How Space Suits Work

Putting on a Spacesuit

An astronaut on a space walk.
Photo courtesy NASA

To prepare for a spacewalk, crewmembers must do the following:

  1. Reduce the pressure in the shuttle to 0.7 atm and increase the oxygen
  2. Pre-breathe 100 percent oxygen for 30 minutes to remove nitrogen from their blood and tissues
  3. Put on the MAG
  4. Enter the airlock
  5. Put on the LCVG
  6. Attach the EEH to the HUT
  7. Attach the DCM to the HUT (PLSS is pre-attached to the HUT)
  8. Attach the arms to the HUT
  9. Rub the helmet with anti-fog compound
  10. Place a wrist mirror and checklist on the sleeves
  11. Insert a food bar and water-filled IDB inside the HUT
  12. Check the lights and TV cameras on the EVA
  13. Place the EVA over the helmet
  14. Connect the CCA to the EEH
  15. Step into the LTA and pull it above their waist
  16. Plug the SCU into the DCM and into the shuttle
  17. Squirm into the upper torso portion of the suit
  18. Attach the cooling tubes of the LVCG to the PLSS
  19. Attach the EEH electrical connections to the PLSS
  20. Lock the LTA to the HUT
  21. Put on the CCA and eyeglasses (if the astronaut wears them)
  22. Put on comfort gloves
  23. Lock on the helmet and EVA
  24. Lock on the outer gloves
  25. Check the EMU for leaks by increasing the pressure to 0.20 atm above the airlock pressure

No leaks mean the airlock is depressurized. Once these steps are completed:


  1. The EMU automatically depressurizes to its operating pressure.
  2. The suits are tethered to the airlock.
  3. The outer airlock door is opened.
  4. The SCU is disconnected from the EMU.
  5. The astronauts step out of the airlock into the shuttle's cargo bay.

And the spacewalk begins. At this point, the EMU is a spacecraft in and of itself, independent of the shuttle/space station. This is why each EMU has a $12 million price tag. After the spacewalk, these steps are reversed to get out of the suit and back into the spacecraft.

When working on the moon, Apollo astronauts had difficulties moving around in their space suits. The Apollo suits were not nearly as flexible as the EMU used today; however, the EMU weighs almost twice as much as the Apollo suit (not a problem because the EMU was designed for work in microgravity, not on a planet's surface). For future space missions to Mars, NASA is developing "hard suits" that are more flexible, more durable, lighter-weight and easier to don than current space suits.

For more information on space suits and related topics, check out the links below.


Related Articles

More Great Links