I was thinking about how easy it would be to perform a crewed tour of the Jovian/Saturnian moons, given the low DeltaV, and the abundant opportunities for potential ISRU.

Then, I remembered with that now-familiar sinking feeling that both gas giants, Jupiter especially, have intense radiation fields in the form of trapped charged particles.

Considering this would be the main hazard, I wonder if any proposals have been put forward to allow for a near-future (next 50 years) mission to either system, and how they proposed to deal with it...

  • $\begingroup$ It's a difficult environment even for radiation-hardened instruments designed to map the radiation, like Juice esa.int/Enabling_Support/Space_Engineering_Technology/… $\endgroup$
    – PM 2Ring
    Aug 17, 2023 at 7:45
  • $\begingroup$ FWIW, Horizons has trajectory data for Juice, upto July 2031 ssd.jpl.nasa.gov/api/… Here's a plot, with a 15 day timestep. Purple: Jupiter, Orange: Juice i.stack.imgur.com/h0Ll3.png $\endgroup$
    – PM 2Ring
    Aug 17, 2023 at 8:11
  • $\begingroup$ I mean, Earth has a pretty intense radiation belt too. It's going to be the case for any magnetically active planet. The gas giants are just big, with proportionally large rad belts. That said, a manned mission to anywhere other than Mars is probably just hypothetical until we actually get to Mars. $\endgroup$ Aug 17, 2023 at 13:50
  • $\begingroup$ Also IIRC Jupiter's radiation environment is worse than its mass would suggest because Io's particle output amps it up, while Saturn's is better than you'd expect because of the water in its ring system... or something like that. $\endgroup$ Aug 17, 2023 at 13:51
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    $\begingroup$ @uhoh ISRU: In-Situ Resource Utilisation. $\endgroup$ Aug 17, 2023 at 22:00

1 Answer 1



I don't think there are any practical plans for a manned Gas Giant tour.

Hundreds of Tons of Lead

Pioneer 10 spent about 2 days in the Jupiter system, and recorded about 250,000 rads of particle radiation in that time. Let's assert that this is typical of a Jupiter interaction. Let's further assert that the particle radiation is the only radiation we care about (ignoring that Jupiter is a Terra-watt strength X-ray source...)

Good News: blocking charged particles is easy! A thin sheet of metal will block nearly 100% of them!

Bad News: blocking charged particles produces gamma rays. For the sake of argument, we'll assert that 1 rad particle radiation is converted into 1 Rem high energy gamma 1 for 1, even though that's probably not strictly accurate.

250,000 Rem in 2 days converts to 45,625,000 Rem per year. OSHA limits rad workers to 5 Rem / year, so we need to knock down the radiation by ~10,000,000, or 7 orders of magnitude.

The tenth thickness of Lead for high energy gammas is between 2 and 4 inches. We'll call it 2 to be generous. We need 7*2 = 14 inches of lead to lower the Jupiter system radiation levels to a (still pretty high!) 5 Rem a year.

Covering a shipping contained sized 10x10x40 area with 14 inches of Lead is about 2,000 cubic feet of lead, which at 708 lbs per cubic foot is over 700 tons!

More Realism

This ignores the actual complexities of atmospheric control, food, water, power generation (almost certainly a full up fission reactor) spare parts, etc. You aren't doing this mission in a shipping container sized area.

You can do some interesting things with stay times - most inanimate objects tolerate high energy gammas just fine, so parts of the ship that aren't visited often can be high radiation zones, as long as the sleeping and working quarters are well shielded. But you're still going to need 100s of tons of dedicated shielding, even if you are clever with your design.

A manned Gas Giant mission would be massive on a scale that we haven't even approached for space travel. The CSM and LEM combined for the Apollo missions were about 50 tons - an order of magnitude smaller than the shielding we're talking about.

Therefore, I don't see a manned Jupiter mission happening in the next 50 years.


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