*Technically* they are removed from the roster. The text displayed for this technical action is, "The officer did not survive the assignment," i.e. they died. Displaying different text for colonial, asylum, or prisoner exchange assignments would require a mechanism to link those specific assignments to a different text string for display. That seems like it would be fairly simple to do, but I don't know how the system is actually set up.
Actually, I hate to break it to you, but your colonists did die.
There's actually several responses now to the colonist resolution.
The one that initially bugged me also was "did not survive" because at the time I hadn't seen others.
Others that I've seen:
"delivered safely to their destination"
There was one that could be considered "in between" but I don't recall it.
SO when you see "did not survive" your colonizing project completed successfully* but hey, due to Aldebaran Bog Flu or a rockslide or alien attack (or insert your red shirt death of choice) they're toast.
*And maybe they lived for 10 minutes after delivery, maybe they lived 10 months.
I also look at it, such that my 4-5 colonists aren't the only ones being delivered; rather, I am part of a "larger mission" delivering "hundreds of colonists" and that the colony as a whole survived, but my few particular ship's colonists are now worm food.
I did a quick search for dying colonists, but didn't find the outcome that my assignments had provided. Even if it has been reported, it's still happening and someone needs to be made aware.
I knew I was going to lose the colonists, my post was predicated by the false text from the completed assignment. I've got 4 toons. I've done a colonist DOff assignment once or twice before. We all know how helpful submitting a bug report in game is.
I think Colony Doff missions should be better layered and tied to the other fields. Not necessarily offered in an obvious chain. Let the player actually develop the strategy to prevent critical failure and loss of colonists.
If exploration and survey were previously completed then failure to establish should be considerably less a problem. Leave the commodities requirement blank and let the player fail or succeed by which ones they send along. So if the failure rate was high enough? Yes. The colonist would die. And the failure text should state why.
Lack of proper medical supplies
Lack of ...
The player's will likely learn quickly to do better. But at least give them the chance to learn it.
Of course the initial struggle is likely more difficult once starship support leaves orbit, right?
Repel Raid on Colony:
Ala Enterprise. A small mining colony is being raided by an unknown alien. The Doff mission requires a specific commodity to assume the place of what is being mined. The Doff mission assumes that five Doffs were sent to support the colonists. I would say that Colonists are only lost due to critical failure. Along with losing the commodities. Success is keeping the commodity to use again later on something else.
Race to Save Colony:
What about those unexpected risks? Say, you've received a distress call from previously established colony. A Crystalline Entity is hungry. In Star Trek, it is the starship itself that would race against time to repel the attack. Challenge the Doff player by only offering this one in further sector blocks. Set a 3 minute timer. The player really does have to drop whatever they are doing to respond. If they reach the original sector block within 3-minutes they get a nice reward. If they fail, the colonists are dead.
My point? If the colonists are going to die give it some meaning. And a reason for the player to make better choices.