After some technical glitches overnight, the Philae lander has separated from the Rosetta probe and is making its way to the comet below. The descent will take several hours. And there’s a bit of extra drama.
When the probe touches down, it will fire several harpoons into the comet to keep from floating away. But Philae also has a thruster on top that was supposed to activate to help push the probe down toward the comet as it lands. That thruster isn’t working, so there’s one less backup if the landing gets rough.