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[darkrider2]

Cargo would burn up in entry.
Cargo would not be able to handle impact.

And... Er... Kinda important thing: you'd be shooting something at the Earth.  People live there, for cryin' out loud!

Our astronauts have already been able to come in on their command pods.

And just land the stuff in the ocean, plenty of ocean, easy to hit that.

Whether the actual cargo itself is able to structurally withstand the G forces of the impact is dependent on what the cargo is, if its just minerals and ores then I'm sure its plausible to shoot it from the moon to earth, unless its like, really volatile or brittle or crystalline.

[MetalSlimeHunt]

Radioisotope thermoelectric generators aren't really viable for human settlements. They produce low but very long lasting and reliable power, which makes them excellent for ion-engine probes and low activity rovers. A settlement's energy needs, on the other hand, would be high and rapidly fluctuate even with the strictest rationing. Anywhere live humans are for an extended period will have that trait.

There is also the issue of your generators all being deadly radioactive and remaining so long after they stop working.

[Thecard]

Hitting the ocean from orbit with a giant gun that fires crates capable of withstanding impact and re-entry is not an exact science.  You could hit a small but inhabited island, a boat, a whale, and you could get "bounced" like most space junk that tries to hit Earth, and the flight path could change drastically and unpredictably.

I am against shooting at Earth from the moon with a giant-ass gun that shoots really structurally solid containers.

Not to mention the recovery of said containers.  While pods can be used to get back to Earth, the space program would rather not do that.  Waste if resources and such.  Also really bloody dangerous.  Also manned.

[Flare]

Err... If you shot stuff from the moon to earth, a couple of things would happen.

Cargo would burn up in entry.
Cargo would not be able to handle impact.


And... Er... Kinda important thing: you'd be shooting something at the Earth.  People live there, for cryin' out loud!

Read carefully , we're talking about shooting stuff to mars.

In any case, you could always aim at Canada or Russia. But most likely Canada. We've got tons of land where no one lives. The main issue I think is how you would design a place that can take multiple payloads aimed at it without becoming a nuclear wasteland. Maybe if you build a long electromagnetic tunnel that will slow down the scaffold of the payload. Engineering on that scale however, is not something we can even dream about at this point though.

[Il Palazzo]

Sure the middle spins, once a day [assuming 1 mile diameter and 1 g].  The spin is minor.

Just noticed this. You need to check your math.

[GreatWyrmGold]

Millennia.  Mil means the same thing it always does as a prefix.

Millennia. Nope, spellcheck doesn't like that either. Oh well.

In any case, supposing that the craft uses a really old school nuclear reactor (diesel punk ftw), you could always just toss it out of the ship. Space, within the region of star is already dangerously radioactive already.

...In what universe is nuclear reactors "diesel punk?" It's some sort of punk, but not really diesel. Nuclear punk? Is that a thing?

Au contrare. Solar energy will be about two and a half times more efficient in space, and while I can't remember the exact stats I seem to recall something like 1,367 watts per square meter available. Even at 10% efficiency (and current photovolkaic cells can get a bit above 17%) would generate over 50,000 watts with just two 5x5 meter squares.

Ah, I thought you would use it on the surface of mars . Around earth solar would be great even with the theoretical limit we have reacted with today's tech. Another way to harness solar energy is to simply skip the solar panel thing. Sticking out copper rods into the vacuum of space can absorb a lot of energy, and can operate like that of nuclear reactor, albeit with a lot more moving parts.

Seems like it would be a lot of work to keep rotating the rods...unless they were sticking halfway into space and halfway into the reactor...probably better to make them sheets.

To be more specific actually, there is likely a large deposit of uranium on mars.

I'm a bit skeptical about fueling a whole fleet on uranium deposits. I guess I'm just thinking a few centuries/mellenia ahead of everyone else. Millenia? How do you even spell that word?

Well a nuclear reactor doesn't need that much fuel to power it. New models of nuclear reactors can be engineered to the size of a large freezer (trouble being funding and the general public's fear of loading nuclear fuel into it every few years). The energy density of uranium is incredibly high, and is vital in areas further from the sun, where sun exposure is limited, and when the star ship might encounter situations that simply call for more power, or consistent power.

I'm not sure about relying on nuclear power. I'm not against it, but I'd rather we moved our spacefleet to renewable energy ASAP.

As for mining, I'd imagine it'd be pretty simple actually. Most of the energy used to mine out uranium is used to ensure that it doesn't kill the people mining it, and that it doesn't pollute the environment. Neither of which is going to be an issue on mars. The only issue on mars, is that it would have to be sent into orbit and require a lot of energy to be done so, even if it's smaller than the earth. A more practical solution is to mine it outside of a large body. Mar's moons are relatively unexplored, but our moon does have uranium, and can be mined and sent into orbit with relatively little energy cost because of the low gravity. Asteroids are another contender. Though they might be mined for other more valuable metals than fuel.

Again, the problem isn't with nuclear power, it's more with finiteness. Also, the tech for solar power is already here. Even that copper sheet boiler idea probably wouldn't be too hard to figure out...and if not, it's not important.

Talking about the energy sources used on the surface of mars is like talking about what the inflight meal is going to be on a proposed jet airliner design, an afterthought.  The huge central problem is the transport costs to get to the surface of mars.  Every kilogram of non-human equipment you send to mars is going to cost as much as sending more then 10 kilograms into orbit.  Human cargo would be even more prohibitively expensive.  Power is a cakewalk in comparison, you could just crash some radioactive material into the planet without parachutes, dig it up then use radioactive decay power generation like deep space probes do.  That wouldn't be cheap but it would be a rounding error compared to getting functioning life support equipment onto the planet or getting living humans to safely touch down in such a thin atmosphere let alone landing the tools for industry.

Hardly true. Even though energy expedentures on the colony for the first little while won't be much, they're vital and WILL add up. Besides, you'd need to lift the same stuff into orbit to make a space station--more, because mining isn't an option in space, so you'll need to bring EVERYTHING with you.

The whole point to the space station colony idea is that it minimizes launch costs whenever possible.

How? You're still lifting the same mass up. Descent is insignificant compared to ascent.

As little of the work is done on the moon because its much more expensive to reach the moon then to go into orbit.  Bulk materials are launched from the moon by catapult rail because that allows you to avoiding using massively expensive rockets.  Keep your population and your work close to earth where they are easier to support.  Then when they develop their own industry they can build propulsion in space far more cheaply then sending it up from space.

Wouldn't it be easier to smelt the ores on Luna before launching them, or better--not launch them at all?

Let your ideas live and die by delta-v costs.

Same to you.

If you can get those to work the idea can be made to work.  If they cant then nothing else matters.

Guess what? Your ideas are harder on delta-v.

Oh, and about shooting stuff into the Pacific or Canada or wherever: Ever read The Moon is a Harsh Mistress? They threw rocks at Terra. Ore is rock; metal is essentially rock. Be very very careful about shooting heavy stuff at Earth...

[Thecard]

Millennia.  Mil means the same thing it always does as a prefix.

Millennia. Nope, spellcheck doesn't like that either. Oh well.

Spellcheck can suck my fat one.

[10ebbor10]

Nuclear has the advantage of being lightweight, reliable and fairly compact. Also, a nuclear reactor can be dug in, and completely shielded. In fact, a small pocket reactor will outlive solar pannels about 20-40 year, depending on the type of reactor. Also, there's lot of uranium around.

Also, for those of you proposing open circuited systems(exposed circuitry), remember that any solar flare will kill the system stone death, unless you protect them. That'll cost lots of energy, reducing efficiency enormously.

As for cheap reentry systems. Remember paper planes. Scale that up. Apply origami. Have a compact, safe, lightweight and cheap reentry device. Won't work for Mars though. Air density is to low. You'd need retrorockets.

The main problem with Martian colonies is radiation. Solar flares especially. They won't kill anybody. Not immediatly. That's what all recent mars projects are proposing. Just don't account for the dangers. If it only kills the astronauts in 20 years, the mission has been a succes. They're sending people to their deaths, should a flare occur during the half a year journey, or during their stay on Mars. (Mars doesn't have a magnetic field).

The other main limiters are launch and design costs. Energy costs are not of the issue, at least not at the moment. Most likely it won't be for a long time.  At the moment it costs 2000 dollar per kg to get in to LEO. Mars orbit is far more costly. Even for nuclear reactors, the largest part of the maintenance cost is safety. Fuel only amounts to less than 20% of the costs. With a space based reactor, you can drop most of that.

Also, uranium has a ridicously high energy density, far outranking any other fuel sources, barring fusion.

Where does the idea come from that renewable means reliable, or that fission supplies are limited. We have reserves for more than a hundred years. By that time fusion should be working. I don't think we'll ever use solar pannels as (sole) powersource on (manned) expeditions. They're just not reliable enough.

[GreatWyrmGold]

A few notes.

1. Who's been suggesting opening circuitry to space? The closest thing is the idea of using copper rods/sheets to concentrate heat for an alternate method of solar energy (which would certainly be more durable that photovolkaic cells).
2. The radiation issues are bigger problems in open space, because you can't make any underground bases in space.
3. I'm aware that the supplies are effectively unlimited for a few centuries, but I'm not interested in delaying fuel problems for our great-great-great-great-great-(inhales)-great-great-grandchildren if we don't have to.

[10ebbor10]

1.Your average solar pannel doesn't have the insulation nessecary to whistand a flare. Luckily the magnetosphere protects us, but sattelites are still often damaged by an errant flare. Most precise equipment is deactivated for that reason. It was a hyperbole to state the difference between large pannels taking the brunt of the blow (also, solar pannels aren't really secure from outside interference. The circuitry is pretty close to the outside.) and a shielded reactor near the middle of the ship

2. I was talking about the voyage to Mars. Hopped into the middle of the discussion here. However, if you're talking about supplying a Mars base with solar power, forget it. Mars has regular dust storms, which can reduce incoming light to 10-5% of normal volumes for months at a time. A robot might survive that*, a human won't. Also, can't dig in solar pannels.

3. Let's just say that the supplies of the elements required to make these pannels are more limited than thorium and uranium will most likely ever be. And unlike thorium/uranium, these rare earths have much more uses than solar pannels.

*One of the two did, at least.

Are you suggesting we fly into mars's atmosphere on top of a huge paper aeroplane?

There is so much wrong with that, but it sounds ridiculously fun.

Probably not paper. But yeah, something similair. Though it's better for freight(don't know if you want to wait a month for reentry to complete), and shouldn't be used on Mars. Athmosphere is a bit too thin.

[mainiac]

Wouldn't it be easier to smelt the ores on Luna before launching them, or better--not launch them at all?

Because rail catapults DONT USE FUEL.  I explain shit to you and then it sails right through your head without interacting with the stuff in the middle.

[10ebbor10]

Wouldn't it be easier to smelt the ores on Luna before launching them, or better--not launch them at all?

Because rail catapults DONT USE FUEL.  I explain shit to you and then it sails right through your head without interacting with the stuff in the middle.

They do use power though. Which might be the same thing, provided the ice deposits on luna are dense enough, which sadly, they don't appear to be for now.

Also, smelting and refining doesn't use any fuel either, and a smart 3D printer might be capable of printing the entire factory by itself.

Idealy, we'd get a space elevator on the mun, so that only a little nudge is required to get things into Earth orbit for complete assembly.

[Aseaheru]

i think the pest power sources on mars would be wind and nuclear.

[10ebbor10]

i think the pest power sources on mars would be wind and nuclear.

Athmosphere is too thin for wind power. Also, above ground power circuits carry a risk.
The martian athmosphere is 1% of ours, which means a 300 mph wind there carries as much energy as a 30mph wind here. (Not accounting for relativistic dynamics, but they shouldn't be relevant.)

[Aseaheru]

thats still something.