We don't know how much Carriers will cost, and some have suggested that there might be a rank requirement too, such as triple-Elite. I think that would be a terrible idea, as it doesn't make any sense that you'd have to be Elite in Combat to use a Carrier for exploration, or Elite in Exploration to use one for combat.
But for the support ships, it does make sense:
Exploration support ship usually needs Elite in Exploration.
Mining support ship usually needs Elite in Trade.
Combat support ship usually needs Elite in Combat.
We don't know if there will be other types of support ship: a longer list of roles for support ships was given, but the three ships that we've seen might cover those.
The currently-useless top Federation and Empire Navy ranks could tie into this too, as another way to gain access to the Combat support ship. It makes sense for a navy to grant access to a warship.
The various Powerplay Powers could also be involved. This is slightly more problematic, as it's easy to get up to Ratiing 5 with a PP Power, but this isn't permanent. However, a Rating 5 player with a Carrier could maybe "lease" an appropriate support ship, that would be "repossessed" (with compensation) if the player drops below Rating 4. The obvious candidate would be Zemina Torval for Mining: other PP Powers could mostly offer Combat support ships, except Li-Yong Rui and Pranav Antal, who are more into scientific research than militarism: for them, maybe Exploration.
But for the support ships, it does make sense:
Exploration support ship usually needs Elite in Exploration.
Mining support ship usually needs Elite in Trade.
Combat support ship usually needs Elite in Combat.
We don't know if there will be other types of support ship: a longer list of roles for support ships was given, but the three ships that we've seen might cover those.
The currently-useless top Federation and Empire Navy ranks could tie into this too, as another way to gain access to the Combat support ship. It makes sense for a navy to grant access to a warship.
The various Powerplay Powers could also be involved. This is slightly more problematic, as it's easy to get up to Ratiing 5 with a PP Power, but this isn't permanent. However, a Rating 5 player with a Carrier could maybe "lease" an appropriate support ship, that would be "repossessed" (with compensation) if the player drops below Rating 4. The obvious candidate would be Zemina Torval for Mining: other PP Powers could mostly offer Combat support ships, except Li-Yong Rui and Pranav Antal, who are more into scientific research than militarism: for them, maybe Exploration.