[InterceptPoint]

Correct me if I’m wrong but it seems to me that the spacecraft will not be in a “gravitational” orbit at all. It will have to continuously expend fuel to remain in a circular orbit. Weak gravity and all that.

[fwdude]

I don’t believe you are wrong. An object that small can’t exert much more gravitational pull than the Empire State Building.

[LibWhacker]

There is plenty of gravity for these two objects to orbit one another. Remember, any two objects with mass attract each other gravitationally no matter how small they are and no matter how far apart they are (ignore quantum theory; these things aren't quanta). So, in principle, any two objects can be made to orbit one another. Of course, there are other considerations: Are we in a perfect vacuum? No. Are there other objects around? Yes. Etc. But here, there are no major obstacles to putting Rosetta in orbit around 67P.

[cripplecreek]

They used minimal fuel getting there. It took 10 years. At least 3 gravitational assists from earth and another from mars.