Is it time to break out the orbital mechanics book?
http://en.wikipedia.org/wiki/67P/Chu...%93Gerasimenko
http://en.wikipedia.org/wiki/Rosetta_(spacecraft)
The term "no gravity" is a bit of a misnomer. Gravity is always present. Weightlessness is an effect of being in orbit. If the craft were to slow down, the object would de-orbit and be pulled toward the celestial body via gravity.