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Oct 4, 2013

Apollo Space Suit (Part 9, Apollo Control Systems)

The Apollo space suit was the result of the evolution that took place during the preparation for the Apollo mission during 1960's and before. One could say that the evolution to protect human against low pressure in high altitudes started already when Wiley Post constructed his first pressure suit in 1934.

Wiley Post's 1935 pressure suit

Most information sources /1/, /2/ and /3/. The following 1960's video is very informative about the space suit development in USA.

Basically the space suit had two parts:

1) the life support system and
2) the actual suit with the helmet.

The life support system may be portable (PLSS, Portable Life Support System) or part of the space craft systems (ECS, Environmental Control Subsystem in LM).

Yellow parts PLSS, ECS on the right and the space suit in the middle


The Apollo space suit shown here with the PLSS

The Apollo space suit is well described in Wikipedia: Apollo/Skylab A7L.

Here are the Apollo era specifications:

Name: Apollo A7LB Spacesuit
Manufacturer: International Latex Corporation (ILC) Dover and Hamilton Standard (PLSS)
Missions: Apollo 15-17
Function: Intra-vehicular activity (IVA), orbital and terrestrial Extra-vehicular activity (EVA)
Operating Pressure: 3.7 psi (25.5 kPa)[4]
IVA Suit Weight: 64.6 lb (29.3 kg)
EVA Suit Weight: 78 lb (35.4 kg)
Total EVA Suit Weight 212 lb (96.2 kg)
Primary Life Support: 7 hours (420 minutes)
Backup Life Support: 30 minutes

A7LB without outer-layer and visor assembly


When not outside the Lunar Module all what astronauts needed (and the charging of the 2 PLSS) was provided by the LM ECS (Environmental Control System). During EVA (Extra Vehicular Activity) the PLSS provided life support for a limited period of time outside the vehicle.

Astronaut inside LM wearing the space suit for extra protection


PLSS parts are shown in the following picture.

PLSS parts

The PLSS is described very well in the above MIT video.

ECS (in LM)

ECS (Environmental Control Subsystem) provided support for the astronauts inside the space suits in the LM or without the space suits directly in the LM cabin. ECS consisted of four sub sections shown in the next picture.

LM ECS block diagram

In summary, the LM-5 ECS was divided into the following functional sections.

1. Atmosphere revitalization section (ARS)
2. Oxygen (02) supply and cabin pressurization section (OSCPS)
3. Heat transport section (HTS)
4. Water (H20) management section (WMS)

HTS section was described in Part 5 of this article series and the other sections will be covered later.

Lunar Module ECS

LM ECS had the same parts as the PLSS but in larger scale and some additional parts.


The following video shows the more recent model of the suit. The upper part of the suit is hardened to support the helmet, PLSS and controls better.

Video: How Astronauts Put on Space Suits


There seems to be some problems to keep the suit water cooling system not to leak in some models used in the ISS nowadays. See the following video.

Video: Astronaut Chris Cassidy Shows Recent Spacesuit Malfunction (Part 1)

Video: Astronaut Chris Cassidy Shows Recent Spacesuit Malfunction (Part 2)

Video: Station Crew Recreates Spacesuit Leak

Let's hope all the problems can be worked out. In the future it might be desirable that the suit would be more compact with less connectors since those seem to always create most problems due to sealing matters.


NASA Developments

NASA is seemingly not interested about bio-suits but adding more hard sliding joints to allow more freedom. The following videos show the latest development there. The entry is now also rear entry as Russians used to have and the suit is made of a single part.

Interview with Amy Ross, Spacesuit Engineer (Part 1)

Interview with Amy Ross, Spacesuit Engineer (Part 2)


There is lot of talk about bio-suits and similar light weight alternatives but we have to remember that you need protection on top of all.

A zentai suit; note that it covers the entire body – hands, feet and face

An inner pressure suit similar to Zentai but with a few mm pressurized air layer with cooling might replace the inner suit in the future. This kind of suit is also sometimes called a bio-suit or a leotard or a space activity suit (SAS). The idea is simply to keep the outer layer of the suit close to the body so that it would not resist the movement. The problem still is how to keep it flexible and pressurized at the same time since the suit wants always to balloon under pressure.

Richard Nixon meets astronauts.


/1/ NASA TN D-6724 - Richard J. Gillen,  James C.  Brady,  and Frank Collier,  MSC -  APOLLO EXPERIENCE REPORT - LUNAR MODULE ENVIRONMENTAL CONTROL SUBSYSTEM  - (Security Classif. of the Report - NONE, for sale by the National Technical Information Service, Springfield, Virginia 22151, price 3.00 $) - 1972




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