Lagrange points

johno · Posted on: Mon Sep 21, 2009 5:43 am

Hello,

I am trying to determine the delta-v required to travel from LEO or LLO (low lunar orbit) to the various lagrange points. I'm specifically interested in the delta-v for L4 and L5. Each of these points is the same distance from Earth as the Moon, and the same distance from the Moon as Earth (384403 kms). So I'm thinking that the calculations will be the same as just working out the delta-v to get from a low orbit to an orbit that takes 655 hours around the barycenter of the Earth-Moon system. I know that the initial orbital angle will have to be considered as well, but to get started I'm going to assume that it is at the optimum angle. Does this sound like a reasonable approach to take to the problem?
I've spent a lot of time googling for more information about the right way to do this but haven't found anything useful yet. Does anyone on here have any pointers or urls that would be useful to me in this project? I know some of the basics behind orbital mechanics and I have a very good working knowledge of Newtonian physics. I'm not looking for the answer to the problem in m/s, part of the fun is working it out for myself.

thanks for any assistance,

johno (not Euler

)

Author	Message
johno Space Walker Joined: Thu Sep 17, 2009 2:25 pm Posts: 157 Location: Ireland	Lagrange points Posted on: Mon Sep 21, 2009 5:43 am Hello, I am trying to determine the delta-v required to travel from LEO or LLO (low lunar orbit) to the various lagrange points. I'm specifically interested in the delta-v for L4 and L5. Each of these points is the same distance from Earth as the Moon, and the same distance from the Moon as Earth (384403 kms). So I'm thinking that the calculations will be the same as just working out the delta-v to get from a low orbit to an orbit that takes 655 hours around the barycenter of the Earth-Moon system. I know that the initial orbital angle will have to be considered as well, but to get started I'm going to assume that it is at the optimum angle. Does this sound like a reasonable approach to take to the problem? I've spent a lot of time googling for more information about the right way to do this but haven't found anything useful yet. Does anyone on here have any pointers or urls that would be useful to me in this project? I know some of the basics behind orbital mechanics and I have a very good working knowledge of Newtonian physics. I'm not looking for the answer to the problem in m/s, part of the fun is working it out for myself. thanks for any assistance, johno (not Euler )
Back to top

SuperShuki Space Station Commander Joined: Mon May 31, 2004 9:47 pm Posts: 737 Location: Yerushalayim (Jerusalem) - capital of Israel!	Re: Lagrange points Posted on: Mon Sep 21, 2009 5:51 pm A (tiny) matter is the difference in atmosphere between LEO and LLO. But maybe you want to ignore that. On the other hand, maybe it would be more fun for you to include that in your calculations . . . _________________ “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Leonardo Da Vinci
Back to top

johno Space Walker Joined: Thu Sep 17, 2009 2:25 pm Posts: 157 Location: Ireland	Re: Lagrange points Posted on: Mon Sep 21, 2009 8:51 pm Well if my current assumptions are correct there will be a significant difference between the delta-v from LEO->L4/L5 and the delta-v from LLO->L4/L5. It's much easier to raise the apsides of a lunar orbit than a terrestrial orbit. The atmospheric drag is negligible, almost unmeasurable at a LEO above 500km. I will be happy with a result that is accurate to within 1%. I know I found an excellent source of information about this topic on the net several months ago, but I didn't bookmark it and I can't find it again. johno
Back to top
Display posts from previous: Sort by