NASA Mulling Earth-Moon L2 Point for Mars Staging Station 186
jamstar7 writes "From the article: 'NASA is reportedly mulling the construction of a floating Moon base that would serve as a launching site for manned missions to Mars and other destinations more distant than any humans have traveled to so far. The Orlando Sentinel reported over the weekend that the proposed outpost, called a "gateway spacecraft," would support "a small astronaut crew and function as a staging area for future missions to the moon and Mars."' This is actually a good idea, using the Moon as a staging base for exploring the cosmos. Once we build manufacturing capability there, why not build spacecraft there? We can build bigger, more spacious craft so as to not lock up future astronauts in a closet for months or years at a time."
Moon base isn't quite accurate: it would be a space station at the Earth-Moon L2 Lagrange point about 60000 km from the surface of the dark side of the moon.
Why not build spacecraft there? (Score:2)
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Yes we do, we just don't want to...
Anyway NASA can make a kickstarter project to raise money, seen silly projects getting 1M from vapor.
Re:Why not build spacecraft there? (Score:5, Informative)
Not having a trillion dollars really hasn't stopped our government from spending like they do, so why not?
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Yes, why not build spacecraft there? Because we don't have a trillion dollars to spare? That might be it.
Another good reason is because we don't have any metal or fuel or supplies or people or vendors or communication infrastructure or USPS addressing locations or anything other than moon dust and nothingness on the moon.
Re:Why not build spacecraft there? (Score:5, Insightful)
Yes, why not build spacecraft there? Because we don't have a trillion dollars to spare? That might be it.
Another good reason is because we don't have any metal or fuel or supplies or people or vendors or communication infrastructure or USPS addressing locations or anything other than moon dust and nothingness on the moon.
Yet.
How many times must it be pointed out that back before Columbus sailed to the Americas, there were no Starbucks or Dunkin Donuts or Apple stores in the area now known as the United States? Wasn't a lot of anything except a lot of forest.
Re:Why not build spacecraft there? (Score:4, Insightful)
"Wasn't a lot of anything except a lot of forest."
So only...
Old growth trees (extremenly valuable at the time for shipbuilding).
Vast tracts of untilled arable land.
"Easily displaced" indiginents.
Not to mention the coal and oil deposits discovered later.
We know a lot more about what's on the moon than Columbus (or the Spaniards) did about North America, but what we know is that it's not all that.
The moon, sadly, is kind of crappy resource-wise. It is, on the other hand, really handy for causing tides, which helped a lot of life proliferate down here, so go moon! (but don't necessarily go TO the moon)
Re:Why not build spacecraft there? (Score:5, Informative)
Not to mention the coal and oil deposits discovered later.
Columbus didn't know about that stuff, and no one found out about or made use of those things until hundreds of years later.
We know a lot more about what's on the moon than Columbus (or the Spaniards) did about North America, but what we know is that it's not all that.
The moon, sadly, is kind of crappy resource-wise.
You don't know that. It's not like we've done any drilling there; all we've done is collect a few rock samples on the surface. There's probably lots of valuable minerals there, just like we've found many in the earth's crust. Most of our minerals on Earth came from meteorite bombardment; well, take a look at the moon. What do you think all those round things are? And without an atmosphere, the minerals won't be dispersed so much on the Moon, they'll be concentrated at the impact sites. There's probably lots of resources on the Moon we don't know about yet, because we haven't looked. We only recently discovered that there's water ice there; sending up a few astronauts in a half-hearted rock-gathering mission totally missed that important detail.
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How many times must it be pointed out that back before Columbus sailed to the Americas, there were no Starbucks or Dunkin Donuts or Apple stores in the area now known as the United States? Wasn't a lot of anything except a lot of forest.
Columbus didn't have to take along all of his food, air supply, fuel, and mountains of equipment. To turn a forest into useful structures, you need a simple blade of an axe and a saw, maybe a pick for the dirt and rocks (and all the req'd labor) and maybe some flint. To turn regolith and rock into simple building supplies suitable for micro-g and airless environ, you need...considerably more. That is unless you have a magic wand. You don't have a magic wand do you?!
Re:Why not build spacecraft there? (Score:5, Insightful)
To turn regolith and rock into simple building supplies suitable for micro-g and airless environ, you need...considerably more.
Exactly. You need a whole infrastructure to support all that stuff and to support itself.
See, this is my minor gripe. Everybody's all about exploring. "We need to put astronauts on Mars! They'll accomplish more in a year than 50 years of Mars probes!" But, to me, this is just more of a circus.
I'd rather see us return to the Moon to stay. That means figuring out how to stay there without getting supplies every month. There's water which we can drink. There's water which we can turn into oxygen. Not sure about the nitrogen part. What will be needed to create a habitat? Above ground? Below ground? Inflatable? Solid? Some combination of the four? How will we handle electricity? Solar? Nuclear? Some combination of the two?
Can we add water to lunar soil and grow stuff in it? [boingboing.net] How will various tasty earth animals react to 1/6th G. Hell, how will human beings react to 1/6 G? Will we have more/less/the same problems we have with zero G? How can we turn lunar ores into useful metal which we could then use to build stuff?
These are all answerable questions. There's no unobtainium necessary to do any of this stuff. You build up the infrastructure on the Moon. It may take 50 years. But, in 50 years, I'd rather look up at the Moon and see a community. I think that would be much better than some flag sitting among a pile of junk on Mars.
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The technology we have today would have looked like magic to Columbus. He was operating 600 years ago, so the technological standards have changed a bit. ...and what seems trivial to us would have been a Big Deal in 1492. Columbus' actions were probably as significant as a moon base would be for us today.
No, just no. The axe and flint and saw had been around for hundreds if not thousands of years prior and all the tech was well known, working with earth and lumber well known, forest animals well known, etc. Not similar at all.
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Plus confirmation that the world was round made a pretty big splash. (Though that was lessened somewhat by the fact that Columbus did not, in fact, find China (the East) by going west.)
2000 years of history would disagree with you: http://www.livescience.com/16468-christopher-columbus-myths-flat-earth-discovered-americas.html [livescience.com]
Other Europeans had sailed to America before (Score:2)
Why this obsession with Columbus? he wasn't the first European [wikipedia.org] in recent historical times to sail to America...
Re:Why not build spacecraft there? (Score:4, Insightful)
No, there's many other improvements too; any ship you build on Earth would have to withstand severe stresses in being launched out of the atmosphere. With a ship assembled in space, you don't have this problem; only the smaller assemblies need to withstand such stress, and that's much easier and cheaper. You don't have to build the ship to be as robust in this case.
The other big improvement is that if you have some space-based or lunar-based infrastructure, you can mine the moon or asteroids for materials to build your ships, instead of mining it on earth's surface in someone's backyard, and then lifting it out of the gravity well. Yes, developing that infrastructure is by no means trivial, but once it's in place, it'll pay for itself over time.
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Yes, why not build spacecraft there? Because we don't have a trillion dollars to spare? That might be it.
Well we DID have a spare trillion, apparently, but it went to da bankers via stimulus...
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Yep. How can it possibly be cheaper/easier to build spacecraft out in space. You still have to send materials up there, surely it's easier to send them into earth orbit than the other side of the moon.
Re:Why not build spacecraft there? (Score:5, Insightful)
1) Money isn't actually used up when we build things. The money goes into the hands of the people who build them, the people who create the materials in them, etc. None of the money will actually leave the planet.
2) I'd rather spend a trillion dollars doing this than spend a trillion dollars fighting wars we don't need to fight.
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1) No the labor and resources the money is a proxy for is instead used up and sent into space.
2) Sure, that's also labor and resources that are used up in destroying things.
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2) I'd rather spend a trillion dollars doing this than spend a trillion dollars fighting wars we don't need to fight.
You can never justify an expense just by pointing out that we spend more on something even stupider. A mission to Mars should be justified on its own merits. The fact that we squander money on other things is irrelevant.
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Yes, why not build spacecraft there? Because we don't have a trillion dollars to spare? That might be it.
really?! [wikipedia.org]
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Most of the Space Station was built in one crappy old NASA building - 4708 at MSFC, in Huntsville, AL (I used to work there). One side was the factory floor where the module and truss structure were fabricated, the other side was the clean room where the equipment was installed. No way that would cost a $ Trillion. We didn't even have robotics, it was almost all manual assembly. With modern robotics, and "seed factory" machine tools you can start with even less stuff. Seed machines take metallic astero
To provide a long term goal (Score:4, Interesting)
A lot of the "basic research" comes from applied research aimed at a specific goal, the spin-offs from that basic research is what provides the expanded benefit.
Hypothetical goal: L2 staging base
Hypothetical applied research: supporting medical facilities there.
Hypothetical spinoffs: remote surgery, 0 G surgery, remote sensing, microrobotic surgery... and reduced medical costs on earth.
Re:To provide a long term goal (Score:4, Insightful)
Why don't we add lunar resource acquisition as spinoff applied research?
With a smaller gravity well than Earth - it could be the future of space based colonization.
This would probably then add to research that could go towards colonizing extraterrestrial bodies.
Re:Why not build spacecraft there? (Score:5, Insightful)
Most of what we consider "high tech" actually came out of WWII and the Space Race. We're in the last stages now of ideas and technologies that were originated to solve those goals. Now we need new goals.
Basic research is of course needed, but if there is no place to focus it, mankind will get bored of it. It's like making national parks but not allowing people to go to them by either telling us we're not allowed to sully their pristine nature or just plain pricing the costs to visit them too high for the average person . Eventually people will forget about the flora and fauna there and not give a shit if some toad or owl goes extinct. Out of sight, out of mind. (Sorry, no car metaphor.)
The same applies for basic research (for the most part). If people can't see it being applied somewhere eventually, they won't give a rat's ass whether funding is cut for it or not. That is what is happening now. To combat this we NEED some place to apply at least some of what we learn in a spectacular way. Then people, average people, the ones who actually pay for most of the research, can actually see some of what they are getting for the money, and how cool that stuff is; and how it is worth it. Even if only a small part is used in a new space race, it will be enough to help pull funding through for all the less glamorous areas of research.
Stop thinking rationally if you want others to pay for your stuff. They'll only do it if they get something out of it. Directly. In the U.S., national pride is huge. The more you can help fuel that, the more money people will give you. Build a space station. A real space station, not just some "let's stick our toe in the water and do a bit of research" space station. Less of a lab, and more of a one that gives meaning to the word 'station', much like train station, and begins to make space travel routine. Use the research to create that in turn to create whole new technological ecosystems (much like the Apollo series did), and help keep people interested in science so they'll pay for more. The economic benefit (if it isn't offshored by some cynical self serving idiot) is that America will have technology to sell to the rest of the world that it doesn't yet have. This in turn fuels a healthy economy which can then afford to finance basic research. But only if the economic benefits STAY in the country.
Cool sells. Space stations are cool. A nerd in some back lab is cool to many technology lovers, but even then, not all. And certainly not to most of the rest of society. Proof? People pay billions for spoiled sports stars to make millions entertaining them. This gives society a place to vent its anxieties and aggressions (even vicariously). And it is labelled cool and spectacular because it allows those human emotions in full force. Face it, some guy writing equations at a desk, or dolling out solutions from a pipette is pretty dull and boring in comparison. The science that excites is big rocket ships, robots, and risk. Give the crowds what they want, give them Orange Flavoured Tang and Space Opera [wikipedia.org] and they will love you. Give them the spectator sport of science. Then you can pay for basic research. There is a grain of truth even in satire. In this case it is more like a boulder.
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I am not pro-Romney, but it is pretty clear that that was a joke (and, for Romney, a pretty good one).
Dark side, really? (Score:5, Insightful)
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Maybe dark as in the other side, so no communication with Earth because the Moon is in the way.
"Houston, we're going dark" (Appollo 13, almost ;-)
Re:Dark side, really? (Score:4, Insightful)
Which could be done really cheaply.
Comsats are pretty much off the shelf these days, and GEO comsats are already hardened to more radiation due to their increased height. Further hardening might not be necessary depending on the design and capabilities.
I still dont know why we havent built a Lunar comms and navigation satellite constellation. It would be trivially within the budget of a number of nations, companies, and could have even been incorporated into the budget of several large science missions. This doesnt need to be an irridium scale network of dozens and dozens of satellites, continuous coverage could be accomplished with just 6 sattelites like the small and cheap (by satellite standards) SN-100s from Sierra Nevada in order to keep the weight down since the lunar orbit boost would cost even more. But since they are small enough to be secondary payloads they could be bunched together on a single booster and sent to the moon together to cut down on launch costs as much as possible. And thats before exploring options like using hall effect thrusters like the SMART-1 mission did and getting to the moon the long slow way to be even more efficient for launch costs.
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There are a few dark places on the moon as in never receives the light of the Sun. They are craters at the North and South Pole.
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Not everyone is talking about the visible spectrum you insensitive clod.
Irrespective of where the sunshine is falling, not being able to maintain direct radio contact seems like a considerable detriment to me. I.e. radio-dark.
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Yep. And ZZ Top would have you believe there's a shack just outside of the Lagrange point already.
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There's always Earthdark :)
But yeah, I too twitched when I read that bit.
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I believe that everyone would agree that a more correct term would be “the hidden side of the Moon”, but it's not as catchy, so let's say “the far side of the Moon” which is as catchy (rhyme-wise) and as literal as it can be for our Earth-centered POV.
Dark side of the moon... (Score:5, Informative)
For something to be X miles above the DARK side of the moon, it would have to be orbiting the moon. You want to say FAR side of the moon, and you would probably not get it wrong if you either paid a little attention to your science classes in school or gazed at the moon enough times to think about the lunar phase cycle.
But, no, you should not be editing something like slashdot causing the readers to pull their hair.
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Let's suppose that this is right... When the moon is new it is between the sun and earth. That's why we see it as dark and it's there that sun eclypses happen, when it is exactly on the light of sight between us and the sun. The next new moon will be on October 10. At that time one side of the moon will get light from sun and the other one will get light reflected by earth. On which side of the moon will be this L2 point at that time?
The only way out is that L2 will be on the night side of earth but I under
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That would be called the Night side. Really people. We have proper names for these phenomena. Let's start using them.
I thought he was just an idiot. But I think he was referring to the farside at night. During those 2 weeks it indeed would be extremely dark, without any earthlight. But the nearside at night would also be pretty dark when the earth above it was full dark, once every 24 hours for an hour or so.
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I thought he was just an idiot. But I think he was referring to the farside at night. During those 2 weeks it indeed would be extremely dark, without any earthlight. But the nearside at night would also be pretty dark when the earth above it was full dark, once every 24 hours for an hour or so.
I don't know what you mean. When the earth as seen from the moon is fully dark, the nearside of the moon is obviously fully illuminated (unless there is a lunar eclipse going on). And when the nearside of the moon is fully dark, the earth as seen from the moon is fully illuminated (unless there is a solar eclipse going on), so the night/near side of the moon would receive a maximum amount of earthlight. And both these things don't happen once every 24 hours or so, but once every 2 weeks or so. Between those
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I don't know what you mean. When the earth as seen from the moon is fully dark, the nearside of the moon is obviously fully illuminated
Yes, I didn't think it through.
The earth is stationary in the moon's sky, and its phase would take a month to change, and be full at lunar midnight. But you'd see the continents spinning around once an earth day, I confused that with the phase.
Sorry about the "idiot" stuff, but your use of "dark side" was pretty confusing; it might have been correct literally, but the (r
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Re:Dark side of the moon... (Score:5, Informative)
Sorry, your explanation has confused me somewhat.
I've always known the dark side of the moon to mean the side of the moon that never faces earth, aka the far side of hte moon.
The dark referes to the fact this side of the moon never recieves any signals from earth NOT that it never recieves any sunlight (which it does during every new moon).
In case you wish accuse me of not paying attention during science class:
http://en.wikipedia.org/wiki/Far_side_of_the_Moon:
"The far side of the Moon, sometimes called the "dark side of the Moon" in the sense that it is in a radio blackout in respect to transmitters on Earth"
IIRC placing an object so that it's constatly observing the dark (as in no sunlight) side of the moon is refered to as in the shadow of the moon, but I'm not 100% on that.
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The definition of "dark side = the side that does not receive signals directly from earth" sounds to me as simply tailored to give a plausible explanation to the incorrect usage of the term (thank god for radio signals, back in my day we didn't have such fancy ways of explaining why we were using wrong terminology).
Think about this: if someone tells you Olympus Mons is right now on the dark side of Mars, would you assume it is in the hemisphere farthest from the earth where there is no direct radio contact,
Better source... (Score:4, Informative)
Also, instead of wikipedia we could link to an actual source. E.g. Phil Plait's excellent blog: http://www.badastronomy.com/bad/misc/dark_side.html [badastronomy.com]
Re:Dark side of the moon... (Score:5, Interesting)
http://en.wikipedia.org/wiki/Lagrangian_point [wikipedia.org]
lrn2orbitalmechanics, it would be orbiting the earth along with the moon.
Not only is it relatively stable (though a halo or Lissajous is usually used), but the relative sizes are such that the moon does not fully eclipse the earth, so continuous communication is available.
It's a lot more sensible than a lunar ground base. Not only isn't there a gravity well, but the Lagrange points are the easiest places from which to leave earth orbit with minimum energy expenditure. If you have a fuel stockpile there, you can top off the tanks and all that fuel goes to the trip, not climbing out of the gravity well.
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Not only is it relatively stable (though a halo or Lissajous is usually used), but the relative sizes are such that the moon does not fully eclipse the earth, so continuous communication is available.
A minor correction: orbits which are stable with respect to minor perturbation are possible at the L4 and L4 points. Some powered correction is needed for any orbit at L2 and L3, since they are only stable for the 3-body case [wikimedia.org], not for the real n-body Solar System.
Also, at the Earth-Moon L2 point, the Earth is fully eclipsed. The Earth's umbral cone extends just over 100000km past the Moon at their average separation of 384000km [wikimedia.org], but the umbral cone for the Earth is quite thin, and has a diameter of less
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L1, L2 and L3 are not stable even in the modified 3-body problem (i.e., where body at L1, L2 or L3 has no mass).
And, there are definitely Lissajous (Halo) orbits of L2 that are always in view of the Earth.
Re:Dark side of the moon... (Score:5, Informative)
The James Web Space Telescope will also reside in the Earth-Moon L2 point, and AFAIK it will transmit data directly to Earth, so communication from/to L2 should not be an issue.
No, the James Webb Space Telescope [wikipedia.org] will be at the Earth-Sun L2 point.
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Stockpiling fuel at the Earth-Moon L2 makes sense if you never make propellant in orbit. Although I believe making a propellant depot at an altitude slightly higher than Earth GEO is a better investment.
I know NASA isn't in the commercial satellite repair business, but at GEO you could have your depot at a reachable location and gain valuable experience trying to revive dead satellites in your spare time. Reopening comm links could provide a small source of revenue, but the experience of doing those ty
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Good for a lot of reasons... (Score:5, Interesting)
By the way, the L2 point is not on the dark side of the moon (the dark side of the moon travels around the moon every 28 days), it is on the FAR SIDE of the moon, that is the side facing away from earth.
My question is why L2 and not L1? L2 is going to be exposed to more meteoric traffic, it will have a hard time communicating through the moon to the earth (yeah you can put a comm satellites at L4 or L5 but that's complicating things and adding cost and new failure modes.) That and L1 is closer and easier to get to from Earth and easier to get things to from the moon with the gravitational assist of Earth.
There are plenty of interesting designs, but such a resource would need to be built of lunar material. Because you'd need a structure with walls thick enough to protect from solar storms, cosmic rays and all kinds of meteoric debris hitting the structure. You would probably want to have hydroponics plants on board for food, oxygen, and synthetic meat from Soybeans... or even better synthetic meat from a 3D printer, endless Filet Mignon, sushi grade Yellowtail and Salmon, and Turkey White and Dark meat as long as you have cell cultures and your meat printer. By the way, you could dissolve vital minerals in water and then use that water to build radiation proof walls. About 3 feet ft. would get the job done nicely, 6 ft would be spectacular. You'd want to harvest a reasonable sized asteroid with plenty of water or a number of smaller asteroids and use it/them to build your base. You'd want to use a swarm of assembly bots to build things with only a small human presence, most remote from the ground. Robots that could self replicate from materials in the asteroids would be perfect.
Re:Good for a lot of reasons... (Score:5, Interesting)
Why not LEO, and use the ISS? (Score:5, Interesting)
Why not put it in LEO (low earth orbit)? It's a hell of a lot easier to send supplies and astronauts. We have decades of experience with that.
Also, why not use the ISS? It has all you need, I think: astronaut habitat, power, docking ports. Add a few modules, and you're done.
All this talk about either the moon or L1, L2... unless there is a source of fuel (i.e. water, as well as a source of power like sunlight or nuclear), it's utterly pointless to drop yourself into another gravity well, not matter how tiny, if you're gonna have to carry all the fuel there yourself from earth. If the fuel comes from earth, your space station is nothing but an assembly point, and that might just as well be in low earth orbit.
The only reasonable alternative is one of those craters on the moon where they have found some water... but only if a station there can get sufficient power to convert that water to hydrogen and oxygen at conditions (temperature, pressure) that are necessary to be put into a large rocket.
Re:Why not LEO, and use the ISS? (Score:5, Interesting)
If I'm not mistaken, ISS is in the wrong orbital plane for planetary missions, so you'd waste a lot of fuel.
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Ok, I didn't know that (thanks). Why not put another station in low earth orbit, in the right orbital plane?
I still don't see the point of going all the way to L2 if we need to carry all the fuel there ourselves from earth anyway.
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You'd have to move it from its current inclination of ~51 degrees to about 23deg.
WAG and I'm not a rocket scientist: 51-23=28, sin(28)=0.47 so you'd have to do a delta-V of about 0.47x orbital velocity which is 12000 km/h applied to 100 tons. A Space Shuttle burns ~1900 tons of fuel to get 100 tons up to 25000 km/h, so call it 1000 tons of fuel to shift the ISS.
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It takes less fuel (a lot less) to go somewhere from L2 than it does from low orbit. Yes, you have to boost all your assembly materials up anyway, but your actual interplanetary spacecraft can be that much smaller because it doesn't have to carry all the fuel to get out of low orbit in the first place. You don't need to carry as many empty fuel tanks all the way to Mars and back.
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You can dump an empty tank as easily as any other rocket does. Disconnect it. All rockets have stages. They all dump their empty tanks. Tanks can either have their own engine, like the booster rockets, or no engine, like the big fuel tank of the Space shuttle. Still, all get discarded without a problem.
I'm sorry if I am attacking you a little hard, but your argument makes no sense. You have to regard every mission from the place where stuff is launched (which is Earth, also if your intermediate location is
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Stages introduce complexity which means weight and more things to go wrong. Also, you have to get back to where you came from. It requires extra fuel to drop back into a low Earth orbit, fuel that you have to drag all the way to Mars and back. Low Earth orbit also requires constant boosting for your assembly facilities and spacecraft (it costs almost a quarter of a billion dollars annually to boost the ISS). There are probably also advantages to slingshot maneuvers around the Earth and moon from L2. An
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A trip to L2 is said to take longer but be cheaper per kg than that to L1... http://www.thespacereview.com/article/1808/1 [thespacereview.com]
I think that the energy (and mass of fuel) required to launch from L2 is a lot less than L1 since l2 is on a gravitational "tether" of about 450,000 km (more or less). launching at a particular spot in the orbit means it has a considerable initial velocity.
L2 Because of it's purpose (Score:3)
I assume it is L2 specifically because it is a mission staging area. Launches to other planets will be easier and use less fuel if done from L2 because they will not have to navigate around the moon, and because they will be that much closer to the target.
Re:Good for a lot of reasons... (Score:5, Informative)
>My question is why L2 and not L1?
Indeed, I have no clear idea, because once an object is located at one of the five Lagrangian points L1-5, very little energy is required to go to any other one.
L1 needs however the least delta-v to be reached from Earth or Moon, and direct radio communications are possible with L1 and L3, contrary to L2 which is hidden by the Moon from Earth. L3, on the side opposed to the Moon would require still a bit more delta-v than L2. L1-3 are dynamically unstable, so a station there would need periodic corrections.
L4 and L5 are more stable than L1 or L2 but require still a bit more delta-v wrt L1-3.
To reach Mars, or any escape from the Earth-Moon system L1_5 are almost equivalent if enough time is available, but L4-5 provide more orbit choice, so more possibilities to choose quick routes.
Note that the station would not need to be located precisely at one of the L1-5 points, but could be on so called halo orbits circling around such a point.
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My question is why L2 and not L1? L2 is going to be exposed to more meteoric traffic, it will have a hard time communicating through the moon to the earth (yeah you can put a comm satellites at L4 or L5 but that's complicating things and adding cost and new failure modes.)
The sensible plan and undoubted intention would be to put the station not at EML2, but in a Lissajous (or Halo) orbit about it big enough so that it was always in view of Earth. Such orbits exist and are energetically easy to get to, although a little station-keeping may be required (as it would be for the L2 point as well).
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Seems to me that if you're going to go to all that trouble, it'd be easier to just build a base on the moon for most operations, except those things which absolutely must be done in zero-g.
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The difference in delta-V to L1 and L2 is (for the Moon) pretty small. In fact, if you are willing to take your time, you can get to either with basically no fuel beyond a geostationary transfer orbit injection, using WSB [utexas.edu] trajectories. (This will take months, so it is not so good for manned voyages, but would save a lot on supply logistics costs, up to doubling the payload delivered per launch.)
By the way, getting a space station from L1 to L2 (or back) is also not energetically hard. The NASA plans on this
Why not modular? (Score:2)
Why cant we simply build it modular? Base the Mars mission craft on the ISS. we can launch the modules over a 3 year time span, use it as a second space station for that time while we build it and then when we finally launch up the main engines, hook em up to the hitch and let it rip.
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Waste of money, go Mars Direct (Score:5, Informative)
Anyone who thinks this is a good idea to get to Mars needs to read Zubrin's "The Case for Mars" or read up on the "Mars Direct" approach. All this talk about moon bases or staging in orbit or at an Lagrangian point originates in NASA designing the Mars mission via lots of committees, in which various teams and [sub]contractors got to insert dependency on their pet projects. Mars Direct presents a very well thought out and fully vetted approach, nothing but politics at this point is standing in the way - if NASA as an agency was still primarily interested in space exploration instead of pork disbursement and fiefdom preservation, and Congress had to provide slightly longer term budget commitments with less constraints and strings atached, we'd already have a permanent presence on Mars.
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Sure, if the only goal is to get to Mars, then other plans might make more sense. What we're trying to do here is create a spacefaring society. Mars is part of that, but not the only thing. Zubrin talks a lot about gravity wells, yet he proposes that we go directly from one to another.
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I understand the argument, and frankly I agree. However, given the political nature of the non private space programs, I also believe that other than a real push to Mars, the US program is destined to remain like the Shuttle and ISS - little more than jobs and pork delivery. Think of how little science has been accomplished by STS and ISS programs, and few actually reusable components other than the STS RS-25 and SRB, which are still restricted to US government program use.
If we fund a moon base or Lagran
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If you just want a place for humans to live, the Moon can do that too, and it's a lot closer. What does Mars have that the Moon doesn't? An atmosphere? Mars' atmosphere is too thin to be of any use. Gravity? Mars has 1/3g, Moon has 1/6g; BFD, they're both pretty low. A magnetosphere to protect you from radiation? Neither one has it. Resources? Maybe I'm missing something, but we don't seem to know a lot about either one as far as resources, because we haven't investigated them that much. It's not
No they won't (Score:2)
With the elections coming all kinds of crazy ideas are floating around. NASA simply doesn't have the resources for a huge project such as this. Also, I don't really see the advantages over LEO, even if they build the station keeping it supplied would be a constant challenge.
That's no moon... (Score:2)
Psychological effects (Score:2)
Iron Sky (Score:4, Informative)
I'm surprised that i saw no Iron Sky comments yet.
http://www.ironsky.net/ [ironsky.net] its a B movie made on a budget with remarkable Hollywood quality. Sequal and prequal are in the works, i've heared.
Relevant because its recent (mid 2012), about the dark side of the moon and an US astronaut.
If you want a good laugh about WW2 germans, watch this.
Far side! (Score:2)
it would be a space station at the Earth-Moon L2 Lagrange point about 60000 km from the surface of the dark side of the moon.
Please. It's the far side of the Moon. It goes through day-night cycles just like the near side.
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"Dark" refers to radio-dark (from the point of view of the Earth), not absence of sunlight.
Are we sure this is a good idea? (Score:2)
https://www.google.com/search?q=ingo+swann+penetration [google.com]
You know, that's near the DARK side of the moon...
L2 is occupied (Score:2)
ESA Planck space observatory is stationing there already, so buzz off NASA!!
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Satellites aren't put at the Lagrange points themselves but on orbits around them.
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Herschel and Planck are at Earth-Sun L2 (solar orbit), not Earth-Moon L2 (earth orbit)
Nuclear Power? (Score:2)
Forgive me if this has already been covered, but does this mean that if we sent up materials for it that it might be possible to build ships with nuclear-powered engines, since firing them won't be on earth?
This could be awesome news in terms of getting fuel up there.
from the surface of the dark side of the moon? (Score:2)
The moon has no dark side ...
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ISS isn't sufficiently shielded to be outside of LEO
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Because LEO is still inside the gravity well. Not that the ISS doesn't need VASIMR for station keeping, but it's not designed to go somewhere else. I'm sure that it would probably take some structural damage from the kind of thrust you need to apply to get up out of LEO, and then it has to go through the Van Allen radiation belts too. You just don't move a fully assmembled multi-segmented space station around like it was an aircraft carrier. Over that kind of scale it should be pretty flimsy.
Besides, there
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IANAE (i am not an expert) but.. yes Earth+Moon gravity are pulling in the same direction. And this combined vector is canceling the centrifugal force of orbiting earth+moon.
I guess that L2 is where the sling (centrifugal force) and gravity of earth+moon combined cancel eachother.
L3 is the same, but sideways. It rotates around the earth in step with the moon.
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IANAE (snip) this combined vector is canceling the centrifugal force of orbiting earth+moon.
This gravitational attraction is creating the centripetal acceleration that creates a closed orbital loop. There is no centrifugal force, only the intertial tendency to move in a straight line.
--Joe
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The Earth-Moon system is approximately stationnary in a particular rotating frame, not an inertial frame. In such a non-inertial frame the centrifugal and Coriolis forces must be added to gravitational force. At the Lagrange stationnary points velocity is zero so the Coriolis force vanishes, and only the centrifugal force adds a contribution to the force balance opposed to the gravity force.
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It's the same force that holds up the moon - centripetal force. The L2 point orbits Earth at the same period (same angular velocity) that the moon does, but further out. That means it moves faster than the moon does.
If the Moon weren't there, a satellite at L2 wouldn't by in a stable orbit: Its centripetal force would be too great.
However, as you said, at that point Earth and Moon pull in the same direction. That means the combined force acts like the gravity of a single more massive body, creating a point
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L1, L2 and L3 are pretty easy. The Moon (or whatever secondary body you want, such as the Earth for Earth-Sun Lagrange points) is in some orbit, with some period, about the primary (Earth, in this case). Are there other orbits that have the exact same period ? If the Moon had no mass, the answer would be, no, except for exactly the same mean distance (AKA semi-major axis) from the Earth. With the Moon having a significant mass, things are not quite so simple, but they are not very much harder.
Suppose you a
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I read all the other answers and they are accurate but not complete. L2 and L3 are not points of stability in the sense that you can put an object there and it will stay there -- they are metastable in that the forces on the object are balanced, but balanced in the sense of balancing on a knife edge. A small perturbation inward or outward from L2 or L3 will be amplified and the object leaves position. That said, there are stable trajectories of the object such that it can "orbit" L2 or L3 such that it st