About 31 million miles away from Earth, the Rosetta spacecraft is circling a rubber ducky-shaped comet and getting reading for touchdown. On November 12 at around 4 a.m. EST, the orbiter will release the Philae lander, which will become the first manmade object ever to touch down (or maybe crash) on a comet.
It will be a challenging landing. Comet 67P/Churyumov–Gerasimenko is small, with a diameter of about 3 miles by 2 miles, leaving little room for error. And it's a lot weirder in shape than scientists ever imagined. The landing site is not flat, and it's surrounded by cliffs and potentially hazardous boulders. Making matters more difficult, the spacecraft is so far away that the 28-minute communications delay means the whole ordeal will basically have to take place on autopilot.
The orbiter will swoop from its altitude of 18 miles down to 14 miles above the comet's surface. From that height, it will maneuver into position above the landing site. When the time is right, the orbiter will open a hatch and activate two motors that will push the lander out in a sort of celestial birthing.