Asteroid Bennu, a leftover fragment from the violent formation of the solar system, is an extraterrestrial time capsule for space scientists. Consequently, NASA’s OSIRIS-REx mission – one of the most ambitious space missions ever attempted – is studying the distant asteroid to unlock its secrets. And scientists have already been confounded by Bennu, mere months after NASA arrived at the asteroid.
US space agency NASA has announced an unanticipated discovery – “particle plumes erupting” from Bennu’s surface.
While details of the discovery remain hazy, it could suggest some asteroids are far more complex and poorly understood than ever expected.
The discovery of the plumes comes from the un-crewed OSIRIS-REx NASA spacecraft, which started orbiting Asteroid Bennu on December 31 last year.
NASA has yet to confirm exactly what the ejections are comprised of.
But the space agency has revealed while some plumes erupt fast enough to escape Bennu entirely, others are recaptured by Bennu’s gravity.
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Dante Lauretta, a principal investigator on the NASA OSIRIS-REx mission said: “The discovery of plumes is one of the biggest surprises of my scientific career.
“And the rugged terrain went against all of our predictions.
“Bennu is already surprising us, and our exciting journey there is just getting started.”
The shock find has led NASA scientists to already herald the OSIRIS-REx mission as a resounding success, as well as raising hopes that more questions will be answered when the NASA spacecraft returns to Earth in 2023.
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Lori Glaze, acting director of NASA’s Planetary Science Division said: “The first three months of OSIRIS-REx’s up-close investigation of Bennu have reminded us what discovery is all about — surprises, quick thinking, and flexibility.
“We study asteroids like Bennu to learn about the origin of the solar system. OSIRIS-REx’s sample will help us answer some of the biggest questions about where we come from.”
Studying Asteroid Bennu is helping NASA scientists to understand the solar system’s origins, gather data on future asteroid mining and monitor the threat asteroids pose to Earth.
NASA project manager Rich Burns said: “Throughout OSIRIS-REx’s operations near Bennu, our spacecraft and operations team have demonstrated that we can achieve system performance that beats design requirements.
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“Bennu has issued us a challenge to deal with its rugged terrain, and we are confident that OSIRIS-REx is up to the task.”
In the three months since the spacecraft touched down on Bennu, the team have made many discoveries.
Chief among these is realising the alteration in the spin rate of asteroids as a result of the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect.
The uneven heating and cooling of Bennu as it rotates in sunlight is causing the asteroid to increase its rotation speed.
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