It's been a long journey, but it's nearly over. On Wednesday, the European Space Agency's Rosetta spacecraft will finally arrive at the comet 67P/Churyumov-Gerasimenko.
Humans have sent spacecraft hurtling past comets before, but Rosetta is doing something very different. It's sidling up next to 67P to join the big, dirty ice ball on its journey past the sun.
Matching 67P's velocity and orbit has been tricky. Rosetta took a torturous, decade-long path that led it past earth three times and Mars once, as well as a couple of asteroids. Ahead of its final approach, it came at the comet from behind at about half-a-mile a second, before a series of breaking maneuvers earlier this year.
"It was a fantastic achievement just to get this far, I think," says Matt Taylor, the European Space Agency's Rosetta's project scientist.
With its final thruster burn on Wednesday, it will bring itself into perfect step with the comet.
Then the science will begin.