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[ajar]

Qualia. ♥

Space colonization is a neccessity. We can't stop consumption. We must consume the space.

[qwertyuiopas]

Ever read Asimov's foundation series? The best ships, only developed near the end, moved by gravity manipulation. Works even where there aren't magnetic fields. And would have a side effect of or be a side effect of, artificial gravity.

[sneakey pete]

Btw, with the Moon always facing the Earth, all that would be needed for a Moon->Earth transportation system (with more or less pinpoint accuracy) is a magnetic acceleration railway a few kilometers in length. Think one of those odd rollercoaster-like thingys, but on a bigger scale and with the track just ending instead of circling around to the exit booth. Solar panels provide power, and cargo can be shipped once a month without trouble. Of course, that's assuming you don't make a whole lot of them solar arrays all over the surface.

Well, i've not done the actual calculations, but the odds are that the launch ramp itself would need to be on the far side of the moon. And as i said before, the moon does have days, so solar would stop working.

I expect to see the moon colonized in our lifetimes, not for the He3, but for the iron and silicon ("moondust" is silicon+oxygen).  With little more then iron, one can create a very large space station at the L4 or L5 lagrange points between the earth and the moon.  Simply rotate the station to produce artificial gravity and viola, you have an environment better then anything on earth. 

Quite true, but as there's no market for minerals in space (yet), getting iron on earth will always be cheaper. Its sort of chicken and egg. need to be in space to make going into space worthwhile, ultimatly i think we'll need a government to kick it off.

[zchris13]

Iron for earth will always (for a long time) be cheaper to acquire on earth, but iron for space? Look to the moon, men.

[mainiac]

Well, i've not done the actual calculations, but the odds are that the launch ramp itself would need to be on the far side of the moon. And as i said before, the moon does have days, so solar would stop working.

The launch ramp would only need to be a few meters long, similar to the launch ramp of an aircraft carrier.  Heck, you can achieve moon escape velocity with a catapult.

Solar on the surface of the moon would only be lit up half the time.  However solar power on a space station at the lagrange points would be lit up 100% of the time and that's where you would want to put your people and factories and everything not mining related.  More importantly, there is no atmospheric interference in either case.

[DJ]

By atmospheric interference you mean radiation shielding, right?

[sneakey pete]

The launch ramp would only need to be a few meters long, similar to the launch ramp of an aircraft carrier.  Heck, you can achieve moon escape velocity with a catapult.

Prove to me that the lunar surface-earth reentry only needs "a catapult's" worth of energy, or your talking shit mate. I said somewhere here before that you need to change your velocity by about 3km/s, and that's when your already in the orbit around the moon. Getting To the moon orbit from the surface itself is another thing entirely.
Every single proposal for a magnetic launcher on the moon that i've seen (ones that are reasearched and calculated), call for a launch rail that's km's in length just to acheive the required velocity.

[DJ]

I think the rail would still be cheaper than rockets. It could be powered by He3, I guess.

[Sean Mirrsen]

With the Moon's gravity being 1/6th of the Earth, I'd suspect you need quite a bit less than 3km/s to leave the Moon's orbit. Since your target is the object you're orbiting, you can further reduce the requirement by launching in the direction opposite to the orbital movement, allowing the target's gravity to do more work. If we're talking constant acceleration rather than raw speed, you need to provide a measly 1.63m/s² of thrust to get off the Moon, versus the Earth's 10 (or 9-point-something).

After some Wiki browsing, the escape velocity on the Moon is 2.38 km/s. A 1kg object could be accelerated to that with 2380 Newtons of force acting over a second, or five times that in the time of a catapult's swing. I think a catapult could well shove something off the Moon.

[IndonesiaWarMinister]

I think the rail would still be cheaper than rockets. It could be powered by He3, I guess.

Or Fusion.

Fission is also enough, I think.

Hey, isn't there was a project to make a (successful) nuclear-powered rockets?
Can't we just use it on the moon?

[Sean Mirrsen]

Nuclear-powered jets. They heat the air with gas pipes passed through a nuclear reactor instead of burning fuel. Only the Soviets were successful in make an actual airplane with the technology, and their design was... messy, at best. Polluting the air, irradiating the crew...

They won't work on the moon, for obvious reasons.

Unless you mean ion thrusters or something of the kind.

[Twiggie]

I think the rail would still be cheaper than rockets. It could be powered by He3, I guess.

Or Fusion.

thats what the he3's for...

[Eidalac]

Hey, isn't there was a project to make a (successful) nuclear-powered rockets?
Can't we just use it on the moon?

Last I checked (and this was quite a while ago), international laws forbid any form of nuclear devices in space.  It's technically an arms treaty, but effectively overs any nuclear power source as well.

And the fact that they made the sun illegal is not lost on me either.


I think that, in the long run, collecting He3 and other such gasses that are not common on Earth will make space exploration take off, but that will have to wait for a large shift in our energy generation methods at home.

[sneakey pete]

With the Moon's gravity being 1/6th of the Earth, I'd suspect you need quite a bit less than 3km/s to leave the Moon's orbit. Since your target is the object you're orbiting, you can further reduce the requirement by launching in the direction opposite to the orbital movement, allowing the target's gravity to do more work. If we're talking constant acceleration rather than raw speed, you need to provide a measly 1.63m/s² of thrust to get off the Moon, versus the Earth's 10 (or 9-point-something).

After some Wiki browsing, the escape velocity on the Moon is 2.38 km/s. A 1kg object could be accelerated to that with 2380 Newtons of force acting over a second, or five times that in the time of a catapult's swing. I think a catapult could well shove something off the Moon.

My figures say 2.7km/s, moon surface-earth (extra if you want to stay in earth orbit instead of doing a ballistic rentry)

We'd need many tones of He3 to power any sort of realstic fusion industry with it, you wouldn't want to be launching 1kg at a time. There's also the fact that a catapult doesn't move at 2.7km/s. Ideally, you'd be launching large payloads due to economies of scale (you need to pick up each items that lands, don't want to be chasing 1kg payloads all over the pacific). Hence the need for a largeish railgun.

quickly reading up on it, mass drivers have about 25% effeciency. Now, if we were sending a 1000kg mass back, your looking at a few km's to get to the 2.7km/s required.

[Sean Mirrsen]

Of course. I don't think anyone actually implied using catapults. Something like the usual cargo containers would be appropriate. Railguns on the moon will make for great killsats, btw, even if firing simple steel rods. Well, steel girders, more likely.

Btw, I remember some people saying that cargo containers will burn up on reentry. Um.. hello? The Moon's relative orbital velocity is tiny compared to the satellites and other stuff in Earth's orbit. Given a "barely sufficient" nudge, they will be hardly experiencing more friction than airliners when they enter the upper layers. Deploy initial chutes for additional deceleration in the upper layers, then main chutes for landing. No need for any additional protection except shielding if the cargo is sensitive to solar radiation.

edit: On second thought.. let me search for some info first. Something tells me I'm not quite right here.
edit2: yep, the orbital speed is "only" 1 km/s. With the low density in the upper layers, and possible launching in the direction opposite to orbital movement, I'm about right.