5 years to Mars?

Discussion in 'Science and Technology' started by Tetragrammaton Invictus, Sep 29, 2017.

  1. Asbo Zaprudder

    Asbo Zaprudder Vice Admiral Admiral

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    NASA is not really up to the job given its underfunding. It might be best for it to provide infrastructure for SpaceX and other companies. We have yet to see how well the SLS works - in many ways, it seems to be decades behind in technology being developed by private companies.

    Last thing I heard China was going to cooperate with ESA on setting up a moon base. NASA is legally prevented from any cooperation with the Chinese space agency.

    But, yes, Trump will likely be out of office by the time China sets up a moon base - unless he gets amendment 22 that restricts him to two terms repealed.
     
  2. Tetragrammaton Invictus

    Tetragrammaton Invictus I like the new Doctor Premium Member

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    Or declares himself ruler for life....... M Bison speech incoming
     
  3. Asbo Zaprudder

    Asbo Zaprudder Vice Admiral Admiral

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    A delta-V map might be of help:
    [​IMG]
     
  4. YellowSubmarine

    YellowSubmarine Rear Admiral Rear Admiral

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    I have kindergarten-level understanding of Delta-V budgets and how orbits work, but I have zero engineering sense in the matter. I never seem to picture transfer orbits as the solution to, well, doing orbit transfers until after I get told about it. It's easy to forget that the intermediate free trajectories towards the destination are orbits, and that these transfer orbits are very close to the final circular orbit at the apogee where they intersect – don't they have, like, the same tangent, and you just slow down? Instead, I picture spacecraft literally going from Earth to Mars on a curve, and even knowing at the back of my head that this constitutes an orbit of some sort, I never picture an elliptic orbit that touches both Earth and Mars at its ends – even though that's quite intuitive.

    During the first SpaceX GTO launch webcast I watched, I was confused when Lauren Lyons announced the target orbit had been achieved (when the second stage was barely at 700 km above Earth or something). Even knowing the real expensive thing is the delta-V, I was still confused, especially since absolute value of the velocity wasn't that big either. It's also non-obvious that the transfer from GTO to GEO would be cheaper, so that you could simply leave a satellite in GTO, and let it reposition itself at low thrust. I expected they would reach GEO altitude on a free trajectory, then fire the Falcon 9's second stage again to get into the final orbit. When she added that's a highly elliptical orbit, and that a manoeuvre at its higher end puts you into GEO, I felt really dumb, as it is pretty obvious. Reminds of gravity assists. Different thing, same confusion.

    The delta-V from GTO to GEO is still like half of that from LEO to GTO, which ain't free. But it's only ~1600 of the 3910 on your delta-V map, if we look at this one:

    [​IMG]

    On both mine and your map, MTO seems not much more expensive than GTO, which is another thing I find odd. If I read the maps right, MTO costs you about the same as GEO. Doesn't really help much, since a Tesla Roadster with no propulsion of any kind won't be able to make it to make it to Mars from there.* It will be perpetually stuck in an elliptical orbit between Earth and Mars, though. So I do hope there's a teapot in the trunk. Or that Elon tweets a suggestion there might be.

    * A hard landing is a cheap source of delta-V, although I guess that goes against any recommendation on contamination and won't help you stay in Mars orbit very much.

    ETA: On a second thought, the second stage won't be recovered on this flight, so it may remain attached to the payload. But I don't believe the second stage can refire again after so long. And I don't believe we're in the window for going to Mars right now.
     
    Last edited: Dec 30, 2017
  5. Asbo Zaprudder

    Asbo Zaprudder Vice Admiral Admiral

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    The map I linked doesn't show the delta-V for GEO to GTO. It's just a bit of fun really. Values change quite a bit depending on a number of factors. You might be interested in Scott Manley's Kerbal Space Program videos on YouTube.
     
  6. Tetragrammaton Invictus

    Tetragrammaton Invictus I like the new Doctor Premium Member

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    Hey things could be worse we could have Trump branded rockets, you know like his plane with his name all over it in big letters.
     
  7. Mr. Laser Beam

    Mr. Laser Beam Fleet Admiral Admiral

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    I could not disagree more. Trump is way too much of a narcissist to be able to inspire the entire country to get to Mars.

    JFK got us to the Moon because he was a natural leader. People cared about him. He made them believe in the good of the country. Trump couldn't give a shit about any of that - in the most literal sense, he cares about nothing but himself.
     
  8. Tetragrammaton Invictus

    Tetragrammaton Invictus I like the new Doctor Premium Member

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    Tell him all the ships will have TRUMP painted on the sides in huge letters, that world leaders will kiss his ass and fawn all over him.
     
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  9. publiusr

    publiusr Rear Admiral Rear Admiral

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    Very tiny though. Similar to this capsule--
    http://www.astronautix.com/s/soyuzob-vi.html

    it is basically a Shenzhou with a hollow shell--a bit more roomy than the usual capsule.

    The LM-5 will give them Mir/ISS black capability--and CZ-9 would allow a Skylab sized module.
     
  10. Dryson

    Dryson Fleet Captain Fleet Captain

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    In order to colonize Mars a reusable vehicle will need to be developed that could launch and land several times. I was watching a video of the Dragon X capsule abort rockets being used which can be watched at the link below:



    Because the gravity of Mars is less then the gravity on Earth the total mass of any ship on Mars would be 38% less then on Earth.

    Since Mars has less mass than Earth, the surface gravity on Mars is less than the surface gravity on Earth. The surface gravity on Mars is only about 38% of the surface gravity on Earth, so if you weigh 100 pounds on Earth, you would weigh only 38 pounds on Mars.

    The Dragon capsule weighs 13,228 lbs on Earth but on Mars the capsule fully loaded weigh 5,026.64 lbs.

    A larger version of the Dragon capsule could be developed where the trunk would be replaced with an extended fuel system as well as more powerful engines that would allow the Dragon Explorer Ship to land on Mars and then return to space without the need of a launch system. If you watch the video the Dragon escape test is basically a free platform test of the capsule and trunk launching without any structures to guide its trajectory.

    If guides were needed to stabilize the launch I could see launch runners being part of the landing struts that over time would drill themselves into the ground. Once an ascent launch was ordered the locking clamps on the landing struts would release for the guides that would then allow a free ascent into Martian orbit.
     
    Last edited: Jan 25, 2018
  11. Tetragrammaton Invictus

    Tetragrammaton Invictus I like the new Doctor Premium Member

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