[Brett66]

Chemical rockets will get people to Mars, but I just can't see us putting very many fully fuelled Saturn V-sized rockets into orbit. Then there are the radiation problems. We won't be able to have any veteran Mars astronauts because two trips would push them close to the safe lifetime dosage limits. If we want an unsustainable rush to Mars, chemical rockets are the way to go. If we want a viable exploration of the planet, we have to do better.

[NonZeroSum]

You don't need Saturn Vs to get to Mars. Small space transports, operating often (for e.g., tourism) can deliver everything that a Mars mission needs, and at affordable costs.