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posted by martyb on Tuesday April 18 2017, @09:56PM   Printer-friendly [Skip to comment(s)]
from the nothing-is-lighter-than-*nothing* dept.

https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Evacuated_Airship_for_Mars_Missions

A vacuum airship made of a homogenous material cannot withstand the atmospheric pressure on Earth for any material humans have yet discovered, which can be proven using the critical buckling load of a sphere. However, from an initial analysis of the vacuum airship structure and relationship to atmospheric conditions, Mars appears to have an atmosphere in which the operation of a vacuum airship would not only be possible, but beneficial over a conventional balloon or dirigible. In addition, a multi-layer approach, in conjunction with a lattice, would circumvent the buckling problems of a single homogenous shell. The lattice used to support the two layers of the vacuum airship shell can be made, using modulation of the lengths of the members, to fit the curvature of the vacuum airship precisely by following an atlas approach to the modulation.

The Martian atmosphere has a pressure to density ratio that is very beneficial to the operation of a vacuum airship; this is a result of the high average molecular weight of the atmosphere (relative to other planets in the solar system) and the temperature of the atmosphere, the trend for which can be observed from the ideal gas law. Through a more in-depth analysis of the vacuum airship model, it can be shown that the vacuum airship may theoretically carry more than twice as much payload as a modeled dirigible of the same size, a 40-meter radius, in the Martian atmosphere.

NASA Innovative Advanced Concepts (NIAC) Program. NBF.


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  • (Score: 2) by richtopia on Tuesday April 18 2017, @10:02PM (5 children)

    by richtopia (3160) Subscriber Badge on Tuesday April 18 2017, @10:02PM (#496042) Homepage Journal

    I never realized this was a real concept before. I wonder what the lifting capacity would be on Mars; yes there is less atmospheric pressure to implode the vacuum airship, but there is also less atmosphere to provide buoyancy force.

    https://en.wikipedia.org/wiki/Vacuum_airship [wikipedia.org]

    • (Score: 2) by Fluffeh on Wednesday April 19 2017, @03:28AM (4 children)

      by Fluffeh (954) Subscriber Badge on Wednesday April 19 2017, @03:28AM (#496127) Journal

      Given the pressure there, which is from memory somewhere around 1% of sea-level pressure here on Earth, propulsion would also be somewhat difficult - there's not much to push as exhaust unless you are making it yourself (read rockets to give you acceleration) so even if you were to lift something, moving it anywhere once you lifted it would be cute.

      • (Score: 2) by takyon on Wednesday April 19 2017, @04:25AM (2 children)

        by takyon (881) <{takyon} {at} {soylentnews.org}> on Wednesday April 19 2017, @04:25AM (#496142) Journal

        Sounds like a job for EmDrive.

        But reeling it into the realm of the real... what about ion drives [wikipedia.org]? They are not supposed to work in the presence of atmosphere, but maybe VASIMR [wikipedia.org] is different.

        The proposal suggests using solar panels on the surface of the airship to power electric motors. Maybe it can remain aloft forever. But if EmDrive was real, both options would require no propellant, unlike an ion drive. If the EmDrive magic was refined to maximum hype levels [nextbigfuture.com], it would be the superior choice.

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        • (Score: 2) by Fluffeh on Wednesday April 19 2017, @06:03AM

          by Fluffeh (954) Subscriber Badge on Wednesday April 19 2017, @06:03AM (#496161) Journal

          Yeah, the EMDrive would work - if it does work :P

          Part of the problem with using an Ion Drive though is due to the extreme velocities that it expels the propellant (why they are so efficient in the first place) would create all sorts of wake issues behind the craft - possibly in a dangerous manner to the craft itself even in a very thin atmosphere. I'm not sure though. I'm not saying it is impossible - just that thrust will be very hard. A propeller won't work much at all - there's 100 times less air to grab (and push) but also what is pushed will move easier due to the air it is pushed into not having the same outward pressure.

          Maybe harvesting the ice, then using water as a propellant to create the thrust would work - but again, that means carrying loads of heavy fuel as thrust.

        • (Score: 2) by PinkyGigglebrain on Wednesday April 19 2017, @07:17AM

          by PinkyGigglebrain (4458) on Wednesday April 19 2017, @07:17AM (#496169)

          Something like this might work well on Mars

          https://en.wikipedia.org/wiki/Ionocraft [wikipedia.org]

          The are aka "Lifters". In a nutshell they use high voltage to create thrust. I recall NASA evaluated using them in satellites but it didn't work out for reasons I don't remember. For thrust just point them sideways.

          And here are instructions to build one yourself if so inclined
          http://www.instructables.com/id/High-Voltage-Lifter-Ionocraft/ [instructables.com]

          --
          "Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
      • (Score: 0) by Anonymous Coward on Wednesday April 19 2017, @06:17PM

        by Anonymous Coward on Wednesday April 19 2017, @06:17PM (#496463)

        I'm not sure that's a big deal, really -- you just put much bigger fans on the same motor. Thrust, drag, and buoyancy all scale with atmospheric density, so while the thing will be freaking big for a given payload capacity, it shouldn't take inordinate power to push through the thin atmosphere at blimp-like airspeeds. (Of course, blimp-like airspeeds may be a problem if you need to travel upwind...)

        I'm not sure what the scaling law for payload vs. length looks like -- obviously total buoyancy scales with the cube of length, but you have to subtract the structural weight, and I don't know how that varies. Should be no worse than squared, though, right? So if you figure thrust, drag, and payload all scale linearly with density, and with the square of length, then you can just scale an Earth blimp up 10x in every direction. And since they say their vacuum airship design can carry more payload for a fixed size, it would be a smaller envelope for the same payload, thus less drag, and either less thrust required, or more speed available.

        (I'm sceptical of the whole vacuum-airship thing -- the idea of being able to repair it and re-evacuate with no need for a supply of lifting gas is nice, but I'm suspicious of how much damage the "lattice" can take before field repairs become impossible. Patching a blimp, on the other hand, is trivial for small punctures, and manageable for large tears; same goes for damage to the envelope in a semi-rigid airship, although a damaged keel puts you in the same fix as the vacuum airship.)

  • (Score: 0) by Anonymous Coward on Tuesday April 18 2017, @10:32PM (3 children)

    by Anonymous Coward on Tuesday April 18 2017, @10:32PM (#496051)

    "Through a more in-depth analysis"
    we assume, also, then, that the superior displacment of the mars atmosphere will also yields some subtile weather and ... air? changes.
    it is, i believe, thank god? possible to "inflate" a "vacuum deligerable" on mars to influence an approaching storm(*). however, a constant, yaerlong vacuum displacement of the mars athmosphere might be considered as "climate change" by the yet undiscovered marsians?
    well, cool, what can i say?
    (*) mathematically, the vacuum derigible would represent a hole in the dynamic solar powered heated mars athmosphere?

    • (Score: 2) by deadstick on Tuesday April 18 2017, @10:53PM (2 children)

      by deadstick (5110) on Tuesday April 18 2017, @10:53PM (#496059)

      Quit bogarting.

      • (Score: 0) by Anonymous Coward on Tuesday April 18 2017, @11:07PM

        by Anonymous Coward on Tuesday April 18 2017, @11:07PM (#496060)

        Hey there, bogart
        Could you help me out
        Talk to be bogart
        What is it all about
        Hey there bogart
        Proud and brave and strong
        Talk to me bogart
        What did I do wrong
        Help me bogart
        If time and space allow
        Talk to me bogart
        What would you do now

      • (Score: 0) by Anonymous Coward on Wednesday April 19 2017, @03:43PM

        by Anonymous Coward on Wednesday April 19 2017, @03:43PM (#496364)

        What?

  • (Score: 0) by Anonymous Coward on Wednesday April 19 2017, @12:29AM (5 children)

    by Anonymous Coward on Wednesday April 19 2017, @12:29AM (#496074)

    Airships need hangers when the weather gets rough.

    • (Score: 2) by bob_super on Wednesday April 19 2017, @01:46AM

      by bob_super (1357) on Wednesday April 19 2017, @01:46AM (#496101)

      In most states, it's still legal to get a proper abortion.

    • (Score: 2) by takyon on Wednesday April 19 2017, @01:56AM

      by takyon (881) <{takyon} {at} {soylentnews.org}> on Wednesday April 19 2017, @01:56AM (#496107) Journal

      The initial hangars might have to be excavated caves, until such time that industrial production on Mars takes off.

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    • (Score: 2) by tibman on Wednesday April 19 2017, @02:38AM

      by tibman (134) Subscriber Badge on Wednesday April 19 2017, @02:38AM (#496114)

      Airship hangers on Mars might need reinforced underground bunkers for when the weather gets rough.

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    • (Score: 2) by PinkyGigglebrain on Wednesday April 19 2017, @07:28AM (1 child)

      by PinkyGigglebrain (4458) on Wednesday April 19 2017, @07:28AM (#496172)

      Wind on Mars is not really that powerful, the atmosphere is too thin to really do much but move the really fine particles of dirt around.

      None of the Mars rovers would be able to handle a really windy day on Earth but they have no trouble with the sand storms on Mars.

      (That was one of my few criticisms of "The Martian", A sand storm would not have been enough of a threat to the crew to abort the mission.)

      --
      "Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
      • (Score: 2) by AndyTheAbsurd on Wednesday April 19 2017, @02:54PM

        by AndyTheAbsurd (3958) on Wednesday April 19 2017, @02:54PM (#496328) Journal

        The author of "The Martian" was actually aware of this - but left it in, because without a reason for the other astronauts to abandon Watney, there was no story. (I learned this from the interview he did with the StarShipSofa podcast [starshipsofa.com]. IIRC, there were a few other scientific inaccuracies as well, but this was the most glaring.)

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  • (Score: 2) by esperto123 on Wednesday April 19 2017, @01:09AM (1 child)

    by esperto123 (4303) on Wednesday April 19 2017, @01:09AM (#496089)

    Reading this I've just imagined a ship arriving compressed and then expanding into a bucky ball, like that toy, it would cool.

    • (Score: 2) by kaszz on Wednesday April 19 2017, @02:18AM

      by kaszz (4211) on Wednesday April 19 2017, @02:18AM (#496112) Journal

      It might be the way to land on Mars actually. Eliminating the need for a risky SpaceX booster type landing.

  • (Score: 2, Interesting) by khallow on Wednesday April 19 2017, @06:04AM (6 children)

    by khallow (3766) Subscriber Badge on Wednesday April 19 2017, @06:04AM (#496162) Journal
    The vacuum ship is not a good idea. You have to add mass and structure to prevent the balloon from collapsing due to atmospheric pressure pushing in. 0.01 atmospheres or less, isn't much, but it requires something to resist it, particular for large balloons.

    Instead, fill it with hydrogen. The atmosphere of Mars is mostly CO2. That means the average molecular mass is around 44. Hydrogen is 2. You will get more than 95% of the lifting power of pure vacuum with hydrogen at equal pressure to the atmosphere. So almost the same lift with far less structure (latex and mylar balloons on Earth already operate at pressures and temperatures similar to summer on Mars.
    • (Score: 1) by khallow on Wednesday April 19 2017, @01:02PM

      by khallow (3766) Subscriber Badge on Wednesday April 19 2017, @01:02PM (#496269) Journal
      In addition, the hydrogen will expand as the balloon rises (the limit being the buoyancy of the Martian atmosphere which would be a much lower altitude than on Earth). Lift from vacuum is pretty much fixed, unless you have some complex, mass-adding mechanism for increasing the volume of the vacuum as the craft rises. But a light gas like hydrogen automatically expands, if allowed to (current high altitude balloon designs generally allow this), and that means near constant lift until one reaches the limits either of the balloon's capacity to expand or the Martian atmosphere to provide buoyancy.
    • (Score: 2) by Rivenaleem on Wednesday April 19 2017, @01:31PM (1 child)

      by Rivenaleem (3400) on Wednesday April 19 2017, @01:31PM (#496283)

      Is there not sufficient O2 in Mars's atmosphere to make the highly combustible Hydrogen still a highly risky choice?

      • (Score: 2, Informative) by khallow on Wednesday April 19 2017, @02:34PM

        by khallow (3766) Subscriber Badge on Wednesday April 19 2017, @02:34PM (#496312) Journal

        Is there not sufficient O2 in Mars's atmosphere to make the highly combustible Hydrogen still a highly risky choice?

        No. For starters, the much lower pressure just by itself would make even a pure oxygen atmosphere considerably safer than Earth's atmosphere. And actual oxygen content of the martian atmosphere is 0.15% which is way below any threshold of risk.

        The real danger from combustion would be hydrogen reacting with human breathable atmosphere in habitats or perhaps the vehicle's interior. There are a variety of designs where that could be a problem.

    • (Score: 2) by AndyTheAbsurd on Wednesday April 19 2017, @02:58PM (2 children)

      by AndyTheAbsurd (3958) on Wednesday April 19 2017, @02:58PM (#496330) Journal

      You have to add mass and structure to prevent the balloon from collapsing due to atmospheric pressure pushing in. 0.01 atmospheres or less, isn't much

      Well, surface pressure on Mars is just 0.00628 atmospheres, so no problem, right?

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      • (Score: 0) by Anonymous Coward on Wednesday April 19 2017, @06:26PM

        by Anonymous Coward on Wednesday April 19 2017, @06:26PM (#496470)

        Averaged over the whole surface, maybe. At the bottom of Hellas it's about twice that.

      • (Score: 1) by khallow on Thursday April 20 2017, @04:45AM

        by khallow (3766) Subscriber Badge on Thursday April 20 2017, @04:45AM (#496692) Journal

        Well, surface pressure on Mars is just 0.00628 atmospheres, so no problem, right?

        Still is a problem. Pressure to resist deflation may be much lower, but so is the lift. Meanwhile with hydrogen, you get more than 95% of the lift without that internal structure. Plus we've already flown gas-filled balloons under near Martian conditions and the balloon can expand as it rises to maintain the lift.

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