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Why not the moon?

Discussion in 'SpaceX' started by Cosmacelf, Aug 30, 2014.

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  1. SwedishAdvocate

    SwedishAdvocate Active Member

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    #21 SwedishAdvocate, Sep 1, 2014
    Last edited: Sep 1, 2014
  2. Bencredible

    Bencredible Galactic Overlord

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    I would ask: why not both? The moon can ask as a pretty awesome launching point for Mars. If we're to colonize Mars there is a good case to be made for using the Moon as a waypoint to get there. Send the initial vehicles from Earth to the Moon. Then have cyclers go between the Moon and Phobos in a ~2 year cycle. Then have a transport from Phobos to Mars. Reduces your need to carry that scary large amount of fuel with you all the way to Mars.

    We will probably just go to Mars directly at first... But the Moon may end up playing a role here. Moon... Mars... I say BOTH!
     
  3. ecarfan

    ecarfan Well-Known Member

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    My understanding is that boosting material to the moon and then bostng from the moon to Mars takes much more energy than launching from earth direct to Mars.

    The moon is a waste of time if your goal is to get to Mars, according to many people much smarter than me.
     
  4. rolosrevenge

    rolosrevenge Dr. EVS

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    But we should have a moon base. Moon bases are awesome and a good front line defense against hostile invaders since it's much easier to launch weapons from the moon than earth.
     
  5. jerry33

    jerry33 (S85-3/2/13 traded in) X LR: F2611##-3/27/20

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    You do Mars first, then you do the Moon. The moon is where you put the environmentally unfriendly manufacturing plants.
     
  6. ecarfan

    ecarfan Well-Known Member

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    Unless the invading aliens approach earth on the side facing away from the moon.
     
  7. woof

    woof Fluffy Member

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    The moon is also a great place to launch kinetic energy weapons (aka rocks) "downhill" to Earth. Not so great if you're on the Earth at the time. Heinlein proposed a railgun I believe to do this.

    The Moon Is a Harsh Mistress - Wikipedia, the free encyclopedia

    I agree with the posters above...the moon is too close to, and thus most likely too dependent on, the Earth to protect the species from political disaster. Mars is (hopefully) far enough.
     
  8. Cosmacelf

    Cosmacelf Well-Known Member

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    Oh, I don't know if even Mars is far enough for a political disaster. Those have huge damage radii!
     
  9. Reykjavik

    Reykjavik Member

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    The moon isn't a good stopping point for going to Mars, because the Oberth effect makes it more efficient the lower your altitude on your escape burn from earth is.

    In the future when there is a small lunar base and thriving Mars colony, people might want to stop by the Moon just to see it, look at the historical Apollo sites, etc., but from an energy standpoint, you want to leave earth from just outside the dense atmosphere. If there were no atmosphere, the best place to do the escape burn would be at the surface.

    I know this because I have a masters degree in Kerbal Science.
     
  10. Bencredible

    Bencredible Galactic Overlord

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    It depends. While it does take more energy overall, you can harvest the water on the moon to make LOx and LH2 for rocket fuel which brings the per launch mass waaay down. Just bring the fuel you need to get to the moon then launch from the Lunar pole to get to Mars. You can also launch from a Lagrange point and simply use the Lunar base as a place to harvest water. L2 is actually a good starting point.

    I did a show with Dave Masten of Masten Space Systems which lightly touches on some of this here: http://www.tmro.tv/2014/07/27/dave-masten-and-darpa/
     
  11. Doug_G

    Doug_G Lead Moderator

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    I don't believe it's been absolutely proven that there is significant water in polar lunar craters, and certainly we do not know if it is economically extractable (could be widely dispersed in regolith).
     
  12. richkae

    richkae VIN587

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    There is no reason to go to the moon for water. There are near earth asteroids floating around that we can use instead. Many are largely composed of ice. Instead of digging for water on the moon and fighting its gravity just carve what you need off a big chunk of ice - or use the whole thing for fuel, water and reaction mass.
     
  13. Doug_G

    Doug_G Lead Moderator

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    There's no reason to expect that near-earth asteroids have significant ice content. Comets do but they mostly live in the outer solar system. They start to sublimate when then reach 1 AU from the sun.
     
  14. richkae

    richkae VIN587

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    My statement that they definitely contain ice was inaccurate. I've talked to former NASA scientists who think it is probable that they do. I think we will find out for sure before Elon gets to mars.
     
  15. flashflood

    flashflood Member

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    One of these days, Alice...
     
  16. Bencredible

    Bencredible Galactic Overlord

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    We did send LCROSS to impact the moon and find water. Here is the NASA press conference after the initial data was analyzed: LCROSS Science Briefing November 13th 2009 - YouTube While the data does show water, how much is still up for a bit of debate.

    - - - Updated - - -

    They may. While not an asteroid, comet 67P which the ESA Rosetta space craft is currently visiting, continues to surprise us. We expected an icy rock, but that's not what Rosetta found! Really cool discoveries going on there.

    Even so, even if we have asteroids with tons of water (we likely do) getting to them, maintaining a stable orbit, mining them and then taking that path to Mars is a lot more complex than simply using the Moon as a launching point to the universe which was the original point. Rather than going out to the asteroid and launching from there, we'll probably send uncrewed craft out there, move the asteroid in to a lunar orbit, convert the ice to rocket fuels and launch from a Lagrange point near the moon like L2. You then use the Moon as your base of operations for your L2 launchpoint/waypoint.

    The question of why Mars and not the Moon, in my opinion is wrong. We will likely do all of them given enough time. It is just a question of what to do first. I think Mars makes a lot of sense to visit before we go back to the Moon, but if we want to set up a sustained colony, the Moon is something we will have to seriously look at. Mars Direct is very expensive to do when you're sending thousands of people over and over again.

    NASA is awesome, but don't put too much stock in to everyone there. Even the higher ups say things are not possible that we are working on and making happen. They look at the universe through the eyes of the Government. SpaceX takes a very different approach.
     
  17. rolosrevenge

    rolosrevenge Dr. EVS

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    But it still takes less energy to launch weapons from the moon. Plus, if they ignore the lunar defenses we can flank them during their major assault.
     
  18. Zextraterrestrial

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    don't we?
     
  19. Grendal

    Grendal SpaceX Moderator

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    I realize I'm a little ambitious but I'd love to see someone go to the belt and grab a big asteroid, drill into the core and spin it up for gravity. Then we'd be doing what I've read in stories for most of my life. I want to see some serious industry happening in space. You have the two big things out there that, with increasing worldwide population, are becoming more and more rare on planet Earth: resources and space.
     
  20. rabar10

    rabar10 Model 3 >> Focus Electric

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    #40 rabar10, Sep 3, 2014
    Last edited: Sep 3, 2014
    Moved a few posts to their own thread: NASA culture and constraints vs. SpaceX

    That would be closer to anti-gravity, with things on the surface being flung off of the asteroid into space.

    And another reason for Mars: The moon wouldn't qualify for Elon's stated goal: to help humans become a multi-planetary species. :wink:
     

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