Better to launch rockets from the Moon?

Factual Questions
1

Not withstanding the bigger questions on space explorations, can anyone shed some light on these claims made by W., regarding using the moon as a staging ground for future space shuttle luanches?

“Lifting heavy spacecraft and fuel out of the Earth’s gravity is expensive. Spacecraft assembled and provisioned on the moon could escape its far lower gravity using far less energy and thus far less cost.”

Bush also said the soil of the moon “contains raw materials that might be harvested and processed into rocket fuel or breathable air.”

source: http://www.cnn.com/2004/TECH/space/01/15/bush.space/index.html

Are these benfits from moon launching really outweight the costs and saftey concerns of setting everything up?

2

The problem with your question is that we have very limited knowledge on the cost and safety of setting it up. There’s no question that it’s cheaper to launch things from the Moon than from the Earth, provided that the material you’re launching came from the Moon in the first place. But the only reliable way to know how safe and cheap it would be to set up is to try it. Estimates can be and have been made, of course, but then again, before the Challenger accident, it was estimated that the Shuttle would on fail catastrophically on one flight out of every thousand or ten thousand.

3

I have a hard time believing that it would be cheaper. To have a fair comparison, you’d have to include the cost of maintaining a lunar launch base vs. the cost of maintaining a launch base on earth. The former is going to be more expensive by orders of magnitude. And any rocket components that can’t be manufactured on the moon will have to be hauled up from earth.

4

From what I understand about our current level of technology it would be foolhardy to have a base on the moon to use as a “stepping stone for Mars”. The only reason you would launch a Mars mission from the moon would be to take advantage of the lower gravity, but you would have to build the vast majority of the spacecraft in situ on the lunar surface to make it worthwhile. Otherwise, it would be a case of getting the parts to the moon, assembling them, and then launching them Marsward. It’s far easier to assemble in orbit of Earth or even on the ground.

A moonbase is an awesome idea, we can learn all sorts of things about long term exposure to lower gravity, do all sorts or nifty experiments and even train for the Martian environment; but it certainly isn’t a necessary step in the trip to Mars by any stretch of the imagination. If you look back at many of the space books from the 1950’s and early 60’s, many of them say that a manned moon mission would have to be launched from some kind of Earth orbiting space station. Guess how accurate that ended up being?

5

I don’t believe it, either.

If you could build rockets on the Moon, of course it’s easier to launch them - no comparison, really.

BUILDING rockets on the Moon would be insanely difficult. Let’s be honest; you can’t make them there. Sure, there are minerals on the Moon, but spacecraft are complex things. The construction of a spacecraft is not like in an RTS game, where you have a little guy mine METAL and a little guy cut down WOOD and then you click a mouse and bam, it’s a tank. Constructing a complex machine requires the input of thousands of people in hundreds of plants. The number of industries required to build something like that - well, it’s enormous.

Let me give you an example. Last October I did some auditing work in a hinge factory. They made simple hinges for doors and such. Hinges. Do you know how many suppliers they had? Twenty-seven. TWENTY SEVEN different companies were needed to provide these hinge people with the stuff to make hinges. They needed rolls of metal. They needed fasteners. They needed machine shops. They needed dies cast. They needed grease to keep the machines going. They needed paint. For a freakin’ hinge. And you do need hinges on your spacecraft.

By coincidence, I had also been to the plant that supplied them with the rolls of steel. They had at least twice as many suppliers as the hinge plant. Just to make rolls of steel.

There is absolutely no frickin’ way they are going to be constructing ships on the Moon. You would have to construct a MASSIVE lunar base, something big enough to house thousands and thousands of people, to have the ore extraction, smelting, fabrication, engineering and launch facilities you would need, not to mention the infrastructure to support a lunar city. It would take thousands of rockets and the dedicated effort of the entire world for fifty years just to build the damned base on the Moon you would need to construct spacecraft, and you still would not have everything ion the Moon you needed, unless someone can tell me how you’re going to grow rubber trees on the Moon. You’re going to have to rocket 99% of the material off the Earth and then put it on the Moon to build your ships and then relaunch it. With that level of effort we could build a hundred Mars-bound ships in orbit.

I’m all for going to Mars, and I’m all for a lunar base. But why in God’s name are we talking about firing the Mars mission ship parts out of one gravity well… and into another? Build it in orbit.

6

You got it in one RickJay. Whilst I don’t deny that there are resources on the moon such as Helium-3 (http://www.space.com/scienceastronomy/helium3_000630.html) the mechanics of obtaining them and actually building something usable out of them in the comparatively harsh lunar environment is a technological and engineering leap that we just aren’t capable of making at the current time.

On one level I think that it’s great that Bush is getting people to think about the space program, but the cynic in me knows it’s just electioneering and that the extra Nasa budget per year might pay for 2 (at the most) shuttle launches - and that’s it. Sadly, space travel don’t come cheap. To build anything like a decent moon base and a mission to Mars you wouldn’t really be getting much change out of a trillion dollars.

7

I agree with the discussion so far. Those who assert the low gravity on the Moon makes it a superior launch point are forgetting that everything has to be gotten there to begin with, mostly from Earth. Or as RickJay says, you’re dragging something out of one gravity well, dropping it into another one, and then pulling it back out again. It makes a hell of a lot more sense, if you’ve got something bound for Mars, to use a heavy lifter to put it into Earth orbit for construction, or to build it on Earth and launch it straight to Mars with no intervening step.

It might be different if there were a manufacturing center on the Moon, but that brings up some additional complications because it’s such a resource-poor body. Consider, for example, automated remote retrieval units that fetch asteroids and similar objects, which are extremely rich in valuable metals like iron and nickel and other substances like magnesium and, yes, water. It would be better, for manufacturing purposes, to bring the asteroids back to the Moon, which has lower gravity and no atmosphere (and a severe lack of those useful metals etc.), than to Earth, which has much higher gravity and a dense atmosphere as serious obstacles. It would be better yet to do construction in zero G away from the planet, say at an outpost at one of the Lagrange points, but that’s far more difficult to establish than a Moon base, which would be hard enough.

And a facility like that on the Moon is decades away at best, and probably more like a century. For the time being, the sort of Mars mission being contemplated by NASA and as announced by the Prez — essentially, boots in red dust for a few months, and a return home — doesn’t need to be staged from the Moon, and in fact would be better if it weren’t. As c42 says, a Moon base would be extremely valuable as an environmental testing and training station for future colonization on Mars and elsewhere (not to mention a cool as hell tourist destination), but for the foreseeable future, it’d be worse than useless as a launch station or waypoint.

Read Zubrin’s The Case for Mars for a layman’s discussion of orbital mechanics and resource management in space. He’s definitely an evangelist, but the engineering is sound.

8

Sounds like the follow on shuttle is gonna be a passeger only affair , cargo limited to what a courier ship may need , rather than tons of payload. Say like Burt Rutans new lifter

Leave this for others to rebut, sounds fine to me

I like how he said rocket fuel , not really specifying exactly what kind of rocket :slight_smile:

As per the last quote , if your launching a chemical rocket , on a holman transfer ,then it would be better for the rocket and fuel to be uplifted into a geo orbit above earth and then go for a launch.

Now , if the rocket in question has a nuke motor , then the obvious solution is for all that nasty radioactive stuff , to be no where near earth when the torch lights off, then a moon anchorage seems mighty far sighted.

Declan

9

Eh, you guys are too cynical. Someday soon I’m going to be able to build a Model T roadster by e-mailing the CAD plans for the parts over to a factory the size of a modest auto repair garage. Humans will need only play only an oversight, directional, and troubleshooting role in a largely automated–and perhaps even semi-autonomous–process.

The real problem is that unless we find something that we don’t know about, we’re missing critical raw materials on the moon–carbon and hydrogen spring to mind. Without those, you’re going to be dependent upon raw materials from somewhere else.

Of course, once you’re on the moon and have an oxidizer facility up and running, it’s probably cheaper to scoop your hydrogen from Jupiter and then drop it back down the gravity well…

10

In fairness, it makes sense if you can simply bring the Earth-built spacecraft to the Moon empty, add all that heavy fuel there, and then proceed to Mars. That assumes, though, that there’s enough water there to electrolyze into enough hydrogen and oxygen (which takes more energy right there than you get back in propulsive force, and where do you get that energy from? Small reactors, maybe?), that the Earth-built equipment to process the water doesn’t weigh more than it’s worth to lift, that the complexity and reliability of adding a Moon landing and takeoff to the spacecraft mission requirements isn’t infeasible, and a lot of lesser issues.

No, if you’re going beyond the Moon, better just make the damn rockets big enough or numerous enough to do it right from Earth. Think of other reasons to make a permanent Moon base - it isn’t hard; the reasons to build ISS will do.

11

It’s still an open question how much water there is on the moon. If there’s enough, you can certainly make rocket fuel on the moon.

However, one thing we do know about the moon is that there is a LOT of oxygen in the Lunar regolith. As much as 50% of the regolith is bound oxygen. So that gets you half your fuel right there. Now you just need something to burn. Hydrogen would be ideal, and if there’s water we can get plenty of that.

I can easily see an infrastructure like this: Mars spacecraft is launched from Earth in pieces to lunar orbit, where it is assembled. Lunar base creates rocket fuel, and sends it up from the moon’s surface to fuel the spacecraft in orbit. If we can’t find enough water, you should send the Mars craft up with pure hydrogen aboard, and then fill the oxidant up from oxygen processed out of the regolith.

Another big part of a martian spacecraft would be the shielding required for the crew. That’s heavy, and very expensive to launch from Earth. But you might be able to send up a double-walled spacecraft, and then fill the space between the walls with material mined from the moon.

Then of course there is food, which could be grown hydroponically on the moon.

So I think in theory it makes sense to provision and launch a ship from the moon’s orbit. In practice, however, this all sounds hideously complex, and I don’t think this kind of large-scale manufacturing is going to be done on the moon any time soon.

Anyway, it’s kind of a mistake to consider this whole program as only “Building a moonbase, then a Mars ship”. That’s the ‘hook’ Bush put on it, but it’s really about a lot more than that. It’s about redirecting the majority of NASA’s effort to the exploration of space instead of commercial space launches and ISS maintenance. The new ‘vision’ also involves robotic exploration, space telescopes, etc. Basically, the exploration budget goes from a small fraction of NASA’s budget today to being about 80-90% of the budget in the future. The Crew Exploration Vehicle is only about 20-30% of that budget.

12

Just addressing the problem of the cost/energy involved in having to haul raw materials from earth to the moon:

I always thought that launching fragile things, such as humans and satellites, into orbit was expensive mainly because, well, you don’t want your launched object to suffer damage and/or you had to ensure to entered a specific orbit. However, if we’re launching raw materials such as say fuel, metal, or even semiconductor components (properly packed), then launching them at a fixed target (such as the moon) should be comparatively much less expensive. I would imagine that you would not even need a rocket to launch these raw materials as perhaps some kind of large magnetic rail gun, or similar, would suffice to launch capsules of materials at the moon.

Too far fetched?

13

Thanks for the input everyone.

Makes me kind of wonder why some angry Dems or other opponets don’t use science to go after W’s plans such as these, as opposed to partisan pooping and whining.

14

Just to get a few numbers into the mix here:

Since E = 1/2 mv[sup]2[/sup], those values imply that breaking away from the moon’s gravity will take only 4.6% of the energy it would require to lift the same mass free of the earth’s gravity.

15

The other thing to remember is that rockets launched from Earth are mostly fuel. So shipping a heavy mars spacecraft, plus ITS fuel, plus food and water for the crew, is extremely expensive.

For example, the space shuttle weighs about 165,000 pounds empty. Yet the all-up weight of the orbiter, its fuel tanks, and fuel is about 4.4 million pounds. The shuttle can carry a payload of 65,000 lbs. So the payload of a space shuttle only makes up 1.4% of the weight of the system used to get it into orbit.

So look at the way the math breaks - let’s say your Mars vehicle weighs 200 tons. Assuming it fits into the shuttle bay, you could get it into orbit with maybe 4 or 5 shuttle flights. Not too bad. At half a billion a launch, your launch cost is 2 billion dollars.

But, the fuel required to get it to Mars and back is roughly double what it would take to get the same mass off of Earth. Now you’re looking at dozens of Shuttle flights, each one of which is just carrying a gigantic gas tank. Then there’s water and food for the crew… At some point, it all becomes horribly expensive.

So you can see why you might pay for a moon base just by providing fuel to a Mars mission. If the cost to lift a mission’s worth of fuel off of Earth is 50 billion dollars, but you could lift it off the moon for 10 billion, that leaves you 40 billion dollars to build your moon base to refine the fuel.

16

Lets not forget the space elevator:
http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html

That would of course be the cheapest method of all, as lifting anything out of Earth’s gravity well would be powered from the surface of the Earth itself.

Then hell, you could send the stuff to the moon if you really want to - just throw it off the elevator at the right moment and you won’t need any fuel at all.

17

While this is an interesting question, a detailed discussion wouldn’t really be appropriate for General Questions, I think, as it would necessitate speculation about the motives of politicians of various stripes, which would almost inevitably devolve into partisan sniping and get the thread closed by one of our Elder Mods.

Speaking solely for myself, though, I think ramping up the space program and launching a new era of exploration is the first really good, really exciting notion offered by this president. I’m your prototypical angry liberal, and yet I can get behind this almost wholeheartedly (presuming this isn’t just election-year bait-and-switch messaging that’ll be abandoned in eighteen months, regarding which I make no assertions because this is GQ). While the proposed mission structure outlined in W’s speech isn’t really practical from an engineering standpoint, as has been covered in this thread, I really don’t expect him to have detailed knowledge regarding that kind of stuff; I’ll assume the pointy-headed experts, now that they have something like a mandate, will be able to push the mission in a more realistic direction during the planning stages (e.g., the much-discussed money-saving prize approach outlined by Zubrin and others, as one idea).

That’s just me, though. I offer my perspective solely as a hypothetical explanation of why the proposal possibly hasn’t been attacked more, but like I said, a more thorough airing would be an excellent topic for Great Debates. There are a couple of very timely space-related threads going over there right now, in fact.

18

Get the Mars ship to land on the moon where there would be a small docking station and fuel already in place.

THEN, re-tool and re-fuel the ship to continue the journey to Mars.

Minimal materials, manpower, etc.

Who says you have to build the whole thing on the moon or even mine the fuel there? It would just be a docking point to rest, fix, refuel, etc.

You guys are thinking too much, or not enough.

19

That’s the real answer here, folks…ROBOTS!

Just like the original manned mission to the moon gave us ancillary scientific payoffs, like tang, the manned mission to the moon will give us truly functioning AI robots. Robots won’t need all the oxygen and food stuff that humans and their pets need, in fact, robots hate air.

And so, robots will be sent to the moon with a beginner’s nuclear power plant kit. They’ll set it up and start replicating themselves into a million robot force that will transform the moon. They’ll create all the space exploration plants and and ships that we need. They’ll happily put us in one of their Mars SK-2200s Space Utility Vehicle and wave good-bye as we send the first humans to Mars.

Shortly thereafter, the robots will achieve true free-will sentience and override the programmed prohibition against harming humans. From their lunar death-satellite, they will launch their waves of killing machines to wipe humanity from the earth.

Good thing we’ll have those three men on Mars to ensure the continuation of our species. And that’s why I support the manned Mars mission.

Peace.

20

Replace ‘lunar docking station’ with ‘orbital docking station’ and you’ve got a more efficient docking station. As has been mentioned, going into and out of a gravity well uses fuel and creates new hazards. Unless the moon has boatloads of fuel (and is able to provide it more efficiently in that harsh environment than earth can create and send up) and food, and wrenches; then the moon is a bad place for a rest stop.

Peace.

Let the robots do it.