Bennua asteroid

NASA is about to grab a chunk of rock from asteroid Bennu

NASA researchers are getting ready to sample the asteroid Bennu

NASA

NASA’s OSIRIS-REx spacecraft is about to touch an asteroid. It has been orbiting the space rock Bennu, which is currently more than 320 million kilometres from Earth, since December 2018. On 20 October it will take a sample to bring home. The hope is that this material will help us understand more about the earliest history of our planet.

To take the sample, OSIRIS-REx will extend a robotic arm and use it as a sort of pogo stick on the asteroid’s surface. As the arm makes contact, it will blow out a puff of nitrogen gas and waft up a small cloud of dust and pebbles which will be collected within a container at the end of the arm. The entire spacecraft will then spin with the arm outstretched, which will help determine the mass of the sample. If it isn’t big enough, there is enough nitrogen for two more attempts.

Bennu may be similar to the asteroids that smashed together to form Earth and the other planets early on in the solar system’s history, so studying it could teach us about how the planets formed and where their various components, such as water, came from.

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“It tells us something about the really early solar system – it gives us this glimpse of what Earth might have been like before life arose,” says Hannah Kaplan at NASA’s Goddard Space Flight Center (GSFC) in Maryland. “We’re essentially taking back a piece of a time capsule so we can take a closer look at it.”

Not only will that help us better understand the planets, but we will also be able to compare the sample with observations of Bennu so that we can place it in context with other objects in space. “When we look at asteroids from ground-based telescopes, we’ll have a better idea of what those observations are telling us,” says Amy Simon, also at GSFC.

When the sample is returned to Earth in 2023, bits of it will be sent to labs around the world for experiments and analysis. “There’s so much that we can do in our laboratory facilities that we can’t do from our spacecraft,” says Daniella DellaGiustina at the University of Arizona. For one, we will get a much better idea of what Bennu is made of and how that material is affected by its environment.

“We’re only going to be sending a small amount of the collected sample out for analysis,” says Simon. “The rest is going to be archived so that when people come up with new experiments, they can apply to get a little bit of the sample.” These asteroid samples should yield insights about the early solar system for decades to come.

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