Spaceship Design: What makes sense, and what's nonsense?

[Anthony]

Originally Posted by Michael Thayne

(Technically, you can get away with a lot as long as your axis of thrust passes through your center of mass, but engineers will usually find that trying to satisfy that requirement with an asymmetrical design is more trouble than its worth.)

It's not that rare -- if you look at models of deep space probes, a lot of them have asymmetric spikes of one sort or another. For example, Cassini is mostly symmetrical but has a single long rod off to one side (not sure what it's for... possibly the RTG). However, you certainly don't do it without a reason.

Looking at models of real world space probes is a good place to start.