OSIRIS-REx will spend another two years with its celestial dancing partner. While circling Bennu, which is about as wide as the Empire State Building is tall, the spacecraft will snap photos of the asteroid while 3-D mapping its surface and measuring temperature, rock mineral content, and x-rays emissions. OSIRIS-REx won’t ever land on its rocky target. But in July 2020, it will also reach out a mechanical arm and tap the asteroid’s surface to take a physical sample of whatever it finds there. The spacecraft will send this sample back to Earth, which, if successful, will be the first specimen collected from an asteroid and returned to our planet. NASA chose this asteroid out of 500,000 others because it’s relatively close to Earth and large enough—with a slow enough spin—to make a mechanical fist-bump possible. It’s also really old, a remnant of the formation of our solar system. Scientists believe asteroids like this one may have delivered water to form our oceans and can help us understand how planets formed. After the spacecraft drops the samples it collects in the Utah desert in 2023, scientists expect they’ll spend another two years looking at Bennu’s makeup to see if, among other materials, the asteroid contains the types of amino acids that made life on Earth possible. Bennu could also collide with Earth one day, and studying it could potentially help scientists develop ways to prevent such a collision. That probably won’t happen until the 22nd century, but no matter which way you look at it—answering life’s fundamental questions, avoiding catastrophic meteorites, or snapping cool images of our solar system—this is one rock to watch.
