Monsterboy said:
Zubrin said in the video that radiation levels in deep space is only twice that of low Earth orbit ,can anyone give any reference to this claim ?
This is a good question. I will start with a peek at low Earth orbit.
http://www.esa.int/Our_Activities/S...ology/Space_Environment/Radiation_environment
RADIATION ENVIRONMENT
Radiation in the space environment comes from the trapped particle belts, solar particle events and cosmic rays.
Trapped Particle Belts
The radiation belts consist principally of electrons of up to a few MeV energy and protons of up to several hundred MeV energy. These are trapped in the Earth's magnetic field; their motions in the field consist of a gyration about field lines, a bouncing motion between the magnetic mirrors found near the Earth's poles, and a drift motion around Earth.
Basic motion of trapped particles in the Earth magnetic field
Radiation is an obvious concern for manned missions. In the near-term, manned activities are limited to low altitude, and mainly low-inclination missions. The International Space Station (ISS), Space Shuttle, EnviSat and other low altitude missions will therefore encounter the inner edge of the radiation belt. This region is dominated by the "South Atlantic Anomaly (SAA)" - an area of enhanced radiation caused by the offset and tilt of the geomagnetic axis with respect to the Earth's rotation axis.
Earth radiation belts with the South Atlantic Anomaly indicated
Besides the SAA, the polar horns also play a role for radiation analysis at low altitudes (e.g. ISS type orbit). Polar horns are parts of the outer radiation belts, which are close to Earth. As can be seen in the simulation below, increased radiation flux due to the polar horns can be expected between 60 and 90 degrees lattitude. The SAA is clearly visible at the South Antlantic region around 30 up to 50 degrees lattitude.
http://wrmiss.org/workshops/sixth/golightly.pdf
http://hps.org/publicinformation/ate/faqs/spaceradiation.html
The Cruise Phase poses a significant radiation problem due to the cumulative effects of isotropic Galactic Cosmic Radiation over 400 days. The occurrence during this period of a large Solar Energetic Particle (SEP) event, especially if it has a hard energy spectrum,
could be catastrophic health wise to the crew. Such particle events are rare but they are not currently predictable.
http://www.sciencedirect.com/science/article/pii/S0032063311002030
Design and test of Orion capsule for radiation.
http://www.engineering.com/Educatio...-Shield-designed-by-High-School-Students.aspx
http://motherboard.vice.com/en_ca/read/orion-radiation-survival
"...radiation can corrupt data. It can turn a 1 into a 0. It can make a processor think that 2+2=5."
On the road to Mars:
http://phys.org/news/2013-05-exposure-journey-mars.html
Energetic protons constitute about 85 percent of the primary galactic cosmic ray flux and easily traverse even the most shielded paths (reds) inside the MSL spacecraft . Heavy ions tend to break up into lighter ions in thick shielding, but can survive traversal of thin shielding (blues) intact.
The solar particles of concern for astronaut safety are typically protons with kinetic energies up to a few hundred MeV (one MeV is a million electron volts). Solar events typically produce very large fluxes of these particles, as well as helium and heavier ions, but rarely produce higher-energy fluxes similar to GCRs. The comparatively low energy of typical SEPs means that spacecraft shielding is much more effective against SEPs than GCRs.
"A vehicle carrying humans into deep space would likely have a 'storm shelter' to protect against solar particles. But the GCRs are harder to stop and, even an aluminum hull a foot thick wouldn't change the dose very much," said Zeitlin.On the road to the Moon; proton backsplash hazards mentioned.
http://www.sciencedaily.com/releases/2013/11/131118133044.htm
