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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 |
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Please elaborate.
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![]() 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. |
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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 Last edited by djellison; 09-February-2008 at 10:18 AM.. |
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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? __________________________________ 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? |
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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 |
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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(((ǰ> |
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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau |
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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 |
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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.
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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 |
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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(((ǰ> |
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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau |
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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.
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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. |
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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(((ǰ> |
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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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Rail launchers have their own issues and shortcomings. Quote:
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 |
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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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"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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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau |
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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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Reality: What a concept!……………………..><Ç(((ǰ> |
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You must be referring to some other sort of electromagnetic catapult, probably a type of coilgun or quenchgun. Quote:
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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau |
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Only a small percentage of the movement. Quote:
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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(((ǰ> |
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