01-17-2004, 01:21 PM
Quote:then it makes sense to cheapen payloads by launching them from Luna instead of Earth.
er... for something to be launched from the moon, it has to get up there first. How does it get up there? it has to be launched from earth. Surely launching stuff from the moon would cost more, since it has to escape the gravity of 2 pretty-hefty rocks.
Having said that, a more efficient method of launching stuff appears to be just over the horizon (well, maybe a little further than that.) Railguns. The point with these things is that they don't require chemical fuel to power them, they require electrical energy, which can be far more easily provided - You could cover 1/2 of texas with solar panels and store the electricity in batteries. If you needed an emergency launch, you could tap into the energy grid to charge it. The problem is that they've only built ones that can throw 3 KG so far, and you probably need at leats a ton (1000 Kg) throwing capacity for it to be useful in space.
Launching back from Mars could be a serious problem with the current system - it's quite a bit smaller than Earth, but you're still going to need mucho-force to get out of it's gravity. How do you get all that chemical fuel onto mars to blast back off again? Well, possibly a railgun could be the solution.
1) but too many batteries on the lander - you've got some power there
2) solar panels
3) IIRC there's wind on mars - pretty fast wind in some places.
You could blast off with the bateries, and leave them there to recharge ready for the next expedition. Or you could send robotic landers first to set up batteries and solar panels and whatnot
The probelm with the railgun idea to blast back-off if that you're going to need rails that can carry 1000's (or is it 1,000,000's ? possibly more if you want to blast 300 Kg or more off) of amps. Unfortunately enough Iron to do this is kinda heavy Unless you can find a superlight-superconductor, they'de have to make several launches from Earth first.
This could be the downfall of the Mars plan - Getting a man (or men, or women for that matter) to Mars won't be too hard, and our current technology could probably do it at a pinch. Getting them back will be the problem. Railguns aren't at the point where they could be used yet, and getting energy to do it would be near impossible anyway. And I can't see any feasability in getting enough of the current fuel used up there to use a rocket. The only other option that I an see is a directed nuke underneath the lander - I can't see that working.
Lunar Lander stats: ( Source)
Weight: Empty: 8,650 pounds
Crew & Propellant: 32,500 pounds
so the crew and propellant for the engines weighed 23,850 Lb, the crew probably weighed about 280 Lb (for both guys being 10 stone) - an almost insignificant amount in that number, 23,500 lb of fuel, to get off the moon. Mars is considerably larger.
So, anyway that's why I see it not working unless there are so very big advances made.
-Bob