Asteroids Spin Faster Due to Solar Power, Studies Show

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"YORP can have a large effect over million-year time scales," said Stephen Lowry, co-author of both Science Express studies.

YORP may be at least partially responsible for puzzling phenomena like binary asteroids—systems in which two asteroids orbit one another like a planet and its moon.

"YORP could, in theory, cause an asteroid to [increase its spin] so fast that it could break apart by centrifugal forces and perhaps lead to the birth of new binary-asteroid systems," said Lowry, of Queen's University Belfast in the United Kingdom.

YORP also likely played a significant role in putting small asteroids into their current orbits. YORP is a variation on an already detected phenomenon called the Yarkovsky effect, in which sunlight alters an asteroid's spin along its axis, changing its orbital path.

The notion of the Yarkovsky effect being able to nudge small asteroids into new orbits has led some scientists to ponder its usefulness for deflecting space rocks that might be on a collision course with Earth.

"Painting" a threatening asteroid with white dust could, in theory, boost the Yarkovsky effect and alter the asteroid's path enough to avoid a hit.

(Related news: "'Gravity Tractor,' Super Telescopes Enlisted to Battle Killer Asteroids" [February 17, 2007].)

Cornell University's Taylor notes that the YORP effect can strengthen or weaken the Yarkovsky effect. But he remains skeptical that modifying an asteroid's YORP would be the most practical method for speeding up an asteroid's shift into a new orbit.

Instead Taylor and colleagues argue that just finding proof of YORP is an important step.

The discovery will further our understanding of the physical properties of asteroids and their movements, Lowry said, providing clues to the solar system's earliest days.

"Asteroids are the only remaining relics from the formation era of our solar system," Lowry said.

"You could think of them as solar system fossils."

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