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Thread: Moon Travel

  1. #1
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    Moon Travel

    All

    My firat post here and I hope some of you can point me in the right direction for a simple explanation of the trajectory to follow to reach the Moon from the Earth. Can you ignore movement around the Sun as both Earth and Moon move at the same speed? Somehow I don't think so but I cannot explain why. Not even to myself!!!

    Regards

    Patrick

  2. #2
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    You can disregard movement around the sun since you are carried by the current Earth's orbit in that trajectory.

    IE even if you launch out of the Earth's atmosphere you are already travelling in a stable orbit around the sun. The only motion you really have to consider is that of the moon and the rotation of the Earth.


    So then it is a matter of how fast you going, where you launched

  3. #3
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    Bob B over at the ApolloHoax.net forum put together a page describing the Apollo 11 trajectory. It's not the simplest thing in the world, but he includes illustrations and also discusses the Van Allen radiation belts and radiation protection.

    Fred
    Hey, you! "It's" with an apostrophe means "it is" or "it has." "Its" without an apostrophe means "belongs to it."

    "For shame, gentlemen, pack your evidence a little better against another time."
    -- John Dryden, "The Vindication of The Duke of Guise" 1684

    Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity.

  4. #4
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    Quote Originally Posted by Nowhere Man View Post
    ... It ... discusses the Van Allen radiation belts and radiation protection.
    Bob's page is very detailed crazy-talk when it comes to "avoiding the most dangerous part of the Van Allen belt". That being said, it does give a lot of good information about the trajectory and what needs to be taken into account.
    Forming opinions as we speak

  5. #5
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    Quote Originally Posted by 106112909 View Post
    All

    My firat post here and I hope some of you can point me in the right direction for a simple explanation of the trajectory to follow to reach the Moon from the Earth. Can you ignore movement around the Sun as both Earth and Moon move at the same speed? Somehow I don't think so but I cannot explain why. Not even to myself!!!

    Regards

    Patrick
    G'day Patrick (easier and nicer to say that 106112909) and welcome to the BAUT Forum.

    Yes, I'm pretty sure you can ignore the Sun. I don't know the exact details, but I think it's because the travel takes place solely within the Earth-Moon system. That is, the part of space where the Earth's gravity predominates.

    I think a relevant issue is the S-IVB of Apollo 12. After it was discarded, it was sent into a very high orbit around the Earth, so high that the orbit wasn't stable. After a couple of years it left Earth orbit to orbit the Sun, but was briefly recaptured in 2002. So what this suggests to me is that the Sun can be ignored for trajectories involving only the Earth and the Moon, but not if you want to travel much further out.

  6. #6
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    Quote Originally Posted by 106112909 View Post
    ...Can you ignore movement around the Sun as both Earth and Moon move at the same speed?..
    It depends on how accurate you want your resultant trajectory to be. In Gravity Simulator I've set up simulation of a spacecraft traveling from low-Earth orbit to the Moon, and then braking into low-Lunar orbit. So it was easy enough to delete the Sun and try it again.

    This simulation was not Apollo by numbers, just an arbitrary free-return trajectory prior to lunar orbit insertion. As you can see, the two trajectories are not identical. They differ by a few hundred kilometers. That might be important to you if you are trying to orbit the Moon at an altitude of under 100 km.


  7. #7
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    Quote Originally Posted by 106112909 View Post
    All

    My firat post here and I hope some of you can point me in the right direction for a simple explanation of the trajectory to follow to reach the Moon from the Earth. Can you ignore movement around the Sun as both Earth and Moon move at the same speed? Somehow I don't think so but I cannot explain why. Not even to myself!!!

    Regards

    Patrick
    http://www.astrojava.com/ has some neat toys.
    Lunar Trajectory has a number of scenarios in the menu and also allows you to enter your own input.

    If you're trying to set up a Belbruno Lo type of trajectory, I believe you would have to look at the sun. Some of these paths can be changed a lot with a small perturbation, and the sun does exert an influence. For example, a nudge from EML1 might go a different route if nudged during a new moon rather than during a full moon.

    Here's an orbital sim I put together using Bob Jenkins orbit sim Java: http://clowder.net/hop/railroad/FromEarth.php

  8. #8
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    Quote Originally Posted by Nowhere Man View Post
    Bob B over at the ApolloHoax.net forum put together a page describing the Apollo 11 trajectory. It's not the simplest thing in the world, but he includes illustrations and also discusses the Van Allen radiation belts and radiation protection.

    Fred
    Nice link!

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