COMMENT OPEN

NASA Space Flight Human-System Standard: enabling

human spaceflight missions by supporting astronaut health,

safety, and performance

Sarah D. Childress 1,2✉, Tara C. Williams2,3 and David R. Francisco2

The purpose of this paper is to describe NASA’s approach to establishing and maintaining a set of Agency-level Space Flight Human

System Standards managed by the Office of the Chief Health and Medical Officer (OCHMO) at NASA that enables space flight

missions by minimizing health risks to astronauts, providing vehicle design parameters, and supporting the performance of both

flight and ground crews. NASA standards capture and provide knowledge, guidelines, thresholds and limits for the successful

design and operation of spacecrafts and missions. The NASA Space Flight Human-System Standard (NASA-STD-3001) consists of

two separate volumes of technical requirements: NASA-STD-3001 Volume 1: Crew Health addresses the requirements needed to

support astronaut health and provide medical care; NASA-STD-3001 Volume 2: Human Factors, Habitability, and Environmental

Health addresses human-integrated vehicle system design and operational requirements that will maintain astronaut safety and

promote human performance. These standards are managed by an OCHMO team who continuously works with national and

international subject matter experts and with each space flight program to provide the best technical requirements and

implementation documentation to support the development of new programs. Through partnerships across the space flight

industry, these technical requirements are constantly evolving to enable successful implementation of NASA programs and the

commercialization of human space flight.

npj Microgravity (2023) 9:31 ; https://doi.org/10.1038/s41526-023-00275-2

INTRODUCTION

Hazards of space flight

There are five primary hazards of space flight1,2 that NASA-STD30013 fundamentally seeks to address. These primary hazards

include:

1. Radiation Exposure: Outside of Earth’s natural protection,

radiation exposure is abundant in space. Crew exposure to

the space radiation environment may pose health risks

including the risk of neoplasm, damage to the central

nervous system, altered cognitive functioning, reduced

motor functioning, and acute behavioral changes. In

addition, based on analysis and limited data from the

International Space Station4

, the impact of radiation on

pharmaceuticals and food should be minimal, but additional

research is being conducted to fully assess the impact5,6

.

Sources of increased radiation exposure include galactic

cosmic rays, solar particle events, and onboard radioactive

technologies. Vehicle design and engineering can provide a

certain level of protection to crewmembers from radiation

exposure, however not all types of radiation can be shielded

from, and crewmembers are invariably exposed to higher

levels of radiation during spaceflight compared to on Earth.

Reference Radiation Protection NASA OCHMO Technical Brief

for additional information7

.

2. Hostile/Closed Environment: Spacefaring humans must

depend on an enclosed vehicle to survive, which involves

inherent risks due to engineering (i.e., oxygen, pressure,

temperature, noise, lighting, carbon dioxide levels, etc.). The

habitability of the spacecraft is imperative for astronaut

health and safety. The spacecraft must also provide

astronauts the essential elements they require to live and

work in space, including food, body waste management,

sleep accommodations, and exercise. Reference Acceleration, Acoustics, Artemis Lighting, Cabin Architecture, Carbon

Dioxide, Decompression Sickness (DCS), Environmental Control

and Life Support System (ECLSS), Food and Nutrition, Electrical

Shock, Lighting Design, Sleep Accommodations, Vehicle

Hatches, Waste Management, and Water NASA OCHMO

Technical Briefs for additional information8–21.

3. Isolation and Confinement: Crewmembers live and work

within a small, enclosed environment with other crewmembers for extended periods of time during space flight. Even

with careful selection of crewmembers and extensive

training, interpersonal and behavioral health issues within

the crew are expected. Workload considerations, circadian

desynchronization and sleep disturbances, and lack of

communication with Earth all play a role in potential

performance decrements, negative health outcomes, and

potentially loss of mission objectives. NASA has developed

several methods to monitor crewmembers’ behavioral

health status during space flight and developed tools and

technology to identify potential issues earlier and provide

the appropriate treatment or intervention. Reference

Behavioral Health and Performance, Behavioral Health

Mishaps, Cognitive Workload, Usability, Workload, Error, and

Sleep Accommodations NASA OCHMO Technical Briefs for

additional information18,22–25.

4. Distance from Earth: As the future of space travel moves

toward longer-duration missions beyond lower-Earth Orbit

to the Lunar surface and Mars, distance from Earth will

become one of the biggest obstacles of safe and productive

1

JES Tech, Houston, TX, USA. 2Office of the Chief Health & Medical Officer, NASA Headquarters, Washington, DC, USA. 3KBR, Houston, TX, USA. ✉email: sarah.d.childress@nasa.gov

www.nature.com/npjmgrav

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human space flight. Lack of resupply vehicles, communication delays, potential medical emergencies, and equipment

failures are just some of the obstacles that astronauts will

face during future space flight missions. Reference Spaceflight Experience and Medical Care Technical Brief26.

5. Altered Gravity Environment: The experience of astronauts

transitioning from one gravitational field to another

introduces a host of considerations for crew health, safety,

and performance. Future missions will involve several

changes in the gravity environment, thus operational

parameters must implement all strategies available to

mitigate these decrements as much as possible. In addition,

humans living and working in space for extended periods of

time leads to many health complications that makes

returning to Earth’s gravitational environment difficult.

Changes to bones, muscles, eyes (Spaceflight-Associated

Neuro-Ocular Syndrome, or SANS), and the cardiovascular

system are just some of the problems that astronauts deal

with when returning from space flight. Reference Principles

of Clinical Medicine for Space Flight27 for a comprehensive

review of the human systems affected by space flight and

microgravity. Appropriate countermeasures and interventions are imperative to keep crewmembers healthy, safe,

and performing at their highest potential. Reference Bone

Loss, Spaceflight Experience and Medical Care, and Pharmaceuticals and Medications NASA OCHMO Technical Briefs for

additional information26,28,29.

When combined, these five hazards of space flight create a

complicated landscape and impact the ability to support the

health, safety, and optimal performance of space flight crews. In

addition, as mission duration lengths increase with a greater focus

on deep space exploration, these hazards become even more

important to address in order to enable the future of space travel.

NASA human system risk mitigation

Over the past 50+ years of human space flight, NASA has collected

an evidence base of medical, environmental and research data on the

effects of space flight on the human body. However, even with years

of collected data, NASA has a relatively small population of flown

astronauts, making it difficult to fully understand the effects of space

flight hazards. In order to address this difficulty, NASA implemented a

new cross-discipline process to understand the hazards of space flight

and gather, assess, and correlate evidence to better predict the

probability of an event occurring and the level of consequence the

event would have on human health and productivity. This strategy

provides the ability to weigh the risks relative to each other and leads

to effective tradeoffs to ensure maximal mission success with the least

risk to human health3,30. The Human System Risk Board (HSRB) was

created to implement this process by the NASA Health and Medical

Technical Authority. Its responsibility includes implementing a

consistent process of gathering and assessing evidence, providing a

likelihood and consequence of the risks, and in turn providing

recommendations to updating the NASA-STD-3001 documents so

that the set of technical requirements remains up to date with the

most current knowledge.

Overview of NASA-STD-3001

The first set of space flight human system standards was baselined

Agency-wide in late 1980s and was known as NASA-STD-3000:

Man-System Integration Standards (MSIS)31. It was first adopted by

the International Space Station Program (ISSP) and written

primarily for the International Space Station (ISS) infrastructure.

As time passed and the development of new programs with needs

separate from the ISS emerged, an updated set of standards with

broader applicability was needed to replace NASA-STD-3000.

Driving reasons behind this update included the fact that the

original standard was too comprehensive, was too focused on

design solutions, and raised questions on the verifiability of some

technical requirements. After a second variation of NASA-STD3000 and an accompanying handbook were created32, NASA-STD3001 was baselined and implemented in 2009 by the NASA

OCHMO. These standards are applicable to all human space flight

programs and projects, enabling the creation of human-centered

program-specific technical requirements. Each technical requirement within these documents includes a ‘shall’ statement that

must be considered in the development of a program-specific set

of human-systems design requirements. Technical requirements

include rationales which provide additional information and

justification for the purpose of the technical requirement, as well

as some potential guidance on how to verify the technical

requirements being met. Figure 1 provides an overview of the

topics addressed by NASA-STD-3001.

NASA-STD-3001 volume 1, crew health

Volume 1 of NASA-STD-3001 focuses on human physiological

functioning and views the human system as an important part of

the overall vehicle design process and mission design. It sets the

standards for fitness for duty, space permissible exposure limits,

permissible outcome limits, medical care, medical diagnosis,

intervention, treatment and care, and countermeasures. Aerospace medicine is deeply rooted in preventive care in addition to

being prepared to respond to known physiological and psychological challenges of space flight, as well as unexpected injury and

illnesses that could impact crewmembers during their career as an

astronaut. Volume 1 seeks to address this comprehensive

approach through screening, preventive healthcare strategies,

medical care, launch and landing contingencies, and post-mission

care, reconditioning, and long-term monitoring. NASA-STD-3001

Volume 1 contains 72 technical requirements as of Revision B

published in 2022 that are levied against all human-integrated

space flight programs. Table 1 provides a sample of technical

requirements from NASA-STD-3001 Volume 1.

NASA-STD-3001 volume 2, human factors, habitability, and

environmental health

Volume 2 of NASA-STD-3001 focuses on human-systems integration, including human physical and cognitive capabilities and

limitations, and defines requirements for spacecrafts (including

orbiters, habitats, and suits), internal environments, ground

processing, facilities, payloads, and related requirement, hardware,

and software systems. These include requirements to the design of

systems that directly interface with the flight crew such as

environmental support systems, architecture, controls and displays,

and operations, as well as requirements for the design of systems

that both ground and/or flight crew access during assembly, test,

checkout, or troubleshooting procedures supporting ground

processing, launch, landing, and recovery operations. NASA-STD3001 Volume 2 contains 471 technical requirements as of Revision

C published in 2022 that are levied against all human space

systems and must be tailored for each individual system to ensure

that the end product meets all the requirements. Table 2 provides a

sample of technical requirements from NASA-STD-3001 Volume 2.

Creation of program requirements from NASA-STD-3001

Each individual NASA program that will include human-rated

systems must implement NASA-STD-3001 in the development of

their specific program requirements. The program is responsible

for reviewing the set of standards, identifying the technical

requirements that are applicable to their specific program/design

reference mission, and tailoring the standards into detailed

requirements to be implemented in the program. In addition,

the programs must provide verification information which details

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the program’s plan to verify that their requirements are meeting

their intent. Examples of a tailored 3001 technical requirement to

program requirement and its related verification language is

provided in Fig. 2.

Human space flight standards hierarchy pyramid

During the early formulation stage of a program, it is helpful to

assess the cross-relationship of standards and how they impact

specific missions and programs. The Human Space Flight

Standards Hierarchy (Fig. 3)

33 was developed to provide a tool

to determine how individual technical requirements impact

future missions and programs. It provides the ability to look

“across” all of the technical requirements and assess their impact

on a mission’s success in relation to loss of crew, loss of mission,

and loss of mission objectives. The pyramid is broken down into

six levels, with the base representing the most fundamental

system needs (both vehicle and human) and the top-level

representing optimization of human and mission performance.

This hierarchy is useful in determining the applicability of

technical requirements for programs during the formulation

stage of development. The pyramid also helps to categorize

technical requirements that increase the probability of achieving mission objectives.

Table 1. Selected examples of technical requirements from NASA-STD-3001 volume 1.

Section and standard title Shall statement Rationale

3.1.8 In-Mission Evacuation to

Definitive Medical Care Facilities

[V1 3008] Plans shall be available to transport severely

ill or injured crewmember(s) to appropriate Medical

Care Facilities, including Definitive Medical Care

Facilities (DMCF) in the event of a contingency.

[Rationale: If a return to Earth of a severely ill or injured

crewmember is possible and is undertaken, coordination

with suitable DMCFs in proximity to potential landing sites

will be made in advance of the crewmember’s landing to

ascertain readiness of the facility to accept and implement

immediate medical care. Mobile ground resources with the

capability to initiate medical care en route to the DMCF will

be deployed at potential landing sites.]

4.8.1 As Low as Reasonably

Achievable (ALARA) Principle

[V1 4029] All crew radiation exposures shall be

minimized using the ALARA principle.

[Rationale: It is important to minimize crew health risk due

to radiation exposure by decreasing crew radiation exposure

from all sources using the ALARA principle. The ALARA

principle is a fundamental guiding principle for radiation

protection which requires programs to minimize radiation

exposures below the limits/standards within the design

constraints of the mission.]

6.2.1 Private Medical

Communication (PMC) Schedule

[V1 6002] A PMC shall be scheduled on a routine basis,

as determined by the Flight Surgeon, at a frequency

dictated for short- or long-duration missions.

[Rationale: Real time communications are preferred for all

PMCs; however, when missions have communication delays,

different modalities can be considered (e.g., stored/ forward

communications).]

Fig. 1 Overview of NASA-STD-3001. An overview of the considerations for astronaut health and performance, and topics addressed in NASASTD-3001 to guide designs to protect the crew.

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Human integration design handbook

The Human Integration Design Handbook (HIDH)32 is a companion

document designed to accompany NASA-STD-3001 Volume 2. It

includes information specific to human space flight history and

lessons learned, design information, reference data and background information, and application guidance for the wide variety

of disciplines and topic areas covered by NASA-STD-3001. The

main purpose of the HIDH is to help requirements writers prepare

Table 2. Selected Examples of Technical Requirements from NASA-STD-3001 Volume 2.

Section and

standard title

Shall statement Rationale

4.1.3.1 Crew

Operational Loads

[V2 4104] The system shall be operable by crew during all phases of

flight, including prelaunch, ascent, orbit, entry, and postlanding, with the

lowest anticipated strength as defined in Appendix F, Physical

Characteristics and Capabilities, Section F.7.

[Rationale: All crewmembers need to be able to perform any

planned tasks efficiently and effectively. The crew operating load

data in Appendix F defines the lowest anticipated forces that can

be applied by crewmembers in unsuited, suited-unpressurized,

and suited-pressurized conditions, taking into account

deconditioning and factors of safety for critical tasks. A task

analysis that identifies planned crew tasks, hardware interfaces,

expected postures, and task criticality, frequency, and duration is

used with Appendix F to define the maximum acceptable value

for actuation and continued operation of hardware interfaces.

Guidance on the evaluation of design using crewmember

strength data can be found in NASA/TP-2014-218556 Human

Integration Design Process (HIDP). The intent of this requirement

is to accommodate the entire potential user population, not just

meet the criteria in the datasets provided, which provide the

most frequently used values. Identification of postures or forces

not provided in the table needs coordination and concurrence

from NASA Stakeholders. A tailored data set may be provided by

NASA based on program or mission specific criteria.]

6.2.9.3 Lunar Dust

Contamination

[V2 6053] The system shall limit the levels of lunar dust particles <10 μm

in size in the habitable atmosphere below a time-weighted average of

0.3 mg/m3 during intermittent daily exposure periods that may persist

up to 6 months in duration.

[Rationale: This limit was based on detailed peer-reviewed

studies completed by the Lunar Atmosphere Dust Toxicity

Assessment Group (LADTAG) and is specific to the conditions

relevant to the lunar surface, i.e., this requirement would not

necessarily be applicable to other missions. The requirement

assumes that the exposure period is episodic and is limited to the

time before ECLSS can remove the particles from the internal

atmosphere (assumed as 8 h post introduction). Although the

requirement is being conservatively applied to all inhalable

particles (all particles ≤ 10 μm), it is most applicable to dusts in

the respirable range (≤2.5 μm) that can deposit more deeply into

the lungs. Studies show that the particle size of lunar dust

generally falls within a range of 0.02–5 μm. The ability to meet

this requirement will depend upon factors such as the level of

lunar dust introduction and ECLSS removal rates. The monitoring

of dust is captured in [V2 6153] Celestial Dust Monitoring and

Alerting.]

10.6.1 Automated and

Robotic System

Provision

[V2 10100] Automated or robotic systems shall be provided when crew

cannot reliably, safely, or efficiently perform assigned tasks.

[Rationale: Systems are to have automated or robotic solutions

that can perform tasks where (1) crew cannot respond as quickly,

precisely, or repeatedly as necessary; (2) crew cannot physically

complete the task; or (3) using automation/robotic solutions

reduces crew risk exposure (e.g., high radiation environments,

limited life support availability).]

NASA-STD-3001:

[V2 7057] Stowage 

Access while Suited

The stowage system 

shall be accessible by a 

suited crewmember. 

Human Landing System 

(HLS) Program 

Requirement: 

HLS-HMTA-0131 Stowage 

Access while Suited

Stowed items to be used 

when crewmembers are 

suited shall be accessible 

by a suited crewmember.

HLS Verificaon 

Statement:

V-HLS-HMTA-0131 

Stowage Access while 

Suited

Statement: Analysis and 

Test - Stowage Access 

while Suited shall be 

verified by test and 

analysis. If able to 

perform suitedpressurized tesng: 

evaluaon of 

task/worksite analysis. If 

unable to perform suitedpressurized tesng: must 

be demonstrated by 

NASA.

Fig. 2 Example of NASA-STD-3001 to program requirement flow. An example of how programs tailor individual technical requirements

from NASA-STD-3001 to create and verify program-specific requirements.

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npj Microgravity (2023) 31 Published in cooperation with the Biodesign Institute at Arizona State University, with the support of NASA
program-specific human requirements and to help designers

develop designs and operations for human interfaces in spacecrafts. The scope of the handbook encompasses all crew

operations both inside and outside spacecrafts in space and on

Lunar or planetary surfaces. It includes design guidelines for crew

interfaces with workstations, architecture, habitation facilities,

extravehicular activity (EVA) systems; information describing crew

human capabilities and limitations (including both physical and

cognitive); and environmental support parameters. The potential

users of the HIDH include program managers, program/system

requirements writers, human factors practitioners, engineers and

designers, crews and mission/flight controllers, and training and

operations developers.

Human space flight technical briefs

The OCHMO 3001 Standards Team has developed a repository of

human space flight technical briefs34 that cover a range of topics.

Each technical brief includes information regarding technical data,

background, reference information, and application notes to aid

with the development of hardware, systems, and vehicles, as well

as human needs and limitations. This information is used by

vehicle developers, program requirement writers, and medical

professionals. These technical briefs integrate content from

multiple technical requirements and provide a quick, informative

resource to reference when working with NASA-STD-3001.

Currently, there are 31 published human space flight technical

briefs with additional topics being added on a regular basis.

Stakeholders, NASA SMEs, and other potential users are encouraged to submit their ideas for future technical brief topics that

would be informative and useful for ongoing work.

Process for updating NASA-STD-3001

The NASA-STD-3001 documents are reviewed and updated in a

continuous cycle in order to keep the technical requirements

current and up-to-date with the latest knowledge and guidance.

Potential updates and recommendations for the technical

Fig. 3 Human space flight standards hierarchy pyramid. The purpose of this pyramid is to provide a top-level view of technical

requirements and how each subsection impacts a mission’s success.

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requirements are identified through several different avenues,

which include but are not limited to:

1. NASA Subject Matter Experts (SMEs) are invaluable

resources for ensuring that current technical requirements

include relevant and important content for each individual

area of interest, utilizing the expertize and experience of the

SMEs to provide the best available information to form new

and update existing technical requirements.

2. Human System Risk Board (HSRB) as described previously,

helps to inform the standards through regular reviews of

identified space flight human health risks which includes an

overview of the related technical requirements and

potential recommendations to update those technical

requirements to address any changes or concerns regarding

each specific risk.

3. NASA Human Research Program (HRP) is a program

dedicated to conducting ongoing space flight research in

many facets of human space travel and includes five

elements: the International Space Station Medical Projects,

Space Radiation, Human Health Countermeasures, Exploration Medical Capability, and Human Factors and Behavioral

Performance35. The results from HRP’s research and findings

helps to inform the technical requirements and provide

important updates using new and updated knowledge,

The process for updating the NASA-STD-3001 documents and

related handbooks includes a specific set of steps to be followed

to ensure consistent and accurately documented changes to the

standards. Figure 4 below provides an overview of this process.

Future exploration and commercialization of space flight

The future of NASA and human space flight is undergoing

significant changes, with the landscape of space travel and

exploration turning toward longer-duration missions on the

Lunar surface and eventual deep space to Mars. In addition,

commercial partners have become the primary contributors to

supporting ongoing human space travel and thus it is

imperative to consider their role in the future of space flight.

The NASA-STD-3001 documents are invaluable resources for the

evolving space flight environment, providing commercial

partners with the necessary knowledge and guidance to enable

safe and effective human space travel. In addition, lessons

learned and feedback from previous programs development

activities and operations helps to inform future programs on

how to appropriately integrate the 3001 technical requirements

to achieve their goals and objectives and overall mission

success.

Received: 7 September 2022; Accepted: 13 March 2023;

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ACKNOWLEDGEMENTS

The author(s) received no external funding for the research, authorship, and/or

publication of this paper.

AUTHOR CONTRIBUTIONS

All listed authors contributed to the preparation and writing of the paper. The

corresponding author, S.C., was responsible for submitting the paper for publication.

COMPETING INTERESTS

The authors declare no competing interests.

ADDITIONAL INFORMATION

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Published in cooperation with the Biodesign Institute at Arizona State University, with the support of NASA npj Microgravity (2023) 31