![]() ![]() ![]() In September of that year, Bennu will swing past Earth - not close enough that there's any risk of an impact, but certainly close enough that Earth's gravity could nudge the asteroid a bit on its path. One factor that scientists were particularly concerned about is called the Yarkovsky effect, which is triggered by the constant temperature fluctuations that occur as regions of the asteroid pass in and out of daylight, gently pushing the asteroid. ![]() In addition to factors like these that affect all solar system objects, the team was also able to check the impact of two unusual characteristics of Bennu specifically: the plumes of dust that regularly shoot off the asteroid and the rock's interaction with the spacecraft itself. If the possibility of an asteroid called Bennu slamming into Earth a lifetime from now was keeping you up at night, NASA scientists think you can rest a little easier.Īs a result, scientists behind new research now say they're confident that the asteroid's total impact probability through 2300 is just 1 in 1,750. That's because Bennu's surface is covered with chunky boulders, which present hazards for sample collection.This is the best tl dr I could make, original reduced by 81%. The sample OSIRIS-REx is due to collect could reveal more - but it's proving a bit harder to grab than initially thought. That could mean that ice was plentiful in the planetary disc during the time in Solar System's formation when Bennu came into being. The only way it could contain ice is if it formed farther out in the Solar System, and somehow made its way closer in.Īmong other discoveries, scientists at the Southwest Research Institute found minerals similar to meteorites called carbonaceous chondrites, which are known to be rich in volatiles and show evidence of interactions with water or ice. ![]() It's not impossible that Bennu contains ice under its surface, although its orbital position is too warm for it to have formed there. Meanwhile, asteroids do not contain ice in fact, it's one of the big differences between comets and asteroids. Those ones were dusty, but astronomers think they may have been caused by volatile ices sublimating in cavities beneath the comet's surface, causing the cavities to collapse and spew the dust outwards. We've seen plumes before, but Bennu's activity may not bear similarities to the plumes ESA spacecraft Rosetta observed on Comet 67P. "The question is, why is this asteroid different?" "We have had spacecraft around other asteroids, and nothing like this was ever reported," planetary astronomer Andrew Rivkin of Johns Hopkins University in Maryland told New Scientist. The OSIRIS-REx team is trying to find out more - where they come from, and what triggers them. The plumes don't pose a risk to OSIRIS-REx - but that's about all we know about them (aside from the indication that maybe asteroids are much more active than we thought). At least four chunks, however, stayed in Bennu orbit - perhaps on their way to becoming miniature asteroid moons. Some of the dust got blown out to space other particles were recaptured in Bennu's orbit, most of them falling back down to the asteroid's surface. Over the following two months, they observed the plumes a few more times, and kept track of the particles of dust therein. Scientists discovered the first plume on 6 January, and the team then kept a careful watch for further activity. ![]()
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