Elon Musk says he will put millions of people on Mars.

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KitemanSA
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Post by KitemanSA »

If you put the mirrors on the SUN side of the L1 point, then any radial outward push on the mirrors would tend to help cancel the radial inward drift of the gravitational fields. HMMM.

They would also be more effective in that they would be closer to the sun. Hmmm again.

Why bother with L1? Just place a big solar sail in Venus synchronous "orbit" blanced on it's own reflective force.

rjaypeters
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Post by rjaypeters »

Lots of ways to skin the cat...

Part of the point was the relative smartness of the mirrors and their small size made it an easily scalable project. Start the mirror building facilities, release the mirrors and one doesn't need to wrestle with a large, flexible structure in orbit (since we're really good at building those!).

One could use the same idea for Mars, just flip it on it's head. Any photon that would normally miss Mars could be deflected to hit Mars. The aestheticians might complain about a newly-bright Martian sky, but they would be shouted down by the people who want to keep warm!
"Aqaba! By Land!" T. E. Lawrence

R. Peters

HopDavid
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Post by HopDavid »

Betruger wrote:
Skipjack wrote:The moon is close and we should be able to colonize it in the near term.
Or Mars. It's a toss up
Launch windows
Mars each 2.14 years
Moon each 2 weeks (from a given low earth orbit)

Trip time
Mars 8.5 months
Moon 5 days

In these respects they're not remotely comparable, much less a toss up.

The big plus for Mars is CHON (Carbon, Hydrogen, Oxygen, Nitrogen). But the Lunar poles have CHON.

Betruger
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Post by Betruger »

The Moon has no atmosphere. Average joes will tend to back Mars more than the Moon.

Aero
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Post by Aero »

Betruger wrote:The Moon has no atmosphere. Average joes will tend to back Mars more than the Moon.
Eatrh atmosphere is ~14.7 psi.
What is the practical difference between no atmosphere and 0.1675 psi atmosphere of Mars.
Aero

Betruger
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Post by Betruger »

It's way more than the Moon has. Until we get to the point where someone, e.g. private push led by the likes of SpaceX, has made outposts on the Moon that are comfy and self-sustaining enough, people will rather back Mars because it's an actual planet. It has sunsets and wind and so on.

At this point you can't say private enterprise is leading the way to settling space. It might be the donkey carrying us there, but the carrot is still public IE unreliable funds. Break even is still only an unrealized prospect.

And the initial reply that Hop snipped above was in the context of the original discussion: millennial timeframe colonization/terraforming scenarios. In that context Mars makes the Moon tiny in terms of real estate and less practicable for terraforming. Skip's premise really kills it for his arguments IMO because anytime you stretch these sorts of technologically-dependent things out to millennial timeframes you invite astronomical amount of unpredictable developments.

williatw
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Post by williatw »

Aero wrote:
Betruger wrote:The Moon has no atmosphere. Average joes will tend to back Mars more than the Moon.
Eatrh atmosphere is ~14.7 psi.
What is the practical difference between no atmosphere and 0.1675 psi atmosphere of Mars.
Because outside of the possibility of a domed over crater(which you could also do on Mars) Martian frozen gases as previously discussed could be nudged to outgas in just a few decades. 300 milibars and liquid water on the service & inclement temperatures. An I am sure in the centuries to follow with cyanobacteria(or maybe kudzu don't know about that) as well as more volatiles(water, Nitrogen, etc.) imported from the moons of the gas giants & the kuiper belt, Mars could become rather earth like indeed.

Skipjack
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Post by Skipjack »

Either way in danger of sounding like a broken record. This is all futile until we get the cost of the pound to orbit waaaaay down.

Luzr
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Post by Luzr »

Skipjack wrote:Either way in danger of sounding like a broken record. This is all futile until we get the cost of the pound to orbit waaaaay down.
Actually, this is all futile until we are able to create small self-replicating machine.

Then the cost of the pound to orbit will not matter that much...

kunkmiester
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Post by kunkmiester »

The machine doesn't have to reproduce, the factory does.

First space colonies are easy--build on earth, launch using non-transuranic nukes in Orion Drive. Solves the chicken-egg problem of destination.
Evil is evil, no matter how small

krenshala
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Post by krenshala »

kunkmiester wrote:The machine doesn't have to reproduce, the factory does.

First space colonies are easy--build on earth, launch using non-transuranic nukes in Orion Drive. Solves the chicken-egg problem of destination.
I'd even be willing to go with a bunch of launches to build something the size of the ISS ... that has the ability to build the rest of the structure using raw materials shipped in from the moon or, preferably, NEAs.

kunkmiester
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Post by kunkmiester »

Since I have the time now(library computers are timed), let me eleborate some, as I have elsewhere:

The problem here is infrastructure in space, and it's a chicken-egg problem to some extent. There's nothing up there, so no one wants to spend the money to go. Since no one wants to go, very few have been working on reducing the price to where people want to go.

Big stuff like colonies are a challenge. With Orion, launching a smaller structure, such as a Bernal Sphere, in one swoop would be no problem. So, build one on earth, launch it, it serves as a work platform. A ship launched similarly will have propulsion modules to spare for asteroid moving and the range to work with it.

Advantage--big thing in orbit real cheap, without having to spend dozens of chemical launches to get things there.

Big deal--Orion uses nuclear bombs for propulsion. You need a nuke without uranium or plutonium and a way to stop HEMP on the way up to do it.

Anyway, it's technically probably the best way to start building orbital infrastructure. Politically, even with 100% clean bombs? No chance. Nice thing about putting up a moon base though, no greenies or politicos to complain, and with a bit more development of 3D printing and other micromanufacturing technologies, it won't be too hard to do with chemical technology.

I think a moon base would be feasible for less than a couple of billion, including a fair amount of habitation. A lot of robotic construction, and sending machines to build machines to build machines and things though. Since the cost for getting to LEO dominates, especially for slower robotic/unmanned missions, a Mars base shouldn't cost too much more.
Evil is evil, no matter how small

Luzr
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Post by Luzr »

kunkmiester wrote:The machine doesn't have to reproduce, the factory does.
There is very little difference between self-replicating machine and factory. In other words, such machine is basically a factory to produce the same machines. It goes without saying that it can produce other things too.
First space colonies are easy--build on earth, launch using non-transuranic nukes in Orion Drive.
That is as likely development as possibility of relatively small (say 10 tons) self-replicator. Launching 10 tons to some NEO asteroid is nothing we could not do easily now...

Luzr
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Post by Luzr »

kunkmiester wrote: I think a moon base would be feasible for less than a couple of billion, including a fair amount of habitation. A lot of robotic construction, and sending machines to build machines to build machines and things though. Since the cost for getting to LEO dominates, especially for slower robotic/unmanned missions, a Mars base shouldn't cost too much more.
Exactly. What I wanted to say is that the space colonization is basically a problem of cybernetics (and/or perhaps genetics), not of launch technology.

HopDavid
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Post by HopDavid »

Betruger wrote:And the initial reply that Hop snipped above was in the context of the original discussion: millennial timeframe colonization/terraforming scenarios.
Um... no. Here is the original post in it's entirety:
Betruger wrote:
Skipjack wrote:
We aren't going to sit around on Earth surface doing nothing for millenia, waiting to reach this technological readiness. Colonization now is better
I would not sit arround for millenia. The moon is close and we should be able to colonize it in the near term.
Or Mars. It's a toss up and frankly colonizing Mars is more inspiring. Unless it falls on its face for some reason (ie because it's too hard compared to e.g. the Moon).
So no, the discussion I entered was about near term development. I bolded the part you seemed to have missed.

Near term the moon is plausible. Mars is not.

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