As far as I know, yes. It's apparently a pretty rare event, fewer than 1% of players on Steam have the achievement for rescuing a friend's character.
This might be because in order to a friend's captured character show up for you to rescue, it seems like the original player must have lost/missed/failed the mission of rescuing them.
I'm playing a char whose personal mission is to save Mali Concept (the character from Egan_BW - which AFAIK Immaterial already saved).
I lost my first character yesterday. It was a damn good character. I was just raiding random ships for almost two hours, but I accidentally risked a docking beside a window and got insta-nukked. As I was still pressing buttons to perform the docking, it registered that for the "emergency repair" mini-game..so it was pretty much instakill.
Although I saw some reviews complaining about repetition or about the "hard-counter" way the game is designed, I think it's awesome and a breath of fresh air. I'm seriously hoping more content gets added on it, there's no reason to stop now.
And after watching a video of someone doing Hard+ missions with crappy gear they get on their first/second Easy/Medium missions, I feel like a coward for getting super geared-up before going for missions.
I just don't like the idea of a character dying a cheese-death like the instakilled pod one. As a DF player, I should know better, though..having drowned whole fortresses more than once.