Author Topic: How to power a settlement at Jupiter or Saturn  (Read 4385 times)

Offline KelvinZero

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How to power a settlement at Jupiter or Saturn
« on: 10/21/2018 10:39 am »
Hi, I recently saw a table on ProjectRho suggesting that a BFS had the delta-v to travel between the 9 or so major moons of Saturn, and trip times were also only on the order of days instead of months, and I thought "that is the Flash Gordon future that was promised us!" .. but how would we survive there? Most importantly what do we do for power when solar may no longer be an option?
http://www.projectrho.com/public_html/rocket/appmissiontable.php

Two thoughts: how about tidal power or electrodynamic tethers?

Tidal power and hydropower:
http://www.geo.brown.edu/research/Milliken/GEOL0810_files/AmScientist_2002_Europa.pdf
This paper says europa flexes by +/- 30 meters*, and it orbits every 3.5 days so this flexing probably happens either 1 or 2 times in that period. Im guessing this works out comparable to tidal energy available on earth. Enceladus has visible ice geysers. Surely that implies concentrated energy that can be tapped.

*or possibly half that, 30 meters all together. Slightly ambiguous wording.

Electrodynamic tethers.
I know jupiter has massive fields. How about electro dynamic tethers that could possibly also be elevators? The moons are all tidally locked to jupiter. Could tethers actually hang from the moons towards jupiter? Otherwise perhaps they just sit at Lagrange points and beam power to the moon. Or possibly they could just be laid on the moon's surface?Ultimately they are dragging on the moon, draining its orbital energy for electrical power. The principle has been shown in low earth orbit.

I found this paper which suggests quite a lot of power could be produced for a robotic vehicle, in fact getting rid of heat and utilising the enormous power was one of their problems. Of course that would be a non-issue if attached to a settlement on an icy moon.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980203952.pdf

Generally saturn is more interesting though because the jupiter radiation makes any near term moon-hopping hard to imagine. Would electrodynamic tethers produce any useful result around Saturn?

Other options:

Postulating fusion is not much fun because if you have science fiction power you might as well have science fiction ships as well. It may well solve everything but you cannot say much more about it.

Fissionable fuel sent from earth is probably very practical, but that introduces the need for trade or some other purpose, and it is hard enough coming up with trade from Mars. He3 won't be useful for trade until we have fusion.

ISRU to gather our own fissionable products? I don't know much about this but Im guessing it is much harder than on earth because many of the moons have many kilometers of ice above the rock that could hold more traditional ores.

Solar power may still be possible? They may be not so good for probes but you can have a heavier fixed set up and collectors would not have to deal with dust storms etc. Power at Jupiter and Saturn is about 25 and 100 times less than at earth respectively. At least this is an option any other method must beat to be considered. All things equal, solar power is the least controversial.
« Last Edit: 10/21/2018 11:34 am by KelvinZero »

Offline speedevil

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Re: How to power a settlement at Jupiter or Saturn
« Reply #1 on: 10/21/2018 11:49 am »
Solar power may still be possible? They may be not so good for probes but you can have a heavier fixed set up and collectors would not have to deal with dust storms etc. Power at Jupiter and Saturn is about 25 and 100 times less than at earth respectively. At least this is an option any other method must beat to be considered. All things equal, solar power is the least controversial.
Massive large mirrors on (for example) Enceladus class bodies - aren't really out of the question, more development is obviously needed in this area.

1% of the surface gravity of earth and no atmosphere makes film mirrors somewhat easier.
On many of these bodies, radiation from trapped radiation belts degrading solar cells is a major issue.

Getting to these bodies is challenging.
In principle, aerocapture can play a role for some of them, and gravity assists - this does not help for getting off them.
You need 300m/s or so to get off Enceladus.
You need some 17km/s to get out of Saturns gravity well, and then a few more km/s to get to Jupiter, or any inner planets.
(this can be reduced a little, but it's in the realm that it makes non-chemical propulsion to get off).

Very outer moons are rather easier.
Iapetus for example is the outermost large moon I could quickly find has lots of ice of Saturn, and is far enough out that the escape velocity to get away from Saturn is only 4.6km/s.

If you're wanting to get to and from closer to the planet, with chemical propulsion, or ion propulsion without very slow transits, you're going to need lots of hops between icy moons closer and closer in, with ISRU plants on each.
« Last Edit: 10/21/2018 12:07 pm by speedevil »

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #2 on: 10/21/2018 01:24 pm »
If you're wanting to get to and from closer to the planet, with chemical propulsion, or ion propulsion without very slow transits, you're going to need lots of hops between icy moons closer and closer in, with ISRU plants on each.
Hi speedevil,
What inspired me was a table on this page: http://www.projectrho.com/public_html/rocket/appmissiontable.php
It is a huge page and I cannot link to the exact table. Search for "Moons of Saturn"
At a glance it looks like you could get between most of the moons listed with a BFS. Some are a bit borderline, but most of the high delta-v values are Titan and I think they said they were not including aerobraking for that one, and also Titan would probably have a depot at a higher orbit or a Lagrange point.

Maybe space based solar power could actually find a use just before solar becomes a non-option. what could possibly make it work around saturn but not earth or mars is the need for massive collection area for only a fairly small beaming infrastructure. Perhaps enormous thin-film mirrors spinning for rigidity.

As I said before, solar power can be the benchmark. It isn't nothing but can we do better? If one of the other ideas does not have markedly more performance we can immediately discard them.

Offline rakaydos

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Re: How to power a settlement at Jupiter or Saturn
« Reply #3 on: 10/21/2018 05:40 pm »
I've long thought that electrothethers would be an amazing power source for the jovian system. Being magnetically bound to jupiters magnetic field, but gravitationally bound to Io or Europa, you can tap the raw inertial potential of entire moons for electricity. At the draw level for any plausable civilization, orbital effects will be neligable before the sun goes out, so it's effectively free energy.

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #4 on: 10/21/2018 11:34 pm »
I've long thought that electrothethers would be an amazing power source for the jovian system. Being magnetically bound to jupiters magnetic field, but gravitationally bound to Io or Europa, you can tap the raw inertial potential of entire moons for electricity. At the draw level for any plausable civilization, orbital effects will be neligable before the sun goes out, so it's effectively free energy.
A couple of ideas occur:

(1) These bases would not need to be assembled under high radiation. You could built tether-propelled stations out at Callisto, and then they could use their tethers to generate drag and manoeuvre themselves down into Jupiter's gravity well and just sort of "dock" with an inner moon or one of it's Lagrange points. No assembly required. (I haven't done the math to see how long a physically docked tether would have to be.. it would have to stretch past it's Lagrange point I guess)

(2) Radiation is a problem, but you could design vehicles that allows the propulsive landing fuel to be used as shielding, and living space could be very cramped because trips only a few days, and you do a hoverslam type landing at the destination so there is only a very short period where you have less shielding.

Does anyone have figures on how much shielding you would need? I know the radiation is massive and can kill you in an hour or so but I would have assumed it was low energy compared to cosmic rays, similar to solar storms.

Offline Robotbeat

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Re: How to power a settlement at Jupiter or Saturn
« Reply #5 on: 10/22/2018 02:49 am »
Solar with giant ultra-thin mirror concentrators.
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Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #6 on: 10/22/2018 06:38 am »
Solar with giant ultra-thin mirror concentrators.
Maybe east-west troughs? Then instead of moving the large flimsy reflector you could just move the thin line of solar cells to follow the focal line. SSP might actually become practical also, because the infrastructure to beam the power might become quite small compared to the massive collector.

Anyone prepared to hazard any maths to see which is more promising around Jupiter and Saturn? Solar or electrodynamic tether? I included a paper above. It mentions some absurd sounding peak power values for either the 10 or 4.7km tether:
". In a circular orbit near the planet, it appears that induced tether voltages
can reach as high as 50,000 V, currents can become greater than 20 A, power levels can reach over a million
watts, and propulsive forces can reach higher than 50 N"

It had all sorts of provisos though, including speculating that performance would be much worse near europa unless it provided its own plasma to the region.. but do we even need that if we are actually on the moon? Could we use the saline ocean as some sort of infinite sink that balances somehow/somewhere, but is not our problem?

(I had a go at the Lagrange point and got 0.02R, or about 13,000km for Europa-Jupiter L1 or L2 but I could easily have muffed that. It is probably too big. Better to postulate a tether at a Lagrange point beaming power down, or perhaps even towers instead of tethers, or something along the surface.)

(edit)

There could also be a dual purpose. How about an east-west railway line along the moons surface.

(edit)

I don't want to bump the thread for a dumb idea but I just wanted to note one other theoretical (if not practical) power source: asteroid bombardment. Maybe you could guide a rock to a position where you could continually use bits of it to target-bombard some precise location on the surface, or perhaps you could survey the millions of near-jupiter rocks and find one that can be used to inject enormous amounts of energy under the ice then exploit it as geothermal/hydrothermal energy for years. Asteroid collisions do not normally do that, but perhaps with foreplanning you could make an atypical crater, eg a string of collisions on the same spot,
« Last Edit: 10/22/2018 10:23 pm by KelvinZero »

Offline mikelepage

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Re: How to power a settlement at Jupiter or Saturn
« Reply #7 on: 11/16/2018 08:34 am »
A couple of ideas occur:

(1) These bases would not need to be assembled under high radiation. You could built tether-propelled stations out at Callisto...

I'm looking forward to Europa Clipper/JUICE results to tell us a lot more about Callisto.  If there's accessible water at Callisto, then in my opinion it immediately becomes much more viable for settlement than just about anywhere else at Jupiter or Saturn.  Everyone's so fixated on Europa's surface ice that the access deltaV & lower radiation advantages of Callisto (or even Ganymede) get largely overlooked.

Offline blasphemer

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Re: How to power a settlement at Jupiter or Saturn
« Reply #8 on: 11/16/2018 08:50 am »
Everyone's so fixated on Europa's surface ice that the access deltaV & lower radiation advantages of Callisto (or even Ganymede) get largely overlooked.

Indeed, radiation environment around Jupiter looks something like this:


Offline IRobot

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Re: How to power a settlement at Jupiter or Saturn
« Reply #9 on: 11/16/2018 09:52 am »
Hi, I recently saw a table on ProjectRho suggesting that a BFS had the delta-v to travel between the 9 or so major moons of Saturn, and trip times were also only on the order of days instead of months, and I thought "that is the Flash Gordon future that was promised us!" .. but how would we survive there? Most importantly what do we do for power when solar may no longer be an option?
http://www.projectrho.com/public_html/rocket/appmissiontable.php

Where do you see that? AFAIK, it is impossible with chemical rockets.

Offline Zed_Noir

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Re: How to power a settlement at Jupiter or Saturn
« Reply #10 on: 11/16/2018 11:45 am »
Hi, I recently saw a table on ProjectRho suggesting that a BFS had the delta-v to travel between the 9 or so major moons of Saturn, and trip times were also only on the order of days instead of months, and I thought "that is the Flash Gordon future that was promised us!" .. but how would we survive there? Most importantly what do we do for power when solar may no longer be an option?
http://www.projectrho.com/public_html/rocket/appmissiontable.php

Where do you see that? AFAIK, it is impossible with chemical rockets.

IIRC that is with a BFS fully top up with propellants at a local propellant depot in Cis-Saturn space.

Offline bad_astra

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Re: How to power a settlement at Jupiter or Saturn
« Reply #11 on: 11/16/2018 01:33 pm »
If you want to settle the outer solar system (or any part of the solar system), support fusion research. You solve the propulsion issues, you solve the power issues. The rest is fait accompli.
"Contact Light" -Buzz Aldrin

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #12 on: 11/17/2018 02:17 am »
Hi, I recently saw a table on ProjectRho suggesting that a BFS had the delta-v to travel between the 9 or so major moons of Saturn, and trip times were also only on the order of days instead of months, and I thought "that is the Flash Gordon future that was promised us!" .. but how would we survive there? Most importantly what do we do for power when solar may no longer be an option?
http://www.projectrho.com/public_html/rocket/appmissiontable.php

Where do you see that? AFAIK, it is impossible with chemical rockets.

IIRC that is with a BFS fully top up with propellants at a local propellant depot in Cis-Saturn space.
You can find it by following that link and searching the massively long page for "Moons of saturn" .. I don't know why they dont have html anchors so I could link to it directly.. it is not rocket science! :)

It is a nice site for hard SF info. The person did note these values were only representative, probably using the simplest formula assuming circular orbits and no other bodies etc.. Im guessing.

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #13 on: 11/17/2018 02:32 am »
If you want to settle the outer solar system (or any part of the solar system), support fusion research. You solve the propulsion issues, you solve the power issues. The rest is fait accompli.
I agree that is very likely the enabling technology. There is so much to do before we bother going as far as Saturn it seems very likely that it will no longer be SF but commonplace before we consider moving out further than the asteroid belt. We may well even have it before moon bases.

Im not sure supporting it is where I would put my effort though specifically to reach Saturn. I definitely support it for other reasons though. I just mean the big hold ups to getting to saturn are at the moment the same ones that stop us leaving earth at all. Fusion will very likely come along before Saturn missions need it.. or it is so hard, so hugely hard that it would be better right now putting that effort into things like BFS, biosphere research, gravity health etc etc.. where we can get almost immediate progress. Even if we had fusion right now, it may well be decades and decades before it is useful in space. It could be way heavier than solar power or fission power. That is no problem on the ground so it could still be very useful.

For this thread, I chose to ignore the obvious answer of fusion power.. really just for fun and to stick to things we have better numbers on. A flash gordon scenario with known technology.

Postulating fusion is not much fun because if you have science fiction power you might as well have science fiction ships as well. It may well solve everything but you cannot say much more about it.

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #14 on: 11/17/2018 02:52 am »
A couple of ideas occur:

(1) These bases would not need to be assembled under high radiation. You could built tether-propelled stations out at Callisto...

I'm looking forward to Europa Clipper/JUICE results to tell us a lot more about Callisto.  If there's accessible water at Callisto, then in my opinion it immediately becomes much more viable for settlement than just about anywhere else at Jupiter or Saturn.  Everyone's so fixated on Europa's surface ice that the access deltaV & lower radiation advantages of Callisto (or even Ganymede) get largely overlooked.
I have long considered Callisto the prime target for Jupiter. My understanding is that it is essentially certain that ice and carbon is available to a civilisation confident enough to send crew out that far. The density implies it contains a lot of ice, and ice and CO2 have been detected on the surface (according to its wiki page which I just checked :) ). You could set up your colony there and perhaps figure out how to use that ice to create highly shielded shuttles to exploit other moons of Jupiter.

For this thread I also have a pet interest in Saturn though.. not necessarily a sensible one: just that apparently a BFS-like performance could travel between all the major moons of Saturn, and my understanding is that shielding from Saturn's radiation is plausible without an entirely different sort of ship. It was just this combination of knowable technology and a mini-solarsystem of worlds that a trader could travel between that I thought was cool. Flash gordon, Serenity, millenium falcon, it is such a common trope of a single-owner ship that can visit multiple worlds. I imagine whatever we use to enter the radiation belt of jupiter to be more like a government-managed subway system. massive shielded cyclers or similar.

Offline mikelepage

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Re: How to power a settlement at Jupiter or Saturn
« Reply #15 on: 11/17/2018 07:31 am »
For this thread I also have a pet interest in Saturn though.. not necessarily a sensible one: just that apparently a BFS-like performance could travel between all the major moons of Saturn, and my understanding is that shielding from Saturn's radiation is plausible without an entirely different sort of ship. It was just this combination of knowable technology and a mini-solarsystem of worlds that a trader could travel between that I thought was cool. Flash gordon, Serenity, millenium falcon, it is such a common trope of a single-owner ship that can visit multiple worlds. I imagine whatever we use to enter the radiation belt of jupiter to be more like a government-managed subway system. massive shielded cyclers or similar.

Along those lines, another possibility you could consider is travelling between hypothetical colonies at trojans in Jupiters L4 and L5 libration points.  The Greeks and Trojan camps could conceivably have whole groups of asteroids that stay (relatively) close together.

Offline KelvinZero

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Re: How to power a settlement at Jupiter or Saturn
« Reply #16 on: 11/17/2018 12:40 pm »
Along those lines, another possibility you could consider is travelling between hypothetical colonies at trojans in Jupiters L4 and L5 libration points.  The Greeks and Trojan camps could conceivably have whole groups of asteroids that stay (relatively) close together.
Thats absolutely true, we can have thousands of different "worlds" in reach of each other if we include asteroids and O'Neill colonies. Still IMO not quite the same as moons with their own memorable characters, in the shadow of a world like Saturn.. and you could find these around Saturn as well. There are many rocks around Saturn beyond the 7 roundish ones (apparently only two of saturns moons are technically classified as being in hydrostatic equalibrium.. I just read that on https://en.wikipedia.org/wiki/Moons_of_Saturn )

Im moving too far into the SF element though. I put this in the Advanced Topics section to get into the technical details.

In particular, would anyone care to have a stab at estimating the potential (pun not intended) of electrodynamic tethers? I included a link to a paper above, suggesting massive potential.

I think the complicated bit about electrodynamic tethers is the part that depends on the plasma environment, that I think closes the circuit.. However I think we could at least put an upper bound on the energy that could be extracted from a wire of certain characteristics moving through a magnetic field of a certain strength. Knowing that would be a good start. If that is already lower than what you could expect from the same mass of reflectors and solar power then we could discard it without getting any more complex.

Edit: here is that link again, reposted from the OP.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980203952.pdf

and also I put a reference about tidal effects there, another energy source that might possibly be superior to solar at Saturn.
« Last Edit: 11/17/2018 12:44 pm by KelvinZero »

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