So I was watching an episode of the oddly excellent Another Life: the one where the captain is floating in space, watching her spaceship searching for her. She knows that there’s no chance they’ll see her in the void so she makes a win or bust decision: she vents the last of her oxygen into space in the hope that someone will see the vapour trail and rescue her.
I have definitely seen this episode before. In fact, I’ve been seeing this episode since the late 70s.
The first time was in Star Trek. The crew had ventured down to a hostile planet, lost everyone wearing a red pullover (aside from Mr Scott, whose red shirt was blessed by wood elves), and had to escape from the surface in a damaged shuttle running on … er … shuttle fumes. Anyway, the good ship Enterprise had no chance of seeing the shuttle which was already falling back to the planet. Then, in a move that apparently defied logic, Mr Spock jettisons the last of the fuel to create … yes, a vapour trail.
Now, I’m not sure how many times I’ve seen this happen in sci-fi, but it does seem to be a favourite way of getting spotted in thousands of kilometres of empty space.