I read the first one, but none of the later ones.
Rama II, Rama comes back for another visit...
Seventy years after the events of Rendezvous with Rama, a second Raman vessel enters the Solar System. Its arrival is expected, and on Earth the chosen crew of twelve readies for the voyage to unlock more of Rama’s mysteries. Interpersonal conflicts among crew members begin prior to the launch date.
After arriving, an accident kills the leader of the group while still outside Rama, and there is debate over who the replacement should be. The tools and vehicles the crew bring to Rama, based on knowledge from the first expedition, make exploring Rama easier.
The novel ends with three of the twelve astronauts abandoned inside Rama as it travels out of the Solar System.