Asteroid skims past as NASA launches OSIRIS-REx

UPDATE: OSIRIS-REx is on its way to asteroid Bennu. The Atlas V rocket carrying the probe blasted off from its launch pad at Cape Canaveral at its earliest possible opportunity, and under clear skies, at 7:05 pm EDT on 8 September.

An asteroid the size of a bus gave Earth a close shave this week – as NASA prepared to launch its own OSIRIS-REx mission to a similar but larger chunk of space rock and bring a bit of it home.

OSIRIS-REx launch
OSIRIS-REx successfully blasts off from Cape Canaveral. Image credit: NASA

The asteroid, labelled 2016 RB1, came to a distance of about 25,000 miles on Wednesday, which is ten times closer than the Moon.

It was as close as our TV, weather and communications satellites, but they were in no danger as the cosmic visitor passed above the South Pole, far from their own orbits.

The asteroid was only discovered two days earlier, on Monday, 5 September, by astronomers using a NASA telescope designed to help guard the Earth against asteroid or comet impacts.

The 60-inch Cassegrain reflector telescope of the Catalina Sky Survey, stands at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona. Its role is to help discover Earth-passing asteroids so their orbits can be checked for the future.

NASA’s OSIRIS-REx spacecraft is due to launch at 7:05 pm EDT today from Cape Canaveral, Florida, atop an Atlas V rocket built by United Launch Alliance. But in case of bad weather, NASA had a 34-day long window until 11 October to launch their unmanned probe.

It will fly to a 500-yard wide, stony asteroid called Bennu which is called a potentially hazardous object because it flies close to Earth every six years. There is a relatively high chance that it will collide in the 22nd century unless ways are found to deflect it.

OSIRIS-REx
The Atlas V rocket carrying OSIRIS-REx is pictured on the launch pad at Cape Canaveral. Image credit: NASA

Scientists are also keen to study Bennu because they believe it contains pristine, carbon-rich material left over from the formation of the Solar System and so can help reveal where Earth and even life came from.

OSIRIS-REx may sound like a species of dinosaur, but it is an acronym that describes the probe’s main functions. They are: O – Origins (bringing home a sample to study how it was formed); SI – Spectral (to study the asteroid’s make-up); RI – Resource Identification (to map the global properties, such as the chemistry and mineralogy of Bennu); S – Security (checking how the force of sunlight – known as the Yarkovsky Effect – affects the asteroid’s orbit to see how close it will pass to Earth); REx – Regolith Explorer (study the surface material at the probe’s sampling site).

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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