A comet capture swarm is a large collection of vehicles capable of escaping Earth orbit, intercepting a comet, and using the comet's material as reaction mass to bring it safely to a Lagrange point near Earth.

A swarm of smaller vehicles is far superior to a single large vehicle because:

1. Hyper redundancy. If a few vehicle lose function, the mission continues.

2. Low impact of a rogue vehicle. Imagine if a single large vehicle is pushing a comet towards Earth, and the engines got stuck full on and it's no longer responding to commands. A lot of people would be... ah.. *angry*. On the other hand, if one of the swarm went rogue, other's in the swarm could be used to counter and/or disable the rogue.

3. Potential for design redundancy, not just unit redundancy. If many different designs are deployed towards the same requirements to work together to capture a comet, there is much lower impact of a design flaw. The same applies to design of security features. Malignant actors would have to hack many security systems in order to make an impact (no pun intended) rather than just one.