The interceptors’ single “missile” actually contains multiple independently-targeted warheads* - which is about the only chance they have of hitting even one UFO moving at SOL decimal 8, anyway.
The aliens tried a mass attack once, in “Reflections in the Water” - while some of them were decoyed into the Earth’s atmosphere where the SkyDivers** took them out, a fair number were destroyed by the moonbase interceptors and ground defences… what we see on screen suggests that the interceptors are just very good at making really fast pit stops.
*Sort of canonical, based on the interminable amounts of background material for the show.
**Definitely canonical; we even got to see SkyDiver 3 in “The Psychobombs”.
Actually, responding to another point earlier in this thread, about people not moving realistically in low gravity - I don’t think Gerry Anderson is guilty on this count. Moonbase Alpha in Space: 1999 had gravity generators to provide Earth-normal conditions inside the base (I realize I’m on a hiding to nothing, trying to defend the physics of Space: 1999, but what the hell). I think the same may be true of SHADO’s moonbase, too - I know it’s true of Moonbase 3, that other justly neglected classic of the Seventies.
And as for the other Anderson series - the characters in those move as if they’ve got no weight at all; why, it’s almost as though they were held up with strings!
OK, sure, but how many people know that? I think it’s perfectly plausible for a movie character, especially one who’s not a psychologist, to have alternate explanations for a phenomenon like that.
The error in that episode was that all the items that were blown out the cargo bay door when the air/fire was vented somehow stayed within a few meters of the ship. They should have continued at the speed imparted to them by the escaping air, relative to the ship.
