I was watching a sci-fi movie or an episode of some TV series as a kid in the early 90s. The only thing I can remember after all these years was that there was a group of kids in a spaceship or on another planet. At some point a young girl (possibly not even a teenager) sacrifices herself by jumping into what was either an alien device or a portal of sorts. After that one of the kids consoles a crying peer by saying something along the lines of "She gave her life for our freedom".
I know this isn't much information, but I'd like to see this thing again because I remember it was my first encounter with the concept of sacrificing one's life when I was a child and it freaked me out for weeks.