Moonbase and Mass drivers etc etc

Tom Kalbfus · 2006-12-06 10:44:07

During 2nd exploration conference today, Scott Horowitz said that the Mars Design Reference missions would be revisted in 2007!

The important thing is that we are taking the first steps, we are going to the Moon and Mars, we are off to a slow start, but we are headed in that direction. After 2008, George Bush will be out of office, it will be up to someone else to continue the program or possibly accelerate it. I don't think much justification can be found for reviving the Shuttle.

I think a polar Moonbase is a good place to start.

The question is, what is going to be the primary pask of the Polar Moonbase? It is basically a space station sitting on the surface of the moon. Its not much different ibn concept from the ISS, except it has the Moon undeneath it. Outside its walls is the same vacuum that is outside the ISS.

Could one build the equivalent of a Solar Power Satellite on the Moon's surface out of lunar material? If you space out the panels so they don't shadow each other and have them in high places so they constantly track the sun, it can be just as effective as an SPS. I think it would be experimental, basically we would be seeing if its possible to process lunar material into solar cells using a compact factory, and a microwave or laser transmitter could be erected, or perhaps a mass driver could be built. From the Lunar Pole, it would be possible to send Lunar material to L4, or L5, or L1. We could experiment with these techniques and see if lunar material can be collected into orbit.

GCNRevenger · 2006-12-06 11:24:43

2020?, that's about 13 years from now. Shuttle flights end in 2010 so we have ten years to focus on the Moon. The objective is to have 180 day missions to explore the Moon's surface. Do you think they will deposit catches of supplies along the Moon's surface so that a long range pressurized rover can travel long distances from one supply depot to another?
Is circumnavigating the Moon feasible or desirable?
2020 is the date set in the VSE. NASA and many others want that date brought forward, 2018 is doable, even earlier is possible given the funding. The pressurized rover was only mentioned officially this week - see the Lunar Outpost forum - note the date is 2027! Maybe that's a mistake, but if it's true there will be plenty of time for new developments. For example, delivery of supplies robotically, ISRU fueled hoppers to transport people and cargo further from the base, and yes maybe prepositioned supply dumps as used by the early Antarctic explorers.

Especially if you are situated on a mountain top, a hopper makes more sense than a long-range rover does.

GCNRevenger · 2006-12-06 11:45:26

During 2nd exploration conference today, Scott Horowitz said that the Mars Design Reference missions would be revisted in 2007!
The important thing is that we are taking the first steps, we are going to the Moon and Mars, we are off to a slow start, but we are headed in that direction. After 2008, George Bush will be out of office, it will be up to someone else to continue the program or possibly accelerate it. I don't think much justification can be found for reviving the Shuttle.
I think a polar Moonbase is a good place to start.
The question is, what is going to be the primary pask of the Polar Moonbase? It is basically a space station sitting on the surface of the moon. Its not much different ibn concept from the ISS, except it has the Moon undeneath it. Outside its walls is the same vacuum that is outside the ISS.
Could one build the equivalent of a Solar Power Satellite on the Moon's surface out of lunar material? If you space out the panels so they don't shadow each other and have them in high places so they constantly track the sun, it can be just as effective as an SPS. I think it would be experimental, basically we would be seeing if its possible to process lunar material into solar cells using a compact factory, and a microwave or laser transmitter could be erected, or perhaps a mass driver could be built. From the Lunar Pole, it would be possible to send Lunar material to L4, or L5, or L1. We could experiment with these techniques and see if lunar material can be collected into orbit.

There is certainly more to do on the Moon than on the accursed worthless ISS!

The Moon is awfully far away to be a solar power station for the Earth, plus it moves in the sky so it would make near-continuous power at any one point impossible. You know those lasers we directed at the Moon to measure its distance? The telescope-directed beam spread out to a diameter of three miles when it reached the Moon.

The LaGrange points suffer similar problems, they are STILL really far away, and they too move across the sky with the Moon, since the Moon causes them.

The "lowest" orbit that makes any sense for an SPS is geosynchronous orbit, where the station is illuminated through the majority of its orbit and stay in the same point in the sky, which makes getting the energy down from it much easier (microwave beam transmission).

I don't care much for the idea of "sending Lunar material" to any place, except for the rare minerals scattered across the surface. Its just so much easier to build solar panels on Earth (and trust me, its going to be REALLY easy when polymeric cells are practical), that space-based ones don't make much sense.

Tom Kalbfus · 2006-12-06 12:10:09

During 2nd exploration conference today, Scott Horowitz said that the Mars Design Reference missions would be revisted in 2007!
The important thing is that we are taking the first steps, we are going to the Moon and Mars, we are off to a slow start, but we are headed in that direction. After 2008, George Bush will be out of office, it will be up to someone else to continue the program or possibly accelerate it. I don't think much justification can be found for reviving the Shuttle.
I think a polar Moonbase is a good place to start.
The question is, what is going to be the primary pask of the Polar Moonbase? It is basically a space station sitting on the surface of the moon. Its not much different ibn concept from the ISS, except it has the Moon undeneath it. Outside its walls is the same vacuum that is outside the ISS.
Could one build the equivalent of a Solar Power Satellite on the Moon's surface out of lunar material? If you space out the panels so they don't shadow each other and have them in high places so they constantly track the sun, it can be just as effective as an SPS. I think it would be experimental, basically we would be seeing if its possible to process lunar material into solar cells using a compact factory, and a microwave or laser transmitter could be erected, or perhaps a mass driver could be built. From the Lunar Pole, it would be possible to send Lunar material to L4, or L5, or L1. We could experiment with these techniques and see if lunar material can be collected into orbit.
There is certainly more to do on the Moon than on the accursed worthless ISS!
The Moon is awfully far away to be a solar power station for the Earth, plus it moves in the sky so it would make near-continuous power at any one point impossible. You know those lasers we directed at the Moon to measure its distance? The telescope-directed beam spread out to a diameter of three miles when it reached the Moon.
The LaGrange points suffer similar problems, they are STILL really far away, and they too move across the sky with the Moon, since the Moon causes them.
The "lowest" orbit that makes any sense for an SPS is geosynchronous orbit, where the station is illuminated through the majority of its orbit and stay in the same point in the sky, which makes getting the energy down from it much easier (microwave beam transmission).
I don't care much for the idea of "sending Lunar material" to any place, except for the rare minerals scattered across the surface. Its just so much easier to build solar panels on Earth (and trust me, its going to be REALLY easy when polymeric cells are practical), that space-based ones don't make much sense.

Well, the closest asteroids to Earth are the ones on the Moon at the bottom of the craters they made. I don't know about Earth, but perhaps the materials can be sent into space with mass drivers where they can be used. Tungtstein is a very dense and heavy material. If tungstein was in any of the asteroids that impacted on the Moon, it has a high melting point, it would have survived and is probably still there. Tungstein makes a good radiation and heat shield. Getting tungstein into orbit from Earth is very expensive, but it is only one sixth of its weigt on the moon and can be catapulted into orbit with a mass driver. You can extract out the tungstein simply by varopizing all the material around it, as it has such a high melting point.

I think we should try some rudimentary matierials processing on the Moon.

GCNRevenger · 2006-12-06 21:07:36

No, enough with the mass drivers and movement of material off the Moon! You keep on making noises about moving vast masses of material at huge expense into space to build stuff.

WHY? What in the heck for?

Tungsten really isn't worth much much, it makes an awful radiation shield because cosmic rays would generate a nasty shower of particles. In fact, the Tungsten would probably multiply the radiation from cosmic rays.

And because of its extreme density, making a large and wide shield out of it would be monstrously heavy. Too heavy to ever want to push with a rocket when you could use light weight carbon instead.

But I digress, the emphasis should NOT be on any sort of zero-gravity manufacturing, materials processing, nor construction from base materials or unassembled bits and pieces.

First of all, you would fail. The ISS proves that space construction is by-and-large a bad idea and generally not needed. If you ship can't be assembled by docking prefabricated components built on Earth, then you aren't using a big enough rocket to launch the pieces.

Furthermore, although we would eventually like to be able to build big O'Neal space station colonies and the like, we should FIRST set up where there are resources: on the planets and moons of the solar system. After we have a self-sustaining and growing Mars colony, and after we have visited out to the icey gas giants, and after the Earth's economy is joined at the hip with space for real... THEN we talk about it.

To expand, the emphasis should be on finding ways to benefit the Earth from space: if you do this, then the expansion into space will come. But, if you spend all your efforts on building big space ships for no good reason, then the money will dry up and you will go no place fast.

The Moon has Platinum group metals on its surface, thats for all intents a certainty, and the Earth's supply of these materials is limited and will dwindle barring a new supply by about the time we are ready to harvest them from the Moon commercially. This, perhaps with science-for-money (NASA contracts AltSpace to run its Moon telescopes) and a little Lunar space tourism, could provide that nucleus of profit that could finally justify the real private expansion into space.

And this is a worthy and major challenge, extracting the small amounts of the rare minerals from the Lunar craters and ejecta will be hard enough! And so would operating a Lunar tourist hotel at a profit... Thats where we should be aiming, not building a huge multikilometer rail gun to fling vast amounts of useless base materials into orbit.

Tom Kalbfus · 2006-12-07 00:28:10

The Moon has Platinum group metals on its surface, thats for all intents a certainty, and the Earth's supply of these materials is limited and will dwindle barring a new supply by about the time we are ready to harvest them from the Moon commercially. This, perhaps with science-for-money (NASA contracts AltSpace to run its Moon telescopes) and a little Lunar space tourism, could provide that nucleus of profit that could finally justify the real private expansion into space.
And this is a worthy and major challenge, extracting the small amounts of the rare minerals from the Lunar craters and ejecta will be hard enough! And so would operating a Lunar tourist hotel at a profit... Thats where we should be aiming, not building a huge multikilometer rail gun to fling vast amounts of useless base materials into orbit.

How about Platinum? I understand Platinum also has a high melting point, a mass driver could fling a platinum slug at Earth, and it would probably survive atmospheric reentry with most of the platinum intact. Platinum is an important metal for building hydrogen fuel cells. If we could devise a cheap method of getting a large amount of platinum from the Moon to the Earth, then we'd have to devise a cheap method of mining all this platinum out and bringing it to the Mass driver. It might make sense only if there was an awful lot of platinum in one spot. Getting spaceships to haul the platinum back to Earth is bound to be expensive. Some method would need to be devised to obtain platinum more cheaply from the Moon than from the Earth's crust.

GCNRevenger · 2006-12-07 11:04:57

No no no, enough with the mass drivers! Mass drivers are horrible because they are so fantastically difficult to build, as big or bigger than particle accelerators on Earth and they cost billions here, it would be ridiculously expensive on the Moon. It would sit there unused most of the time anyway since it would require precise alignment with Earth.

We don't need huge amounts of Platinum here on Earth, in fact high-kilo/low-tonne quantities annually should do just fine; in this case, it makes WAY more sense to refine the metal on the Moon, where energy is plentiful, and send the pure or at least partially refined ore to Earth by rocket. That way, you only need to send small-to-modest amounts across the gulf of space. Rockets from Earth with Hydrogen and Carbon (if we can't find any) for fuel and Carbon Monoxide refining respectively land, the same rockets with PGM/PGM-ore come back.

The PGMs on the Moon are without a doubt mixed in with lots of worthless base metals and are there in quite small amounts, easily one part in thousands at most. Therefore if you want to get a tonne of PGM, you would have to send thousands of tonnes of raw ore back to Earth. Thats just crazy no matter how you do it!

And I want to repudiate this insane idea of shooting missiles at the Earth for fun and profit: firing large numbers of things at the Earth, hoping to hit one particular spot, and unguided too is crazy! One miss and you drop a bomb as big as any conventional bomb - even bigger maybe - on peoples' heads! Think of an Oklahoma City sized explosion, with little warning, any place in the world, if you mess up the firing? And you will have a mess-up eventually, just from the law of averages and the extreme precision required.

Tom Kalbfus · 2006-12-07 14:00:16

No no no, enough with the mass drivers! Mass drivers are horrible because they are so fantastically difficult to build, as big or bigger than particle accelerators on Earth and they cost billions here, it would be ridiculously expensive on the Moon. It would sit there unused most of the time anyway since it would require precise alignment with Earth.
We don't need huge amounts of Platinum here on Earth, in fact high-kilo/low-tonne quantities annually should do just fine; in this case, it makes WAY more sense to refine the metal on the Moon, where energy is plentiful, and send the pure or at least partially refined ore to Earth by rocket. That way, you only need to send small-to-modest amounts across the gulf of space. Rockets from Earth with Hydrogen and Carbon (if we can't find any) for fuel and Carbon Monoxide refining respectively land, the same rockets with PGM/PGM-ore come back.

Would a rocket take up less space than a mass driver?
I see no reason for the rocket to go all the way to Earth with its payload, it should simply take off from the Moon's surface achieve the right velocity, and then seperate from its cargo and head back to the Moon for another load. The cargo itself can have a heat shield fabricated on the Moon and then reenter the Earth's atmosphere and hit a landing zone for pickup. the rocket should run on fuel that's locally produced on the Moon and should be able to be reused many times without having to make the complete journey all the way to the Earth's surface. It basically would do the job of the Mass Driver, send the payload on its way, but stay locally in the vicinity of the moon so there is no opportunity costs due to the rocket's absence. Taking off from the Moon's surface and achiving lunar escape velocity is not a big deal. Perhaps a nuclear or solar rocket could do the job.

The PGMs on the Moon are without a doubt mixed in with lots of worthless base metals and are there in quite small amounts, easily one part in thousands at most. Therefore if you want to get a tonne of PGM, you would have to send thousands of tonnes of raw ore back to Earth. Thats just crazy no matter how you do it!

I never suggested that, that's why we have to learn how to process materials on the Moon.

And I want to repudiate this insane idea of shooting missiles at the Earth for fun and profit: firing large numbers of things at the Earth, hoping to hit one particular spot, and unguided too is crazy! One miss and you drop a bomb as big as any conventional bomb - even bigger maybe - on peoples' heads! Think of an Oklahoma City sized explosion, with little warning, any place in the world, if you mess up the firing? And you will have a mess-up eventually, just from the law of averages and the extreme precision required.

If we are to mine the Moon for profit and you repudiate the idea of using lunar material in space, then that logically means sending lunar material to Earth, and that's got to be accomplished somehow. What is it in particular you want to do with the Moon? A ton of platinum can survive reentry quite nicely. Plantinum isn't a highly reactive metal, it has a high melting point and a high density, it can be allowed to hit the Earth and make a nice crater, then the platinum is picked up. Most of the Earth's surface is uninhabited, 3/4 of it is water, and the payloads won't be aimed at random. But if you so worried, then Perhaps Antartica would make a nice drop zone.

GCNRevenger · 2006-12-07 18:49:11

Rockets make more sense for moving small masses too/from the Moon than trying to build a CERN-sized machine on the Moon! Replete with the power supplies, living quarters for staff, and the stuff required from Earth to support such an operation.

The rockets would not return to Earth's surface, but rather enter Earth orbit where RLVs would bring up fresh Hydrogen, load Lunar cargo payload (or crew module), and bring back the PGM payload (or crew) to the ground.

This would permit easy interchangeable payloads to be brought to the Moon, take advantage of reuseability where it will work best (earth-LEO, LEO-moon). This way when you want to send cargo to the Moon, you have a vehicle on hand that can do it. Especially important if, say, a mining machine needs a replacement part of if you want to expand operations quickly.

It also gives one very important capability, that the chance that water ice is available in quantity, and hence Hydrogen for rocket fuel, are not so good. Even if it is there, it would probably require some serious industrial capacity to extract in any useful way, and so either way we need an Lunar RLV first that doesn't need Lunar Hydrogen.

We have plenty of Hydrogen right here on Earth, and efficient Earth-LEO RLVs could bring it to orbit cheaply and in respectably large quantities. What it can't do however is get that Hydrogen to the Moon, because the Oxygen needed to burn it (which is very heavy) would also have to be lugged from Earth. So what happens is, Lunar ships will burn Oxygen extracted from Lunar dirt, but Hydrogen imported from Earth. You can't do that if the Lunar rocket doesn't go to Earth on a regular basis.

A rocket that "doesn't go all the way to Earth" doesn't make a whole lot of sense anyway, since if you push a payload capsule to Earth, the rocket has to slow down so its momentum doesn't carry itself to Earth too, and then has to brake into Lunar orbit or descend to the surface. And, "taking off and achieving escape velocity" IS a big deal that will still require many tonnes of rocket fuel for even a modest craft.

I think the regular opportunity to import cargo (and rotate crew) from Earth, including precious Hydrogen and Carbon in the likely event that these are not found on the Moon in quantity, and if they are, then such a system still makes sense because mass extraction would take some time to set up and perfect.

And you would STILL be shooting missiles at the Earth under your scheme, totally unguided after separation, and hoping that they all fall pretty close to where you aim them. A full Moon-to-LEO vehicle on the other hand, if it failed to brake into Earth orbit it would fly right past us and safely enter Solar orbit. It would have full ability to maneuver too.

Neither nuclear nor Solar rockets are suited for the Moon either, the former requiring gobs of Hydrogen, which would not likely be available in that quantity even if some ice were discovered, and would be a radiation hazard both to astronauts but more importantly people on Earth if a failure were to occur during launch... remember, it would be on escape velocity pointed directly at us!

Solar rockets? No way, the mirror size would be too large and they too require Hydrogen just like nuclear rockets. In fact, ones with reasonably sized mirrors have no more thrust than ion engines hardly. They would only be able to fire one week out of the month too, when the Sun is overhead.

Since PGMs are not needed in huge amounts, there is no reason to build rail guns to ship vast amounts of it to Earth if it is refined on the Moon. Another reason for rockets that go all the way to Earth is that the current "favorite" method for extracting the PGMs uses significant amounts of Carbon. While it is possible that there are Carbon-bearing asteroid fragments on the Moon, we don't know for sure nor do we know where. Most of the Carbon can be recycled, but on occasion a fresh shipment from Earth would be needed to make up the difference.

Dropping Platinum through the atmosphere onto Earth is just silly, first of all it would make a tremendously destructive meteor thanks to its density and thermal characteristics if you were to miss. Second is that recovering falling rocks seems crazy, will they have a radio locater beacon? How will it survive reentry? And you can't tell me that you won't lose significant amounts of material from ablation or fragmentation as it comes down. And thats assuming the rocks all fall roughly where you want them to. What happens if you miss and the rock is lost (or even stolen)? How many tens or hundreds of millions of dollars would be out then?

No no, the metal ingots will ride quite nicely in the cargo hold of an RLV as it rolls to a stop at the end of the runway. After all, you have to send up the RLV to provide the Hydrogen to bring the Platinum to Earth in the first place.

samy · 2006-12-07 19:33:47

although we would eventually like to be able to build big O'Neal space station colonies and the like, we should FIRST set up where there are resources: on the planets and moons of the solar system. After we have a self-sustaining and growing Mars colony, and after we have visited out to the icey gas giants, and after the Earth's economy is joined at the hip with space for real... THEN we talk about it.

I disagree on this point. I think in order for us to have the expertise and know-how to build fully self-sustaining bases *far* away, we need to first get the technology perfected. We should perfect the art of building fully closed cycle ecosystems *near* Earth first where help is quickly available, before sending people to Mars to try to implement a closed ecosystem. Space also provides the most clinical environment to build those experiments in, without interference from planetary environments. Would we want to perform the first lung transplant in the world in a surgically clean room or in a battlefield? The first advances, the steps forward, will need to be perfected in a sterile environment, before starting to apply them to a wide variety of environments.

Because of these two reasons 1) relative nearness while perfecting the technology and 2) relative sterility while perfecting the technology, I believe that it will make more sense to try to build larger orbital stations before building bases on other celestial bodies.

Once we're good and skilled at creating closed ecosystems, and can create pretty good closed cycles, *then* it's time to head further away when we feel secure in our ability to provide the *basics* of survival.

GCNRevenger · 2006-12-07 21:28:03

Nonsense, we don't even need a totally closed environment for a Mars colony, Mars has all the elements needed, the rest is just chemistry. As far as the Moon, its unlikely that large numbers of people will ever live there, because its not that nice a place to live (lowish gravity, radiation, no easy domes, no 24hr days).

And why would anyone want to live on a free-floating space colony? Barring a space elevator, such a thing would have to be built from materials harvested in space. Since the amount of material needed is so huge, it will obviously be a long, long, long time before it would be practical to make such a thing. We can start building a colony, a colony on Mars by mid way through this century easy. The elements are on Mars, gravity and room and radiation protection and meteor protection etc etc etc are on Mars. So that is where we'll start, and we don't need 100% closed systems for Mars.

And even if we did want to make a totally closed system, we could do it just fine right here. Earthly contamination of the system is by far the least of the worries of making such a thing work. If you are going through all the trouble of making a closed system, you'll be using it some place with gravity. Hence, all the conditions can be simulated just fine right here on Earth.

samy · 2006-12-08 00:26:08

Nonsense, we don't even need a totally closed environment for a Mars colony

Of course we don't -- if we want to take risks. IMO, it is very important that any of our off-Earth colonies be able to go into a fully closed cycle in emergencies, and any colonies have to be constructed with such contingencies in mind.

And why would anyone want to live on a free-floating space colony?

Are you seriously asking that question on this site?

GCNRevenger · 2006-12-08 08:12:34

You aren't catching me here, its way way easier to run a Mars colony with a non-biological, partially open loop system (like 90% recycling) than it is run it fully 100% closed-loop like Biosphere. Total recycling is very very difficult. In fact, in the event of failure of the open-loop equipment, the obvious solution is just to have a spare open-loop plant.

I think it is a valid question, because people ultimately will live where the resources necessary for construction and survival are. Asteroid mining is a pipe dream, and the show-stopper details are numerous and often simply ignored by proponents, intractable basic physics problems casually relegated to the future.

So what? So no space colonies. Ding. Thats it, forget about it. Barring a space elevator, thats a show-stopper too. So thats why people will, for the most part, live exclusively on planetary bodies, and ones that are favorable for life. Besides, living in a tin can, even a nice tin can, can't really compare to mountains, horizons, and distant sunrises.

C M Edwards · 2006-12-08 08:37:05

And why would anyone want to live on a free-floating space colony?
Are you seriously asking that question on this site?

GCNRevenger, I think you've got a good point about bringing down large payloads of any type from LEO to Earth. They've got to be guided, not just shot out of a cannon. But your argument starts to fall apart the further from Earth you get.

Solar rockets, for example, even with small mirror sizes, would have higher thrust than you're giving them credit for. And I have no idea where you got the idea of one week on, three weeks off for their operation in cislunar space, unless you are rejecting the idea of gimbals along with mass drivers.

As for mass drivers, not using them for the last 6000 km of the transit still leaves you 380000km to play with. If they have enough precision to hit the earth, they probably have enough to miss it, too.

Using a mass driver to get loads up from the lunar surface can save a great deal of that fuel you recommend hauling back (and forth) from Earth, even allowing for the use of rocket powered craft to recover the payloads. A mass driver load shot into space would have an orbital path just like anything else. If you want to catch it, all you need to do is match its orbit. Unmanned vehicles soaking in Earth orbit have troubles of their own, true, but eliminating the mass driver doesn't eliminate our reliance on them.

The mass driver might end up being the most reliable component of such a system.

As for how to actually build a mass driver, well, I reaffirm that your analysis is more correct the closer it gets to Earth. Bringing all the parts up from Earth would not be cost competitive with simply continuing to use conventional rocketry. To get away from that, we need to get manufacturing capacity on the moon.

C M Edwards · 2006-12-08 08:41:58

Asteroid mining is a pipe dream, and the show-stopper details are numerous and often simply ignored by proponents, intractable basic physics problems casually relegated to the future.

To what intractable basic physics problems and show stopper details are you referring?

Tom Kalbfus · 2006-12-08 10:35:27

I think the easiest thing to build would be a Moon base, as it is close to Earth and there is a continous launch window open to the Moon at all times. the Moon lacks certain elements to be sure, but an initial Moon base or Mars base would not be that self-sufficient anyway. Food can be grown on the Moon, especially at the Lunar Pole where all you need is mirrors to reflect sunlight down into a domed pressurized greenhouse containing plants. Fertilizer would come from human waste, water would be recycled, and food would not have to be constantly shipped from Earth to feed the Astronauts. The atoms would continuously be recycled between the plants and the astronauts. The is really not that much difference between a free floating space colony and a lunar settlement. On the Moon space begins at the surface, and the same old vaccum and the same harsh sunlight shine down on a Moon base as it does on a space station. At the Lunar Poles, you can arrange for any day/night cycle that you like, you just need mirrors to reflect sunlight into the colony for when you want day. A polar Moon base would have a continous view of the Earth and of half the sky at all times, it would be a good site for an astronomical observatory, though you'd never see what's below the Lunar horizon as all the night sky does is rotate above you on a monthly basis.

Probably initially lunar material would be sent to Earth via rocket. What GCNRevenger says does make sense if you need to obtain hydrogen from Earth. probably initially that would be how its done. A rocket could use Earth's gravity to bend its course back to the Moon if done right. The payload could have a seperate smaller rocket to guide the payload into the Earth's atmosphere. I think antartica is a rather big target for any decent guidence system to hit, alot of other meteors were found there. The platinum dropped on Earth is likely to be alot heavier than any hydrogen lifted up. Perhaps the payload would need ablative shielding so it can survive reentry intact. Platinum is very heavy, I'm not sure its worth the areodynamic structures to ensure a soft landing for such a heavy hunk of metal, what is important is that the metal arrives in one piece so that its easy to recover. I think an Antartic glacier would make a great target zone. The meteor would excavate a crater in the ice and vaporize alot of ice into water vapor as it hit. Since it is only a hunk of metal, there is no need to treat it as you would human passengers, all that's important is getting it down to Earth as cheaply as possible.

Hydrogen would have to be brought to the Moon if it is not already there. Initially it would be brought from Earth, later on it could be brought from Mars. The cost of bringing hydrogen to the Moon from Mars may be less than bringing it from Earth.

A Mars colony would be more expensive, the ability to live off the land parly compensates for its greater distance from Earth.

Eventually as the volume justifies the initial investment, it will make sense to build a mass-drive on Mars and to build space colonies, and a lunar colony is not much different from a space colony in any case, the same requirements need to be met. With a space colony however, you can provide Earth normal gravity, and there is enough material in space to provide for a living area of about a thousand times that of Earth if not more. The asteroids are an obvious source for materials to construct O'Neill type colonies, but the Moon is alot closer and access to it is continuous, as opposed to each asteroid where their is a launch window for access to each. The Moon is kind of like the 8th continent, it has the surface area of Africa, and it will eventually be possible to schedule trips to the Moon like one does for the Airlines. You launch to Orbit and when your properly aligned with the Moon you make a translunar injection. People will be coming and going to the Moon at all times, where as at Mars their are times when the journey is optimal and their are other times when it is nearly impossible. A Mars Spaceport will be very busy at certain times with incoming and outgoing spaceships and at other times it will be quite and nearly deserted.

The most obvious place to build space colonies is in Earth orbit, as that provides for continuous access to Earth and near real time communication which maximizes the opportunity for trade and commerce. The Moon with thusly figure prominently in the supply of construction materials that can be easily had from the Moon, and thus mass-drivers will be constructed. For other elements, other extraterrestrial sources will be considered such as the asteroids and Mars. Hauling stuff off the Earth is expensive due to the gravity.

publiusr · 2006-12-08 16:31:20

With enough infrastructure, mass drivers or at least ramps can fire guided (craft) with some retro capability. We might be lucky and find a lava tube oriented a particular way to allow a below ground LV--perhaps even using gas pressure from below?

RedStreak · 2006-12-08 16:46:47

No, enough with the mass drivers and movement of material off the Moon! You keep on making noises about moving vast masses of material at huge expense into space to build stuff.
Furthermore, although we would eventually like to be able to build big O'Neal space station colonies and the like, we should FIRST set up where there are resources: on the planets and moons of the solar system. After we have a self-sustaining and growing Mars colony, and after we have visited out to the icey gas giants, and after the Earth's economy is joined at the hip with space for real... THEN we talk about it.
To expand, the emphasis should be on finding ways to benefit the Earth from space: if you do this, then the expansion into space will come. But, if you spend all your efforts on building big space ships for no good reason, then the money will dry up and you will go no place fast.

Amen to that. The Moon may be no Mars or Europa but it is as optimal you can get for a space-based construction site.

The minerals are right there and steady power at the poles if not water ice, no atmosphere to demand a protective shroud (or clouds to scrub launches like ol' STS), shadows that can ease the trouble of storing cryogenics, sufficent gravity to allow normal manufacturing practices (you try handling a free-floating glob of molten metal, even with a robotic arm) and yet light enough gravity to easily send craft anywhere in the solar system, and with Earth always within a week's travel away...

I would think many alien civilizations would envy our sheer luck of having a habitable world paired with a rocky spaceport-to-be.

RedStreak · 2006-12-08 16:53:15

Asteroid mining is a pipe dream, and the show-stopper details are numerous and often simply ignored by proponents, intractable basic physics problems casually relegated to the future.
To what intractable basic physics problems and show stopper details are you referring?

If any I'd say finding an asteroid with a stable-enough orbit to allow frequent revisists. Mars you can visit one ever two years but NEOs are trickier - they can get closer than the Moon but only once in a blue Moon...

If somewhere out there there's a rock that's allow revisits, say, once every two to nine months (or at least once a year if our asteroid sojourns are really robust) then you're in buisness.

Still I think asteroids at best will be second to the Moon due to launch window access. Someone will just have to look for an ideal candidate rock...and with several small NEO-watching-groups already on the job there is potential for this route.

Tom Kalbfus · 2006-12-09 01:21:49

There are asteroids on the Moon already. Every crater you see has the asteroid that made it underneath its surface.

Grypd · 2006-12-10 18:27:55

There are asteroids on the Moon already. Every crater you see has the asteroid that made it underneath its surface.

Yes but most have been destroyed in the collision. PGMs come from the class of asteroids that are metal rich and in this case due to there strength they may well have survived depending on the collision dynamics more or less intact.

Tungsten really isn't worth much much, it makes an awful radiation shield because cosmic rays would generate a nasty shower of particles. In fact, the Tungsten would probably multiply the radiation from cosmic rays.

I agree tungsten from the Moon would not be a realistic effort for any civilian programme. But there is a military use that if it is cheap enough could make it happen. The use of so called rods from god is a weapon system where tungsten inert impactors are dropped from orbit to destroy deeply embedded and strengthened bunkers. Cost has always been a limiter and if it is decided to go with this system then cost becomes the single most important issue. And supply of such rods from the Moon would likely be cheaper from an already present medium size PGM working base.

PGM deliveries to Earth will be more effectively financed if it was part of a regular shuttle service between the Earth and the Moon. But it would benefit from an electric space tug which could take cargoes from LEO capable RLV's to the more expensive in energy GEO area for cargo transfer and then to return the incoming cargo for later collection by RLV.

Electric field generating space tugs can use the simple effect of being opposite to the Earths magnetic field to propel themselves from LEO to GEO and can use the opposite effect to attract themselves in.

Tom Kalbfus · 2006-12-11 09:11:39

You could certainly knock out alot of bunkers with tungtein rods. Another use is as lighting elements for underground facilities on the Moon where you just don't want to bother with windows.

GCNRevenger · 2006-12-11 21:59:25

My I have gotten behind, where to begin:

-Solar rockets, I mean their thrust compared to chemical or nuclear rockets is almost nil. You can't get off the ground with a solar rocket, even off the Moon.
-Mass drivers to Earth are not a good idea if for no other reason than the Earth will be out of alignment for the shot except for a small fraction of the month. This breaks the usefulness of "many smaller payload" method. The only place such a gun should be aimed is a LaGrange point, where you wouldn't need orbital circulization. This is probably the only good way to build an O'Neil style colony, though I don't think those things will ever become very popular. Its going to be an extremely long time before we'd need the room I would think.
-On the equator of the Moon, you only get about one week out of the month of peak solar power when the Sun is overhead. Maybe stretch it to 10-11 days with gimbaled panels, but thats extra trouble. Since a railgun will be power hungry, this is the worst-case time you would have to operate the thing.

Next item on the list: "dumb" reentry of Platinum mined on the Moon to the Earth:

It makes no sense at all to drop big chunks of platinum somewhere in the deep snow and un-traversable wastes of Antarctica for pickup when you have to launch an RLV to fuel up the delivery ship in the first place! You just swap fuel for Pt ingots! RLV comes back down! FREE reentry! Its cost is zero compared to hunting Pt chunks on the south pole! Plus if you drop them there, the delivery ship would have to enter polar Earth orbit probably, no good for refueling.
-Hauling Hydrogen from Mars makes no sense when you have real live honest to goodness "we're not kidding this time" RLVs on Earth. Hydrogen extracted from Martian water will continue to be a fairly precious commodity for a very long time due to the energy required to extract it, and will be exclusively reserved (perhaps forever!) to make travel between Earth and Mars more efficient. The lack of power sources native to Mars will be a long-term issue. We have an atmosphere for unpowered landings, and by comparison unlimited energy and unlimited rocket fuel right here on Earth, Earth wins.
-Ion or other ultralow thrust tugs for Earth/Moon travel don't make that much sense, good ion drive fuel is scarce and expensive, the wide scale use of which would lead to its total depletion on Earth. The best fuel, Xenon, is produced as a product of nuclear decay deep in the Earth. The Moon might have a little bit, but the huge operation to get at it would be far beyond reasonable. Anyway, for efficient and economical Moon mining, you need your fleet of ships to make as many trips as possible per year, which you don't get with ion drive. With real RLVs on Earth and LOX on the Moon, rocket fuel isn't such a big problem for PGM mining. Oh, and tugs using electric fields to push off the Earth's? Uh, the Earth doesn't have an electric field. Try a MagSail instead.

Then this business about asteroid mining:

-As said by others, the lack of suitable launch windows and longish travel times means that only a big expensive hauler could move enough mass to be worthwhile, reducing efficiency, increasing risk, and basically making the whole operation harder.
-No gravity, which makes digging basically impossible. Without down force there is no good way to dig a hole or pull off good looking rocks from the surface. This also makes metal smelting essentially impractical and is hard on even medium-duration crews.
-Spinning, most rocks have multi-axis spins, which means you can't orbit, hover, or deploy a tether from the surface without continuously burning rocket fuel to compensate. This make solar power pretty precarious too. Theres that physics thing again.
-Overall, asteroid mining is overrated. The only real selling point they have is low Delta-V to get there and back compared to having to land on the Moon. But, if 85%+ of your descent/ascent propellant comes from the Moon (native oxygen) then this isn't such a big deal. The Moon is the place to be for digging materials in space.

Tom Kalbfus · 2006-12-12 02:08:09

My I have gotten behind, where to begin:
-Solar rockets, I mean their thrust compared to chemical or nuclear rockets is almost nil. You can't get off the ground with a solar rocket, even off the Moon.
-Mass drivers to Earth are not a good idea if for no other reason than the Earth will be out of alignment for the shot except for a small fraction of the month. This breaks the usefulness of "many smaller payload" method. The only place such a gun should be aimed is a LaGrange point, where you wouldn't need orbital circulization. This is probably the only good way to build an O'Neil style colony, though I don't think those things will ever become very popular. Its going to be an extremely long time before we'd need the room I would think.
.

A few things can be said for O'Neill type colonies.
1) They have more volume per given surface area and thus provide more shielding per inhabitant per unit mass than a small space colony.
2) O'Neill colonies can provide Earth normal "spin gravity" and you avoid the problem of humans adapting to lower gravity environments with weak bones, weak muscles, and a weak cardio-vascular system.
3) O'Neill are better at simulating a natural environment than a "tin can" habitat. They provide little bits of Earth away from Earth, and provides the feeling of being outdoors rather than being either indoors or in a spacesuit fogging up the face plate and unable to scratch your nose.

Grypd · 2006-12-12 06:23:02

Oh, and tugs using electric fields to push off the Earth's? Uh, the Earth doesn't have an electric field. Try a MagSail instead.

The Earth does have a magnetic field it is this that is used to repel a tug from LEO to higher altitudes and it can then attract itself back down to LEO.

Electrodynamic Tethers: Getting into the Swing

It is not a fast system but it does benefit from simplicity.

-On the equator of the Moon, you only get about one week out of the month of peak solar power when the Sun is overhead. Maybe stretch it to 10-11 days with gimbaled panels, but thats extra trouble. Since a railgun will be power hungry, this is the worst-case time you would have to operate the thing.

The solution is simple using our plans to create automated solar cell production we then build solar cell farms to the west and east and connect by buried cables then keep going to increase power supply to the point we actually are working. At the lunar poles it makes sense with the horizon being so close and that we then we will have almost constant power supply. The lifeblood of our space exploration. And when we move to another point we simply connect into what will be a quazi lunar power grid. When we leave the poles to go to the equator we do the same there and connect to the poles.

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