Human System Risks

Human System Risk Board

Risk is inherent in human spaceflight. However, specific risks can and should be understood, managed, and mitigated to reduce threats posed to astronauts. Risk management in the context of human spaceflight can be viewed as a trade-based system.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk to Crew Health Due to Electrical Shock (Electrical Shock Risk)

It is important to protect humans from unintended electrical current flow during spaceflight. The thresholds for contact electrical shock are well established, and standards and requirements exist that minimize the probability of contact electrical shock. Current thresholds were chosen (vs.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk to Vehicle Crew Egress Capability and Task Performance as Applied to Earth and Extraterrestrial Landings

New spacecraft that will transport crews to the Lunar and Martian surfaces and return them to Earth may have diverse landing modalities which will function in different landing environments.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Spaceflight Associated Neuro-ocular Syndrome

Exposure to altered gravity can cause ocular and brain structural changes to develop during spaceflight; these changes could lead to vision alterations, cognitive effects, or other deleterious health effects. SANS is a syndrome unique to humans that fly in space, and there is no terrestrial disease equivalent.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Toxic Substance Exposure

Safe, breathable air is essential for crew health. Human spaceflight has involved toxicological events ranging in severity from trivial to life-threatening.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Urinary Retention

Exposure to the altered gravity in the spaceflight environment may cause physiological changes. One of these changes is the inability to completely empty the bladder or urinary retention.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Reduced Physical Performance Capabilities Due to Reduced Aerobic Capacity (Aerobic Risk)

Spaceflight causes measures of maximum aerobic capacity to decline, which can result in impaired mission task performance. Based on ISS data, if crew adhere to existing exercise schedules and have access to adequate exercise countermeasure systems, then on average, they return with minimal losses of aerobic fitness.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Reduced Physical Performance Capabilities Due to Reduced Muscle Size, Strength, and Endurance (Muscle Risk)

Exposure to the microgravity environment causes muscle size, strength, and endurance to decline. Based on ISS data, if crew adhere to the exercise schedule and have access to adequate exercise countermeasure systems then on average, they return with minimal losses of muscle size, strength, and endurance.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Renal Stone Formation

Exposure to microgravity induces bone atrophy/bone loss which increases circulating calcium, impacting the renal stone risk. Risk mitigation strategies including exercise and hydration are well-defined although the ability to treat a renal stone during exploration missions is not yet available.

Posted March 11, 2025

Human Health and Performance

Human System Risks

Risk of Adverse Health Outcomes and Performance Decrements resulting from Non-Ionizing Radiation during Spaceflight

Sunlight exposure primarily affects the eye and skin and is mitigated by current standards and countermeasures. An increase in the prevalence of high-power ground-based lasers capable of reaching the ISS, and possibly even the Moon, could cause acute laser exposure damaging hemorrhagic retinal lesions resulting in temporary or permanent damage to

Posted March 11, 2025