'You couldn't make all three of them fit quite right,' said Mike Nolan, lead author on the new research and a geophysicist at the Lunar and Planetary Laboratory at the University of Arizona, who is also head of the OSIRIS-REx mission's science team. The authors say that the change in Bennu's rotation could be due to a change in its shape, 'similar to how ice skaters speed up as they pull in their arms', an asteroid could speed up as it loses material. To date, this acceleration has only been detected in a handful of asteroids. The idea that the rotation of asteroids could speed up over time was first predicted around 2000 and first detected in 2007. One possible explanation is that material moving around on the surface of Bennu or leaving the asteroid entirely could be allowing the rotation rate to speed up. The OSIRIS-REx mission is scheduled to bring a sample of Bennu to Earth in 2023.Įven at Bennu, the observations leave the mystery of what's causing it.
Scroll down for video A distant space rock called Bennu is spinning faster meaning its rotation period is getting shorter by about 1 second every 100 years - but scientists are still trying to figure out why. NASA are exploring the B-type asteroid (pictured), which is 1,614-foot (492 m) diameter, and is spinning once every 4.3 hours WHAT'S CAUSING THE ACCELERATION?
SCIENTISTS FINETUNE ODDS BENNU HITTING FULL
As it moves through space at about 63,000 miles per hour (101,000 km per hour), it also spins, completing a full rotation every 4.3 hours. Because Bennu is a relic from the age of planet formation in the early solar system, these samples may help us understand how planets like Earth formed and where Earth got its water and complex chemistry.Bennu is 70 million miles (110m km) away from Earth. We won’t know for sure where Bennu’s diversity comes from until OSIRIS-REx brings its sample back to Earth in 2023, Dworkin says. The observations, presented today at the Lunar and Planetary Science Conference in The Woodlands, Texas, led Dworkin and his colleagues to suggest that Bennu is probably between about 100 million and one billion years old, which is older than we expected, and its surface may contain rocks that are even older than that. If the diversity is really there, it may mean that Bennu’s surface has some pristine areas that are remnants of the original, larger rock it originally chipped off from, as well as some relatively fresh spots that have undergone recent activity. NASA/Goddard/University of Arizona/Lockheed Martin Particles are being ejected off the surface of the asteroid Bennu It isn’t clear yet if this is due to an actual texture difference, a result of compositional differences on the surface or simply a trick of the light, says Dworkin. NASA is still working on chemical analysis of Bennu’s surface, which would provide firmer answers. The spacecraft spotted individual boulders containing variations in brightness of up to 33 per cent. Read more: We’ve lost track of more than 900 near-Earth asteroidsĬhoosing exactly where to take a sample will be a hard choice, because the surface appears to vary considerably. “Some areas look smooth and shiny, and some look dull and bumpy,” says Dworkin.
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