A couple of billion years ago, a piece of rock about the size of the Empire State Building broke off from a large asteroid and hurtled into the depths of space. It was called Bennu, and it floated along in the void, alone, until one day in October 2020, when a little craft with an extended arm — the asteroid’s version of a mosquito, essentially — swooped in close and sucked up a few ounces’ worth of rock before buzzing away again.
That craft, called OSIRIS-REx, went on to send the rocks it had collected from Bennu back to Earth. The samples touched down safely back in September, and yesterday we got our first look at what was inside: whispers from the earliest days of the solar system, and a hint at how our planet as we know it came to be.
“As we peer into the ancient secrets preserved within the dust and rocks of asteroid Bennu, we are unlocking a time capsule that offers us profound insights into the origins of our solar system,” Dante Lauretta, a planetary scientist at the University of Arizona, Tucson, and the principal investigator of the OSIRIS-REx mission, said at a NASA event on Wednesday. “These discoveries, made possible through years of dedicated collaboration and cutting-edge science, propel us on a journey to understand not only our celestial neighborhood but also the potential for life’s beginnings. With each revelation from Bennu, we draw closer to unraveling the mysteries of our cosmic heritage.”
OSIRIS-REx was designed to collect just a couple of ounces of rock from Bennu; instead, it came back with more than 8 ounces — a veritable bounty of asteroid material. When scientists opened the capsule containing the samples, they found the rocks were rich with sulfur, magnetite, carbon, and waterlogged clay: the building blocks of life.
The water molecules in the clay might even help answer the question of how our planet got its water to begin with: one of the prevailing theories is that water-rich asteroids slammed into our planet as it was forming. The samples will no doubt keep scientists occupied for years to come — they are, according to Daniel Glavin, a NASA astrobiologist, “an astrobiologist’s dream.”
Bennu continued on its path after OSIRIS-REx left it. It’s a near-Earth asteroid that mostly keeps to an orbit between Earth and Mars, but there’s a 1-in-1750 chance it could return the favor and slam into our planet sometime between 2175 and 2199. It wouldn’t be a dinosaur situation — it’s too small for that — but it wouldn’t exactly be, you know, fun. Still, we might have bigger problems by then.
