Two years after launching from Florida, a NASA spacecraft is closing in
on an ancient asteroid, Bennu, for a sample of space dust that could
reveal clues to the start of life in the solar system.
The spacecraft, OSIRIS-REx, has even snapped its first, blurry pic of
the cosmic body, which is about the size of a small mountain, about 500
yards (meters) in diameter.
The spacecraft is designed to circle Bennu, and reach out with a robotic
arm to "high-five" its surface, then return the sample it collects to
Earth in 2023.
The first images of Bennu were taken on August 17 at a distance of 1.4
million miles (2.3 million kilometers) from the $800 million spacecraft.
"This is the closest we have even been to Bennu," said Dante Lauretta,
OSIRIS-REx principal investigator at the University of Arizona, Tucson.
"This is significant in that we are now in the vicinity of the asteroid,
closer than we have ever been even during the close approaches of the
asteroid to the Earth."
Bennu was chosen from the some 500,000 asteroids in the solar system
because it orbits close to Earth's path around the sun, it is the right
size for scientific study, and is one of the oldest asteroids known to
NASA.
Astronomers say it poses a slight risk -- a one in 2,700 chance -- of colliding with Earth in 2135.
It is also a carbon-rich asteroid, the kind of cosmic body that may have
delivered life-giving materials to Earth billions of years ago.
The OSIRIS-REx mission is not the first to ever visit an asteroid and
attempt a sample return -- Japan has done it before and Europe has
managed to land on a comet.
But it is the first asteroid-sample-return mission for NASA, and it aims
to bring back the biggest sample ever, on the order of 2.1 ounces (60
grams).
The US men who walked on the Moon during the Apollo era of the 1960s and
1970s collected and carried back to Earth 842 pounds (382 kilograms) of
moon rocks.
In December, the spacecraft will begin a detailed survey of asteroid's
surface, which NASA has defined as "arrival" at the asteroid.
Orbital insertion is expected on December 31.
The sample, however, will not be taken until July 2020.
OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer.
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