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[PTTG??]

...Martian solar power actually makes a lot of sense. There isn't any free oxygen on mars, so any combustion requires twice the fuel mass per watt-hour, while solar functions endlessly. Nuclear fuels require heavy shielding in transit, or else some kind of extremely complex mining and refining rig that I haven't even hear of being designed.

The big problem with earthly solar panels is night/day. Mars has the same problem, but fortuitously has the same solution- wind. Mars has higher-speed, lower-density wind, which we may be able to use at all times.

Batteries are hard to ship, yes, but most electrical use is during the day anyway. Keeping the place warm and lit at night can be done with minimal power, possibly provided in part by wind turbines.

The biggest advantage of solar for space, of course, is that photons are free- they don't require additional mass for your spacecraft's or bases' electrical fuel.

[MonkeyHead]

Solar power on Mars is a non starter. The dust issue has been raised so many times in this thread. Do people not know that the Spirit and Opportunity rovers shut down over the martian winter as thier quite low power requirements could not be met? Its not really feasable to run a colony/base/outpost on such a mechanism.

As for wind - the Martian atmosphere is one tenth (IIRC) as dense as Earths. A 100 MPH martian storm would feel like a 10 MPH gentle breeze on Earth. Whilst yes there is energy there to be harnessed, Mars simply doesnt have extended and widespread 100 MPH winds - they are intense, but localised and shifting. The large Martian dust storms might have high(ish) speeds and pretty wide spread, but not a lot of energy to harness due to the lack of atmospheric density.

You dont need to ship the nuclear fuel in its bare form, or even as a material needing processing. Nuclar batteries would be a sensible option, and these have been proven as a reliable and safe option on many, many space missions. Make them on Earth, in orbit or the Moon, and send them to Mars. Or send them down our space elevator - more on that below.

Or, of course, Hydrogen fuel cells, if sufficient water can be found there.

Or, again, collect the solar energy in orbit and microwave it down. If you have a space elevator (which to be fair if we had a colony building programme, we probably would), use the orbital hub to generate the power and transmit it in the tether.

[PanH]

Solar and wind power aren't enough for humans needs, as for the low production, and for the variability (because, you don't use the same amount of energy sleeping, the morning, the evening, night, etc).

Considering we're talking about the future, I would more consider fusion reactor, with easy fuel requirements. Of course, there's still issues, as it's very complex, and needs a lot of energy to be set up, etc. And it also needs a quite big settlement to use all the energy produced. But the potential for this technology are just huge.

[10ebbor10]

No it doesn't. Besides, why would nuclear fuel need heavy shielding. Pretty much every long term probe/instrument runs on a small fuel cell, and these aren't really shielded extensively. Nuclear fuel cells also have an enormously large energy density, unlike solar pannels. Oh, and keeping the place warm and supplied with energy is actually one of the more energy consuming things.

Just a recap:

Solar pannels:
     -Day/night problems
     -Sandstorm problems (These can be global, and last several months during which power is reduced by up to 99%. Top production on Mars was about 50% of max capacity)
           -Wear and tear (Don't expect solar pannels to last longer than 10 years in space. I give them maybe 15 on Mars. Longer if you use low power, high durability pannels)
     -Weakness to solar flares (Solar pannels tend to be really inefficent when buried underground, so no shielding them)

Wind mills
     + High wind speeds
           -Irregular wind speeds (Those really fast winds are quite rare), often it is slower
     -  Athomspherical density is near nihil. A 300 km/h wind at 0.6% airpressure is the equivalent of a 23km/h wind down on Earth. And 0.6% is at the deepest canyons. Often, the pressure is far lower
     -Wear and tear due to frequent temperature changes and sand getting in the moving parts.

Nuclear power
      +Constant,reliable power source
      +Can be put wherever you want it
      +A single fuel cell can supply an average town for 30 years.
      + Modern day reactors are mostly failsafe
      +Waste heat can be reused to heat the base or produce rocketfuel (The latter requires to run the reactor at quite high temperatures, but a properly designed reactor should be able to handle them ).

As for wind - the Martian atmosphere is one tenth (IIRC) as dense as Earths. A 100 MPH martian storm would feel like a 10 MPH gentle breeze on Earth. Whilst yes there is energy there to be harnessed, Mars simply doesnt have extended and widespread 100 MPH winds - they are intense, but localised and shifting. The large Martian dust storms might have high(ish) speeds and pretty wide spread, but not a lot of energy to harness due to the lack of atmospheric density.

Or, of course, Hydrogen fuel cells, if sufficient water can be found there.

Some corrections are needed. Mars athmos is actually only 0.6%. Also, kinetic energy=m*v²/2. So a 100mph wind in a 1/10 athmosphere feels like 31 ish Mph wind.

Hydrogen cells are a means of storing power, not producing it. You can't get more energy out of the burning of hydrogen fuel then you used to create it from water. Also, Mars has extensive underground glaciers and  polarice , so no water prblems.

 

Solar and wind power aren't enough for humans needs, as for the low production, and for the variability (because, you don't use the same amount of energy sleeping, the morning, the evening, night, etc).

Considering we're talking about the future, I would more consider fusion reactor, with easy fuel requirements. Of course, there's still issues, as it's very complex, and needs a lot of energy to be set up, etc. And it also needs a quite big settlement to use all the energy produced. But the potential for this technology are just huge.

While fusion is indeed promising, I doubt we'll see it soon. Sustainable Fusion generator power's output ranges from a midsize nuclear generator to a small country.

[PanH]

While fusion is indeed promising, I doubt we'll see it soon. Sustainable Fusion generator power's output ranges from a midsize nuclear generator to a small country.

There is some civilians prototypes running, and an important test plant should be finished in 2020 (including already 3 years late). Lots of prototypes are running since years, even though they're mainly about testing, potential uses, and not much about energy production.
And it's already used since decades in military devices.

[10ebbor10]

While fusion is indeed promising, I doubt we'll see it soon. Sustainable Fusion generator power's output ranges from a midsize nuclear generator to a small country.

There is some civilians prototypes running, and an important test plant should be finished in 2020 (including already 3 years late). Lots of prototypes are running since years, even though they're mainly about testing, potential uses, and not much about energy production.
And it's already used since decades in military devices.

There's about a hundred different fusion power plants, but the technology needs it's time. After the Iter test plant, there's another plant planned before we'll see the first commericial ones.

[sneakey pete]

Nuclear power
      +Constant,reliable power source
      +Can be put wherever you want it
      +A single fuel cell can supply an average town for 30 years.
      + Modern day reactors are mostly failsafe
      +Waste heat can be reused to heat the base or produce rocketfuel (The latter requires to run the reactor at quite high temperatures, but a properly designed reactor should be able to handle them ).

You seem to be getting nuclear reactors and Radioisotope thermoelectric generators confused, and taking the best points of both while ignoring the downsides of both.

Namely that RTG's are terribly mass inefficient, their power output slowly degrades over time, and they dont' have radiation shielding on space craft because no humans are on said spacecraft.
A reactor, on the other hand, is rather heavy, but probably more mass efficient. There is the whole issue with the global outcry you'd get trying to launch one.

[10ebbor10]

I was talking about  pocket reactors. Small, lightweight and mostly autonomous IV gen reactors. Not quite deployment ready, and still pretty heavy but their benefits should outweight the costs.

Completely trustworthy and neutral source

Edit: Similair things have been build into submarines, so a slightly upscaled version should work.
Edit 2: And considering the alternatives and how often nuclear fuel is used in space, I don't think there'll be much outcry. The green parties will throw a fuss, of course, but they always do, even if it means that they're actually hurting both the environement and their voters.

[Sheb]

Re: reactors: what will you use for cooling on Mars?

[10ebbor10]

Re: reactors: what will you use for cooling on Mars?

Underground ice layer. Recycle the heat as base heating, ice melting and maybe even fuel production. It's a win-win situation.

[Sheb]

It'll be a logistical nightmare to mine the ice fast enough to cool your reactor, but I guess it could work.

[10ebbor10]

It'll be a logistical nightmare to mine the ice fast enough to cool your reactor, but I guess it could work.

It's a fourth gen pocket reactor. It doesn't produce that much waste heat. I mean, some of the reactor designs don't even have any cooling. Completely passively cooled. (Besides, this isn't Earth were a reactor can warm the water with only a few degrees before the fish die. Here you can dump heat en masse.)

((Also, you can use the cooling system as the ice exavation system. Just pump hot steam into the ice using one pipe, and pump up the melted water using another. Warning, might cause Earthquakes. And explosions.))

[Starver]

2. The rovers have a max speed of 500 meters a day, run out of power frequently(I'll mis you, Spirit) and are screwed every time a dust storm happens. Also shading increases energy absorbtion, so it doesn't help. It just increases overheating.

This came up the other day.  Can't remember which rover it was (Sojourner, Spirit or Opportunity), but when one of them landed, the power it collected was (IIRC) 900Wh.  Then the dust started to build up, and it fell, fell, fell, down to 350Wh.  250Wh would have been "death", they think.  Then a wind came along and dusted the panels clean.  And because of a more favourable elevation of the sun, at that latitude in that particular season, the panels actually produced more power than they had upon landing.  They had to schedule an afternoon "siesta" for the robot to prevent the electronics from overheating, having now more than enough power to run the robot for far longer than they could actually make use of it for.

A shade would absorb light and itself heat up, yes, (unless it was reflective, of course), although you needn't have the shades conducting heat towards anything you don't want (either anchored in regolith or free-floating in orbit).  But, hey, why not just tilt the panels?  Louvre them according to the need for power, using the same mechanism that would normally track the sun for best energy conversion to take them off the optimal perpendicular?

Anyway, this station has a guy with a brush stored in the airlock, if that's still a problem.  And spare bits and pieces ready to be fixed if something like Spirit's semi-broken wheel happened to a bit of base equipment.


Ah, hang on, we're on Space Stations again, aren't we, I see...

       3. Orientation mechanics clash with the fact that the station has to rotate. This combined with a large size means that the pannels will suffer severly from centrifugal force. After all, in order to get decent efficiency you have to point your cilinder at the sun, and only use one layer of pannels (any next layer would just be shaded by the first) This means that they have to extend a long way from the station, hence enormous centrifugal force. They'll tear the station apart.

You're designing the station wrong.  Even if you had to set your panels further out from the station, plenty of Earth structures withstand 1G, and can handle more.  It's quite possible to ensure that you can make the station withstand the centrifugal or centripetal forces, as necessary, for quite a range beyond the 1g 'nominal'.

I'd set up a stationary solar array station in close proximity (to allow some form of Broadcast Power to be easily used and coordinated) and not bother spinning it, if it were actually troublesome (and I don't think it is) to attach most of the panels to the rotating wheel/cylinder/whatever...

4. A space station always needs to be in orbit of something. Otherwise it's crashing into something, or wasting ridiculous amounts of energy for maintaining it's position.

I'd never even consider the latter 'station-keeping' effort as practical.  Being in freefall, of some kind, is going to be a given, whether that be in a stable/semi-stable Lagrange point (a little bit of station-keeping may be needed, but only a little, as long as you keep it under control), pretty much any standard orbit you care to mention or some kind of 'resonant' orbit ('horseshoe' around two barycentre-sharing bodies, or a carefully-timed inter-body transfer orbit between co-orbiting bodies of a parent mass).

And then there's the outwardly-going hyperbolic freefall path of a future inter-solar exploration vessel.  (But I wouldn't consider counting on solar power for that mission...  I'd start by equip ping the hollowed-out asteroid/minor planet with something nuclear, I think...  But it'd depend on the contemporary tech available near the time of launch, really...)

The only thing angular momentum does is creating artificial gravity and allowing the spacecraft to maintain it's current heading. It doesn't supply any force to negate gravity. (If it did that, It would either need to slow down or be producing infinitive energy)

I sort of understood where you were at with your original response here.  I thought you'd probably misunderstood what was meant (i.e., you can move space-stations around, doesn't need to be stuck in LEO at all), but where you're going with what you just said, I don't really know.

Are you, perchance, conflating the angular momentum of the station's own frame of reference ('artificial gravity', by way of applying centripetal force to the soles of those standing inside the wheel) with the angular momentum of the station travelling in whatever orbit/freefall path it is currently instanciated in?

I get the idea you have no bloody idea what you're talking about.

I think, perhaps because you're misunderstanding things that I think I understand, but that you're seemingly interpreting quite differently, I'm perfectly entitled to fire that statement back at you.  However, I'm going to restrain from saying that you misunderstand your understanding, because there may still be more confusions at my end, regarding one or more bits of what I've snipped...

[Starver]

Loads of minor points to many posts, so (after the above reply) I decided to compile them instead.  Hopefully my formatting/attribution is correct for each of them and I haven't missed anything in the back-and-forth...

There isn't any free oxygen on mars, so any combustion requires twice the fuel mass per watt-hour,

Erm....  Combustion would use the same fuel, but need to be supplied more oxygen.  There's 0.13% Oxygen on Mars, IIRC, compared to nearly 21% on Earth, so you'd need to concentrate that oxygen to anything up to 160 times what it normally is.  Or less, if you can feed it faster without removing the "heat" third of of the "fire triangle".

Nuclar batteries would be a sensible option, and these have been proven as a reliable and safe option on many, many space missions. Make them on Earth, in orbit or the Moon, and send them to Mars. Or send them down our space elevator - more on that below.

By "Nuclear Batteries", you mean Radiothermal Generators, yes?  I'm not sure they're quite as good as straight fission (or possibly available fusion) power generation plants.

IIRC, the devices so far rarely reached more than a few tens of Watts each.  (There was one which was an actual reactor at the core of the thermoelectrical jacket, which was quite powerful, though.  A few kW.  But I'd consider a standard reactor/turbine concept a bit more efficient, with the inevitable maintenance problems surely improved by future developments.  There's probably an intermediate step that's better though.  What's that Thorium concept supposed to be again?)

Or, of course, Hydrogen fuel cells, if sufficient water can be found there.

You also need a source of energy to split the water so that when you recombine it you can recover (a portion of) it...  Of course, if you manage to split it with some photoactive method (perhaps bacteria/something akin to photosynthesis) then you can have that going and pipe the split components in the appropriate parts of the 'uncharged' cells ready for use.  But you still need to get the sunlight on the generation units.

There is some civilians [Fusion generator] prototypes running, and an important test plant should be finished in 2020 (including already 3 years late). Lots of prototypes are running since years, even though they're mainly about testing, potential uses, and not much about energy production.
And it's already used since decades in military devices.

Wut?  I've not heard a thing about fusion power, civilian or military, having been "in use" at all.  They've got various machines where, for a few milliseconds or so they can pump in a huge amount of power and momentarily get...  well, I'm not even sure if they've broken even, just yet, but a (not so?) huge amount back for just that moment, straight from the fusion (or from the heat generated, or something)...  But they're a long way from being self-sustaining.

Unless I've been asleep and missed something.

It'll be a logistical nightmare to mine the ice fast enough to cool your reactor, but I guess it could work.

Poke metal rods down there, connect the rods to the hot stuff, let it radiate away.  Perhaps suck some meltwater back up, but ensure there's still a water-jacket and if you did have excess heat (and I'd be surprised, given how cold the atmosphere is, as well) it'd mildly raise the ground temperature.

The biggest thing to watch out for would be sinkage into the (ex-)permafrost.  But given the general Mars environment I think I'd assume that if we were going to suffer from that, we were going to suffer from the weird "spouts" we've already seen erupting on Mars, anyway, and we've chosen a bad bit of Mars despite all the surveryine we will have done by then (or not a good enough 'bedding structure' beneath the base itself to withstanding the shifting and erupting surface that we should be expecting).

[GreatWyrmGold]

Well, unless you give me an exemple of something that can threaten a Earth base, yes, I'll consider you as an uninformed pessimist who like space. And war ain't it. Just dig deep enough, keep the location more or less secret. If there is anything that can threaten you, humanity is advanced enough they don't need your help.

"Just dig deep enough." Yes, self-sustaining underground bases are so cheap and easy...especially housing 2-3,000 people. How deep is it before it starts costing as much or more than a Lunar base to build and keep alive? (Hint: A Lunar base could be built for a "mere" $35 billion; I calculated that, under ideal circumstances and assuming solar panels of merely 15% efficiency, and putting a $50-60 billion price tag on the whole thing, exporting solar power to Earth at well below market price repays that in weeks. Solar power alone.) That's not good for ya? Ignoring environmental issues as good problems, too? How about political crap? That could be more devastating than a war. If, for example, you put this hypothetical, expensive, base in Alaska, and after a war Russia annexed Alaska, what happens to the base? Even if this is unlikely, consider the basic concept: As long as a base is on Earth, it is susceptible to Earth-based attacks. Don't buy that, either? Somehow you've made it immune to every kind of attack known to man? Seismic events would ruin your base. They're not much of a problem for a Lunar base near the surface, but an underground base hit by an earthquake would probably risk caving in. Still not good enough? What did you use to get down there? Your seal on the door had better be pretty good, or your little base is going to get water trickling in from rain or melting snow, assuming that the aquifers in the area are nonexistent or properly sealed. Too improbable? How about your settlement breaking down because you're always a mile or several underground, with no chance to have fresh air, see the stars, or even be in a relatively open area? (A lit dome a couple hundred feet across might help, while rendering it more vulnerable to attack or earthquakes.)
Not good enough for you? Gimme a bit.

-Solar flare: Survivable, and a Martian colony will be hit much harder than Earth.

Isn't Mars farther away from the Sun? And wouldn't a Martian base presumably be built with a temporary radiation shelter for stuff like this?

-WWIII: You really think that an off planet colony will be able to maintain neutrality? After all, an offworld location is one of your best assets to break the MAD stalemate

I can't imagine an offworld base being worth the resources it takes to attack, let alone the time. Enemy missile stockpiles and such are much bigger threats, and don't require you to lift nukes into space to attack them. Also, you're assuming that the colony is built by a government. Why would Russia, the US, North Korea, or anyone waste resources on, say, an AT&T base on the Moon when they've probably got a dozen or more Terran threats to nuke?

And besides, the requirements for a fully, completely autonomous colony are enormous.

Define "fully, completely autonomous." Once you have food, water, oxygen, shelter, and power, it seems you're mostly set. The first three can be mostly or entirely solved by greenhouses; shelter and power should be obvious.

Mine oxygen from asteroids. 
Or send the rocks from the moon.  Silicon aluminum and oxygen rich stones, they are.  Yoda speaking I don't know why I am.

Can you explain to me how that would be easier than an Mars based colony (or an moon colony, or an "asteroid" colony) ?

Sure --1. the energy to go to a whole bunch of asteroids and mine them is much less than landing on Mars.  (the joke among astronomers is that leaving the earth gravity field is the half way point to the rest of the universe.  Mars is probably only about a fourth as bad as the earth, but it's still a lot of fight to leave and return)

You seem to be assuming that we're collecting the minerals for export to Earth. We're not. The costs of falling safely on Mars or wherever are fairly trivial compared to the costs of leaving Terran gravity.

2 the energy collected on Mars vs. a full time space station is significant (Mars gets less than half the solar energy that Earth does Mercury gets like 10 times more)  And no energy is expended on cleaning off the solar panels.  (Mars is awfully dusty -- which is a problem with the spirit and opportunity [rovers&  b4 curiosity])

True, but there's also a lot of space to set up solar panels...or anything. And power's even worse out in the asteroid belt, so you'd best find a lot of near-Earth asteroids...

3. More variety of mining [or at least less friction to mess up the travel to mine]  Importantly WATER is much more common in asteroids -- or it may be possible to mine a comet for water.   (This does exclude the poles but according to the wiki article  "When the poles are again exposed to sunlight, the frozen CO2 sublimes, creating enormous winds that sweep off the poles as fast as 400 km/h" -- I don't think that's a smart place to put a station)

We can do that on Luna or Mars, too.

4. Once you've gotten it started you can make other things (such as something to mine out the whole of Mars -- which you can't do with a planet without causing instabilities and messing up with gravity (there is virtually no gravity in the middle of the planet because the pull goes in all directions equally)

Why would you need to mine out Mars?

Solar and wind power aren't enough for humans needs, as for the low production, and for the variability (because, you don't use the same amount of energy sleeping, the morning, the evening, night, etc).

Nice thing about non-Earth areas, they have acres to burn. Dust and low atmospheric pressure are still issues, but a bit of labor (maybe brushing off the panels once a week?) and using lots of windmills as a backup only can help compensate.

Don't bet on fusion. I'm reminded of a quote about stem cells: They're 20 years away and always will be.