Pressure vessels, life support systems, rockets, what exactly doesn't exist yet that is needed, technologically? If you want to be a pedant and say that any sp

Pressure vessels, life support systems, rockets, what exactly doesn't exist yet that is needed, technologically? If you want to be a pedant and say that any specific tool that doesn't exist yet represents technology that doesn't exist then sure, that's the case, but there's nothing especially beyond state of the art that is required to live in space or colonize other planets. Technological advancements are mainly advantageous in increasing the success rate and cost efficiency of doing so. But we could have sent people to Mars in the 1970s. We had the rockets, we had the know-how to build the vehicles.