On the KoL Gameplay/Discussion forum, jon_diaz said this:

Also does the spacegate KAWOOSH when you dial up a planet? If not that's a travesty
KoLmafia can do that. This thread - Add sounds to barrel smashing! (patch-included) resulted in us adding barrel smashing sounds (opt in).

It was discussed doing it as a relay script, but was rejected at the time, since we didn't have good support for choice overrides based on choice #. We do now, so it could certainly be a relay script or built in, as with the barrel sounds, controlled by the same preference: relayAddSounds

We'd need an ash file in relay - choice.1235.ash - to inject javascript into the choice page.
We'd need an mp3 file - spacegate_activate.mp3 to play when any of the options that activate the gate are selected
We'd need a javascript file to play the sound.

Seems like a fun little project. I'm game to try a relay script for it. I'm not sure of the desired sound, however, having never actually seen the show.

The net has lots of resources - videos, as well as a variety of downloaded .mp3 files.

Here are a couple of examples I found and saved. If somebody (like jon_diaz) has a "canonical" version of the sound in mind, I'd appreciate it if they could point me to it.

Thanks.

spacegate-activate1.mp3 (59 KB)
spacegate-activate2.mp3 (1.07 MB)