[exch]

I am guessing OP is referring to the ability to reliably orbit and land on comets (and asteroids). We can use them for manned way stations or construction platforms. Not to mention mining them for whatever useful stuff may be in there.

[XorNot]

If we could show that comets have available surface water ice in the right form, then their gravity is low enough that you could plan to drill it off and melt it to be fed into water-ion thrusters. That would let you at the very least launch a mission which could study one comet, refuel, then slingshot away to a different target.