Apollo-Era EMU (Extravehicular Mobility Unit)


The spacesuit worn by Apollo astronauts on the lunar surface was known as an EMU (Extravehicular Mobility Unit). In many ways, it was the "world's smallest spacecraft." Thousands of small parts working together provided astronauts with the life support, environmental protection, mobility, and communication systems necessary to perform extravehicular activity (EVA) in space and on the Moon.

The two primary pieces of the Apollo EMU were the A7L Pressure Suit Assembly (PSA) and the Portable Life Support System (PLSS). The PSA was manufactured by the International Latex Corporation (later ILC Dover) in Delaware, and the PLSS was produced by Hamilton Standard in Windsor Locks, CT with the support of many sub-contractors. The final EMU "package" was assembled and tested by NASA.

Before stepping foot onto the Moon, astronauts would put on additional pieces of equipment to allow them to survive on the surface without the spacecraft's life support systems, aid their mobility, and protect them from the extremes of the lunar environment.

Portable Life Support System (PLSS) Backpack [A]:

Designed, developed, and tested by Hamilton Standard, the PLSS provided life support to an astronaut during lunar EVA (extravehicular activity). It supplied oxygen, removed carbon dioxide, pressurized and cooled the spacesuit, and controlled humidity to provide a comfortable environment for the astronaut. Twelve of these backpacks (one for each astronaut), left behind to conserve weight, are still on the surface of the Moon.

Oxygen Purge System (OPS) [B]:

An emergency oxygen supply that was mounted on top of the PLSS, this system consisted of two tanks at a pressure of 6000psi. It was designed to give astronauts a half hour of oxygen, enough to return to the Lunar Module if they ran into trouble.

Remote Control Unit (RCU ) [C]:

This unit would be mounted on the chest area of the space suit for easy accessibility and provided proper control of the PLSS and OPS.

Lunar Overboots [D]:

Fitted on top of the boots already worn and integrated into the space suit, these overboots incorporated blue silicone tread and an outer covering made of Chromel-R, a woven nickel-chrome fabric designed for thermal protection and abrasion/puncture resistance.

Extravehicular (EV) Gloves [E]:

These slipped on over the astronaut's IV pressure gloves. They had silicone fingertips and, like the overboots, were protected by an outer layer of Chromel-R.

Lunar Extravehicular Visor Assembly (LEVA) [F]:

Designed to fit over the Pressure Helmet Assembly, the inside of this visor was vacuum coated with 24-karat gold thin enough to see through. The entire assembly was designed to protect astronauts from the sun's harmful ultraviolet rays.

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