Nine months have passed since NASA’s OSIRIS-REx returned its samples of asteroid Bennu to Earth. The samples are some of the Solar System’s primordial, pristine materials. They’ve made their way into scientists’ hands, and their work is uncovering some surprises.
Some of the material in the samples indicates that Bennu had a watery past. NASA chose Bennu for the OSIRIS-REx sampling mission for several reasons. First, it’s a near-Earth asteroid (NEA), so it’s relatively close to Earth.
It’s also not very large at about 500 meters in diameter and rotates slowly enough to allow for a safe sampling procedure. But the overarching reason was probably its composition. It’s a B-type asteroid, a subtype of carbonaceous asteroids, which means it contains organic molecules .
Finding organic molecules throughout the Solar System is one way of tracing its origin and formation. Returning samples to Earth is the best and most complete way to study asteroids. Asteroid fragments that fall to Earth are scientifically valuable.
But much of their lighter material simply burns up when entering Earth’s atmosphere, leaving a huge crater in our understanding. Space missions always seem to surprise us somehow. If they didn’t, there’d be less impetus to send them.
In this case, the sample contains chemicals that OSIRIS-REx didn’t spot when it was studying Bennu. “Bennu potentially could have once been part of a wetter world.” New research in the journal Meteoritics and Plan.
