team has an ambitious agenda set for observing Apophis.

In addition to observing Apophis for 18 months and collecting data all along the journey, the spacecraft "will make a maneuver similar to the one it made during sample collection at Bennu, by approaching the surface and firing its thrusters. This event will expose the asteroid's subsurface, to allow mission scientists to learn more about the asteroid's material properties," according to the statement from the University of Arizona.

The scientists plan to study the asteroid's composition, along with how it will be affected by the gravitational pull of our planet when it gets close to us. Apophis and Bennu are roughly the same size (roughly 1,000 feet (300 meters) across), but are different types of asteroids. Apophis is in the same S-type family as ordinary chondrite meteorites, while Bennu is a B-type linked with carbonaceous chondrites that potentially delivered water to Earth, early in our history.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: