Hi SDAI-Tech1

Your point is valid, but hard to do on a budget.

My title is due to his "Das Mars Projekt" being written in 1948, long before anyone knew about solar flares, the effects of cosmic rays, before hard knowledge of nuclear rockets and so on. His English versions in 1953, and 1956, was merely more readable and artistic, but differed not in basics. As a result his plan was unsafe from start to finish.

His 1969 revision, for the Space Task Group report, was an improvement, but probably still took too long getting between the planets. The twin Nerva-pushed Interplanetary Vehicles did have solar-storm shelters, but back in 1981 (the proposed launch date) there was not much advanced warning of flares, if at all. And there was no provision for avoiding cosmic-rays, meaning the astronauts could probably never go into deep space again after a single mission. The neurological damage, particularly irreversible damage in the cerebral cortex, would have serious problems for the whole program, especially the 72-person Mars Colony targeted for 1989.

The desirable target is very fast transit times between the planets - 90 days or less. Free-return trajectories of 130-180 days mean 260-360 days of cosmic-rays per mission, which has unknown implications for brain function. Von Braun style Opposition-class missions, with ~ 610 days in space per mission are seriously bad news.

Krafft Ehricke made similar demands (<1 year cumulative exposure over a career) on mission design back in the early 1960s, for similar reasons. NASA has ignored those facts for political reasons, and I think the Zubrinites are overly sanguine about cosmic-ray exposure. But if I knew I would get Alzheimer's at age 70, then would I risk getting it at 50 instead, after going to Mars?

Would you?