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Astronaut Training: Station 1 - Water-Cooled Underwear

Learn about how the cooling system in an Extravehicular Mobility Unit (EMU) works.

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  • What materials will you need for this activity? Where will you get these materials?
  • Where will you get the water for this activity?
  • How can you make sure not to make a mess while doing this activity?


  • Wrap your bare arm with the plastic tubing.
  • Grasp the end of the tube and point it toward the plastic container on the ground
  • Place the opposite end of the tube into the plastic container full of water on the table.
  • To feel like you are wearing a garment with the tube sewn in (like the liquid cooling and ventilation garment that astronauts wear), you can slide a sock with the toes cut out over your arm and wrap the tube around it.
  • Attach the siphon bulb pump to the bottom end of the tube.
  • Make sure the siphon bulb’s outlet is pointed toward the container on the floor.
  • Start a siphon from the water container through the tube by pumping the siphon bulb until water begins to flow.


  • Did you notice a temperature change?
  • Spacesuits are designed to be very well-insulated, so why is a water-cooling system necessary?
  • When would an astronaut on a space-walk want to increase the amount of cooling?
  • What would it be like if the tube were wrapped all around your body?
  • Is there anything about this simulation that would not work in space?
  • How could you improve this design to ensure it worked in microgravity? (e.g. The siphon wouldn’t work in space because there is no gravity to “power” the siphon, so the water must be pumped through the LCVG).
  • Remember to submit your activities on our Scouts for Sustainability Take Action Map


  • Aquarium tubing (approx. 0.5 m)
  • Siphon bulb pump
  • 2 containers
  • Ice water
  • Towel or sock with toes cut out

Keep it Simple

  • Ice water might be too uncomfortable for some people, so you can try using water that is cold, but not ice cold!

Take it Further

  • How could you apply this system to another scenario? Would a cooling or warming suit be helpful on any of your adventures?