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An interplanetary visitor has arrived at asteroid Bennu.

On Monday, NASA's OSIRIS-REx spacecraft reached the relatively small asteroid after an over two-year journey through the solar system. The 1,600-foot diameter space rock, about the height of the Empire State Building, is of great interest to scientists as the lump of rubble and organic materials might provide a future fuel depot for deep space missions, and likely holds ancient clues about our solar system's formation.

Now that OSIRIS-REx -- short for Origins, Spectral Interpretation, Resource Identification, Security,Regolith Explorer -- has arrived at Bennu, the eight-foot-long spacecraft will spend more than a year and a half surveying the asteroid, in preparation to carefully descend to the ground and perform its ambitious, primary mission.

In July 2020, NASA intends to send OSIRIS-REx to the surface of Bennu and gather 4.4 pounds of rock, put the rocks in a sturdy capsule, and then blast back to Earth. If all goes as planned, this asteroidal bounty will plummet down to the Utah desert in 2023.

Artist's conception of OSIRIS-REx collecting space rocks on Bennu.Credit: nasa

It would be the first-ever asteroid sample return by the U.S.

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Bennu is an attractive exploration site for quite a few reasons. For one, it's close to Earth -- as far as space goes, anyways. Every six years, Bennu passes within 185,911 miles of Earth.

But because Bennu naturally spins through Earth's space neighborhood, there's a slight potential that Bennu will travel dangerously close to Earth in 2175 and 2195. "Bennu is one of the ones we are watching," Dante Lauretta, the OSIRIS-REx principal investigator, said in August.

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Accordingly, NASA wants to know exactly what Bennu -- and asteroids like it -- are composed of, should future engineers have to use lasers or still-unknown technology to deflect the ominous space rock away from our planet.

SEE ALSO:3 small moon rocks are coming up for auction. Here's why.

Bennu may loom large in other futuristic ways, too.

NASA scientists suspect Bennu might contain bounties of valuable resources that can be used for future deep space exploration. Specifically, Bennu holds clay deposits, and embedded in clay is water. This is significant because water is composed of hydrogen and oxygen, two necessary components for rocket fuel. In short, Bennu could be an extraterrestrial gas station for future endeavors into deeper space, places like Mars, and beyond.

Although the OSIRIS-REx mission has futuristic potential, the mission -- if fully successful -- will shed critical light on Earth's distant past, some four billion years ago. Bennu is believed to be a well-preserved, ancient asteroid, containing cosmic fragments older than our solar system. An asteroid like Bennu, which contains frozen water, may have brought water to Earth during an ancient collision -- a collision that ultimately may have allowed life to flourish on our humble blue home.

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