In physics (and probably in other scientific fields, as well), a delta is used to indicate change. Thus "delta-v" stands for "change in velocity." I'm tempted to make some attempt to relate this fact to Vila's highly changeable personality, but I'll resist.
There's also the delta particle, which is extremely short-lived and of highly indeterminate mass. Any fanicful connections to be drawn between this fact and "Orbit" are left as an exercise for the reader. :)
-- Betty Ragan ** bragan@nrao.edu ** http://www.aoc.nrao.edu/~bragan Not speaking for my employers, officially or otherwise. "Seeing a rotten picture for the special effects is like eating a tough steak for the smothered onions..." -- Isaac Asimov