The spacecraft arrives at the tiniest object ever visited today.
Update: NASA has released stunning visuals of OSIRIS-REx’s approach to the asteroid Bennu. Take a look:
Here’s a look at Bennu’s full rotation:
NASA’s OSIRIS-REx spacecraft was launched in 2016, but today it will begin to orbit its destination: the asteroid Bennu. When it does, Bennu will break the record for the smallest object ever orbited by a man-made spacecraft. NASA will begin a process of learning more about the small asteroids that reside in our part of the solar system.
You can watch the livestream of the arrival here:
OSIRIS-REx is designed to do something that only one other spacecraft has ever done before: collect a sample and return it to Earth. The Japanese spacecraft Hayabusa managed that feat in the early 2000s, but its target was the large asteroid Itokawa. Bennu is much smaller, which makes it both a trickier target to rendezvous with and more difficult to land on.
That landing is pretty important, since the sample return is the whole point of the mission, but there is a whole list of factors that make it extremely difficult for NASA to pull off. The agency is actually not sure what exactly Bennu is made of, which is a problem for a spacecraft looking to touch down. Bennu could have a hard, rocky surface or a soft one, and if NASA guesses wrong it could screw up the entire landing.
That’s why NASA is opting to avoid the landing altogether. Instead, OSIRIS-REx will perform something of a drive-by sample collection. The spacecraft will touch the surface with its sample-collection arm for only a few seconds, hoovering up some rock samples before taking off again. This is something no one has ever done before, so it’ll be exciting to see how it works.
After the arrival at Bennu today, OSIRIS-REx will spend the next year surveying the asteroid and trying to find a good location to collect its samples. Then, it will begin that sample-collection process—NASA will get several tries to pull it off—and is expected to return to Earth sometime in 2023. Then, scientists can use those samples to learn more about Bennu and other asteroids that orbit in the vicinity of Earth.