NASA tags an asteroid

NASA's OSIRIS-REx spacecraft briefly touched the surface of an asteroid Tuesday in a bid to collect a sample from the space rock that will one day be returned to Earth.

Why it matters: Scientist are hoping to study a sample from the asteroid, named Bennu, to piece together more about the solar system's evolution. Asteroids are thought to be leftovers from the formation of planets billions of years ago.

The state of play: OSIRIS-REx — which arrived at Bennu in 2018 — was able to use its sampling arm to touch the surface of the asteroid.

• The spacecraft needed to avoid large boulders and rocks on the way down to tag Bennu, further complicating the delicate work.
• Yes, but: NASA doesn't yet know how much of a sample the spacecraft was able to collect. Mission managers will now need to perform a test to see how much extra weight is onboard the probe.

The big picture: Space agencies have returned samples of asteroids to Earth before, but if this maneuver is successful, it will be the most material ever fetched from an asteroid and brought back to our planet.

• Being able to analyze these rocks and dirt on Earth is key because tools in labs on the planet are far better than those on spacecraft.

What's next: The sample is expected to arrive back on Earth in 2023.