I'm thinking of something akin to a space lifeboat designed to rescue crews of ships that are disabled in orbit and that would need to launch in a hurry without a lot of warning but that would also potentially have to sit for years before it was used. I'm also assuming more or less current tech but that the overall cost is not a major concern as this is only for emergency response as opposed to regular launches.
Current rockets are fueled before the crew boards, which takes a fairly long time to do. One possible idea is something based on a similar principle to ICBMs probably using SRBs.
So how would you build a rocket that was intended to launch quickly with a crew but might need to sit for years before being used?
Also, how long can RCS monopropellant be stored for orbital maneuvering?