Lagrange points: gateway to the solar system

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CalliArcale

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Hello!<br /><br />I don't know how many folks may be interested in this, but I happened to mention it in a thread in Free Space about Iapetus, and as it was not topical there, I thought I'd provide a place to discuss it here. It's really cool.<br /><br />Martin Lo was the original navigation manager for the Genesis project. (He has since moved on to other things, now that the primary mission is complete. There is a new navigation manager who presumably is watching the Exodus mission, which is using the spacecraft bus from Genesis that is still in space.) There's a fascinating interview with him on the Genesis website: Martin Lo interview. Unusually for such a role, he is not an engineer. He's a mathematician specializing in chaos theory. The trajectory he designed for Genesis meant that after a successful launch, the spacecraft could (theoretically) cruise uncontrolled to L1, complete the planned sequence of halo orbits, and drop naturally back towards Earth on a path to land in Utah <i>with no intervention from human controllers, and no thruster firings</i>. As it is, there were a few slight trajectory corrections to improve the aim, especially at the end of the mission and to push the spacecraft bus so it would miss Earth after the reentry canister separated. He describes it as a collision orbit -- it's planned to smack into Earth.<br /><br />Theoretically, he says you could plan a mission that went anywhere in the solar system without any fuel expenditure after the initial boost (apart from minor tweaks as the spacecraft flies past asteroids with more chaotic orbits). You could also use it to move asteroids towards the Earth, a feat which would normally require far more thrust than our technology can reasonably provide. It's a principle which is demonstrated all the time in our solar system. The return of the Apollo 12 S-IVB booster occured using Lo's "Interplanetary S <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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starbaby57

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I agree except that I see the small trojan asteroids orbiting just ahead and behind the Earth as the most natural of outposts or space stations. Each provides building materials, shielding from temperature and radiation, and an opportunity to learn resource utilization just a few weeks flight time from earth. Much easier to get to than even the moon.
 
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CalliArcale

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Depends on what you want to get out of it. It's hard to get from Earth to Sun-Earth L2. But it's relatively easy to get to Earth-Moon L1. Apparently it's not hard to get between those two. So once you get to the Lagrange point, the rest is relatively easy.<br /><br />Personally, I think this would mostly be useful for unmanned missions, which are comparatively small and can afford to dawdle. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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CalliArcale

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<blockquote><font class="small">In reply to:</font><hr /><p>I agree except that I see the small trojan asteroids orbiting just ahead and behind the Earth as the most natural of outposts or space stations.<p><hr /></p></p></blockquote><br /><br />Actually, it would be about as difficult to get them as to the moon. Maybe slightly less difficult, but not by a lot. It would be a lot easier than getting to Mars, or going directly to the Sun-Earth L4 or L5 points, though.<br /><br />One minor point to consider, however, is that there are no known Earth trojans. So until somebody discovers one, there's nothing to exploit there anyway. There are some interesting Earth companions, however. They have different relationships to Earth than trojans, but like trojans they have a gravitational relationship with Earth. Cruithne is the most famous of these. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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najab

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><i>This is such an important topic, and one that I think is getting short-shrift in the current NASA strategizing....</i><p>I think NASA did send out a RFP for an L-1 station.</p>
 
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nacnud

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I've not seen a RFP for an L1 station but I have seen lots of images that might have been the resulting proposal. See below, note the different vehicles for Earth/LEO to L1 and from L1 to the Moon.<br /><br />
 
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yurkin

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<font color="yellow">7) EML-1 is the lowest delta-V launch site to deep-space of anywhere in the local neighborhood. NEOs, Mars, Aldrin Cycler taxis, they'd all benefit from having EML-1 as their departure point from cislunar space.</font><br /><br />Do you have a link to this? I’m not sure it’s true. The most energy efficient way to get to the local neighborhood is the ESL-1 & ESL-2, depending on which way you are heading.
 
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najab

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><i>Do you have a link to that?</i><p>I did some Googling, and I was wrong. They haven't got as far as the RFP stage, but it is one of their goals. The image posted above is probably the result of an informal "request for concepts". There's been a lot of talk about it from NASA-types: New Scientist, Space.Com.</p>
 
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alokmohan

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Since these are intermediate stations before visiting moon and nars,there should be concrete efforts from NASA.
 
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