NASA spacecraft reaches tiny space rock Bennu

NASA's robotic explorer Osiris-Rex successfully arrived on Monday at the ancient asteroid Bennu, following a two-year journey. The aircraft positioned itself within 12 miles (19 kilometers) of the diamond-shaped space rock.

Its arrival comes exactly one week after NASA successfully landed a spacecraft on Mars. Osiris will continue to approach Bennu in the coming days and enter its orbit on December 31.

Read more: Asteroids and comets: How to tell them apart

No spacecraft has ever orbited a cosmic object of Bennu's small size, with an estimated diameter of just over 500 meters (1,600 feet).

Osiris-Rex to return in 2023

Located more than 122 million kilometers away from Earth, word of Osiris-Rex's arrival took seven minutes to be delivered to flight controllers in Littleton, Colorado. Lead scientist Dante Lauretta of the University of Arizona took to Twitter to express the team's jubilation.

"Relieved, proud, and anxious to start exploring!" Lauretta wrote.

Osiris-Rex is set to shadow Bennu for about a year and collect at least 60 grams (2 ounces) of dust and gravel to bring back to Earth in 2023.

Read more: 7 facts about NASA's 7-year OSIRIS-REx mission to the asteroid Bennu and back

The spacecraft will use a 3-meter mechanical arm to obtain the samples, as it is not set to actually land on the asteroid.

NASA has collected comet dust and solar wind particles before, but never asteroid samples. If Osiris Rex is successful, its samples would be the biggest cosmic collection since Apollo astronauts hand-delivered moon rocks to Earth in the late 1960s and early 1970s.

An astronomical time capsule

Both the spacecraft and the asteroid's names come from Egyptian mythology. Osiris is the god of the afterlife, while Bennu represents the heron and creation. For the asteroid, the name symbolizes the lessons it could have for researchers.

Read more: Protecting Earth from an asteroid strike - what can we do?

Scientists say that material from a carbon-rich asteroid such as Bennu could hold evidence that dates back to the beginning of our solar system 4.5 billion years ago. 

"With asteroids, you have a time capsule. You have a pristine sample of what the solar system was like billions of years ago," said Michelle Thaller, a spokeswoman for NASA's Goddard Space Flight Center.   

Scientists hope Bennu will provide more clues about the early formation of the solar system, but they will also be looking out for precious resources like metals and water.

jcg/jm (AFP, AP, dpa)

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