Which Lagrange Point is Best

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Boris_Badenov

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Which Lagrange point would be best to put a station in & why? <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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qso1

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This link may be of help.<br /><br />http://en.wikipedia.org/wiki/Lagrangian_point <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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mikeemmert

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Hint: the Lagrange points are the solution to the <i>three body problem</i>. If there are stations at both points, then it becomes the <i>four body problem</i>. The n-body problem cannot be solved if n>3.<br /><br />You might think that the mass of stations there would be negligible, but the mass of New York City was negligible 500 years ago.<br /><br />Below is posted an image of the solution to the four body problem at Uranus' moon, Miranda. Note the oval-shaped features:
 
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vogon13

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<i>Below is posted an image of the solution to the four body problem at Uranus' moon, Miranda. Note the oval-shaped features<br /></i><br /><br /><br />Huh?<br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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MeteorWayne

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steve, why did you have to add the human cell and brain comments? <br />They were not needed to explain the concept of chaos, and were totally off topic for the discussion at hand.<br /><br />Please stay focused. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Boris_Badenov

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At the risk of appearing redundant;<br /><br /> Which Lagrange point would be best to put a station in & why?<br /><br /> Everybody that has answered so far has said why they can't be used. <br /> I personally like L2 because of it's proximity to Earth. Any staion in that point, or any other, is of course going to have engines for station keeping. The question is, which Lagrange point is best to get to & from Earth & other points in the Solar System.<br /><br /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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mikeemmert

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Fair enough, L-5, trailing the Moon. It's pretty stable as long as there isn't a huge station at L-4.<br /><br />Getting out of the Earth's gravitational well is simplest from L-5, involving the shortest times and distances.<br /><br />(Earth/Moon) L-2 would create radio interference for any radiotelescopes that may be installed on the far side of the Moon. (Sun/Earth) L-2 already has at least two satellites there and the James Webb Space Telescope is scheduled to be installed at that location. This is a prime location. So is Earth/Sun L-1 (SOHO).<br /><br />On most outbound journeys, any of the five Lagrange points can get you a delta V of just about a maximum of lunar escape energy. If your launcher had a good strong rocket or a rotovator system, you could utilize both (Earth/Moon) L5 <i>and</i> L1. Passing <i>through</i> a Lagrange point usually gives you as much energy as starting from it. So actually any of the Lagrange points will work.<br /><br />But, since you pinned me down, (Earth/Moon) L-5 is the winner!
 
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spacester

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If I may try to focus the discussion on the title subject . . . <br /><br />"When a body is put into those (orbits) . . ."<br /><br />Let's think about this from an operational standpoint.<br /><br />L-4 & L-5 are just another pair of Earth orbits, but in an interesting volume of the gravitational field of cis-lunar space. To get there, you are going to be transferring from some other Earth orbit, or possibly from lunar orbit, or possibly from outside the Earth's SOI (Sphere Of Influence).<br /><br />The cool thing is that if you hit your target just right, at the end of your transfer orbit, you are done, your station-keeping goes to zero.<br /><br />But everything has a tolerance. If you miss your end-of-transfer burn by just a little bit, you are going to need just a little bit of station-keeping later. <br /><br />Does anyone have a handle on the numbers? As in, if I miss the target by 10 m/s of dV, how many months until I need to make a corrective burn or lose my L-5 position? Is a 10 m/s perturbation equivalent?<br /><br />I hope to get around to researching questions like these, as NASA starts considering manned NEO missions. The L points seem to be ideal parking orbits for NEO missions. I guess this post is step one in that study. <img src="/images/icons/smile.gif" /><br /><br />BTW, the brain comments made were in fact very interesting but also were in fact quite off-topic. A reasonable request to stay focused was reasonably made which has changed the tone of the thread in terms of the reaction. One hopes other ones can talk about the title subject without being overly defensive to correction in subject matter, and one also hopes that interesting diversions are tolerated by other other ones in the first place, due to the judicious placement of them by the first other one. :grin: Also, contrition in some form would be nice. <br /><br />What is the size and shape of the volume of space corresponding to a 10 m/s variance from perfect L-5?<br /><br />I'm not sure if these questio <div class="Discussion_UserSignature"> </div>
 
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Boris_Badenov

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<font color="yellow"> This has already been asnswered. One need only read the above posts and refs. L-2 is NOT stable and would require a consistenlty large and repeated energy usage to maintain a body at that site. </font><br /><br /><font color="yellow"> It's called reading comprehension. </font><br /><br /> I am curios why you tell MeteorWayne not to show you disrespect, & in your very next post you insinuate that I am stupid?<br /> <br /><br />The ISS needs regular boosts, are you saying an L2 station would need more energy than the ISS needs? If so why?<br /> Solar L4 & L5 are stable but quite a bit further distance. Would the stability factor outweigh the distance & time it would take to get there? <br /> The Lunar L points are not stable, but they are much closer. Again, station keeping thrust is not a problem for the ISS, I fail to see why it would be a problem here, & these points are easier to get to & you get the added bonus of a thrust cheat when your ship leaves the Earth Moon system. <br /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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robnissen

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"the brain comments made were in fact very interesting but also were in fact quite off-topic. A reasonable request to stay focused was reasonably made which has changed the tone of the thread in terms of the reaction. One hopes other ones can talk about the title subject without being overly defensive to correction in subject matter, and one also hopes that interesting diversions are tolerated by other other ones in the first place, due to the judicious placement of them by the first other one. :grin: Also, contrition in some form would be nice. "<br /><br />Hear, Hear.<br /><br />As regards your comments on the topic, a fine and very enlightening post.
 
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mikeemmert

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Howdy, Boris, I have done some of your questions on GravitySimulator about a little less than a year ago.<blockquote><font class="small">In reply to:</font><hr /><p>Solar L4 & L5 are stable but quite a bit further distance. Would the stability factor outweigh the distance & time it would take to get there?<p><hr /></p></p></blockquote>Working with the Sun/Neptune Lagrange points L4 & L5, I can attest that, strange as it may seem, the orbital period of massless test objects which are situated at various distances from the Lagrange point have the same orbital period. Long ago somebody in the Space Studies Institute determined that the orbital period around the Sun/Earth Lagrange points is a little over 700 years. This would be, for example, to get from near L3, assume a higher, slower orbit around the Sun, pass over L4, approach Earth, be pulled into a lower, faster orbit around the Sun, and arrive near (but not at) the L3 point again to start over. That's 700 years; an object in a much tighter orbit around L4 (L5 is the mirror image) would also take a little over 700 years. Sorry I forgot the exact period. You can get there much quicker, of course; just burn a little more rocket fuel. This requires braking when you get to the Lagrange point.<br /><br />Contrary to much popular belief, Lagrange points do not attract material into them. Things have to be <i>put</i> there. Or form there.<blockquote><font class="small">In reply to:</font><hr /><p>The Lunar L points are not stable, but they are much closer. Again, station keeping thrust is not a problem for the ISS, I fail to see why it would be a problem here, & these points are easier to get to & you get the added bonus of a thrust cheat when your ship leaves the Earth Moon system.<p><hr /></p></p></blockquote>Thrust cheat can be gotten from any Lagrange point and is about the same. For the Earth/Moon Lagrange points travel time is not too horrendously long. It is possible to force fly through <i>two</i> Lagrange po
 
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mikeemmert

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<blockquote><font class="small">In reply to:</font><hr /><p>Anything less than a 100 kms. in diameter would not appreciably destabilize a body's orbit at the L-4 or L-5 point. <img src="/images/icons/smile.gif" /><p><hr /></p></p></blockquote>That is true over relatively short periods of time, like, say, the length of time of the Cretacous or Holocene or Triassic ages. Longer than that, I really couldn't guarantee.<br /><br />How about shorter periods? Let's say, the length of time writing has been around (Let's define that as the message, "King Menes united Upper and Lower Egypt" rather than some more primitive form like "Mr. Gazelle paid King Scorpion 40 bushels of wheat as taxes", since the former message is well-dated). That's about 6000 years. Note that in this time period, the massive Pyramids were built, and there was no power machinery except pulleys. It was all muscle power.<br /><br />Since we now have power construction equipment, it would not take much more vision than a John Kennedy or Al Gore to envision a mighty metropolis at a Lagrange point. In fact, moving asteroids there might exceed the mass limits pretty quick. But the mass limit for only one point is actually larger than the Moon itself! So one of the points needs to be kept clear of all but maybe an observation post or a few rotovators or something.<br /><br />I'm working on finding those mass limits, BTW. Patience...<br /><br /><font color="black">Common Buzzard:</font>
 
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Boris_Badenov

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In the Wiki article that dgm1 referenced above they suggest Lunar L1 as the place to put a station that is dedicated to assisting travel to & from the Moon. This seems like a good place to build a manufacturing facility that utilized lunar materiels & sent them on to Earth or back to the Moon.<br /> Solar L2 has always seemed like the better place to site a station for access to the rest of the Solar System though. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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mikeemmert

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Hi Boris <img src="/images/icons/laugh.gif" /><br /><br />stevehw33 said:<blockquote><font class="small">In reply to:</font><hr /><p>Some months ago Ms. Calli gave a detailed explanation about privileged areas in the solar system, which allow far lower energy use in order to travel around.<p><hr /></p></p></blockquote>I know that sometimes as a target, one has a tendency to establish a superlative on some particular attack, like "That's the lowest quality post I've seen from that */deleted/*." One should resist that temptation, though. This isn't Steve's worst by a long shot, at least he gives some arguments. But I do note that there is no link to Calli's interesting post, which I missed (<img src="/images/icons/tongue.gif" />).<blockquote><font class="small">In reply to:</font><hr /><p>Solar L2 has always seemed like the better place to site a station for access to the rest of the Solar System though.<p><hr /></p></p></blockquote>But Solar L2 is the preferred location for the Microwave Anisotropy Probe and the James Webb Space Telescope! Putting a launching facility there would be like building a launchpad for a smoky rocket on Mauna Kea. Solar L-2 is the best place to look outwards for many missions. Though the Earth's shadow does not cover the Sun at that distance, Earth's magnetic field should block some light pollution from the Solar wind.<br /><br />There shouldn't be any problem just sailing through, <i>if</i> all trajectory corrections are made well away from the point. There should be regulations prohibiting thruster firings there except for stationkeeping and insertion/deorbit firings; those will cause enough pollution there.<br /><br />Oh, yes; I mentioned the Wilkinson Microwave Anisotropy Probe? That's one of the best sites for learning about Lagrange points.
 
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nexium

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L1 is about 1.2 light-seconds from Earth allowing almost normal telephone conversations, operation of waldos, cheap transportation to and from the moon via a space elevator anchored on the moon and pointed toward Earth. According to mikeemmert 9:53 PM, the space elevator can easily solve the metastable property of L1. Neil
 
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mikeemmert

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But, L5 is about the same distance from Earth. And although a tether (yes, you can enlarge a tether into a space elevator, I didn't say space elevator) can solve the metastability problem, in L5 you don't even need to solve it.<br /><br />I think, all in all, mass drivers (for mass) and maglevs, which can reach orbital velocity on the moon, at which time the train flips upside down and then can acheive higher velocity, can solve manned spaceflight problems. This is actually simpler than a space elevator, which would have to have a motor just like a mass driver or maglev. That's because the Moon does not have an appreciable atmosphere. Do remember, the situation concerning escaping gravity is profoundly different between the Earth and the Moon.
 
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dragon04

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FYI.. You won't get an answer from him.. He's no longer a member here...<br /><br />But someone may come along and answer your question. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>
 
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