Europa

Palomar · 2002-06-22 12:29:23

Rob S: "As for Europa, it will be very hard to explore it directly by humans because it is imbedded in Jupiter's van Allen belts, and thus is bathed in very lethal levels of radiation."

*I brought this over from the Human missions section, "Exploration of Venus."

I became interested in the exploration of Europa after reading that there may be life in its oceans (beneath its thick, outer crust of ice). Arthur C. Clarke treats the topic quite extensively in his sequels to "2001: A Space Odyssey."

I'd like to see probes land there and tests carried out.

--Cindy

Byron · 2002-06-22 13:31:02

I certainly second your opinion..if there's any place other than Mars to look for life, Europa would be it. Probes could be landed on the ice surface and perhaps melt or drill their way down to the liquid ocean beneath.

Too bad about the radiation, though. Perhaps someone will invent a radiation shield for manned landings there someday...

B

Palomar · 2002-06-22 16:27:59

I certainly second your opinion..if there's any place other than Mars to look for life, Europa would be it. Probes could be landed on the ice surface and perhaps melt or drill their way down to the liquid ocean beneath.
Too bad about the radiation, though. Perhaps someone will invent a radiation shield for manned landings there someday...
B

*Hi Byron. Actually, I was surprised when I read Rob S's comments about Europa being smack-dab in the middle of Jupiter's (very dangerous) radiation belts. I understand that Clarke, in his story, wouldn't want to get overly scientific in the telling of a science fiction tale; however, his story included humans landing on Europa. I suppose he neglected to mention the lethal levels of radiation by taking "artistic liberty," but he's also a scientist. I'm not sure he should have taken that much liberty in his tale-telling. I'd had my hopes up for a manned mission to Europa in the future, most likely after I'm dead and gone. Now I read about these lethal levels of radiation...you get the drift. It behooves storytellers with backgrounds and degrees in science to be a bit more mindful of how they present a story, especially to an audience which is sure to contain a few persons genuinely interested in human space exploration.

--Cindy

Aetius · 2002-06-22 19:50:01

Enough to kill a human inside an EVA suit within twelve minutes, or so I read. That's pretty nasty. Maybe a Mini-Magnetospheric Plasma Propulsion (M2P2) 'bubble' could provide adequate protection.

Phobos · 2002-06-23 12:15:44

The Artemis Society designed a manned mission to Europa just as something of an intellectual exercise. They assumed that once you got close enough to the ocean beneath the ice there would be large pockets of dwellable space in the ice that would be deep enough to protect you from radiation. I don't remember how they intended to protect the people from the radiation outside of the ice even though there was a time interval that had to be observed. Anyways, it's not a mission I'd volunteer for. :0

Canth · 2002-07-07 13:44:30

I beleive that europa (as well as jupiters other moons) only has short term lethal doses of radiation at certain times, when it is passing through the heart of the radiation belt. At other times I understand that you could explore the surface, although the radiation is pretty intense. You would need somewhere to go during the very lethal times though. Also, I don't think that the intense radiation enviornment of jupiuter was understood at the time Arthur C. Clark started his 2001 series. I beleive that the series was started before interplanetary probes measured the radiation. The radiation may not have been totally recognized untill long term observations were carried out by the gallileo probe.

Aetius · 2002-07-07 15:05:14

Actually, most of the Galilean satellites have a consistently nasty radiation environment. Here is a breakdown of radiation doses I got from Zubrin's excellent book, "Entering Space" (page 167):

Io...3600 rem per day
Europa...540 rem per day
Ganymede...8 rem per day
Callisto...0.01 rem per day

Zubrin says on page 166: "A radiation dose of 75 rem or more, if delivered during a short time compared to the cell repair and replacement cycles of the human body, say 30 days, will generally cause radiation sickness, while doses over 500 rem will result in death."

Also: "...On Ganymede the dose rate is not too bad, provided that people generally stayed in shielded quarters and only came out on the surface for a few hours now and then to perform essential tasks. On Callisto and those moons farther out, Jupiter's radiation belts are not an issue, except during the time of magneto tail pass-through..."

Europa? Not a mission I'd volunteer for, either.

Shaun Barrett · 2002-07-08 06:40:46

Phobos mentions the Artemis Society and its assumption that there will be "large pockets of dwellable space in the ice" on Europa to afford explorers some protection from radiation.
Surely the jumbled, cracked and broken slabs of ice we see in pictures from Galileo are an indication that the Europan crust is unstable?
Would you sleep well in a creaking ice cave deep in the Europan crust?! I'm pretty sure I wouldn't!

Canth · 2002-07-08 11:27:59

The ice is unstable over thousands of years but it appears to be stable in the short term. No changes in the ice structure has been documented, just the appearance of change on a large scale. You are likely much safer on europa than on the ice sheets near the north pole of earth.

Shaun Barrett · 2002-07-08 18:24:04

Thankyou, Canth, for clearing that up. I suppose what you have said should have been obvious to me ... in view of the latest opinions that the Europan ice crust is probably much thicker than we were hoping. (Was the figure 18 kilometres, or was it more? Sorry ... can't remember now.)
Still, you could happen to be in your Europan ice cave just as the crust decides to shift its weight a little bit!! Then, if I were there, despite the fact that I don't have a uterus (a nod and a smile to Cindy) I think I'd probably get "hysterical" anyway!!

Palomar · 2002-07-08 21:43:29

Would you sleep well in a creaking ice cave deep in the Europan crust?! I'm pretty sure I wouldn't!
Thankyou, Canth, for clearing that up. I suppose what you have said should have been obvious to me ... in view of the latest opinions that the Europan ice crust is probably much thicker than we were hoping. (Was the figure 18 kilometres, or was it more? Sorry ... can't remember now.)
Still, you could happen to be in your Europan ice cave just as the crust decides to shift its weight a little bit!! Then, if I were there, despite the fact that I don't have a uterus (a nod and a smile to Cindy) I think I'd probably get "hysterical" anyway!!

*Um, yeah. Radiation outside that could kill you in less than an hour versus sleeping and living in pockets of creaking ice caves deep in the Europan crust...I and my uterus say NO THANK YOU!

Apparently robots/probes are our best bet for Europa. I sure hope to see a touch-down exploration of Europa by a robot expedition in my lifetime.

--Cindy

Palomar · 2002-07-16 09:15:14

Actually, most of the Galilean satellites have a consistently nasty radiation environment. Here is a breakdown of radiation doses I got from Zubrin's excellent book, "Entering Space" (page 167):
Ganymede...8 rem per day
Also: "...On Ganymede the dose rate is not too bad, provided that people generally stayed in shielded quarters and only came out on the surface for a few hours now and then to perform essential tasks

*Ganymede. What are the possibilities of human exploration and eventual settling there?

And I'm also wondering what other planetary satellites might be considered for human exploration and eventual settlement?

--Cindy

Shaun Barrett · 2002-07-16 19:34:15

You have to take into consideration the low gravity on these outer solar system moons.
Although Ganymede seems relatively large, it is a low density world and therefore its mass is small .... it would take 40 Ganymedes to equal Earth's mass.
As a result, its surface gravity is only 1/7 of Earth's
This means that any problems we may have envisaged for settling Mars, in terms of gravity, are at least twice as bad on Ganymede. And solar cells will likely be borderline technology due to the low insolation so far from the sun. Nuclear power is probably the only way to keep warm on Ganymede, and we don't know where you'd get new fuel rods (except from Earth) when the old ones become exhausted.
With our present level of technological development, exploration of Ganymede is just about feasible, but I think settlement is a whole different question (IMHO).

Aetius · 2002-07-16 21:29:37

For settling planetary systems beyond Jupiter, I actually prefer O'Neill-type rotating habitat cylinders whose superstructures are made mostly out of water ice. At Saturn and beyond, cryogenically frozen H2O behaves like industrial steel...and it's incredibly abundant. Placing the colonies at Trojan points (co-orbital with major moons like Triton or Oberon, but 60 degrees ahead or behind in their orbital path) would allow mining outposts using mass drivers to regularly transport millions of tons of natural resources from the icy moons to habitat cylinders. Hybrid fission-fusion reactors which have ALREADY been designed could provide enough electricity to support billions in a level of comfort that would be envied by most in the world today.

I love the idea of settling Mars. But the truth is, I like the idea of settling the Uranian system much more. As little as Terrans might care about what happens on Mars, they'd probably care even less about Uranus. 'Ariel Co-orbital Cylinder One' sounds nice to me.

Aetius · 2002-07-16 21:33:08

But I have to agree with the preceding poster. Any idea of settling the outer solar system is probably a long way off.

Shaun Barrett · 2002-07-17 01:56:44

Aetius, it appears to me you're way ahead of most of us mere Martians!
Your enthusiasm for O' Neill settlements way out among the gas giants is highly infectious, though!!
One of the questions that springs to mind, at least for me, involves those hybrid fission/fusion reactors. Even if you can import material from the icy moons out there, how much of it needs to be fissile material?
My basic problem is that I don't know much about fission/fusion reactors! But I'm under the impression that there's probably not much in the way of elements with high atomic mass in the outer suburbs of solaria! What little there may be, is probably concentrated in the rocky cores of the ice moons under many kilometres of steel-hard ice. If your reactors need recharging with, say, uranium every few years, would you need to import it from Mars or even Earth? Would that be much of a problem? Is the asteroid belt likely to have heavy elements suitable for the purpose?
There's no heavy irony here (groan! ... sorry!! ). I'm genuinely curious, not having given much thought to this region of the solar system and how best to utilise it.

Palomar · 2002-07-17 07:54:26

You have to take into consideration the low gravity on these outer solar system moons.
Although Ganymede seems relatively large, it is a low density world and therefore its mass is small .... it would take 40 Ganymedes to equal Earth's mass.
As a result, its surface gravity is only 1/7 of Earth's

*Oh, of course. Now it's GRAVITY being the problem. Why won't these other planets and satellites cooperate with us a little, hmmmm? Why must they be so difficult?!

You know, Star Trek made it look oh-soooo-easy. Every planet they visited had just the right amount of gravity so no one's crawling or bobbing around...every native speaks your language as well as you, maybe even better!...every atmosphere [with the exception of 1 or 2 episodes where the civilization was enclosed] was totally breathable by mere mortals from Earth [and/or Vulcan]...occasionally gorgeous, sleek, tanned humanoid natives of both genders would greet the crew with refreshments...

Hooray for Hollywood! ::shakes head with exasperation::

--Cindy

Byron · 2002-07-17 11:37:13

*Oh, of course. Now it's GRAVITY being the problem. Why won't these other planets and satellites cooperate with us a little, hmmmm? Why must they be so difficult?!

That's what I think as well... ??? The *nerve* of these tempting worlds keep themselves offlimits to us mortal humans with their deadly radiation, lack of atmospheres, and too-low gravity..LOL.

That's why I have the firm belief that Mars will be the only place in the Solar System (besides Earth, of course) where humans will be able to establish any kind of meaningful society...and even that won't be easy, as we all very well know...

B

Alexander Sheppard · 2002-10-29 19:04:21

Well, one idea is to place large floating structures in the gas giants' atmospheres which would be supported by the density of the gas beneath them. These structures could regulate their position in the atmosphere by taking in or letting off ballast, and could rely on the atmosphere for many essential elements. Power could be provided for by fusion reactions, which would be even better assuming we had He3 fusion, as He3 is very cheap to come by in the giants' atmospheres. There are many layers in a gas giants atmosphere, and each contains many interesting materials. By regulating the relative density of the station by taking on ballast, the station could shift to each level somewhat like an elevator, collecting the materials it needed, and then shifting back to some optimum position. Of course, there are several alternatives-- perhaps it would be more economical to simply use shuttles to pick up materials, or smaller stations. We'd have to develop this concept more to see which makes more sense, and how much this would cost at all. I don't really see why it would be prohibitive, though.

More speculatively, it seems possible that eventually, if this proved to be economically feasible, the stations could be joined into some sort of planetary scale network, perhaps a ring of some sort. For many reasons, however, that might prove to not make sense: for example, the winds might wreak havoc structurally, or mabye it would just be uneconomical. On second thought it seems like a large station would make more sense than a ring, as why would one want that?

Josh Cryer · 2002-11-01 01:52:33

Heh, I had the same idea about floating large platforms in Venus' atmosphere. It may even prove more feasible due to the increased gravity and radiation of the gas giants.

Aetius · 2002-11-02 19:01:32

Shaun, I don't believe that it would be difficult to establish a balance of trade between Martians and denizens of the outer solar system. Colonists on worlds near Saturn, Uranus, and Neptune could (hypothetically, anyway) export Helium-3 and volatile-rich comets (for terraforming) to Mars.

Maybe the Martians could build an empire of their own by establishing settlements out there, to supply a need for the outer solar system's virtually unlimited natural resources.

Aetius · 2002-11-02 19:29:01

Holy "Empire Strikes Back"!

A City In The Clouds, on Venus?

I love that idea! You know, I'd bet you could extract enough hydrogen from the sulfuric acid in the atmosphere to create water for dozens of people!

I also wouldn't mind seeing a water-rich, near-Earth asteroid moved into orbit around Venus. It would test our abilities to move a potential Doomsday asteroid, and provide a nice worldlet to colonize as well. The gravity well of Venus might not provide too much of an obstacle to mine some of the gases from the atmosphere with a spacecraft designed to skim the uppermost layers.

Phobos · 2002-11-02 20:22:03

Shaun, I don't believe that it would be difficult to establish a balance of trade between Martians and denizens of the outer solar system. Colonists on worlds near Saturn, Uranus, and Neptune could (hypothetically, anyway) export Helium-3 and volatile-rich comets (for terraforming) to Mars.

It'll be a great day when nuclear fusion using helium-3 becomes a reality for generating power. Even though a lot of people think the moon would be the best source for that kind of fuel the outerplanets practically have an unlimited supply of it as far as Earthly power needs go and we'd wouldn't have to go clogging up land and space with solar cells, windmills, etc.

Aetius · 2002-11-02 21:09:17

When I think of how much deuterium the Chinese are going to extract from the water going through that gigantic dam they're building, it makes me very hopeful about the future of fusion research. Whether the anti-nuclear activists like it or not, they won't be able to bully the Chinese government with lawsuits and the like. I honestly believe that clean fusion power will eventually become available, just not on the timetable the science fiction writers imagined.

Then again, "2001" may depict our space activities in 2100 AD more accurately than it did the year gone by.

I am always hopeful.

Phobos · 2002-11-02 22:14:56

That's one thing that's good about China, they haven't been brainwashed into irrational hatred of nuclear power the way the USA has. Western style reactors, particularly the newest generation designs, are very safe and people are usually surprised to find that coal burning powerplants usually release much more radiation into the environment than do nuclear power plants. In any case I agree that it will probably be a country like India or China that first develops nuclear fusion and uses it commercially. From everything I read India is starting to devote a lot of attention to fusion-power research. I'd definately support having (relatively) small fusion reactors generating power than to pave millions of acres of deserts with windmills or solar arrays or clutter up the night sky with them. I'm almost to the point of stepping up on my soapbox so I better restrain myself while I can. :angry:

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#1 2002-06-22 12:29:23

Re: Europa

#2 2002-06-22 13:31:02

Re: Europa

#3 2002-06-22 16:27:59

Re: Europa

#4 2002-06-22 19:50:01

Re: Europa

#5 2002-06-23 12:15:44

Re: Europa

#6 2002-07-07 13:44:30

Re: Europa

#7 2002-07-07 15:05:14

Re: Europa

#8 2002-07-08 06:40:46

Re: Europa

#9 2002-07-08 11:27:59

Re: Europa

#10 2002-07-08 18:24:04

Re: Europa

#11 2002-07-08 21:43:29

Re: Europa

#12 2002-07-16 09:15:14

Re: Europa

#13 2002-07-16 19:34:15

Re: Europa

#14 2002-07-16 21:29:37

Re: Europa

#15 2002-07-16 21:33:08

Re: Europa

#16 2002-07-17 01:56:44

Re: Europa

#17 2002-07-17 07:54:26

Re: Europa

#18 2002-07-17 11:37:13

Re: Europa

#19 2002-10-29 19:04:21

Re: Europa

#20 2002-11-01 01:52:33

Re: Europa

#21 2002-11-02 19:01:32

Re: Europa

#22 2002-11-02 19:29:01

Re: Europa

#23 2002-11-02 20:22:03

Re: Europa

#24 2002-11-02 21:09:17

Re: Europa

#25 2002-11-02 22:14:56

Re: Europa

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