Whenever anyone talks about sending manned missions to Mars and beyond, the subject of radiation and shielding must crop up. Its is a subject that often gets put aside in discussions as people wax lyrical about space exploration and colonies on the Moon and other planets etc, but it is an annoying "elephant in the room" that is going to have to be addressed at some point.
For the Apollo missions, the van Allen belts were dealt with effectively (despite what some HBs will have us believe) by selecting the "safest" trajectory. The main danger was some sort of Solar eruption (a CME or Solar Flare) but with mission durations being so short, the chances of one happening were quite small, and even if Murphy's Law did strike, IIRC, there was a contingency for this which involved lining up the CSM stack to use the SM as a shield. There was also the danger of exposure to cosmic radiation once we got beyond the van Allen belts but again, with short duration missions, exposure was not considered significant.
Now while transiting the van Allen belts would be dealt with the same way, and occurrence of a CME or solar flare during a Mars mission could be dealt with in a similar fashion, by aligning the spacecraft so that the crew cabin is shielded by the bulk of the spacecraft, this is not going to resolve the issue of long term exposure to cosmic radiation. Cosmic particles shower the solar system from every direction 24/7/365, so some kind of very effective shielding is going to have to be used. With solid shielding there is potentially an awful lot of weight to be carried into space and also an also an issue with something called secondary radiation, which IIUC, is caused by radiation being emitted by the shield itself when it is struck by high-energy cosmic particles. Also, quite aside from the protection of humans, there is also the exponential increase in complexity from the computer systems in use during the time of Apollo (RTL chips etc) to the USLI chips of today's computers. There is little doubt in my mind that USLI technology would be much more susceptible to cosmic radiation.
About 20 years ago (maybe more) I read a paper by a NASA (Ames?) researcher about the possibility of shielding future spacecraft with an electromagnetic field. It sounded like something out of science fiction (shields up Mr Scott!!), but the more I read the paper, the more I realised that this was a serious proposal and he might have been onto something. The idea was to try to deflect or divert cosmic rays around the spacecraft rather then try to than try to stop them altogether. One of the conclusions the writer came to was that the greatest issue was that it would require a lot of power to create a magnetic field capable of deflecting cosmic particles. He expressed the hope that the future would see materials developed that would allow for greater power generation.
Well, it is now the future from that writer's perspective, or at least its 20 or more years into it, and I can't say I have read much more stuff on this idea of magnetic shielding. I have seen stuff on blogs and websites about it but nothing really definitive from NASA or other researchers. Is this an idea that has died a natural death or been put in the "too hard" basket? Do any of our aerospace experts here at Apollohoax know if there has been any fresh opinions or new developments in this idea?
