Counterweight, directed by Paul Stanley.
Volunteer explorers sign up for a 261 day simulated space flight. Anyone who can't take the stress: just push the "panic button" and the whole test is scrubbed.
(Note: if the test is successful they are going on the actual mission for another 261 days. Same for the return, I suppose. That's dedication).
There is a strange presence on board: a traveling light accompanied by an eerie music cue. It visits sleepers and reads their minds. It plays tricks on them, driving the passengers mad.
That's not a bad concept but it is developed so slowly, with so much TV psycho-drama and talk-talk that this becomes one of the duller episodes.
What are these people even doing on the mission? Especially the crude construction tycoon: he expects to make billions on another planet.
These "moral little tale" stories are always disappointing.
The cast:
Jacqueline Scott returns from The Galaxy Being. I feel sorry for her: she has to do a ridiculous turn from sober scientist to attention-starved pearl-swinging sex bomb.
Crahan Denton, the doctor who finds a doll belonging to his dead daughter in his bed, returns from The Children of Spider County. I remember him most distinctly as the nasty gang boss in The Great St. Louis Bank Robbery (1959) with young Steve McQueen.
Several other familiar faces, including Michael Constantine and Sandy Kenyon.
Directory Stanley returns from Second Chance and The Guests.
Notes:
The alien light is similar to the concept used in Star Trek Day of the Dove where it hopes to have Federation and Klingon crews locked in eternal battle. That effect was some sort of composite; this is an actual Tinkerbell light.
I thought The Zanti Misfits had the only stop motion animation in the series, but we have a bit more with hostile plants here.
This may have caused a dream when I was nine: rolling over and finding a network of lights over my bed. "Got you!" I thought, as it faded away.
The Blu-ray commentary track is by Reba Wissner. As for previous episodes she identifies the Ondes Martenot as a keyboard instrument producing a sound much like the theremin.