Caveat: this is liable to be the first achievement you get for this game and it's incredibly hard to avoid it for any length of time.
While the game intends for this to happen when you go on an away mission and roll a positive result that's an image of a Redshirt and not a Critical (the white star), in practice the game awards you this achievement the very first time you actually lose any crew at all.
This can happen via the random events that interrupt your journey or as a consequence of failing an event when [ - Crew ] or [ - Random ] are one of the options.
This is step one on the way to getting:-