Visiting the inner moons of Jupiter

[SomeGuy12]

If you wanted to put astronauts on the inner moons of Jupiter, what would it take? Wikipedia says it's about 8 rems a day on Ganymede, with a fatal dose at 100, so it doesn't seem very habitable. Some of the radiation belts are just charged particles, which you could in principle shield against with magnets or something, but these accelerated particles emit gamma and x-rays, which you would need a massive quantity of shielding for.

What alternative is there besides a spacecraft that is weighed down by carrying a submarine sized (probably more cramped than that) lead lined "vault" for the crew, and then exploration of Ganymede would be done via robots while the crew huddles in their vault or in a cavern deep under the surface. Even if you suppose there might be treatments for the long term damage of radiation exposure (the various leukemias and tumors and stuff), you gotta survive the short term acute exposure as well...

[UmbralRaptor]

Robots.

A longer version of this reply would discuss how radiation exposure is not like using hitpoints, it seems a bit odd to refer to Ganymede as an inner moon (wikiality seems to treat the Galilean moons as a middle distance group), shielding against high energy photons basically requires lots of high-Z material (traditionally lead, though one can find examples of regolith, bismuth, and even depleted uranium!) even though that causes secondary radiation when whacked by charged particles, shielding against protons may be best done by lots of a low-Z material (water is a classic example, though NASA has looked into various hydrogen-rich plastics), magnetic shielding may limit equipment options in the crew areas, crew require lots of additional life support resources blowing the mass up enormously even without the harsh radiation environment, and the high ÃŽâ€V of Jupiter orbit and especially landing on those moons.

There are probably additional factors, but still... robots.

Edited November 1, 2015 by UmbralRaptor

[B787_300]

^esssentially what Umbral Said. You can make Robots Rad-Hard, you cant do that to humans (yet?) and shipping out that much sheilding is not worth it from a mass standpoint when you could just send a whole bunch of robots instead.

[UmbralRaptor]

Heh. From a mass standpoint it looks like Vostok was comparable to Galileo and Cassini.

[magnemoe]

Robots.

A longer version of this reply would discuss how radiation exposure is not like using hitpoints, it seems a bit odd to refer to Ganymede as an inner moon (wikiality seems to treat the Galilean moons as a middle distance group), shielding against high energy photons basically requires lots of high-Z material (traditionally lead, though one can find examples of regolith, bismuth, and even depleted uranium!) even though that causes secondary radiation when whacked by charged particles, shielding against protons may be best done by lots of a low-Z material (water is a classic example, though NASA has looked into various hydrogen-rich plastics), magnetic shielding may limit equipment options in the crew areas, crew require lots of additional life support resources blowing the mass up enormously even without the harsh radiation environment, and the high ÃŽâ€V of Jupiter orbit and especially landing on those moons.

There are probably additional factors, but still... robots.

Yes radiation is not hit points, real world is not fallout. You do not want to get half an lethal dose radiation.

It should be possible to shield against the radiation around Jupiter with an strong magnetic shield as its mostly charged particles. Yes this require superconductors, bonus is that its cold around Jupiter so you can get away with 100 kelvin superconductors.

Robots also have problems with radiation. Integrated circuits are nanoscale devices. Benefit is that nobody get killed, boring then your 3 billion Europa drill get bluescreen 3 km above the surface with an kerbal result.

[MichaelPoole]

There are no high energy photons in Jupiter's radiation belt, because magnetic fields only capture charged particles = solar wind from the Sun. Jupiter does not make any appreciable ionizing radiation. Lead would make this a lot worse because it not only doesn't protect you from charged particles, it actually creates more of them when impacted by charged particles! So if you wanted to put humans there, just put regolith bags on the outside of your bunker, or ice, that will protect you way better than lead - simply adding mass. Robots are not magical solutions to everything.

[_Augustus_]

Callisto requires nothing more than a normal spacesuit.

Ganymede can be visited if you don't stay for more than a day or two or you wear some bismuth shielding.

Europa is hard for robots (as is evident with Europa Clipper) and impossible for humans.

Io actually has less radiation than Europa, but why do you want to go there anyway?

[SaturnianBlue]

Callisto requires nothing more than a normal spacesuit.

Ganymede can be visited if you don't stay for more than a day or two or you wear some bismuth shielding.

Europa is hard for robots (as is evident with Europa Clipper) and impossible for humans.

Io actually has less radiation than Europa, but why do you want to go there anyway?

Unless I'm mistaken, doesn't Io receive 3600 rem vs Europa's 540? To be honest, while the search of life doesn't have much prospect on Io, the volcanoes and geography (Iography?) would be a sight to behold!

[fredinno]

Europa surface exploration would be impossible with spacesuits, but using a pressurised rover for Surface exlloration, and building colonies in the ice would mitigate the radiation issue. We will probably want to drill into Europa's ice anyways for scientific studies- major bonus points if there is life, wich would validate a long-term base having a submarine.

Landing on any of the Galilean Moons is a pain due to lack of atmosphere and large size. I doubt one would want to use Jupiter for aerobraking.

Io- forget about it. Even robots would have a difficult time there.

Ganymede- Apollo-Style missions probably won't be affected, but a base there will definately prefer staying indoors. Maybe a specially-designed spacesuit would be necessary to allow for extensive EVAs.

Castillo- No radiation problem.

There's a reason Zubrin considers the Saturn System a better destination- just as interesting, but without Jupiter's radation belts.

[Bill Phil]

You're just gonna have the whole crew section be a fallout shelter.

But once on the surface, it's not as big of a problem.

If only we had Rad-X and Radaway...

[Rakaydos]

What's the lightspeed latency from Calisto to Europa? Could a manned mission on Calisto (low rad shielding) teleoperate a robotic exploration mission on ganamede and Europa?

[MichaelPoole]

If only we had Rad-X and Radaway...

Actually, we have something like that. Those are called radioprotectives http://ispub.com/IJIM/8/2/3973 .

[SargeRho]

There are no high energy photons in Jupiter's radiation belt, because magnetic fields only capture charged particles = solar wind from the Sun. Jupiter does not make any appreciable ionizing radiation. Lead would make this a lot worse because it not only doesn't protect you from charged particles, it actually creates more of them when impacted by charged particles! So if you wanted to put humans there, just put regolith bags on the outside of your bunker, or ice, that will protect you way better than lead - simply adding mass. Robots are not magical solutions to everything.

Jupiter's magnetic field is a giant particle accellerator. And emits synchrotron radiation (high energy photons, emitted when you bend the path of a charged particle)

Ganymede has its own magnetosphere though, shouldn't that offer some protection?

Edited November 2, 2015 by SargeRho

[MichaelPoole]

Also, "why would you go on Io anyways?". To study this wonderful, active world? Why has everything to be about finding life, life, life? I honestly don't care that much about finding alien life, I am an enthusiast into astronomy, I find planets, moons and their geology and sceneries to be beautiful in the same way I find desert rock formations or the Grand Canyon to be beautiful. If you ask me, I'd gladly put Deinococcus radiodurans genes into me to see Io's surface in person. And I believe modification of humans is the future of space colonization instead of huddling under hardened spacesuits or pharaohic terraforming projects.

[PB666]

[url]https://www.nasa.gov/press-release/nasa-s-europa-mission-begins-with-selection-of-science-instruments[/url]
7 instruments so far, if the went to the inner moons what should they look for?

[lajoswinkler]

What I found, but can't verify, is this

[I][URL="http://www.dailykos.com/story/2013/1/19/1177486/-Getting-to-Know-Your-Solar-System-24-Ganymede"]Daily radiation dose on Ganymede is about 80 mSv (millisieverts) or 0.08 sieverts (Sv) per day. This is 450 times smaller than radiation on Io (36 Sv), and about 68 times smaller than the dosage on Europa (5.4 Sv),(...)[/URL][/I]

It is plausible. Absolutely plausible. Imagine 36 Sv/day on Io. That is [B]1.5 Sv/h[/B]. We will [B]not[/B] go to Io, I assure you. This dose gives severe radiation poisoning. By the time you get away from Jupiter, even if you just land on Io to quickly pick a rock, you'a walking dead man. At least.