NASA-STD-3001 Technical Brief

Relevant Technical 

Requirements

EVA Mishaps

OCHMO-TB-040

Rev B

NASA-STD-3001 Volume 1, Rev C

[V1 4014] Completion of Critical Tasks

NASA-STD-3001 Volume 2, Rev D

[V2 3006] Human-Centered Task Analysis

[V2 4102] Functional Anthropometric 

Accommodation

[V2 5007] Cognitive Workload

[V2 7083] Cleaning Materials

[V2 9009] Sharp Corners and Edges – Fixed

[V2 9011] Sharp Corners and Edges - Loose

[V2 9012] Burrs

[V2 9024] Fluid/Gas Release

[V2 9027] Equipment Protection

[V2 10200] Physical Workload

[V2 11013] Suited Body Waste Management 

– Provision

[V2 11024] Ability to Work in Suits

[V2 11028] EVA Suit Urine Collection

[V2 11031] Suited Relative Humidity

[V2 11033] Suited Thermal Control 

[V2 11034] Suited Atmospheric Data 

Recording

[V2 11035] Suited Atmospheric Data 

Displaying 

[V2 11036] Suited Atmospheric Monitoring 

and Alerting

[V2 11037] EVA Suited Metabolic Rate 

Measurement

[V2 11038] EVA Suited Metabolic Rate 

Display

[V2 11039] Nominal Spacesuit Carbon 

Dioxide Levels

Executive Summary

Over the course of an extravehicular 

activity (EVA), the crew, equipment, and 

mission are all exposed to extraordinary 

risks. Tools can be damaged or lost, 

mission objectives can fail, and 

astronauts can suffer a wide range of 

injuries, from minor cuts and bruises to 

thermal burns. The astronauts’ lives 

depend on a long list of hardware and 

procedures operating as intended; if 

anything goes wrong the crew might 

not survive. EVA mishaps typically fall 

under three categories (or some 

combination thereof): hardware 

failures—where a tool or system does 

not perform its intended task, hardware 

damage, or missteps taken by the 

crew/mission control. Special 

considerations must be taken so that all 

the equipment used by the crew can 

withstand the rigors of the EVA tasks, 

and that the operations required of the 

crew do not put them at unnecessary 

increased risk.
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

Risks

Due to the nature of the activities performed 

during EVAs, mishaps that occur over the course 

of an EVA pose a number of unique risks to the 

hardware, the crew, and the mission. Damage to 

the hardware might be as simple as a cracked 

casing or a lost wrench, or it could be as serious 

as a punctured suit that could lead to a fatal 

decompression. The crew experiences—or risks 

experiencing—injuries that range from minor to 

deadly. Missions have reported everything from 

bumps and contusions to more serious burns, 

exhaustion, and suffocation. A large number of

mishaps also prevent mission objectives from 

being completed, either from hardware failures 

or crew injury. In extreme cases, the whole 

mission may have to be abandoned.

10/12/2023

Rev B 2

Astronaut Rick Mastracchio wearing the Extravehicular 

Mobility Unit during an EVA on STS-118. Photo: NASA

NASA astronaut Greg Chamitoff of Space Shuttle Endeavour during an EVA. Photo: NASA
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

Hardware Failures

When hardware doesn’t function as intended, an 

astronaut is forced to improvise (which may increase 

risk of injury) or abandon the task.

Voskhod 2: During the first spacewalk, cosmonaut 

Aleskei Lenov’s suit ballooned, impeding 

maneuverability and ingress. He eventually had to let 

out some air from his suit to gain enough flexibility to 

re-enter the crew capsule. In addition, the workload of 

the spacewalk exceeded the ability of the suit’s cooling 

system to maintain temperature. By the end of the EVA 

the suit was filled to the knees with perspiration. 

Relevant Technical Requirements: [V2 11024] Ability to 

Work in Suits, [V2 11037] Suited Metabolic Rate 

Measurement, [V2 11038] Suited Metabolic Rate 

Display. From: NASA-STD-3001 Volume 2 Rev D

STS-136/137: In both missions, an astronaut 

experienced unsafe elevated CO2 levels during EVA 

when the EMU’s CO2 scrubbers stopped working 

adequately. In both cases the EVAs were terminated 

early. Relevant Technical Requirements: [V2 11034] 

Suited Atmospheric Data Recording, [V2 11035] Suited 

Atmospheric Data Displaying, [V2 11036] Suited 

Atmospheric Monitoring and Alerting, [V2 11039] 

Nominal Spacesuit Carbon Dioxide Levels. From: NASASTD-3001 Volume 2 Rev D

3

Common Issues:

• Elevated CO2 levels

• Helmet fogging

• Heating/cooling system failures

• Equipment coming unlatched

Aleksei Leonov's training suit and Voskhod 2 airlock 

Skylab 2: Primary EVA heat exchangers suffered 

minor clogging during an EVA. A redesign was 

implemented, but there have been numerous 

issues with the heating & cooling systems that 

cause helmet fogging and pose health risks to the 

crew. Relevant Technical Requirements: [V2 

11031] Suited Relative Humidity, [V2 11035] 

Suited Atmospheric Data Displaying, [V2 11036] 

Suited Atmospheric Monitoring and Alerting. 

From: NASA-STD-3001 Volume 2 Rev D

STS-121: The latches on a Simplified Aid For EVA 

Rescue (SAFER) became detached, putting an 

astronaut at an increased risk of drifting away 

from the shuttle. EVA tasks were postponed until 

the astronaut could be re-secured. The SAFER was 

later fixed using Kapton tape. Relevant Technical 

Requirement: [V2 9027] Equipment Protection. 

From: NASA-STD-3001 Volume 2 Rev D STS-121 SAFER latch taped with Kapton tape

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

Substances Present in Suit

While this type of mishap is usually the result of a 

hardware failure, it happens frequently enough 

that it falls into its own subcategory. It often causes 

discomfort or irritation, and sufficient quantities of

loose fluids in an astronaut’s helmet puts them at 

risk of suffocation or drowning.

4

ISS-36: An hour into EVA 3, a large amount of water 

had collected in astronaut Luca Parmitano’s suit and 

helmet. He was unable to complete his to-do list, 

had impaired visibility, and ran the risk of 

suffocating. The EVA was terminated early and he 

was assisted back into the airlock. Water intrusion is 

a common occurrence among EVA mishaps. 

Relevant Technical Requirement: [V2 9024] 

Fluid/Gas Release. From: NASA-STD-3001 Volume 2 

Rev D

STS-100: An astronaut experienced severe eye 

irritation during the spacewalk due to the anti-fog 

solution used to polish his spacesuit visor. Relevant 

Technical Requirement: [V2 7083] Cleaning 

Materials. From: NASA-STD-3001 Volume 2 Rev D

STS-130/ISS-24: Astronauts were exposed to 

ammonia from a leaking quick-disconnect fixture in 

the EMU. Relevant Technical Standard: [V2 9024] 

Fluid/Gas Release. From: NASA-STD-3001 Volume 2 

Rev D

STS-41-C: The urine containment system in the EMU 

failed and caused discomfort to the astronaut, but 

the EVA was not terminated early. Relevant 

Technical Requirements: [V2 9024] Fluid/Gas 

Release, [V2 11013] Suited Body Waste 

Management—Provision, [V2 11028] EVA Suit 

Urine Collection. From: NASA-STD-3001 Volume 2 

Rev D

Water inside Luca Parmitano’s helmet

Urine Collection 

Device (female)

Urine Collection 

Device (male)

EVA 23: The most dangerous spacewalk in US history

https://youtu.be/9iE_69aeVZ4

Common Issues:

• Water

• Anti-fog agents

• Ammonia

• Urine

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

Hardware Damage

Similar to hardware failure, hardware damage results in an 

inability to use equipment, and exposes the crew to increased 

risk. Damage to the suit is particularly concerning; in the past 

even minor punctures have resulted in early EVA terminations.

5

Example Events

Gemini 9: Over the course of his spacewalk, Gene 

Cernan’s EVA suit became frayed and torn in spots 

along his back. As a result, he experienced painful 

heat exposure and suffered burns. Additionally, the 

workload required by the EVA overloaded the suit’s 

cooling system; Cernan became overheated and 

exhausted, and his visor completely fogged up. 

Relevant Technical Requirements: [V2 9027] 

Equipment Protection, [V2 11031] Relative Suit 

Humidity, [V2 11037] Suited Metabolic Rate 

Measurement, [V2 11038] Suited Metabolic Rate 

Display. From: NASA-STD-3001 Volume 2 Rev D

STS-37/118/125: At some point during 

each of these missions, an astronaut’s 

glove was cut or punctured. These were 

likely caused by normal wear and tear, as 

well as handling equipment which may 

have had burrs or sharp edges. Relevant 

Technical Requirements: [V2 9009] 

Sharp Corners and Edges—Fixed, [V2 

9011] Sharp Corners and Edges—Loose, 

[V2 9012] Burrs, [V2 9027] Equipment 

Protection. From: NASA-STD-3001 

Volume 2 Rev D

Gene Cernan Gemini 9 EVA June 5, 1996

STS-118 glove damage leading to early ending of third EVA

Common Issues:

• Wear and tear

• Suit punctures

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

Crew Actions/Operations

Even when all the hardware is intact and functioning correctly, 

actions taken by the crew or operational conditions of the mission 

can directly or indirectly increase the risk to an EVA. Mistakes are 

made by crew or support personnel, which can be exacerbated by 

external factors.

6

Salyut 6 PE-1: A cosmonaut’s safety tether was not 

properly secured prior to his EVA. Although he was still 

connected to the Salyut via his umbilical, he was 

exposed to an increased risk of becoming detached and 

drifting away from the vehicle. Relevant Technical 

Requirement: [V2 3006] Human-Centered Task 

Analysis. From: NASA-STD-3001 Volume 2 Rev D

Gemini 11: EVA 1 was terminated early due to astronaut 

fatigue. Relevant Technical Requirements: [V1 4014] 

Completion of Critical Tasks, [V2 3006] HumanCentered Task Analysis, [V2 10200] Physical Workload. 

From: NASA-STD-3001 Volume 1 Rev C & NASA-STD3001 Volume 2 Rev D

STS-37: Ground control recommended against EVAs on 

consecutive days due to concerns over crew fatigue and 

time constraints. Relevant Technical Requirements: [V1 

4014] Completion of Critical Tasks, [V2 3006] HumanCentered Task Analysis, [V2 10200] Physical Workload. 

From: NASA-STD-3001 Volume 1 Rev C & NASA-STD3001 Volume 2 Rev D

Apollo 15: The tight gloves, combined with the stress of 

repeating certain actions, resulted in minor hand injuries 

to the crew. A number of other missions have reported 

this phenomenon. Relevant Technical Requirements: 

[V2 3006] Human-Centered Task Analysis, [V2 4102] 

Functional Anthropometric Accommodation. From: 

NASA-STD-3001 Volume 2 Rev D

STS-57/63: Crewmembers reported feeling extremely 

cold in their EMUs. This was partly due to EVA 

operations taking place in complete shadow. Relevant 

Technical Requirements: [V2 3006] Human-Centered 

Task Analysis, [V2 11033] Suited Thermal Control. 

From: NASA-STD-3001 Volume 2 Rev D

Common Issues:

• Hardware secured or configured 

improperly

• Fatigue (pre-EVA and during EVA)

• Injuries from repeated actions

• Exposure to extreme conditions

STS-57 EVA

Hand injury due to inadequate performance of EVA 

glove

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

While keeping in mind that tradeoffs must be balanced 

and 100% safety cannot be reasonably achieved, there 

are steps that can be taken with regards to hardware 

design and operations structure that can mitigate risk 

and address common issues. Bear in mind that any 

recommendation has to be considered alongside other 

requirements imposed by the program (cost, weight, 

etc.).

Adding redundant features to hardware systems ensures 

that crew can continue using them even if one element 

fails or breaks. If there’s a particular tool or piece of 

equipment that sees repeated use, it can be reinforced 

to withstand the extra stress. Lessons can be learned 

both from systems that fail regularly (are there common 

errors?) and resilient ones (why are they reliable?).

7

Mission operations can be designed to give crewmembers an advantage during EVAs. Scheduling mission 

operations with workload taken into consideration (before and during EVA) will reduce the risk of both 

human and hardware error. To that effect, other mission objectives must be taken into consideration when 

planning EVAs. Scheduling EVAs during favorable environmental conditions (low SPE activity, ample 

sunlight) helps astronauts work safely and effectively. Rigorous training can prepare crew for contingencies 

and reduce unfamiliar situations. 

Bruce McCandless tested the Manned 

Maneuvering Unit (MMU) on the first tetherless

spacewalk in February 1984. Photo: NASA

Astronaut Ed White became the first American to walk in outer space on June 3, 1965. Photos: NASA

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

8 10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

9 10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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 4014] Completion of Critical Tasks The planned number of hours for in-mission completion of critical 

tasks and events, workday, physical activity/exercise, and planned sleep period shall have established 

limits to assure continued crew health and safety.

NASA-STD-3001 Volume 2 Revision D

[V2 3006] Human-Centered Task Analysis Each human spaceflight program or project shall perform a 

human-centered task analysis to support systems and operations design.

[V2 4102] Functional Anthropometric Accommodation The system shall ensure the range of potential 

crewmembers can fit, reach, view, and operate the human systems interfaces by accommodating 

crewmembers with the anthropometric dimensions and ranges of motion as defined in data sets in 

Appendix E, Physical Characteristics and Capabilities, Sections E.2 and E.3.

[V2 5007] Cognitive Workload The system shall provide crew interfaces that result in Bedford Workload 

Scale ratings of 3 or less for nominal tasks and 6 or less for tasks performed under degraded system 

conditions.

[V2 7083] Cleaning Materials The system shall provide cleaning materials that are effective, safe for 

human use, and compatible with system water reclamation, air revitalization, waste management 

systems, spacesuits and other spacecraft materials.

[V2 9009] Sharp Corners and Edges – Fixed Corners and edges of fixed and handheld equipment to which 

the bare skin of the crew could be exposed shall be rounded as specified in Table 9.3-1—Corners and 

Edges.

[V2 9011] Sharp Corners and Edges – Loose Corners and edges of loose equipment to which the crew 

could be exposed shall be rounded to radii no less than those given in Table 9.3-2—Loose Equipment 

Corners and Edges.

[V2 9012] Burrs Exposed surfaces shall be free of burrs.

[V2 9024] Fluid/Gas Release Hardware and equipment shall not release stored fluids or gases in a manner 

that causes injury to the crew.

[V2 9027] Equipment Protection Systems, hardware, and equipment shall be protected from and be 

capable of withstanding forces imposed intentionally or unintentionally by the crew.

[V2 10200] Physical Workload The system shall provide crew interfaces that result in a Borg-CR10 rating 

of perceived exertion (RPE) of 4 (somewhat strong) or less.

[V2 11013] Suited Body Waste Management – Provision Suits shall provide for management of urine, 

feces, menses, and vomitus of suited crewmembers.

[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 11028] EVA Suit Urine Collection EVA suits shall be capable of collecting a total urine volume of Vu = 

0.5 +2.24t/24 L, where t is suited duration in hours.

[V2 11031] Suited Relative Humidity For suited operations, the system shall limit RH to the levels in Table 

11.2-1—Average Relative Humidity Exposure Limits for Suited Operations.

Referenced Technical Requirements

10

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

OCHMO Standards website

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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 2 Revision D

[V2 11033] Suited Thermal Control The suit shall allow the suited crewmembers and remote operators to 

adjust the suit thermal control system.

[V2 11034] Suited Atmospheric Data Recording Systems shall automatically record suit pressure, ppO2, 

and ppCO2.

[V2 11035] Suited Atmospheric Data Displaying Suits shall display suit pressure, ppO2, and ppCO2 data to 

the suited crewmember.

[V2 11036] Suited Atmospheric Monitoring and Alerting Suits shall monitor suit pressure, ppO2, and 

ppCO2 and alert the crewmember when they are outside safe limits.

[V2 11037] EVA Suited Metabolic Rate Measurement The system shall measure or calculate metabolic 

rates of suited EVA crewmembers.

[V2 11038] EVA Suited Metabolic Rate Display The system shall display metabolic data of suited EVA 

crewmembers to the crew.

[V2 11039] Nominal Spacesuit Carbon Dioxide Levels The spacesuit shall limit the inspired CO2 partial 

pressure (PICO2) in accordance with Table 11.3-1—Spacesuit Inspired Partial Pressure of CO2 (PICO2) 

Limits.

Referenced Technical Requirements

11

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

OCHMO Standards website

10/12/2023

Rev B
NASA-STD-3001 Technical Brief

OCHMO-TB-040 EVA Mishaps

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

12

1. Gernhardt, M.L, Jones, J.A., Scheuring, R.A., Abercromby, A.F., Tuxhorn, J.A., & Norcross, J.R. Risk of 

Compromised EVA Performance and Crew Health Due to Inadequate EVA Suit Systems. Human Health 

and Performance Risks of Space Exploration Missions. 

https://humanresearchroadmap.nasa.gov/evidence/reports/eva%20suit.pdf

2. Dervay, J., Sanders, R.W., Thompson, M.S., & Snow, T.J. (2020). Medical Aspects of Extravehicular 

Activity. Principles of Clinical Medicine for Space Flight, pp. 519-543. 

3. Significant Incidents & Close Calls in Human Spaceflight. JSC SMA Flight Safety Office. 

https://sma.nasa.gov/SignificantIncidents/

4. Significant Incidents & Close Calls in Human Spaceflight: EVA Operations. JSC SMA Flight Safety Office. 

https://sma.nasa.gov/SignificantIncidents/assets/eva_incidents2016.pdf

10/12/2023

Rev B