The Case Against Mars - Why Mars is not a good target!

smurf975 · 2004-06-14 08:26:47

I don't understand why you guys are talking about star trek technologies as it's not needed at this point.

If it were needed why are there profitable companies on Earth now? You just need a factory, energy and resources. The getting and designing the factory for Mars or Space, getting energy and resources that is the problem not ST nano tech.

Just robots building other robots thats what needed. Other robots can be anything from resource collectors to maintenance drones.

Basically you need something like this to start anything serious non Earth:

1. No Humans needed on the spot. Telecontrol
2. Enough energy be it nuke or solar.
3. Resources, all the elements needed are there. Or are cheap to ship like microchips.

JimM · 2004-06-14 11:19:45

On Deuterium:

Who says it's 5 times commoner on Mars than Earth? What is the basis of this belief?

As I understand it, deuterium is used in heavy water to act as a moderator in a fission reactor. There are many suitable alternative moderators.

OTOH, deuterium with tritium is/will be used as a fuel in fusion rectors. The trouble is we don't have a viable fusion reactor technology developed yet, never mind a commercial (that is, profitable) one.

How would you transport deuterium back to earth?

-- As heavy hydrogen? If so, have you allowed for the cryogenic tankage requirements and the 1%/week boil-off rate? You better plan on getting it back here fast. No leisurely cruises back by solar sail or ion thruster, etc.

-- In the form of heavy water? Think of the weight penalty just getting the stuff off Mars for a start.

If you go for the D2O transport method, first you have to distill out the heavy water. That will require prodigious amounts of power and a huge distillation facility weighing thousands of tons at least-- and at least at first, that'll all have to be brought from earth. If OTOH you want to send D2, you'll need even vaster power and plant requirements on the Martian surface to refine it from the heavy water.

And anyway, are you certain Mars is going to give up its water so easily for your D2O plant, at the probable rate of thousands of tons a day, to make the whole thing worthwile in any case?

There must be an easier way to earn a crust or develop a planet...

Rxke · 2004-06-14 12:23:58

I was just pointing out Drexelers views on nanotech, to show why he came to those conclusions of Mars not being the target etc.. With nano, a factory on Mars is easy, without it's complex to set up, because in essenc, of launch-costs... Even a primitive, inefficient foundry (small electrically heated vessel, filled by rovers etc for instance...) on Mars will cost Billions, because it had to be hauled from Earth...

Ian Flint · 2004-06-14 13:48:44

Who says it's 5 times commoner on Mars than Earth? What is the basis of this belief?

Robert Zubrin, that's who. (Case for Mars p. 224) And, just about anybody else that knows anything about Mars. Just do a google search. I researched it a little bit online and found out that this number comes from a measurement of the atmospheric water vapor (probably Viking).

As for extracting deuterium from regular water, there will be a lot of electrolysis being done on Mars, so half the work will already be done. Just separate the heavy hydrogen from the light hidrogen. Here's an excellent website I just found:
http://www.airliquide.com/en/business/p … ...RD26=78

It says that the boiling points of hydrogen and deuterium are slightly different, so just cool your electrolized hydrogen down to -249.6 C. Since regular hydrogen liquifies at -252.8 C it will still be a gas, so just release it and you have your pure deuterium.

On Mars you'll probably need a lot of liquid hydrogen anyway, so why not collect the deuterium 3.2 degrees before you liquify the hydrogen. On second thought, it looks like 99% of the work will already be done.

We don't need electrolysis or liquid hydrogen much here on Earth, so extracting deuterium is very difficult for us. On Mars it will be a logical thing to do as part of the daily routine.

I don't think deuterium mining will be the driving force behind colonization. But, since it is the only resource in the $10,000,000/tonne range proven to exist on Mars, it is pretty much the only concrete thing we can talk about.

Bill White · 2004-06-14 14:11:52

Who says it's 5 times commoner on Mars than Earth? What is the basis of this belief?
Robert Zubrin, that's who. (Case for Mars p. 224) And, just about anybody else that knows anything about Mars. Just do a google search. I researched it a little bit online and found out that this number comes from a measurement of the atmospheric water vapor (probably Viking).
As for extracting deuterium from regular water, there will be a lot of electrolysis being done on Mars, so half the work will already be done. Just separate the heavy hydrogen from the light hidrogen. Here's an excellent website I just found:
http://www.airliquide.com/en/business/p … ...RD26=78
It says that the boiling points of hydrogen and deuterium are slightly different, so just cool your electrolized hydrogen down to -249.6 C. Since regular hydrogen liquifies at -252.8 C it will still be a gas, so just release it and you have your pure deuterium.
On Mars you'll probably need a lot of liquid hydrogen anyway, so why not collect the deuterium 3.2 degrees before you liquify the hydrogen. On second thought, it looks like 99% of the work will already be done.
We don't need electrolysis or liquid hydrogen much here on Earth, so extracting deuterium is very difficult for us. On Mars it will be a logical thing to do as part of the daily routine.
I don't think deuterium mining will be the driving force behind colonization. But, since it is the only resource in the $10,000,000/tonne range proven to exist on Mars, it is pretty much the only concrete thing we can talk about.

Deuterium and video tape are perhaps the most plausible exports to Earth.

Exports to Luna or even LEO make more sense and in the centuries to come Mars resources (including steel) could be very valuable exports to people moving into the Main Belt.

I agree with Ian, deuterium mining cannot justify a base on Mars (and deuterium mining might not even be feasible) yet it is perhaps an early leading candidate as a possible export that can be used to soften the burden of settling for other reasons.

= = =

Might settlers be able to fabricate the parts needed to assemble liquid fuel engines from technology http://www.denford.co.uk/metalcasting.htm]like this? Go with a KISS rocket design and maybe build "made on Mars" liquid fuel boosters.

clark · 2004-06-14 14:15:44

mars exports?

Sweat shops and sneakers. just do it.

JimM · 2004-06-14 14:26:53

I don't understand why you guys are talking about star trek technologies as it's not needed at this point.
....getting energy and resources that is the problem not ST nano tech.
Just robots building other robots thats what needed...

Unfortuinately, robots building other robots is at this time also ST technology, just to exactly the degree that nanotechnology is, because they are actually the same technology.

The feasability of self-replicating machines was first postulated and given a sound theoretical basis by John von Neuman (1903 - 1957), a Hungarian genius who, courtesy of Hitler, ended up at the Institute for Advanced Studies in Princeton alongside Einstein & co. This is why such devices are known as von Neuman machines.

Unfortunately for your proposal, and despite the huge advances in computing since the 1950's, real von Neuman machines stil remain some way away, somewhere over the current-day 'event horizon'.

Thus, the same is true of real nanotechnology because real nanotechnology depends on our being able to create tiny von Neuman machines. That would be the only practical way for it to come about, as you can see when you stop and think about the problem.

So if one idea is star trek technology, so is the other. On the other hand, neither is as futuristic as all that; just out of reach for the near-term future.

The same can be said for commercial fusion reactors.

I think we would be well advised, as Robert Zubrin has been, to base all our plans and proposals for traveing to, exploring, settling and exploiting Mars, on existing, established technology. It needlessly weakens our case by coming up with proposals that depends on some scientific or technical breakthrough that has not happened yet-- especially as this is really not necessary.

JimM · 2004-06-14 15:32:27

Who says it's 5 times commoner on Mars than Earth? What is the basis of this belief?
Robert Zubrin, that's who. (Case for Mars p. 224) And, just about anybody else that knows anything about Mars

OK, thanks. I should have thought of checking 'Case for Mars'. (Although my google search-- look at http://www.agu.org/sci_soc/prrl/prrl001 … l0019.html --suggests that the quantity may actually be just 2 times commoner when you get to the Martian groundwater. And I see no information on this topic from the latest visitors to Mars this year yet.)

But that is not the main problem about this proposal, in my view.

It says that the boiling points of hydrogen and deuterium are slightly different, so just cool your electrolized hydrogen down to -249.6 C....

You make it sound like a dawdle. It is not. Engineering this sort of fractional distillation process plant to work is a major engineering effort on earth, never mind Mars.

We don't need electrolysis or liquid hydrogen much here on Earth, so extracting deuterium is very difficult for us.

What has our need for the stuff got to do with how difficult it is to extract?
When we have full-scale commercial fusion reactors, we will need deturium, and it will not be all that difficult or expensive when compared with making the stuff on Mars and shipping it back to earth. It will be produced though fractional distillation process plants that take a tiny fraction of the power from the reactor to deliver all the deuterium needed for it.

It would very silly to depend on deliveries from Mars, when you can make all you need on your doorstep. In fact, I suspect the reactor's waste heat would be more than enough to drive the distillation, meaning the real incremental cost/Kg would be zero.

So it would certainly be useful for Mars-based thermonuclear reactors, but that's about it. It's landed value on earth might well turn out to be almost zero.

geo_flux · 2004-06-14 20:00:52

I agree with JimM, I can't see how mining, separating, condensing, launching, landing, and recovering deuterium will be cheaper than just doing it on Earth. Deuterium may be more abundant on Mars but the number of steps added to get it to a reactor are huge.
On top of that, if the boil-off rate is 1% a week the whole idea becomes completely impossable instead of just unfeasable.

The only marketable products coming from Mars in the near future would be advertising and multi-media entertainment. Information based products that can be transported cheaply without loss of quality. Find a multi-billion dollar advertising/entertainment product from Mars and you've got the means to a colony.

smurf975 · 2004-06-14 23:12:37

I don't understand why robots building machines is ST technology? Don't they build cars now?

And I'm not talking about Mr. Data like robots but robots that you see now in any modern manufacturing plant.

As if you would walk now into a modern car factory you would see basically this is already happening. If you ever saw footage of a modern car factory you will know what I'm talking about. For example steel plates come in, they are put into a machine that presses them to door shapes or parts of the car frame. Then a robotic arm takes the part to a welding robot who then welds the parts together this is followed by a robot that screws on smaller parts. etc etc. Almost no humans needed.

Look at this picture to see what I mean:

I have also worked in a food factory where they made instant food and there the assembly workers were basically just to turn on the machine and turn it of. The pusher of the button job

Steel and chemical plants are also very automated. Basically humans are only needed to stop the machine when it goes wrong and then start it again. Same goes for microchip plants, a design is fed in and the computer know what to do.

However now in then you still see humans getting in the picture as sometimes its cheaper to have a human doing a task then build a robot for it. But in Space you have no choice.

But just as someone else said getting those robot plants to space or Mars is expensive but if money wasn't an issue you could have them now. Nanotech is to far away. And this would of course be only an option is you want to start to colonize space. As it will be cheaper then building everything on Earth or sending tons of people. Like any investment in automation it takes a big initial investment but in the long rung you are better off.

JimM · 2004-06-15 01:39:33

I don't understand why robots building machines is ST technology? Don't they build cars now?

Yes they do build cars and many other things, but that's not what I presumed you to mean when you said…

Just robots building other robots thats what needed.

Robots building other robots--in other words, von Neuman machines --is what you need to automatically build a factory (actually a process plant in the case of D2) on Mars. That is what is significantly beyond our abilities today.

In fact if we had von Neuman machines, all sorts of things would become possible like for example, asteroid mining to create virtually free SSPSs and the terraforming of Venus-- just to start with.

The thing is, we don't have them yet.

------

On top of that, if the boil-off rate is 1% a week the whole idea becomes completely impossable instead of just unfeasable.

Yes. I seems to me that's another reason why fusion reactors on earth would want to make their own D2. Apart from it being effectively free to them, it is clear that with H2/D2's boil-off rate, which applies on earth as well as heaven (sorry about that) it would be essential to create D2 for almost instant use; the stuff is effectively unstoreable over the medium term.

And the earth's oceans are awash with the stuff anyway; it's just rather more dilute than on Mars.

Anyway I'm curious to learn how a large low density cargo that must be kept below -249.6 C is going to be induced to reenter earth's atmosphere without exploding, imploding, blowing every pressure relief valve in sight, or otherwise failing to deliver itself intact to the ground?

smurf975 · 2004-06-15 02:14:17

No I meant with robots building robots: Robots building machines. For instance if you agree that robots now do almost all the car building. Now if you would put in a remote radio control and a computer and make it do stuff like the mars rovers are doing, then you have robots building robots.

Why is this impossible if its already happening? Only thing missing for the machines being build to be called robots is a telecontrol. You just need to feed in another design in to the manfacturing plant and there are your machines (robots).

From the http://www.wordiq.com/definition/Robot]wordiq site the definition of a robot:

In practical usage, a robot is a mechanical device which performs automated tasks, either according to direct human supervision, a pre-defined program or, a set of general guidelines, using artificial intelligence techniques.

So why can't such a mechanical device build a similair mechanical device? Considering you have enough energy and resources.

Here is an example http://www.spacedaily.com/news/robot-00g.html]of robots being used in mining.

Yes the initial cost will be high but the initial cost of doing anything more then sending rovers into space will be high. Having automated factory plants and resource gathers in space would be the smartest thing to do (if you going to do anything at all). As as soon as its there it basically costs you nothing. As in space you don't have to pay energy bills, taxes, pay for the resources. It will only cost you if you don't use it.

In the initial fase you would make the plants build other plants (meaning the parts and machines that make up the factory and have robots assemble them). So if this works you will only have to pay for the first manufacturing plant all the others will be build locally using almost zero Earth resources.

Disclaimer:
1. When I say space I mean anything but not Earth, so it can be the moon, space, asteroids, mars or other.
2. Yes I know that you will need humans on the spot to do repairs. But mostly telecontrolled robots to do repairs. So one human can oversee a huge area. I think its not pratical to do this from Earth if you are not talking about the Moon. Due to the time lack in communications.

smurf975 · 2004-06-15 02:22:24

Anyway I'm curious to learn how a large low density cargo that must be kept below -249.6 C is going to be induced to reenter earth's atmosphere without exploding, imploding, blowing every pressure relief valve in sight, or otherwise failing to deliver itself intact to the ground?

From what I gather the inside of the space shuttle is pretty cool. Else we would have fried astronauts So I don't think thats the problem.

JimM · 2004-06-15 05:19:38

From what I gather the inside of the space shuttle is pretty cool. Else we would have fried astronauts

Uh, we have had fried asronauts (in Columbia).

And anyway it's a long, long way, temperature-wise, from room temperature (about 20 C, say) to -249.6 C, which is not all that far from absolute zero. The D2 would have to be some 270 C cooler than the inside of the Shuttle is when it behaves. That is no minor detail.

JimM · 2004-06-15 07:37:06

No I meant with robots building robots: Robots building machines. For instance if you agree that robots now do almost all the car building. Now if you would put in a remote radio control and a computer and make it do stuff like the mars rovers are doing, then you have robots building robots.

Robots building machines, even other robots, are not the same thing as von Neuman machines.

The sort of robots that we have in car plants today are really pretty primitive. Indeed, they only just qualify as robots. They can’t ‘see’ or otherwise know anything about their environment. They can repeat the same sequence of actions over and over, but as soon as something unplanned happens they can either ignore the change and cause chaos, or switch themselves off. IOW, they are completely and utterly dumb.

The current crop of Martian Rovers are certainly a step forwards, but still they need constant help from us humans. They can’t decide for themselves where to dig a hole and then take or not a sample because they don’t know what’s interesting and what’s not, they can’t decide what route to take, they can’t go beyond the point we can see because they have no automatic way of adjusting their travel to take account of unexpected obstacles like rocks. And they sure as anything can’t replicate themselves, let alone turn themselves into machines that do other things. And of course, they can’t repair themselves. They’re good, don’t get me wrong. But they’re not that good.

Why is this impossible if its already happening? Only thing missing for the machines being build to be called robots is a telecontrol. You just need to feed in another design in to the manfacturing plant and there are your machines (robots).

I’m all in favor of optimism, but you can get too much of a good thing.

A machine that replicates itself is not so straightforward as you make it sound. For a start, it has to go prospecting and find the right suitable raw materials. Then it has to turn them into the right sort of refined materials needed to make every one of the components that goes into its make up. Then it has to manufacture all—every one—of these components. Then it has to assemble them all together into a twin of itself. Then it has to program its twin. And unless you want it to stop and wait for new instructions from earth (or even from somewhere else on Mars) every time it hits a snag in all these millions of millions of steps it has to be able to do all this on its own initiative or the whole business will take for ever. So forget remote radio control. And its computer will have to vastly more powerful than any made so far—and that’s just one of the things that will have to be replicated to make a true copy.

Of course, to carry out this replication process, it will be necessary—

(A) Either to have a machine that is, among other things, a minerals prospector and miner, universal materials refiner, universal component manufacturer, and so on,

(B) or a machine that can also manufacture other machines that are specialist prospectors, miners, refiners, component makes, etc., etc…. but of course it can do none of that until the first of all these are made so it can make them (it’s getting a little circular here, isn’t it?)

So, in the end—or rather, in the beginning, (B) does not work out; only (A) does, which means you need a sort of universal machine.

How far do you suppose we are away from having this sort of machine? 10 years? 25? 50? 100? 200? Never?

Because we sure don't have this technology now.

smurf975 · 2004-06-15 08:47:22

Robots building machines, even other robots, are not the same thing as von Neuman machines.

I'm not interested in von Neumann; I just want affordable and working solutions. If I were thinking like you I could say: “Well just wait until we have faster then light travel.”

The sort of robots that we have in car plants today are really pretty primitive. Indeed, they only just qualify as robots. They can’t ‘see’ or otherwise know anything about their environment. They can repeat the same sequence of actions over and over, but as soon as something unplanned happens they can either ignore the change and cause chaos, or switch themselves off. IOW, they are completely and utterly dumb.

Who ever said that robots must be smart to be a robot? They just need to be able to do the job. About seeing and sensing if you read the link to the article about robots in mining you would know they exist. However it’s not needed in certain tasks. It seems you are waiting for the ultra robot.

Those primitive robots in factories don’t need to see at all. You know the principle KISS? It means Keep It Simple and Stupid. Why do you think that the Space Shuttle program failed? Its because they wanted to the shuttle to able to do everything while that’s not needed. The KISS principle keeps things affordable and working with out all the bloat.

But really why build robots that can do everything? Or that are smart? What the use for that? I just need something that does the job!

The current crop of Martian Rovers are certainly a step forwards, but still they need constant help from us humans. They can’t decide for themselves where to dig a hole and then take or not a sample because they don’t know what’s interesting and what’s not, they can’t decide what route to take, they can’t go beyond the point we can see because they have no automatic way of adjusting their travel to take account of unexpected obstacles like rocks. And they sure as anything can’t replicate themselves, let alone turn themselves into machines that do other things. And of course, they can’t repair themselves. They’re good, don’t get me wrong. But they’re not that good.

There you go again thinking that the only true robot is able to discuss Shakespeare and that has several degrees from a uni.

You are wrong about this and it makes no sense. With six billion humans on Earth, why would you need a smart robot? Humans can do robots smart tasks cheaper.

A robot is an automated machine and it just needs to do the task not impress science fiction writers.

A machine that replicates itself is not so straightforward as you make it sound. For a start, it has to go prospecting and find the right suitable raw materials.

Yep you would need a scout for this like what the rovers and satellites are doing now. And humans. Both humans and scout robots will mark the areas that have certain minerals with beacons and the digger robots will follow.

Then it has to turn them into the right sort of refined materials needed to make every one of the components that goes into its make up. Then it has to manufacture all—every one—of these components. Then it has to assemble them all together into a twin of itself.

You are making it sound like I'm talking about one machine, which I'm not. You will have a lot of specialized machines with each its own task. What I was saying is a manufacturing plant that houses these specialized robots and processes.

Can you do everything? Do you have a farm and raise livestock and vegetables while having an office job? Why should a machine be able to do this? It’s just not efficient to do so.

Then it has to program its twin. And unless you want it to stop and wait for new instructions from earth (or even from somewhere else on Mars) every time it hits a snag in all these millions of millions of steps it has to be able to do all this on its own initiative or the whole business will take for ever.

Well that’s why you will have humans in proximity they will solve these snags by using telecontrolled robots. And those same snags will occur on Earth or even when using von Neuman machines. Errors will be always there. But you make it sound like an error will occur every 10 minutes. If that’s so then you should think about the general design of the factory on Earth or Space.

Question why would a snag happen more in Space then in an Earth car plant? The robots from car plants also do millions of steps. So does you operation system. Do you know how many lines of code Windows 2000 / Linux / OSX has? It has millions but in general it works just fine.

And programming its twin is nothing more then uploading software to the twin’s memory.

And its computer will have to vastly more powerful than any made so far—and that’s just one of the things that will have to be replicated to make a true copy.

Ok it looks like you are not familiar with electronics and IT. But really a robot that just follows simple steps and orders would not need more processing power then a 20 year old CPU has. You know that those rovers on Mars have a CPU similar to a Pentium 1? And that’s already overkill as they are under clocked. The space shuttle is using i386 processors.

You can run Windows 2000 one a Pentium 1 CPU, which is now, what, ten years old? And its far more complicated then what a robots software would be.

And as computers work digitally there is nothing lost in making copies.

An example would be that they would be working like ants. Each doing its own little thing but with higher goal that they are individually unaware of.

(B) or a machine that can also manufacture other machines that are specialist prospectors, miners, refiners, component makes, etc., etc…. but of course it can do none of that until the first of all these are made so it can make them (it’s getting a little circular here, isn’t it?)

Its not. You need to invest before you can profit. Or are you saying that you will swing your magic wand and von Neumann machines will appear on Mars?

On discovery channel I often watch programs on WWII tanks. And you know what most of them were the same. For example the Germans had one basic design, which included the frame and engine. For different tasks they would fit them with different weapons. The Americans did the same. On one tank they would fit a heavy gun on another they would fit a lighter gun but with a flamethrower and there was also a tank with no gun at all but with equipment to clear mines.

What I'm saying the basic models can be the same but with other specialized tools attached.

It also looks like you are waiting for besides von Neumann machines for some human like artificial intelligence. I think you can wait a long time for this. And really its not needed. KISS, and if it works then its good enough. But you want all the bells and whistles.

How far do you suppose we are away from having this sort of machine? 10 years? 25? 50? 100? 200? Never?

I’m sorry but everything I said is already happening here on Earth except for human intelligence like robots. Which is not needed. We got six billion humans.

JimM · 2004-06-15 10:11:39

I'm sorry but you started out a few messages back saying...

No I meant with robots building robots: Robots building machines. For instance if you agree that robots now do almost all the car building. Now if you would put in a remote radio control and a computer and make it do stuff like the mars rovers are doing, then you have robots building robots.

...which sounds remarkably like you plan on making the whole process automatic, which no humans actually present, but just at the end of a radio link.

I'm not interested in von Neumann; I just want affordable and working solutions. If I were thinking like you I could say: “Well just wait until we have faster then light travel.”

Now you say you don't want von Neuman machines. But that's pretty much what you said you wanted without actually using the name, as quoted above!

(You see, the only "affordable and workable solution" is, in the end, a von Neuman machine. So I suggest you get interested.)

I’m sorry but everything I said is already happening here on Earth except for human intelligence like robots.

Without enormously more intelligent machines than today, none of what you say is or will happen with robots. The car factory robots you use as an example, for instance are nothing but highly, highly specialist idiots.

Which is not needed. We got six billion humans.

Absolutely. and of course we can do it that way. But that's not what you started out proposing. And if you do do the job with humans that's fine, but the cost will be out of sight.

I thought the idea was to do this economically. And that'll happen with von Neuman machines one fine day, but not this century. OTOH, you're not going to have enough humans on Mars to do the job this century either.

smurf975 · 2004-06-15 10:28:30

Quote
No I meant with robots building robots: Robots building machines. For instance if you agree that robots now do almost all the car building. Now if you would put in a remote radio control and a computer and make it do stuff like the mars rovers are doing, then you have robots building robots.
...which sounds remarkably like you plan on making the whole process automatic, which no humans actually present, but just at the end of a radio link.

Yes and...?

Now you say you don't want von Neuman machines. But that's pretty much what you said you wanted without actually using the name, as quoted above!

I'm sorry but I'm not to familair with von Neumann, I thought his ideas were about nano technology. Which I think is not needed to get things rolling.

(You see, the only "affordable and workable solution" is, in the end, a von Neuman machine. So I suggest you get interested.)

Today's commercial robots are profitable else they wouldn't exist. No need to wait and pray for a breakthrough in science.

Without enormously more intelligent machines than today, none of what you say is or will happen with robots. The car factory robots you use as an example, for instance are nothing but highly, highly specialist idiots.

What wrong with them being stupid as long as they get the job done? I don't need to impress my investors with how smart my machines are but how effective they are.

Absolutely. and of course we can do it that way. But that's not what you started out proposing. And if you do do the job with humans that's fine, but the cost will be out of sight.

I never said humans aren't needed if you read point two of my disclaimer:

2. Yes I know that you will need humans on the spot to do repairs. But mostly telecontrolled robots to do repairs. So one human can oversee a huge area. I think its not pratical to do this from Earth if you are not talking about the Moon. Due to the time lack in communications.

And yes it will cost you money like doing anything costs you money. If you want to save money then just do nothing at all and pray for your nanomachines while I will do something real today.

Your arguments sound like lets not build sailing ships and windmills as one day we will (or may) have steam engines.

BTW: The research for those nanomachines also cost money.

GCNRevenger · 2004-06-15 10:41:41

The only real practical concept for robot-make-robot situation I can see is to make a "car factory" style robot assembly line which is built to make the robot arms, conveyers, etc for another car factory in manageable chunks and be able to build moderate-to-complex machines of other types (Martian electric bulldozer, train-track layer, nuclear reactor parts) from already-refined materials (sheet and plate Mg alloy, granulated thermoplastic polymers, Cu wire, packaged ICs from Earth)... Make the thing with construction of heavy equipment, airlock doors, LSS machinery in mind but build it in such a fasion that it could build and package modular copies of the robot arms, cutters, welders etc. Such a thing wouldn't be easy, but it would be possible.

Now about cryogenics... on Earth the trouble is protecting it from the warm air, so the simplest thing to do is not to liquify it at all, hydrogen is moved around as a gas down here. In space, the only heat sources of consequence are from the Sun and the vehicle itself; thermally isolating a tank to achieve extremely low boiloff isn't that hard, the SIRTF does it just fine with dozens of gallons of even-colder liquid He... adding a small condenser setup would mostly take care of the boiloff problem, we've gotten better at handling LH2 than we were 30-40 years ago. On Mars, I don't see a reason why it couldn't be handled as a gas most of the time either, and just like on Earth, only liquified as needed. The lower temperatures, thinner air, and dimmer sun would make it even easier... The only biggie issue is how you get the stuff down through reentry on either end of the trip. MarsDirect aims to put 6-8MT of LH2 down with the ERV all the way from Earth launched 6mo ago through aerocapture and Mars reentry, so it can't be that hard... So much for "LH not simple, LH bad!"

smurf975 · 2004-06-15 11:02:28

from already-refined materials (sheet and plate Mg alloy, granulated thermoplastic polymers, Cu wire, packaged ICs from Earth)

You do realize that on Earth that modern refineries are fully automated? So whats stopping it from happening in Space?

An example when I was still at school we went on a field trip to a sugar plant. You know what there were no humans there except for the tourguide.

I also went to a conventional powerplant and it was the same thing. The only humans were the tourguide and the guys in the control room. The only other humans were the ones delivering coal (or what ever it was) by boat but that was handled by machines also. The captain just had to park his ship at the right place and everything was handled.

But as I said in a previous post:

So if this works you will only have to pay for the first manufacturing plant all the others will be build locally using almost zero Earth resources.

With that I mean stuff like ultra high tech devices like what you see in the hubble telescope. And also food for the limited number engineers.

However I expect sooner or later that a plant would rise that could build them locally as soon as there is energy and resources to spare. But more importantly by uploading a design of machine (plant, factory) thats able to build it by robots.

Thats the way it works on Earth, first you get a product then you think of ways to make it cheap and mass produced.

GCNRevenger · 2004-06-15 12:13:12

Certainly they can be highly automated, but the point is, that is a job for a seperate factory with seperate machines, and not for one jack-of-all-trades mega factory.

smurf975 · 2004-06-15 12:28:45

Well if you think of a mega factory as just one building then no but if you think of a mega factory as a site containing several buildings then yes. As now industries related to each other tend to be in the same area.

John Creighton · 2004-06-15 12:35:53

Some thought experiments:
1)If we had one commander data on mars, how long would it take him to make another commander data. Assume has tools, but not people robots, or any other means of productions. Also assume that the total weight of the tools weigh no more then data.
2)What is the minimum infrastructure needed on mars to produce a microchip? Assume no advanced technology. Remember with know microchips there will be know artificial intelligence as we know it. Granted we could still have some computers based on transistors, diodes or vacuum tubes.
3) What is the minimum infrastructure needed to build a factory that can produce the machines to make microchips?
4) With current technology what is the minimum possible size (weight and volume) of a factory that can produce iron, steel, nickel, silver, tungsten, silicon, plastic, lubricants, platinum.
5) What isotopes will we use on mars to dope the semi conductors? How will we obtain them?
Some thought experiments:
1)If we had one commander data on mars, how long would it take him to make another commander data. Assume has tools, but not people robots, or any other means of productions. Also assume that the total weight of the tools weigh no more then data.
2)What is the minimum infrastructure needed on mars to produce a microchip? Assume no advanced technology. Remember with know microchips there will be know artificial intelligence as we know it. Granted we could still have some computers based on transistors, diodes or vacuum tubes.
3) What is the minimum infrastructure needed to build a factory that can produce the machines to make microchips?
4) With current technology what is the minimum possible size (weight and volume) of a factory that can produce iron, steel, nickel, silver, tungsten, silicon, plastic, lubricants, platinum.
5) What isotopes will we use on mars to dope the semi conductors? How will we obtain them?

JimM · 2004-06-15 14:10:13

In space, the only heat sources of consequence are from the Sun and the vehicle itself; thermally isolating a tank to achieve extremely low boiloff isn't that hard...

In space, no-one has ever bettered a 1%/week boil-off rate for LH2. I'm assuming no improvement for LD2. So, a 'standard' Hohnmann elipse from Mars to Earth taking 260 days or 37 weeks and a bit, will loose over 30% of its LD2 cargo in transit. A solar sail or ion powered transit is likely to take longer and loose more.

On Mars, I don't see a reason why it couldn't be handled as a gas most of the time either, and just like on Earth, only liquified as needed. The lower temperatures, thinner air, and dimmer sun would make it even easier...

The difference beteen terrestrial and Martian ambient temperature, etc., is as nothing compared with LD2's boiling point of abouit -250 C. And I really don't see how you're going to either launch into orbit or have reenter a planetary atmosphere something with roughly the density of the Hindenburg airship, if not the overall size. Just think about the heat shield requirements!

The thing that really sinks this project-- as I said before-- is that fusion reactors (when we have them) will make their own D2 almost as a byproduct from their waste heat, making the cost to them of D2 effectively zero and available as and when required, right on their doorstep. Apart from a small tank of the stuff sufficient for the occassional re-start--which they can fill for themselves easily anyway, why should they want to bother with huge storage facilities? Why ever should they want to import the stuff at astronomic cost from Mars?

I think it might be best to drop this idea as the non-starter it is and look for some other way to make a profit from the Red Planet.

GCNRevenger · 2004-06-15 14:28:47

No one has ever beaten a 1% per-week boiloff because nobody has ever needed to. The only time cryogenic fuels have ever been really needed recently, now that we are better at handling them, is for launcher upper stage engines where boiloff isn't a problem.

The SIRTF space telescope, launched into Solar orbit recently, must be kept quite cold. The coolant is liquid Helium, which is even colder than LH2 or LD2, stored in a rather large tank and connected to the thermal "optics" to draw the heat away. This tank of LHe will last for many years, shielded from the sunlight by a shade and relativly isolated from the rest of the vehicle.

And as you have pointed out in earlier threads, that the volume increases with the cube and the surface area with the square, so for a larger LH2/LD2/etc tank there would be even less energy flow into the tank for a given mass of the liquid. With a decent solar or nuclear power source, particularly if it were operated off the shaft or waste heat directly, a modest mechanical or thermoacoustic condenser would make space storage of high-cryogenic substances practical.

The SEI "Battlestar Galactica" and the more recent NTR-powerd Boeing "Mega CEV" nor the MarsDirect liquid hydrogen-from-Earth operate ERV concept wouldn't even enter the realm of reason with that kind of 1%/wk boiloff rate. The short times spent as a liquid before being launched on either body combined with decent shielding for entry shouldn't be a problem if a little boiloff is accepted.

Though ultimatly I agree, that without a gigantic market for Deuterium that makes abundance in nature a limiting factor, I don't think Martian sources of the substance will ever be profitable for anything except domestic and Mars-orbit fusion power.

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