Japan's Hayabusa-2 spacecraft has been traveling through space for almost four years, and it has finally reached its destination. The spacecraft has traveled all this way to a small asteroid, named Ryugu, for a singular purpose: to collect a piece of it and bring it back to Earth.

Hayabusa-2 is the successor to Japan's original Hayabusa spacecraft, which visited the asteroid Itokawa in 2005. The original Hayabusa snatched a sample from Itokawa and brought it back for scientists to study. This was the first successful asteroid sample-return mission, and scientists learned so much from it that they decided to launch a second spacecraft to collect more asteroid material.

This time around, Hayabusa-2 is focused on a slightly different type of asteroid. The original Hayabusa visited an S-type asteroid, a lighter variety made mostly of silicon. Hayabusa-2, however, is visiting a C-type asteroid, which are far more common than S-types and are typically made of older material. Studying a C-type asteroid can tell us more about the rocky bodies in our solar system and what the system looked like when it was young.