101955 Bennu is a carbonaceous asteroid in the Apollo group discovered by the LINEAR project on September 11, 1999. The space rock is a hazardous object listed on the Sentry Risk Table with the second-highest cumulative rating on the Palermo Technical Hazard Scale. It currently has a 1-in-2,700 chance of impacting Earth in the future, which could change following new observations.
Scientists working on NASA’s OSIRIS-REx mission used data gathered before the probe’s arrival to calculate Bennu’s rotation speed.
The asteroid was previously measured to rotate once every 4.3 hours.
However, new research has calculated it to be increasing by about one second every century.
Mike Nolan, lead author of the Lunar and Planetary Laboratory paper said: "As it speeds up, things ought to change, and so we're going to be looking for those things and detecting this speed-up gives us some clues as to the kind of things we should be looking for.
