NASA-STD-3001 Technical Brief

Relevant Technical 

Requirements

Decompression 

Mishaps

Launch, Entry, & Abort 

(LEA) Suits

OCHMO-TB-038

Rev B

NASA-STD-3001 Volume 1, Rev C

[V1 3004] In-Mission Medical Care

[V1 5001] Medical Training

[V1 5002] Crewmember Training

NASA-STD-3001 Volume 2, Rev D

[V2 6006] Total Pressure Tolerance Range for 

Indefinite Crew Exposure 

[V2 6007] Rate of Pressure Change

[V2 9053] Protective Equipment

[V2 9055] Protective Equipment Automation

[V2 11024] Ability to Work in Suits

[V2 11100] Pressure Suits for Protection 

from Cabin Depressurization

[V2 11032] LEA Suited Decompression 

Sickness Prevention Capability

Executive Summary

During the Soyuz 11 mission in 1971 and 

the STS-107 Columbia mission in 2003, 

both crews were subjected to violent 

decompressions which resulted in their 

deaths. Each incident was caused by 

different factors, but in both cases the 

crew would have survived the 

decompression event if they had been 

properly wearing their Launch, Entry, & 

Abort (LEA) suits. The Soyuz 11 crew were 

not wearing LEA suits at all, and the 

Columbia crew were likely not wearing 

their gloves or had their helmet visors 

lifted. NASA-STD-3001 outlines technical 

requirements with regards to LEA suits. 

The suits must be easily accessible by the 

crew, available for quick donning/doffing, 

and able to accommodate any activity the 

crew is required to perform.

Testing of Orion docking hatch while wearing 

LEA suit (NASA, 2019)
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Background

Entry Events

Soyuz 11 – June 30, 1971

During separation of the orbital and service modules from the descent module, the pyrotechnic system 

did not operate as intended. All of the pyrotechnics fired simultaneously rather than the designed 

sequential firing mode, which was believed to be due to the excessive vibration loads on the vehicle. This 

caused a pressure equalization seal to open in the descent module at a higher-than-designed altitude, 

resulting in the rapid depressurization of the crew module. The rapid depress led to loss of consciousness 

of the crew despite attempts by one of the crew to block the leakage of air from the vehicle. The spacecraft 

otherwise made a nominal automatic touchdown with no known anomalies at the time of the recovery 

team. 

Contributing factors:

• Crew were not wearing pressurized suits for re-entry

• Absence of an open-valve warning system

• The valve was located under a seat and could not be reached and closed in time to prevent 

decompression 

• Absence of an emergency valve-choking system 

• No structural shock testing performed for a worst-case scenario

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Rev B 2

The lives of Georgi Dobrovolski, Vladislav Volkov, and Viktor Patsayev were lost due to the 

vacuum experienced. The cause of death for the cosmonauts was hemorrhaging of the 

blood vessels in the brain, with lesser amounts of bleeding under their skin, in the inner ear, 

and in the nasal cavity, all of which occurred as exposure to a vacuum environment which 

caused the oxygen and nitrogen in their bloodstreams to bubble and rupture vessels. 

Soyuz 11 Landing Site
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

3

Background

Entry Events

STS-107 Columbia – February 1, 2003

Damage to the Thermal Protection System from a debris strike on ascent resulted in the loss of crew and 

vehicle on entry. At 81.7 seconds Mission Elapsed Time, a piece of foam insulation from the External Tank 

(ET) left bipod ramp separated from the ET and struck the orbiter left wing leading edge in the vicinity of 

the lower half of reinforced carbon-carbon (RCC) panel #8, causing a breach in the RCC. During re-entry, 

this breach allowed super-heated air to penetrate through the leading edge insulation and progressively 

melt the aluminum structure of the left wing, resulting in break-up of the orbiter. 

The break-up occurred in a flight regime in which, given the design of the orbiter, there was 

no possibility for the crew to survive. David Brown, Laurel Clark, Michael Anderson, Ilan

Ramon, Rick Husband, Kalpana Chawla, and William McCool lost their lives.

Contributing factors:

• Depressurization of the crew 

module, which started at or 

shortly after orbiter break-up. 

Existing crew equipment 

protects for this type of lethal 

event, but inadequate time 

existed to configure the 

equipment for the environment 

encountered. Forensic 

investigations showed that 

while the crew were wearing 

their LEA suits, several STS-107 Columbia Investigation

crewmembers were not wearing their gloves, and others had their visors raised at the time of the 

accident. The crew would have only had about 40 seconds to don gloves and helmets.

• The combination of the lack of upper body restraint and a helmet that, by design, does not internally 

conform to the head while exposed to cyclical motion resulted in lethal mechanical injuries for some of 

the unconscious or deceased crew members. If the harnesses had been locked or the crew had been 

conscious and able to brace, the injuries likely would not have been lethal.

• Separation from the crew module and the seats with associated forces, material interactions, and 

thermal consequences. Seat restraints played a role in the lethality of this event. Although the seat 

restraints played a significant role in the lethal-level mechanical injuries, there is currently no full range 

of equipment to protect for this event. 

• Exposure to near vacuum, aerodynamic accelerations, and cold temperatures. Current crew survival 

equipment is not certified to protect the crew above 100,000 feet.

10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Background

Overview of LEA Suits

Launch, Entry, and Abort (LEA) suits are worn by crew during active phases of the mission, 

rather than typical intra-vehicular activities (IVA) or extra-vehicular activities (EVA) suits. 

They are designed to pressurize in the event of a cabin depressurization, remain buoyant 

during a water landing*, and assist in crew survival following an emergency or off-nominal 

escape**.

Below is a comparison of NASA’s Advanced Crew Escape Suit (ACES), used at the time of 

the Columbia disaster, and Roscosmos’s Sokol suit, introduced after Soyuz 11 and still in 

use today. 

4

Sokol

5.8 psi nominal pressure

Used following Soyuz 11 disaster where 

crew succumbed to decompression 

symptoms.

ACES

3.5 psi nominal pressure

Designed to provide sufficient time of 

useful consciousness to escape vehicle 

(not decompression sickness mitigation).

*NASA realized the importance of buoyancy after a Mercury test mission when Gus Grissom’s suit 

took on water upon landing in the ocean and he nearly drowned.

**The crew of Voskhod 2 landed in remote Siberian wilderness and made use of their emergency 

supplies to survive relatively unscathed.

See OCHMO-TB-039 Mishaps During Entry, Descent and Landing

10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Reference Data

LEA Suits – Decompression Sickness (DCS) Mitigation

Overview of DCS

DCS is the result of nitrogen bubbles (emboli) causing damage to tissue. When atmospheric pressure 

drops, existing nitrogen bubbles in the blood expand, which can be fatal if they make their way to the 

brain. DCS is split into two categories: Type I (characterized by joint pain, single extremity tingling or 

numbness, and mild skin symptoms), and Type II (characterized by potentially fatal central nervous system 

or cardiovascular symptoms ranging from muscle weakness, confusion, impaired balance, to stroke).

5

Reference OCHMO-TB-037 Decompression Sickness (DCS) for additional information.

LEA Suit Pressure Mitigates DCS Onset and Symptoms

If the vehicle experiences a rapid loss of pressure, the crew risks suffering from DCS. Their pressurized LEA 

suits can help mitigate the effects of DCS.

Generally, the higher the LEA suit pressure, the lower the risk of Type II DCS. At an LEA suit pressure of 5.8 

psi, there is less than a 20% chance of a serious DCS case.

[V2 11032] LEA Suited Decompression Sickness Prevention Capability LEA spacesuits shall be capable 

of operating at sufficient pressure to protect against Type II decompression sickness in the event of a 

cabin depressurization. From: NASA-STD-3001 Volume 2, Rev D

Based on Bubble 

Dynamic Models 

for the 

predication of 

DCS. See Conkin

et al., Evidence 

Report:

Risk of 

Decompression 

Sickness (DCS). 

Human Research 

Program, 2016

10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Application Notes

• Crew should always wear LEA suits during takeoff and reentry and be ready to 

pressurize. The crews of both Soyuz 11 and Columbia would have had a better chance 

of surviving their decompression events if they had been wearing their LEAs. NASASTD-3001 Volume 2, Rev D [V2 11001] Suited Donning and Doffing states that The 

system shall accommodate efficient and effective donning and doffing of spacesuits 

for both nominal and contingency operations.

• For a time after Soyuz 11, Soyuz missions moved to two member crews, which allowed 

enough space for both crewmembers to wear their LEA suits. Later, LEA suits were 

redesigned to be smaller, which allowed for a three-person crew again. Special 

consideration should be taken to ensure that the crew can perform all needed tasks 

while wearing their LEA suits.

• Any valve that vents air out of the vehicle should have automatic fail-safes as well as 

manual shutoffs. After Soyuz 11, manual ventilation valve handles were added to the 

spacecraft. Adequate stress testing of critical components must be undertaken to 

ensure those components operate correctly, even during off-nominal circumstances.

6

Soyuz 11 Crew STS-107 Columbia Crew

See Chapter 11. Spacesuits of NASA-STD-3001 Volume 2 for relevant standards 

associated with LEA suits.

10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Back-Up

7 10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Rev A  Rev B

• Updated information to be consistent with NASA-STD-3001 

Volume 1 Rev C and Volume 2 Rev D.

Original  Rev A

• Updated information to be consistent with NASA-STD-3001 

Volume 1 Rev B and Volume 2 Rev C.

Major Changes Between Revisions

8 10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

NASA-STD-3001 Volume 1 Revision C

[V1 3004] In-Mission Medical Care All programs shall provide training, in-mission medical capabilities, 

and resources to diagnose and treat potential medical conditions based on epidemiological evidencebased PRA, individual crewmember needs, clinical practice guidelines, flight surgeon expertise, historical 

review, mission parameters, and vehicle-derived limitations. These analyses consider the needs and 

limitations of each specific vehicle and design reference mission (DRM) with particular attention to 

parameters such as mission duration, expected return time to Earth, mission route and destination, 

expected radiation profile, concept of operations, and more. In-mission capabilities (including hardware 

and software), resources (including consumables), and training to enable in-mission medical care, and 

behavioral care, are to include, but are not limited to: (see NASA-STD-3001, Volume 1 Rev C for full 

standard).

[V1 5001] Medical Training Medical training shall be provided to crewmembers, flight surgeons

(FSs), mission control support staff, and other ground support personnel (GSP).

[V1 5002] Crewmember Training Beginning with the crewmember candidate year, general medical 

training, including but not limited to, first aid, cardiopulmonary resuscitation (CPR), altitude physiological 

training, carbon dioxide exposure training, familiarization with medical issues, procedures of spaceflight, 

psychological training, toxicology, medical equipment, and supervised physical conditioning training shall 

be provided to the astronaut corps.

NASA-STD-3001 Volume 2 Revision D

[V2 6006] Total Pressure Tolerance Range for Indefinite Crew Exposure The system shall maintain the 

pressure to which the crew is exposed to between 34.5 kPa < pressure ≤ 103 kPa (5 psia < pressure ≤ 15.0 

psia) for indefinite human exposure without measurable impairments to health or performance.

[V2 6007] Rate of Pressure Change For pressure changes >1.0 psi, the rate of change of total internal 

vehicle pressure shall not exceed 13.5 psi/min. 

[V2 9053] Protective Equipment Protective equipment shall be provided to protect the crew from 

expected hazards.

[V2 9055] Equipment Automation of Rescue Aids Automation of protective equipment rescue aids shall 

be provided when the crew cannot perform assigned life-saving tasks.

[V2 11024] Ability to Work in Suits Suits shall provide mobility, dexterity, and tactility to enable the 

crewmember to accomplish suited tasks within acceptable physical workload and fatigue limits while 

minimizing the risk of injury.

[V2 11100] Pressure Suits for Protection from Cabin Depressurization The system shall provide the 

capability for crewmembers to wear pressure suits for sufficient duration during launch, entry, descent 

(to/from Earth, or other celestial body) and any operation deemed high risk for loss of crew life due to loss 

of cabin pressurization (such as in mission dockings, operations during periods of high incidence of 

micrometeoroids and orbital debris (MMOD) or complex vehicle maneuvers).

[V2 11032] LEA Suited Decompression Sickness Prevention Capability LEA spacesuits shall be capable of 

operating at sufficient pressure to protect against Type II decompression sickness in the event of a cabin

depressurization.

Referenced Technical Requirements

9

View the current versions of NASA-STD3001 Volume 1 & Volume 2 on the 

OCHMO Standards website

10/11/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-038

Decompression Mishaps

Launch, Entry, & Abort (LEA) Suits

NASA Office of the Chief Health & Medical Officer (OCHMO)

This Technical Brief is derived from NASA-STD-3001 and is for reference only.

It does not supersede or waive existing Agency, Program, or Contract requirements.

Reference List

1. Columbia Crew Survival Investigation Report. NASA/SP-2008-565. 

https://www.nasa.gov/pdf/298870main_SP-2008-565.pdf

2. NASA System Failure Case Studies. Descent into the Void. September 2010, Volume 4, Issue 9. 

https://sma.nasa.gov/SignificantIncidents/assets/descent-into-the-void.pdf

3. Evidence report: Risk of Decompression Sickness (DCS). (2016). Human Research Program – Human 

Health Countermeasures Element. NASA. 

https://humanresearchroadmap.nasa.gov/evidence/reports/DCS.pdf

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