Back in 2004, the European Space Agency launched a spacecraft called Rosetta that had a mission to meet up with a comet and land on its surface. The comet that was the target for the mission is called 67P/CG and after a decade of traveling through space, Rosetta has entered the gravitational pull of the comet.
Rosetta is set to land on the surface of the comet in November. When Rosetta is ready to start the next phase of the mission, it will fire an explosive harpoon into the surface of the comet to send the Philae lander down to the surface of the comet.
Mission controllers are putting the spacecraft into a series of triangular paths around the comet that will each take 3-4 days to complete. The goal is to gather all the data possible so we can learn more about comets.