Marines work well in the core, two ideas for using them more in exploration. The abandoned sector should be a dangerous place, and your crew are in danger when exploring barbaric decivilized words or AI defended stations.
1) decivilized worlds/ruins: marines could be required to secure area before investigating ruins, OR having them present improved the yield (your salvagers aren’t scared off the barbarians attacking)
2) research stations/mining stations: just like derelict probes have AI defense ships, stations would logically would have security drones/droids internally. Maybe marines could be used to give another option: if marines present, can have a ‘raid’ mechanic were they clear out the station so your crew can investigate for tech/equipment/etc. if no marines, then you’d have to externally destroy the station and salvage- still get supplies/metal/fuel, but that AI core or nanoforge would be destroyed
