That will make Bennu the smallest object ever to be orbited by a spacecraft in space.
As of Sunday afternoon, OSIRIS-REx was less than 20 miles from the asteroid, which itself is now about 76 million miles from Earth in its orbit around the sun.
USA based space agency NASA's spacecraft OSIRIS-REx rendezvoused with its targeted asteroid Bennu on Monday after a two-year space travel.
A live NASA broadcast of the OSIRIS-REx spacecraft's formal arrival begins at 11:45 am (1645 GMT). That probability ranks Bennu No. 2 on NASA's catalog of 72 near-Earth objects potentially capable of hitting the planet.
Although Bennu has been characterized well by ground-based instruments over the years, "maneuvering around a small body that basically has no gravity is a very challenging endeavor", OSIRIS-REx Deputy Principal Investigator Heather Enos, of the University of Arizona, told Space.com.
For the next 12 months, a suite of five scientific instruments will survey every inch of Bennu looking for the ideal place to grab a scoop of asteroid stuff.
And OSIRIS-REx's precise tracking of Bennu through space will help researchers better understand the non-gravitational forces (specifically, the Yarkovsky effect) that shape asteroids' trajectories.
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The Touch-and-Go Sample Acquisition Mechanism (TAGSAM) will suck up the regolith, kicked up by its nitrogen gas thrusters, and hopefully collect enough to study back at home.
The $800 million probe's mission is monumental in scale and in importance.
The thing that excites me most about the OSIRIS REx mission is the fact that we are literally going to a world that we've never been to before.
Bennu's orbit runs between those of Earth and of Mars instead of in the farther asteroid belt between those of Mars and Jupiter.
The spacecraft is slated to return to Earth in September 2023. It will first survey the asteroid's surface for a year, before selecting a safe and "scientifically interesting' location to scoop up some rocks".
Achievement unlocked and "we have arrived", NASA announced on its official Twitter account. It launched in September 2016 and will spend two years up close and personal with Bennu.
'We know from having studied Bennu through Earth- and space-based telescopes that it is a carbonaceous, or carbon-rich, asteroid.
This meeting will provide scientists with a rare window to look back at the beginnings of Earth's solar system, said Jay McMahon, an assistant professor in aerospace engineering at CU Boulder.
NASA's OSIRIS-REx mission and the asteroid Bennu have had a date planned for two years, and just after noon ET today, they finally got to meet face to face. OSIRIS REx is led by the University of Arizona and it's the first US spacecraft to visit an asteroid with plans to bring a sample of it back home.