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posted by hubie on Monday June 10, @11:38AM   Printer-friendly
from the very-cool-idea dept.

Arthur T Knackerbracket has processed the following story:

Astronauts driving a vehicle around the landscape of the moon must not only face dangers related to [low] gravity and falling into craters, but also the problem of extreme fluctuations in temperature. The lunar environment oscillates between blistering highs of 127°C (260°F) and frigid lows of -173°C (-280°F).

Future missions to explore the moon will need reliable machines that can function under these harsh conditions. This led a team from Nagoya University in Japan to invent a heat-switch device that promises to extend the operational lifespan of lunar-roving vehicles. Their study, conducted in collaboration with the Japan Aerospace Exploration Agency, was published in the journal Applied Thermal Engineering.

"Heat-switch technology that can switch between daytime heat dissipation and nighttime insulation is essential for long-term lunar exploration," said lead researcher Masahito Nishikawara. "During the day, the lunar rover is active, and the electronic equipment generates heat. Since there is no air in space, the heat generated by the electronics must be actively cooled and dissipated. On the other hand, during extremely cold nights, electronics must be insulated from the outside environment so that they don't get too cold."

[...] The thermal control device developed by the team combines a loop heat pipe (LHP) with an electrohydrodynamic (EHD) pump. During the day, the EHD pump is inactive, allowing the LHP to operate as usual. In lunar rovers, the LHP uses a refrigerant that cycles between vapor and liquid states.

When the device heats up, the liquid refrigerant in the evaporator vaporizes, releasing heat through the rover's radiator. The vapor then condenses back into liquid, which returns to the evaporator to absorb heat again. This cycle is driven by capillary forces in the evaporator, making it energy efficient.

At night, the EHD pump applies pressure opposite to the LHP flow, stopping the movement of the refrigerant. Electronics are completely insulated from the cold night environment with minimal electricity use.

[...] The implications of this technology extend beyond lunar rovers to broader applications in spacecraft thermal management. Integrating EHD technology into thermal fluid control systems could improve heat transfer efficiency and mitigate operational challenges. In the future, this could play an important role in space exploration.

The development of this heat-switch device marks an important milestone in developing technology for long-term lunar missions and other space exploration endeavors. All of which means that, in the future, lunar rovers and other spacecraft should be better equipped to operate in the extreme environments of space.

More information: Masahito Nishikawara et al, Demonstration of heat switch function of loop heat pipe controlled by electrohydrodynamic conduction pump, Applied Thermal Engineering (2024). DOI: 10.1016/j.applthermaleng.2024.123428

[Ed Note: Corrected first line to read 'low gravity' - not zero gravity: 20240610-13:29 JR]


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  • (Score: 4, Interesting) by ElizabethGreene on Monday June 10, @12:20PM

    by ElizabethGreene (6748) Subscriber Badge on Monday June 10, @12:20PM (#1360018) Journal

    If you'd like to read about other nifty on-off switches for moving heat, the book "Spacecraft Thermal Control Handbook, Volume 2: Cryogenics" is human readable and available from some university and illegal Russian pirate libraries. There are several, mentioned in it, but the one that comes immediately to mind immediately is a munch of carbon fibers connecting two plates that works like a flexible heat conduit. Mechanically pulling one of the plates away from the heat or cold source disconnects it and breaks the thermal connection.

    I was always curious how they prevented these plates from cold welding to each other, and never found a satisfactory answer for that.

    Related, the little carbon fibers in this gizmo are some wizard tech. The heat transfer coefficient through them is like two orders of magnitude higher axially than radially. (iirc)

  • (Score: 2, Interesting) by Anonymous Coward on Monday June 10, @01:04PM (7 children)

    by Anonymous Coward on Monday June 10, @01:04PM (#1360021)

    From tfa,
    > ... must not only face dangers related to zero gravity and falling into craters ...

    Is there anyone awake at the controls at phys.org? First off, the moon isn't zero gravity (iirc it's something like 1/6 Earth gravity) and second, if it was truly zero gravity how could you "fall into a crater"? I don't think that falling into a crater is a real danger anyway, it's easy to see a crater coming up ahead.

    Under normal circumstances, I'm sure our SN editors are smart enough to catch these kinds of dumb mistakes, but I'm happy to give them some help in the current overload situation...

    • (Score: 2) by mcgrew on Monday June 10, @01:23PM

      by mcgrew (701) <publish@mcgrewbooks.com> on Monday June 10, @01:23PM (#1360026) Homepage Journal

      That little brain fart (or "senior moment" as my Mom called it) struck me, too. You kids aren't getting enough sleep!

      --
      mcgrewbooks.com mcgrew.info nooze.org
    • (Score: 3, Informative) by janrinok on Monday June 10, @01:30PM

      by janrinok (52) Subscriber Badge on Monday June 10, @01:30PM (#1360028) Journal

      Corrected in TFS, thanks.

      --
      I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
    • (Score: 2) by captain normal on Monday June 10, @05:45PM (3 children)

      by captain normal (2205) on Monday June 10, @05:45PM (#1360054)

      Totally agree about Phys.org. Maybe if the ATK bot could be pointed toward https://scitechdaily.com/ [scitechdaily.com] ,or another such real science/ technology news source.

      --
      Everyone is entitled to his own opinion, but not to his own facts"- --Daniel Patrick Moynihan--
      • (Score: 2) by janrinok on Monday June 10, @05:54PM

        by janrinok (52) Subscriber Badge on Monday June 10, @05:54PM (#1360055) Journal

        I've added a RSS feed from scitechdaily. Thank you for the feedback.

        --
        I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
      • (Score: 3, Informative) by janrinok on Monday June 10, @05:56PM (1 child)

        by janrinok (52) Subscriber Badge on Monday June 10, @05:56PM (#1360056) Journal

        If you find any feeds that you think will be useful please just include them in a comment.

        --
        I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
        • (Score: 2) by sbgen on Tuesday June 11, @03:10AM

          by sbgen (1302) on Tuesday June 11, @03:10AM (#1360113)

          Some articles in technologynetworks.com are pretty good too. I dont know if they have RSS feeds though.
          Thank you for all the work you and other editors put in.

          --
          Warning: Not a computer expert, but got to use it. Yes, my kind does exist.
    • (Score: 3, Funny) by cereal_burpist on Wednesday June 12, @03:05AM

      by cereal_burpist (35552) on Wednesday June 12, @03:05AM (#1360235)

      I don't think that falling into a crater is a real danger anyway...

      Space tourists trying to take a selfie?

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