![]() With all these data in hand from the in situ measurements, the scientists extrapolated Bennu's orbit into the future. The scientists who looked into the OSIRIS-REx data on Bennu's orbit even looked into whether jamming the spacecraft into the asteroid's surface to get a sample may have changed its trajectory (but, confirming earlier results, they found the effect negligible). ![]() Not only that, but Bennu is spitting rocks in to space (for reasons that are still not clear) and that acts like a very low rocket thrust, changing its orbit. There's a subtle force called the YORP effect as well sunlight has a very small amount of momentum that pushes on the asteroid in ways difficult to predict. The gravity of the planets can affect it, for example, and other asteroids, too. Getting more precise measurements means a more precise prediction.Īn asteroid's orbit is determined by much more than just the gravity of the Sun. Observing asteroids from Earth means there is some uncertainty in the asteroid's position and velocity, so trying to extrapolate that into the future means its predicted location gets fuzzier with time, and more difficult to determine if it will impact us or not. NASA/Goddard/University of Arizona/Lockheed Martinīut it did more than that: It was able to precisely measure the trajectory of Bennu simply by being there, allowing astronomers to get a far better orbital calculation for it than ever before - we can get the spacecraft's exact location over time via telemetry, and use that to determine its orbit. Credit: NASA/Goddard/University of Arizona/Lockheed Martin Photo: A composite of two images (one short exposure to show the asteroid and a longer one to show the particles) shows a cloud of small rocks the asteroid Bennu has somehow ejected from its surface.
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