My thoughts on Rendezvous with Rama are documented in a Goodreads review. For me, the problem with this book is the unsatisfactory ending. I know that there have been sequels but I read Rendezvous with Rama before they were written and often wondered how I would have ended the story, had I been the writer.
One reader of my review commented that she liked “the lack of answers, the possibility to use my brain just a little bit, to sit and imagine for myself”. Prompted by this (to me) surprising comment, I tried again to come up with some explanations that would make a suitable ending to the book. Here is what I came up with.
1. The ship contained creatures in suspended animation. This in turn leads to possibilities, if the creatures wake up, if the explorers find them and leave them, or of they are found but are dead. And who are these people, explorers, slaves, convicts, emigrants?
Perhaps some texts are found, a history of the people on the ship. The people are left, but the books are copied and later, when the copies reach Earth, they are decoded to reveal some incredible or horrifying secret.
2. The ship was being shipped; to another planet for their use. Who built it and what do their customers want to do with it? The trouble with this is the time scale, probably thousands of years to order the ship, build it and deliver it. Perhaps it was intended to be the first ship to travel to another galaxy.
3. The ship was a robot. So why a breathable environment, water, warm temperature? Perhaps a robotic civilization created organic creatures to carry out work requiring a little more flexibility than the robots have. Maybe they cleaned up (dusted, lubricated, replaced broken parts, etc), Or perhaps Rama was a laboratory for creating organic creatures. Maybe these organisms were a weapon, being sent to infiltrate another organic civilization, to destroy them as the microbes destroyed the Martians in War of the Worlds.
Man has long speculated about sending robots into space, but what would robots send? Would they see advantages to creating organic creatures. Organic creatures give you evolution, self healing, flexibility, reproduction without a factory, adaptability, etc.
Perhaps the future of civilization is a robot/organism mutual symbiosis.