a semi-utopian world would maybe exhaust resources on planet quickly OR environmental impact too much and they focus really hard on mining asteroids. but after the bombs, the people up mining asteroids on colonies etc would still be there, but have no like… docking station w/ever to return to. of course, some tried, but they were forced to crash-land on an irradiated earth

those who didn't live in isolated colonies.

- do they know and how much?

if they have hella resources AND a consistent schedule to bring them to earth on, some will follow that without knowing what happened.

this would have to be like… with expectation that they receive regular resupply ships, can stretch out the time between shipments to ~100 years so if players run into one of these colonies it's just as they are starting to realize no supply ship will be coming anytime soon and shit is kinda fucked

maybe their mission is to get them off or regular resupplies and one of the members of generation that grew up only on colony after the bomb is refusing to leave because they dont want to know about fucked up outside world, this causes parent (who technically saw a supply ship arrive at some point??? or some other way of giving them a real connection to Earth) to also stay cause fuck letting your only child die alone on a doomed station

in the absence of the original company (or with! bunkers designed for this scenario and instructions for those in them on how to receive delivery etc?) who would A. know about the delivery B. be able to actually transport it C. be able to sell it successfully without getting fucked (or use it themselves)

- forsure have a colony that has no idea what happened on earth and has just been cut off super diligently following their orders to 1. mine and store 2. when storage close to full, radio to command and keep mining to fill 3. either fill, then wait for word back or get word back immediately and scramble to fill

- one that's found out a way to get small amounts of materials back, they had super dank radios or like… used data disks and theory from initial trip to build sick ass communication syustems, eventually made contact with govt power structure radios and have dealzz with them too (and of course some corruption selling on side within acceptable bounds)

- theoretical (whatever field) scientists on a colony, for whatever reason being in space there gives them access to substances or materials or techniques etc they are doing experiments with under real world conditions. very well stocked, had consistent supply ships when supported by functioning, not-bombed government and otherwise has or HAD a large stash of emergency rations. after 100 years, maybe none of original are left but their descendents still doing shit and have pieced together roughly what happened. without full expertise from earth education, maybe doing not as well as their parents and need help contacting earth to do shit dankly. will have rare materials or cool experiment results