http://www.sciencedaily.com/releases/2012/12/121231180632.htm

Excerpt: “Galactic cosmic radiation poses a significant threat to future astronauts,” said M. Kerry O’Banion, M.D., Ph.D., a professor in the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy and the senior author of the study. “The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer’s disease.”

It appears when Eugene Parker wrote “Shielding Space Travelers” in 2006 he was right- and all the private space sycophants claiming radiation mitigation is trivial are wrong.

Only a massive water shield a minimum of 14 feet thick and massing 400 tons for a small capsule can shield human beings in deep space on long duration missions. And since a small capsule will not have sufficient space to keep a crew psychologically healthy on a multi-year journey it is likely such a shield will massive over a thousand tons.

This mass may seem to make Human Space Flight Beyond Earth and Lunar Orbit (HSF-BELO) impractical but in fact it is not an obstacle but an enabler. Nuclear Pulse Propulsion using bombs to push a spaceship to the outer solar sytem becomes more efficient the larger the ship and this amount of water is useful in a closed loop life support system.

Lighting off bombs in the Earth’s magnetosphere is not acceptable and this points to the Moon as the obvious place to launch nuclear missions and also to acquire the water for radiation shielding. The Space Launch System (SLS) is the human-rated Heavy Lift Vehicle (HLV) with a powerful escape system that can safely transport the required fissionables to the Moon.

2013 may be the year of the comet and the year of the spaceship if the two goals of protecting the planet from impacts and establishing off world colonies are finally recognized as vital to the survival of humankind.