Scientists used data gathered during the OSIRIS-REx mission, before the probe's arrival, to calculate that Bennu's rotation rate is speeding up over time. 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. Scientists used data gathered during the OSIRIS-REx mission, before the probe's arrival, to calculate that Bennu's rotation rate is speeding up over time. 'The reason for the increase in Bennu's rotation is more likely due to a phenomenon known the Yarkovsky-O'Keefe-Radzievskii-Paddack effect,' Dr. Nolan said. The OSIRIS-REx mission will determine Bennu's rotation rate independently this year, which will help scientists nail down the reason for the increase in rotation.

Source: Daily Mail March 15, 2019 18:56 UTC