Surprised scientists learn distant asteroid spews dust
NASA scientists said Tuesday they were shocked by what they found on the asteroid Bennu after an agency probe began orbiting it New Year’s Eve.
Bennu — about 100 million miles from the sun between Earth and Mars — was spewing particles of dust.
“This is one of the biggest surprises of my scientific career,” said principal investigator Dante Lauretta of the University of Arizona, Tucson, during a teleconference Tuesday.
That makes Bennu an active asteroid — the first of its kind researchers have encountered close up, according to the journal, Nature. Scientists hope it will help them learn more about where humans come from and where we are going.
OSIRIS-REx (short for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) was launched in 2016 to collect samples from Bennu and return them to Earth. The asteroid is the smallest celestial body ever orbited.
Lauretta said scientists noticed the first ejection of particles on Jan. 6. They’ve noted 11 in total since, some of which included over 100 particles.
“We don’t know the mechanism that’s causing this right now,” he said. “We’re still trying to make sense of what’s going on.”
They’re also trying to identify the ejections’ origins, he added.
The size of the particles being ejected range from a few centimeters to tens of centimeters, Lauretta said. They move at different speeds and some are ejected off Bennu while others orbit the asteroid before returning to its surface.
Scientists still are unsure how this new discovery impacts plans to sample the asteroid. The probe is set to collect samples from the asteroid in July 2020.
But another discovery made since the probe’s orbit began could make sample collection more challenging.
Researchers thought the asteroid would have a smooth surface, but they have now learned that it is covered with boulders.
Lauretta is confident his team still will be able to swipe a sample — it just will
be a little harder.
“Regardless of the final site selected, the requirements for guidance, navigation and control accuracy need to be tightened,” the OSIRIS-REx team said in the letter published by the journal Nature on Tuesday.
OSIRIS-REx is studying the rock to find the best place to collect samples. Burns said a location will be picked this summer.
With the samples stowed securely onboard, OSIRISREx is scheduled to land back on Earth in September 2023.
“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,” said Lori Glaze, acting director of the Planetary Science Division at NASA Headquarters in Washington, D.C.
“We study asteroids like Bennu to learn about the origin of the solar system.”