Project Apollo
Extravehicular Mobility Unit (EMU)
1. Portable Life Support System (PLSS)
2. Oxygen Purge System (OPS)
3. Remote Control Unit (RCU)
4. PLSS Tool Carrier Harness
5. Links to related sections of
    My Little Space Museum

Portable Life Support System (PLSS)
pronounced "Pliss"

Very nice photo of Haise's (left) and Lovell's PLSS (right), rear and front.  Note the serial numbers: #020 for Haise and #021 for Lovell.  Lovell's PLSS shows how the system was packed before being stowed on board the LM.  The OPS is a separate unit that was installed prior ro EVA.
Width 20.5"
(J-Series PLSS with Auxillary Feedwater Reservoir)
Length 26.4"
(top to bottom, without OPS)
Above photo courtesy Kipp Teague's Project Apollo Archive

Above - The innards of a PLSS
Center photo has interior details labelled

Above - NASA PLSS Diagrams
Left - Note the location of the LiOH canister, and stowed antenna on top of OPS
Left Center - Location of fill and drain ports
Right Center - Excellent diagram showing location of indicators, dials, and controls
Right - Ther interconnections between the PLSS, OPS, and RCU

Interesting photo of Armstrong practicing recharging the water system

Oxygen Purge System

My diagram of the OPS

Left - NASA photo of PLSS showing PLSS/OPS combination
Center - Very nicely detailed diagram of the inner workings of the OPS
Right: Beauty photo of an OPS.  Note the actuator umbilical coiled around the side

The OPS was designed as an emergency backup system to provide oxygen to a crewman while on EVA on the moon in the event of PLSS failure.  In combination with the Buddy Life Support System (BLSS) for cooling, it could give the crewman enough life support time to return to the LM and repressurize the ascent stage cabin.  It was primarily made up of a pair of oxygen cylinders and an actuator cable which was mounted on the side of the RCU.
To run the system, the crewman pulled down on the actuator cable to start flow of O2 then opened the diverter valve of the front of the suit to create a presure gradient which would force the O2 into the suit.
The OPS was covered by a plastic shell which in turn was covered by a Beta cloth cover.  The American flag was stitched to the back of it.
The OPS was carried on board the LM into lunar orbit to serve as a backup system in case the LM crew had to make an emergency EVA from the LM to the CSM.  On the later J-Series missions it was also used by the CMP and LMP during the SIM Bay data retrieval EVA.  None of the OPS flown on Apollo were ever used in an emergency situation, a great testimonial to the reliability of the PLSS.

PLSS Remote Control Unit
Above: Side, front, and top views of RCU
Photos above and first 2 photos below courtesy Mr. Paul Kashuk
Above:  Alas, the mystery of how the RCU attaches to the EMU is solved!!!
Photo at right shows Jim Irwin in training, with the PLSS clips attached to the EMU.
The 2 "fingers" that would clamp down on the bars on the clips are visible in the center image.
Right photo courtesy Kipp Teague's Project Apollo Archive

Left - Diagram of the RCU control displays, switches, etc.
Center - Photo of top of RCU and electrical connector to the PLSS, with labels
Right - Similar to center photo

PLSS Tool Carrier Harness

Above- Three pages of diagrams of the PLSS Tool Carrier Harness

Above Left - LMP PLSS Tool Carrier Harness. Note the geology hammer and core tube rammer.  The Core Tube Cap Dispenser was mounted in the small cylindrical holder at the bottom right of the photo, just to the right of the hammer.
Left Center - Another shot of the LMP's PLSS Tool Carrier Harness
Right Center - Opposite side of the LMP's PLSS Tool Carrier Harness, showing the Sample Collection Bag (SCB) mounted on the side of the PLSS.  The CDR's PLSS Tool Carrier Harness held only a single SCB, mounted on the other side of the PLSS, so that it would be outboard while he was driving the LRV.
Right - The Core Tube Cap Dispenser

Above Left - CDR's PLSS Tool Carrier Harness, showing the quick release straps mounted on the side of the LEVA
Right - Interesting closeup from a photo taken on Apollo 17, showing a PLSS Tool Carrier Harness after it was removed from the PLSS just prior to closeout of the final EVA

Links - for more information on the PLSS
PLSS, OPS & RCU Diagrams & Blueprints - includes Hamilton Standard blueprints!
NASA EMU Diagrams
My EMU Diagrams - drawn by me
You must also go to the Apollo Lunar Surface Journal PLSS page

Click here to return to EMU Gallery