NASA’s OSIRIS-REx spacecraft arrived at asteroid Bennu in December, 2018 and has since spent two years orbiting the gigantic space rock. Last month, OSIRIS-REx completed its final task of the Bennu mission, by collecting samples from the massive space rock which are now on their way back to Earth where they can be studied.
However, a recent study has suggested asteroid Bennu may be hollow and the huge internal space is so vast that it could fit two football pitches inside.
Scientists from the University of Colorado Boulder have collected data from OSIRIS-REx to determine there may be a vast void within the asteroid.
The scientists measured the gravitational field of Bennu and found inconsistencies.
The asteroid spins quickly, while its gravitational field is weak, which would suggest the centre of Bennu is empty, or it has a “squishy” centre.
Andrew French, a coauthor of the new study and a former graduate student at CU Boulder, now at NASA’s Jet Propulsion Laboratory (JPL), said: “If you can measure the gravity field with enough precision, that places hard constraints on where the mass is located, even if you can’t see it directly.”
With the asteroid rapidly spinning, a hollow core could mean that it could eventually become nothing as bits of debris are flung into space.
Professor Daniel Sheeres said: “You could imagine maybe in a million years or less the whole thing flying apart.
“It was a little like someone was on the surface of the asteroid and throwing these marbles up so they could be tracked.
“Our colleagues could infer the gravity field in the trajectories those particles took.
“It’s as if there is a void at its centre, within which you could fit a couple of football fields.”
Bennu completes a full spin every 4.3 hours, and it is slowly speeding up.
The team believe that the spin of the asteroid and its potential hollowness could mean that it eventually fully comes apart.
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Prof Sheeres continued: “If its core has a low density, it’s going to be easier to pull the entire asteroid apart.
“We were hoping to find out what happened to this asteroid over time, which can give us better insight into how all of these small asteroids are changing over millions, hundreds of millions or even billions of years.
“Our findings exceeded our expectations.”
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