Since this topic has been lightly discussed before in various threads, I would like to dedicate this thread to this one subject, testing equipment for planetary missions. Please restrict comments to this topic.

It has been suggested that our Moon should be used to test equipment to be used on other planets, specifically Mars. This has been suggested many times, and even NASA has been credited with the idea, but I have yet to see any detailed credible reason for testing on the Moon.

On the other hand, I find a many valid reasons to do most of the testing for Mars here on Earth. Briefly:

a. Testing could be done far less expensive here on Earth.
b. Testing could be done far safer here on Earth.
c. Testing could be done much faster, and problems corrected much faster here on Earth.
d. The day/night cycle is almost identical.
e. The temperature ranges are relatively similar to certain regions on Earth.

For comparison, here are some basic statistics.
Mars: Gravity is .38 of Earth's, Moon: is .17 of Earth's
Mars: thin atmosphere of CO2, Moon: none
Mars: Large amounts of water at poles and possibly elsewhere, Moon: Probably none
Mars: Plenty of Carbon for growing food, Moon: virtually zero.
Mars: 44% of the harmful radiation that the Moon receives.
Mars: usable wind for wind power, Moon: none
Mars: Day 24 hours 37 minutes, Moon: four weeks
Mars: has two moons, Moon: none

IMO, testing for any and all equipment to be used on Mars can be done here on Earth. Every aspect of Mars, except the .38G gravity, can be simulated using sites such as Devon Island, or in low pressure domes and structures using climate control equipment.

I am interested to see what testing others think can be done better on the Moon, not even counting the cost/safety/time differences.

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Well, I think you have a couple small errors there. The Martian day is slightly longer than Earth's, not shorter. The wind on Mars is probably not capable of being harnessed because of the low pressure. It might be able to pick up dust and skip sand, but it probably can't spin turbines.

You should add that Moon dust is especially troublesome and has no martian analog. That one issue might be enough to make it a bad testbed. Testing mechanical devices in a lunar dust environment makes as much sense as testing them in a Hawaiian hot lava bed, it adds a critical damage characteristic that is not representative of the deployment environment.

The only compelling reasons to test on the Moon are psychological, not physical.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Thank you, I corrected the data.

The wind is capable of creating a global dust storm. I am sure it can be harnessed with wind turbines. The Martian atmosphere may be thin, but it extends up a long ways.

Actually, Martian dust is very fine, making it a different problem than the abrasive dust on the Moon.

Please elaborate.

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The atmospheric density on Mars is at best about 1/50th of the density on earth, so for a given size wind turbine you get 1/50th the power. And what does the upper atmosphere have to do with this? The higher you put your turbine the less density and power.

That's basically what he said

Anyways I agree with both of you guys there is no point in testing equipment for mars on the moon because they are so different and better test sites can be found on earth or created in laboratories. Some testing will have to be done in space or on mars, like EDL systems.

However, the wind on Mars blows at up to 200mph. The force created by wind increases as the square of the velocity. Wind turbines on Mars would be a practical auxiliary power source, providing power when the wind was blowing up the dust and obscuring the sunlight from the solar panels.

Not exactly. I was pointing out what those differences are. Martian “fines” create their own special problems, especially with seals.

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The fact that the Martian atmosphere extends higher also means that, as you gain altitude, the density does not decrease as rapidly as on Earth. All lf the weather on Earth occurs within the first 7 miles, but on Mars, the dust storms nearly reach the top of Olympus Mons which is 15 miles high. That means that you can put wind turbines at relatively higher elevations on Mars without losing as high a percentage of the force of the wind.

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It does on Earth from time to time as well.

Given the 1/2 p v ^2 equation for dynamic pressure:

Peak turbine performance on earth is typically at about 33 mph ( 15m/sec )

1.23 kg/m^3 x 15 ^2 = 138 Pa

To match that on Mars - with atmospheric pressure of 0.02 kg/m^3 - you would have to have...

138 = 1/2 * 0.02 * x^2

117 m/sec - 261 mph.

So - to get peak turbine performance as produced by 33 mph winds on Earth - you would require 261 mph winds on Mars. The average wind speed on Earth ( about 6.6 m/sec ) would have to be matched by Martian wind speeds of 51 m/sec (114mph)- which is over the peak value I have seen for observed Martian winds. If you think think the very best way to spend mass budget to the surface of Mars is with wind turbines - you're mad. That they would generate SOME electricity is a certainty, some of the time - but it wouldn't be a lot and they make nowhere near as much sense as they do on Earth. What about when the wind stops? It will from time to time, for periods of time that might be anything between minutes and days - and it's not a case of 'turn off the lights' - it's a case of people dying because of failed life support. Every single iota of power you intend to generate via turbines HAS to be match by non-environmentally variable means ( i.e. small RTG derived platforms such as those proposed for Mars Direct ). If you've got the power you need from those, then why both with turbines at all.

I agree, however, that the moon offers little usefull analogy to the Mars in terms of exploration systems testing. Things the Earth can't provide however - are the UV radiation - the temperature swings - the air pressure - and the simple reality of being 250,000 miles from home when something breaks down. The argument of going to the Moon so as to make going to Mars easier is without merit. But the brutal fact is that there is currently, political will to revisit the moon -and none to visit Mars. When GWB announced the VSE, I think his words describing the lunar visits as a stepping stone to Mars was a programmatic one, not an engineering or practical one.

Doug

Doug,

Give him a break! Of course the air is thinner on Mars--but so is the sunlight! Everything is less good on Mars. That's why Mars is Mars and Earth is Earth. Get used to it. . . .

The only thing that works the same is nuclear. Is that what you propose?
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Mental,

As for testing on the Moon. What is the argument? That we need to blow off the Moon so we can go to Mars? That we can't do both somehow? Like we have to blow off the Azores so we can colonize Massechusetts? What's wrong with the Moon? Why do you hate it so much?

The differences are not "less good" enough to rule them out. The main objection to nuclear on Mars is that it's heavy, so shipping it there is expensive in energy. Solar, as the rovers demonstrate, works and is low-maintainence, the only problems are dust and night. Wind turbines can work on Mars, according to the number-crunchers who have researched it. In terms of reliability and maintainance, it's somewhere between nuclear and solar. No doubt all three will get some use on the red planet.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

The efficiency of any wind turbine depends on many factors, including the shape of the blade and the type of turbine. Designs are chosen to maximize efficiency for given location.

Strawman. No one is claiming to “match” or “compare” Earth with Mars, except perhaps you. They are two dramatically different atmospheric environments and each will employ the best design for the location.

Ignoring the Ad Hominem…….. That is another Strawman. I never said, indicated, insinuated or alluded to any such thing.

Once again, Strawman, comparisons with Earth in this respect are irrelevant.

I strongly suspect the wind turbines will stop turning.

Good grief, your Strawman army is growing rapidly. As I specifically pointed out, ” Wind turbines on Mars would be a practical auxiliary power source, providing power when the wind was blowing up the dust and obscuring the sunlight from the solar panels.”. In addition, like most auxiliary power systems, a battery backup, a fueled generator, or a nuclear power system could be included for times when there was no sunlight or wind. There are many ways to store power, including lifting water, batteries, and flywheels.

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Reality: What a concept!……………………..><Ç(((Ç°>

Well, it looks like I'm wrong on this one, and I gladly admit it. The numbers posted by djellison show that even if it's not as good as Earth potential, there is at least some potential for wind turbines on Mars. I had expected them to just sit still in the martian atmosphere. Now, we'd have to make them lightweight and dust-resistent.

Well, djellison got my point. Lunar dust is a different problem. But I suspect that lunar dust will be more of a problem for lunar exploration that martian dust will be for Mars exploration. It's not just type of dust, but the magnitude of the problem. Equipment designed for work on mars would fail prematurely on the moon, which would make the test data useless.

Psychology in terms of both participants and the public. I'm not referring to the Moon as a Mars analog in this respect, just that the advantages in a lunar base outweigh disadvantage of the failure in analogy. The communications lag time is less, allowing for real-time communications when troubleshooting new basic space technology. Establishing an offworld base on the moon will go farther in convincing the public that a Mars colony is feasible. Overcoming obstacles in planetary colonization will be considered generic by the paying public, which will go a long way towards promoting space exploration in all its forms and destinations. If we consider business and the market as strongly driven by psychology, then generating a market for basic space tech by going to the Moon and staying will be enormously helpful in making a Mars trip and colonization later.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Hear, hear. And it'll do the same for all future manned space missions and bases.

Plus, having a base on the Moon is useful in and of itself.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

First off, unless the metal is mined, refined, and constructed there, Mars bases will not have industrial sized 100 ft+ turbines like we have here. An array of smaller sized turbines would work a whole lot better than 1 or 2 huge turbines, and be much easier to transport there. Plus, a Mars base will be built for maximum operating efficiency as possible, not like our energy gobbling systems here on Earth, so they will not need 2 megawatts of wind power to run their systems.

I doubt that. Chances are a colony, a real colony --not a temporary space base-- will be driven by economic considerations that result in suboptimal efficiencies.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Thank you. I respect you for that.

From what I have read, the Martian dust is so fine that it would be a problem in several areas. One is that it might be able to work its way into conventional seals, especially seals around rotating parts. Therefore, a new kind of seal may have to be developed. Another thing is that it may cling to clothing, much like talcum powder would, making it difficult to remove the dust when entering the habitat. It might not be healthy to bring that dust into your home. Therefore, special cleansing systems may have to be developed to remove the dust efficiently.

I understand. Education is the key to preventing uniformed emotional reactions from preventing the implementation of practical applications.

It would be preferable to get the troubleshooting phase over with before taking the equipment to the Moon. The Moon would be a really bad place to “work out the bugs”.

True. But establishing a viable colony on Mars would go a lot further.

IMO, the best role for the Moon to play in all of this is in providing processed materials for use in Earth orbit, LaGrange points, Mars orbit, and other space vehicles. The less we have to boost from Earth, the more we can explore for the same money.

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Reality: What a concept!……………………..><Ç(((Ç°>

Hmm, I wonder if the Mars dust powder could be used as a lubricant in the dry atmosphere in the same way that graphite and corn starch can be lubricants. I suppose silicosis might be a real problem for surface explorers. They may need to use cheap and disposable plastic coveralls over their pressure garments.

True, but as the saying goes: "One test is worth a thousand expert opinions." Poo happens, and we wouldn't want a repeat of Apollo 13 half-way to mars. It helps to have an analogy to "sea trials" for some vehicles and onboard equipment. Orbiting the moon (or placed into a LaGrange Orbit) might be a simple way to keep it outside the Earth's magnetosphere for testing. Of course, it might be more realistic to send an unmanned version to Mars and back but the expense may prohibit such a test. I don't think the Moon is a good analog for Mars, but it can be useful for testing some space technology. It might be critical for testing space-elevator and rotovator concepts.

Possibly, depending on what raw materials are available. There's lots of aluminum, oxygen and silicon, but not much carbon or hydrogen. They may not be able to make Mylar, but then, Mars or Mars moons may not be able to either. We may have to make due with polished aluminum foil for a Mars reflector.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Lots of aluminum, oxygen and silicon in moon rocks. Didn't they basically just pick those up off of the surface to bring home? I wonder what the geology is 10m down? 100m? If there was better ores down deeper, refining materials for habitats and space craft there wouldn't be that hard, especially with oxygen as a fuel base. There may be more to the moon than we think.

I agree. There's absolutely no condition save for 1/3 G that cannot be simulated here on Earth.

Stop wasting our taxpaying dollars with pie in the sky "testing" ideas.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

It depends upon the composition and the shape of the particles. If they are very round and smooth from being blow around the surface of Mars for eons, them perhaps they might be used as a lubricant.

Every condition can be recreated here on Earth, except for the .38G, and the Moon cannot duplicate that.

The Moon would be a great place for a space elevator, if it rotated. Fortunately, without an atmosphere, rail launchers will work there.

The point of manufacturing on the Moon would be in making the bulky, massive structural components, such as hulls and girders. Lightweight materials could still be boosted from Earth, especially those that require specialized manufacturing processes.

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Reality: What a concept!……………………..><Ç(((Ç°>

Oh? Have we BAUTers suddenly gained control of Congress and spent actual money on this? Quick, let's make a bunch of laws before they catch on to us!

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

That's my point. It probably won't have the fractured glass morphology of lunar dust. Martian dust may be more like loess, the grains of which are angular in shape, but probably still not as bad as lunar dust.

I know, I myself made that very argument. But, can we replicate Galactic Cosmic Rays and Solar Wind safely and affordably on earth on a scale large enough to test whole spacecraft? I assume we can do that on a small scale, but to thoroughly understand radiation cascades and their geometry, a full size test is useful. Maybe I should reiterate that I was considering an analogy to "sea trials" not surface trials. The item would not be on the moon, it would be in orbit around it, either directly, or in a LaGrange point.

"If it rotated." Do you mean the cable (i.e. a rotovator) or the moon? Studies have suggested that a lunar space elevator could work if connected to a Lagrange point. The suggestions I've seen usually refer to L1 and consider L2 as possible. I suppose L3 and L4 are less likely or impossible; I don't know if it's due to gravity or the 400,000km of cable needed.

Rail launchers have their own issues and shortcomings.

Essentially yes, although I suspect lunar manufacturing would be less about mass and more about physical volume and sheer size. Space and low-gravity structures don't need to be massy, but they may need to be voluminous. They could be so big that even if the mass could be lofted from Earth with rockets, the physical shape and size makes the aerodynamic penalty prohibitive. I'm not disagreeing with you, just expanding upon what you said.

Unfortunately, lots of specialized materials, even lightweight materials like mylar, can be massy in bulk and probably can't be made on the moon from local resources. A single industrial roll is around 2 metric tons. A total reflector might weight 200,000 metric tons or more, requiring a few thousand launches from Earth. I suppose it would depend on launch costs versus the cost of emplacing and operating a facility on the moon to make aluminum foil for a reflector statite capable of the same performance as metallized boPET. Even if we forego the martian statite reflector, many material designs for solar sails call for carbon instead of aluminum. So, getting back to my point, lunar manufacturing will be of important, but limited use.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Do you know of any information regarding that aspect of Martian dust. I have heard that it can be as fine as talcum powder, but that is all.

The question is, do we need to? Also, wouldn’t a single test craft, filled with appropriate sensors, be able to tell us everything we need to know for all future spacecraft?

Possibly, but that would be a bit of a “stretch”.

But the technology is fairly uncomplicated, and relatively reliable.

The term “massive” was used to denote any materials or structures that are heavy and therefore expensive to lift from Earth.

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No, unless you meant coil launchers (AKA Gauss guns, mass drivers, magnetic launchers) instead of rail launchers.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

????????????

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Reality: What a concept!……………………..><Ç(((Ç°>

http://en.wikipedia.org/wiki/Coilgun
http://en.wikipedia.org/wiki/Railgun

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
"The Mayan symbol for "book" looks a lot like a triple hamburger, but I've never seen them claiming it as proof the Mayans had Big Macs." - KaiYeves
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Well, I was guessing that it would have properties similar to rock flour, but I could be wrong. The articles I've read suggest that martian dust is mostly finely ground silicates and iron-rich clay and iron rust particles.

As far as shielding and general performance, yes. But no manufacturing process is perfect and I'd want each and every craft to be proven spaceworthy before trusting it to shirtsleeve status. If you build a structure in a gravity field, you may want to give it time to adjust to free-fall before you trust your life to seals and bearings and welds whose tolerances may have relaxed as loadbearning in one direction shift to loadbearing in a different direction when under propulsion.

From what I've read, it's realistic now without needing miracle fibers.

Not from what I've read. Rail guns may be uncomplicated, but they are anything but reliable unless you intend them to be used only once. Rails might erode rapidly and require replacement or refinishing after every single launch. Such problems may be overcome (I hope so, or better resolved with a type of coilgun/quenchgun) but I don't assume that makes it any more likely than a lunar elevator.

All materials and structures are heavy in sufficient quantities. I had been referencing mylar in our discussion, which is lightweight in area when effectively deployed, but can be heavy when rolled up, making it a significant payload if lifted from Earth. It may not be possible to make mylar on the moon if certain chemicals are not available. That was my point. Perhaps I missed your point. Maybe you can explain why you responded to my lunar mylar manufacturing issue with references to making aluminum girders.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Most manned mission spacecraft will probably be built in Earth orbit, due to their size. They will be designed for the environment they will perform in, and probably never encounter any real gravity.

I meant, that is a long tether. And of course, the Moon wobbles, and is also in an non-circular orbit, so it would wobble and move in relation to the la Grange points.

MagLev rail launch assist probably won’t have any such problems on the Moon. With no atmosphere, and no moving parts, they should be quite stable.

Once more. Spacecraft hulls and other structural parts are necessarily “massive”, that is they weigh a lot in a gravitational field, and they require a lot of energy to move. Other parts, such as microprocessors, which are difficult to manufacture, and do not individually weigh much, are better boosted from Earth. For example, a spacecraft will need just one hull (including bulkheads, struts, etc), but it may need a few dozen microprocessors. The hull may weigh (in Earth’s gravity)two million pounds, but all the microprocessors put together may weigh only 3 ounces. That is why I recommended producing the “massive” components off Earth, and boosting the small specialized parts from Earth.

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But you say below that such things might be built on the moon and, frankly, I think it'd be easier and safer to construct the entire thing on the moon. Moving big girders about in free-fall is not easy. Maybe it would be easier if we constructed an orbiting shipyard and drydock in LEO and then sent parts from the moon, but we'd have to built that first. We could probably launch a whole ship from the moon with a big dumb booster made of martian regolith or that electromagnetic gun you're confused about.

The Lagrange points move with it. The L1 point is not stable like L4 and L5 are, but I think that an extension beyond L1 towards Earth would balance it.

Aha, I see the problem. When you wrote railgun, I thought you meant railgun. Railguns, by definition and physics, cannot be levitated. They must be in contact with the rails in order to complete the electric circuit. Hence the "rail" in railgun.

You must be referring to some other sort of electromagnetic catapult, probably a type of coilgun or quenchgun.

Well, you'll get no argument from me on your statement. Although I'm still wondering how it related to my discussion about bulk mylar. But anyways...

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Entire spacecraft might be built on the Moon, but the manufacturing I was referring to was the finished materials for building spacecraft, such as hull plates, girders, and other massive components.

Exactly.

You may be confused about it, I’m not.

Only a small percentage of the movement.

Ah, I didn’t say railgun, you did. I said rail launchers, referring to the MagLev rail launch or launch assist discussed in previous threads. MagLev rail launchers would have rails, but the cradle would be suspended magnetically to reduce friction and vibration, similar to MagLev trains.

Neither, not even close.

Your statement regarding bulk Mylar was in response to my use of the term “massive”. Anything can create a massive load if enough of the item is included. But, as explained, hull sections and girders are individually massive. I was also referring to something we might be using in the near future to get space travel going. I don’t see massive amounts of Mylar being used for anything in the foreseeable future, if ever.

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Reality: What a concept!……………………..><Ç(((Ç°>

Magrail launcher cost and completion estimates?

Maglev Rail launch assist

Magnetic launch

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