19

This is a hypothetical question I'm asking as a SF writer, and the time setting would be approximately 2,250 AD.

Nathan Tuggy
  • 4,566
  • 5
  • 34
  • 44
Mike Ackerman
  • 299
  • 2
  • 4

1 Answers1

25

Yes, it absolutely would! The radiation on Europa is about 5.4 Sv (540 rem) of radiation per day. Looking at this guide, and assuming you want to meet OSHA standards of 5 rem per year, you would need to only allow 1 part in 40,000 of the base radiation to make it through. The website linked indicates you want a mass of about 375 pounds/square foot to only allow 1 part in 1000. The chart says 72 inches of water. Ice isn't quite as dense, so a bit more ice. Let's say 2 m of ice will do. The factor is roughly $31^{\text{thickness}(m)}$, so to get the 40,000 value, you need about 3.1m. I would say leave an extra meter or two just to have a large buffer.

This has been further studied by a more scientific paper, if you would like to know more details.

PearsonArtPhoto
  • 121,132
  • 22
  • 347
  • 614
  • 8
    Just out of curiosity, I wondered how thick that ice layer actually is, before you start to get into the ocean underneath? The answer seems to be "between 19 and 25 km" so there's plenty of material to work in! – KlaymenDK Feb 15 '18 at 14:25
  • 10
    And you really want to go a bit better than the OSHA standard here, for the standard is specifically for radiation workers. You don't want to expose ordinary colonists (including I presume children and pregnant women) for multiple decades to 5 rem a year. Luckily you got plenty of ice available, so I'd try to bring it down to 500 milirem a year whenever possible. – Mast Feb 15 '18 at 14:34
  • 1
    Sure, the OSHA standard is just a starting point. Getting radiation down to 500 millirem would be quite a bit more ice, but there is plenty that could be done, luckily. – PearsonArtPhoto Feb 15 '18 at 14:36
  • 9
    Suffice it to say... I think you're going to wind up with more ice above you for structural purposes than you are for radiation purposes. Convenient, honestly. – corsiKa Feb 15 '18 at 15:58
  • 2
    Relevant xkcd/what-if https://what-if.xkcd.com/29/. "What if I took a swim in a typical spent nuclear fuel pool? Would I need to dive to actually experience a fatal amount of radiation? How long could I stay safely at the surface?" – csiz Feb 15 '18 at 18:35
  • 3
    Dropping by to wonder if, after a few million years of previous irradiance, the upper layers of ice might be somewhat radioactive themselves. Granted, H and O don't have many nasty byproducts, but I'd like to see the estimates. – Carl Witthoft Feb 15 '18 at 19:17
  • 2
    @CarlWitthoft, it takes a heck of a lot of radiation to turn water into something hazardous. Starting from oxygen, it takes eight neutron captures by a single atom to get something with a half-life longer than a few seconds (Na-24, 12 hours), and dozens to get something that decays by something other than beta emission (Cu-64, which decays by positron emission). Hydrogen would be more of a problem (it eventually turns into He-4, which responds to neutron capture by releasing a neutron) except that helium doesn't tend to stick around. – Mark Feb 16 '18 at 00:38
  • Mark, I think that even if it was the case the thermal insulation plus the walls of the pressure vessel ought to be enough to block the alpha and beta particles emitted by such isotopes anyways. – TCAT117 Feb 16 '18 at 00:51
  • I thought ice would be more practical and convenient than constructing a magnetic shield, but while the colonists' robots are drilling into the ice, they'd probably have to stay on board a ship protected by one. NASA expects to develop magnet shields for space crafts in three years' time with CERN and the European Space Agency. Any chance that they'll develop magnets for space suits in that time frame too? – Mike Ackerman Feb 16 '18 at 01:10
  • @MikeAckerman If it's not specifically on their roadmap, it may take a lot longer than that. – Mast Feb 16 '18 at 10:59