I know that passive radiation shielding blocks radiation.

Layer 1: tin and lead - 1.5m

Layer 2: Kevlar, Mylar - 0.5m for MMOD protection

Layer 3: Carbyne - 1m for strength

Layer 4: beta cloth and Nextel - 1m for MMOD protection and heat insulation

Layer 5: Kapton cloth and polythene - 0.5m for MMOD protection as well as radiation shielding

Total thickness of the shield 4.5m

This is the composition of the outer wall of the settlement which acts as a whipple shield as well as a passive radiation shield.

Can hydrogen and/or water be suitable choices?

Would this shield be enough to block radiation emitted from Jupiter and shield a small space settlement in Jupiter's magnetosphere? The settlement orbits around Ganymede.

  • $\begingroup$ Please read en.wikipedia.org/wiki/Radiation_protection#Radiation_shielding and related content. At the moment you are not giving any dimensions of the materials, the target orbit or the target radiation level so question is impossible to answer and indicates a lack of basic research. Suggest editing to flip the question round to give a target orbit (so the moon of interest), target radiation level (1 milli Sievert is a current public exposure limit) and ask how much shielding thickness would be required to achieve that, since actual make up of the shield is largely immaterial. $\endgroup$ Sep 12, 2021 at 5:36
  • $\begingroup$ OK, can I get some time for providing these details $\endgroup$ Sep 12, 2021 at 6:54
  • $\begingroup$ edited the question, may I know if it is fine now $\endgroup$ Sep 12, 2021 at 7:01
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    $\begingroup$ where in Jupiter's orbit is relevant. The planet itself emits almost no radiation other than a comparatively harmless flood of radio waves. But the magnetosphere has trapped electrons and protons, and there is that pesky flux tube from Io that does nasty things to anything between Io and Jupiter. The intensity of radiation, and more importantly the type of radiation, differs immensely at different altitudes. Shielding from an intense flood of 50Mev electrons is vastly different than shielding from a diffuse zone of 200Gev death-protons. Ganymede region is outside the worst of it, but bad $\endgroup$ Sep 12, 2021 at 8:36
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    $\begingroup$ From the wiki: "The radiation level at the surface of Ganymede is considerably lower than at Europa, being 50–80 mSv (5–8 rem) per day, an amount that would cause severe illness or death in human beings exposed for two month".. Shielding from that requires quite a bit less of the "heavy" stuff than your example, and a lot more light elements, hydrogen especially. Yes, water makes for an excellent shield against the sort of radiation trapped in a magnetosphere. $\endgroup$ Sep 12, 2021 at 8:48

1 Answer 1


Yes, the described shield will protect a station orbiting Ganymede, but is not the right way to go about it.

While some tweaking can be achieved using graded-Z shieldingthe first order approximation for radiation shielding is by placing the maximum mass of material in the path of the radiation. For the described shield, the vast majority of the mass will be in the lead component (density 11g/cm3 vs ~1g/cm3 for the poorly defined remainder). The halving distance of lead is 4.8mm. So 1500mm of lead will get 312.5 halvings, enough to make any banana's onboard the primary source of radiation in any environment where shielding is not melting.

This shield will be massively heavy however. Each square cm of shield weighs 1700g in lead alone, so a cubical craft with same work space of the ISS (1000 cubic meters, 10 meters a side, area 6 million cm2) is going to weigh 68 thousand tonnes (ignoring corners etc).

More relevant, taking the comment from PcMan of 50-80 milli Sieverts for Ganymede, and target safe level of 1 mSv, we need 7 halvings or 7*3.4mm=23.8mm of lead. This gives a needed mass of our ISS like base of around 27 g per square cm or 162 tonnes. This is substantial (current ISS is around 400 tonnes total) but much more plausible.

Since the material of the shield is not particularly relevant, this lead can be swapped out for water tanks, food and fuel storage, and further reduced by making the shielding asymmetrical and accepting higher exposure levels.

Designing for one halving (~40mSv 3.4mm of lead/38mm of water) may be a reasonable starting point if doing design concepts.


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