For almost two years, NASA’s OSIRIS-REx spacecraft has been orbiting an asteroid named 101955 Bennu. It’s done tons of science, scanning the rock from many angles. Right now, OSIRIS-REx is preparing to head back to Earth. But before leaving Bennu, the spacecraft reached out and touched the asteroid.
OSIRIS-REx was always designed to bring rocks back to Earth to study. In fact, one of the reasons it spent so long scanning Bennu was so it could find a good landing spot. The scientists found a flat area with lots of dust and pebbles to pick up, and no big boulders to crash into.
OSIRIS-REx’s landing might look precarious, standing on a long spindly robotic arm, but it was quite safe. Bennu is only about 500 metres wide, so it has much weaker gravity than Earth. Plus, OSIRIS-REx only spent six seconds touching Bennu. That’s just enough time to use jets of nitrogen to blow a sample into the collection head. Then OSIRIS-REx turned on its thrusters and backed away from the asteroid.
The sample collection was a success. But as OSIRIS-REx flew away, mission control noticed pebbles falling out of the collection head. Experts think that some bigger rocks have jammed open a flap designed to keep the sample contained.
When scientists noticed the leak, they cancelled a plan to weigh the sample by spinning it. Instead, the sample was swiftly stored in a return capsule, ready to be dropped back to Earth when OSIRIS-REx finally makes it back home in 2023.
OSIRIS-REx isn’t the only one bringing asteroid rocks back home. The Japanese spacecraft Hayabusa2 is almost home after visiting asteroid 162173 Ryugu. Its sample of space rock should touch down near Woomera in South Australia on 6 December!
If you’re after more science news for kids, subscribe to Double Helix magazine!