Crazy Eddie wrote:
What I can't figure out is why they aren't cutting the mission weight by getting rid of the giant lariat and just pushing the asteroid along.
Because "just pushing the asteroid along" only SOUNDS simple and is in fact anything but.
I was making a joke because cables and space don't get along very well. ^_^
I think pushing it is how they're going to do it, using a big expanded cup as a container, because tiny asteroids tend to have very little internal cohesion - unless they're going for a solid iron asteroid.
Pulling on an asteroid would require either a very long cable or introduce large cosine losses from using multiple thrusters that are angled so their exhaust misses the asteroid they're towing.
If all the exhaust hits the asteroid then you're just tensioning a cable and might as well dump the fuel overboard because nothing is going to accelerate. The other problem with a cable is that it's elastic and would be under tension, like a rubber band, and after engine-cutoff the spacecraft and asteroid are going to become much more intimate.