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NASA's OSIRIS-REx Will Arrive At Asteroid Bennu Today After Two-Year Journey


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

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Artist's concept shows the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft making contact with the asteroid Bennu. NASA

Today is the big day for OSIRIS-REx. After traveling for two long years across billions of kilometers, the spacecraft will finally make its rendezvous with asteroid 101955 Bennu. While here, it will embark on a truly incredible feat: survey and map out the asteroid for almost two years to find a good collection of rock and dust, then return home to Earth with the treasure. 

You can even join members of the mission team for a live-streamed NASA broadcast on Monday, December 3, at 11.45am ET (4.45pm GMT) at the Lockheed Martin control room. Check it out in the YouTube video below.


The spacecraft itself is around 3.15 meters (10.33 feet) high and 6.2 meters (20.25 feet) long when its solar arrays are fully deployed. OSIRIS-REx (short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) won’t actually touch down and land on Bennu, although its robotic arm will touch the surface for five seconds in July 2020 as it collects the crucial sample. For the rest of the time, it will use a bunch of small rocket thrusters to match the velocity of Bennu.

"Bennu's low gravity provides a unique challenge for the mission," Rich Burns, OSIRIS-REx project manager at NASA's Goddard Space Flight Center, said in a statement in August 2018. "At roughly 0.3 miles [0.48 kilometers] in diameter, Bennu will be the smallest object that any spacecraft has ever orbited."

Bennu is an ideal candidate for such an investigation. It’s relatively close to us with an orbit that crosses Earth, it’s a decent size, and it’s unbelievably old. In fact, some of the mineral fragments inside Bennu might be older than the Solar System.

The sample of dirt and rocks will only weigh around 60 grams (2 ounces), equivalent to about 30 sugar packets. Despite the small size, it could hold some huge insights. It’s hoped that this invaluable carbon-rich sample will shed some light on the nature of the asteroid, the origin of the Solar System, and even the vital building blocks that formed the planets and enabled life.


"The story of this asteroid is the story of the solar system," added Bashar Rizk, Senior Staff Scientist on the OSIRIS-REx team. "When we understand Bennu, we will understand something fundamental about our Solar System."

This is asteroid 101955 Bennu. NASA/Goddard/University of Arizona

By March 2021, it will be prime time to depart the asteroid and OSIRIS-REx will begin its return journey to Earth. All being well, OSIRIS-REx and its sample will make it back to Earth on September 24, 2023, following the epic two-year journey.

Now's your time to shine, OSIRIS-REx – best of luck.


spaceSpace and Physics
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