To clarify, I am writing a science fiction story in which a manned Mars mission in 2025 discovers a previous manned mission to Mars sent in the 1990's using modified Apollo lunar technology. Even though it is science fiction I want my story to be as scientifically accurate as possible. For example I have researched methods of shielding from Solar and Cosmic radiation such missions would require and I have surmised that the 21st century mission uses Hydrogenated Boron Nitride Nano Tubes, whilst the earlier mission used a form of polyethylene shielding.
I realise the technology would have to be significantly modified, but would it have been feasible to send a manned mission to Mars using Apollo technology?
I realise it would probably be unfeasible that something like this could have been kept secret, but it is science fiction, this is hypothetical, that is a plot point I can work out.