space colonies around the gas giants

On 10/3/14 1:09 PM, sailorbarsoom@... [spacesettlers] wrote:

> Aren't the high-radiation areas around Jupiter and Saturn (*) basically
> very strong Van Allen belts?

Yep.

> In this neighborhood you can avoid that by
> in staying low orbits; could you hunker down in JEO and be safe that
> way? But then you'd need heavy shielding if you left for any reason.

Well, that's the thing. In terms of today's spacecraft (which deal with
the problem of cosmic rays by, well, ignoring it), yeah, we're talking
about heavy shielding. But in terms of a space colony, I don't think
it's heavy at all. I haven't worked out exactly how penetrating those
particles are, but I saw one source that said the trapped electrons that
hit Europa penetrate the ice to "several centimeters" and the photons
they give off may go up to a meter. But photons don't carry a lot of
punch, so I don't know that those matter.

So we may be talking about a couple of centimeters shielding... but the
pressure hull alone on a 250-m radius cylindrical colony is about 25 cm
thick. So, in other words, radiation shmadiation.

In cislunar space, at least, it's the cosmic rays that kill you. They
just do it very, very slowly. That's why (it turns out) it's best to
build your colonies in LEO if you can. I suspect the same may be true
about LJO and LSO and so on (don't know if those are real acronyms; I
just made 'em up).

Neat, eh?

Cheers,
- Joe

P.S. Of course your point about coming and going is a good one. Your
colony may be fine, but all your cargo & passenger ships might need
heavier shielding than you would otherwise like. Not to mention the
delta-V... but by the time we're looking seriously at the Jovian system,
delta-V may not be the painful issue it is today.