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One note for each of NASA's 17 Human Research Program risks: what it is, and what Hygieia can and cannot observe. ⓘ source Evidence links are study records in NASA's Open Science Data Repository ⓘ source (metadata fetched 2026-11-14).
In weightlessness body fluids shift toward the head and the heart and vessels adapt to a lower workload. NASA tracks this as a risk for long missions and for the return to gravity.
Resting heart rate, heart-rate variability and blood pressure every day, each compared with your own 30-day baseline. Drift shows on the Heart & vessels region.
Heart structure, vessel stiffness or rhythm problems. Those need ultrasound or an ECG read by a clinician.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Without gravity to work against, muscles and aerobic fitness decline unless the crew exercises. NASA reports that station crews exercise about two hours a day.
Logged exercise minutes and daily activity from the actigraphy band, against the profile's exercise prescription.
Actual strength or aerobic capacity. Hygieia sees adherence, not fitness test results.
The Transit profile has no treadmill. NASA's Zero T2 study is examining how exercising without a treadmill affects health and performance; it is research in progress.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Weight-bearing bones lose mineral in weightlessness. Exercise is the main countermeasure in use.
Exercise adherence over 14 days, as a proxy. Below 80% of the prescription raises the bone and muscle alert.
Bone density. Hygieia does not measure bone at all; the alert is inferred from exercise adherence and says so.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Shifted schedules, workload, noise and unusual light make sleep on missions short and irregular, which affects performance.
Sleep hours, sleep regularity and daytime light from the actigraphy band (modelled on NASA's ARCHeR study on Artemis II). Two short nights can trigger a standing order from the flight surgeon.
Sleep stages or sleep disorders.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Isolation, confinement and distance from home can affect mood and behaviour over a long mission.
A daily mood check-in and shared crew time, alongside sleep. Mood is a sharing category the astronaut can keep private.
Any clinical condition. Hygieia never diagnoses; it shows drift from your own baseline and suggests small changes.
The private journal is never shared and is not read by the flight surgeon or the AI assistant.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Spaceflight can change how the immune system behaves, and a closed cabin makes infections easy to pass on.
An infection early warning: body temperature and resting heart rate rising together while heart-rate variability falls, for two of three days.
Immune markers in blood, or which infection it is.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
The crew must eat and drink enough from a fixed food system for the whole mission.
Logged energy intake, fluids and glucose. Two low-fluid days raise the dehydration alert.
Nutrient status (vitamins, minerals) or body composition.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Too little oxygen reaching the body, for example from a cabin atmosphere problem or a lower-pressure habitat.
Blood oxygen (SpO₂) daily with a hard red limit, and cabin pressure and CO₂ on the crew dashboard. Low SpO₂ can trigger a standing order.
The cause. A low reading can also be a cold finger or a loose sensor, so the first advice is to re-measure.
The surface-habitat pressure and SpO₂ limits in the Lunar and Mars profiles are design assumptions.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Beyond low Earth orbit the crew receives a steady dose from galactic cosmic rays, plus bursts from solar particle events.
Dose tracking only: a personal dosimeter with a neutron channel, the mission-to-date total against the plan, and real solar particle events replayed from NASA DONKI with a storm-shelter checklist.
Cancer risk. Hygieia does not estimate risk from dose, and it has no biological measurement of radiation damage.
Daily dose rates per environment come from published measurements (MSL RAD, Chang'E 4 LND, ESA DOSIS).
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Changes to the eye and optic nerve seen in some astronauts on long flights. NASA describes it as its leading spaceflight-related health risk.
A weekly vision self-check: gap-direction acuity trials, a grid, and two questions. Three falling results raise a prompt to repeat the check and tell the flight surgeon.
The eye itself. Finding SANS needs imaging of the back of the eye. The self-check is a screening prompt, not a diagnosis.
NASA's Thigh Cuff study is testing whether tight thigh cuffs keep more fluid in the legs, and its B Complex study is investigating a daily B vitamin supplement. Both are under investigation. Hygieia does not present either as a treatment.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Balance and coordination adapt to weightlessness and must re-adapt after each change of gravity, such as landing on Mars.
A weekly balance self-check, and extra balance checks after a gravity transition in the Mars surface profile.
Inner-ear function directly.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Gas bubbles can form in the body when pressure drops, as it does when moving into a lower-pressure spacesuit.
A check after every spacewalk in the surface profiles, and a triage tree for joint pain or breathing trouble after EVA.
Bubbles. Hygieia relies on symptoms the crew report.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Spacewalks are physically hard work in a pressurised suit and carry a risk of injury and fatigue.
Go/no-go before each spacewalk from projected readiness, a reaction test the evening before, and a post-EVA check reminder.
Suit fit, hand injuries or workload during the spacewalk itself.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
A small crew far from Earth depends on working well together for the whole mission.
Shared crew time as a recovery lever, and cooperative team goals with no leaderboard.
Team dynamics. Hygieia has no measure of how the crew gets along.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Microbes and the people carrying them both change in a closed spacecraft, which may affect infection risk.
Nothing directly. The infection early warning is the closest related signal.
The microbiome, or microbes on cabin surfaces.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
Launch, landing and aborts put sudden forces on the body.
Nothing. This note is for reference before landing day.
Loads on the body or injuries from them.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
With long communication delays the crew must operate complex systems, including medical ones, with less help from the ground.
This is the problem Hygieia is built around: offline triage, standing orders written in advance, and a delayed-link queue.
Whether the crew has the right training or procedures for systems other than this one.
Source: NASA Human Research Program — Risks (https://www.nasa.gov/hrp/risks/) ⓘ source
Evidence in NASA OSDR
Related open datasets, not proof of any claim in this note.
On Earth the rescuer's body weight does the work of chest compressions. In weightlessness there is no weight to push with, so the rescuer must hold on to the patient.
The emergency screen shows one method by default, the Evetts-Russomano method: the rescuer's legs are wrapped around the patient's torso, the arms are locked, and compressions come from the upper body. A metronome runs at 110 beats per minute.
Two other methods are described for microgravity. In the handstand method the rescuer braces their feet against the opposite wall and pushes down on the patient's chest. In the reverse bear hug the rescuer holds the patient from behind and compresses the chest with both arms. These are different methods; the Evetts-Russomano method is not the handstand method.
In the Lunar base and Mars surface profiles the screen shows kneeling CPR instead.
Hygieia's triage trees stand in for procedures a flight surgeon would approve.
Source: Hygieia triage content ⓘ source