WIA-SPACE-009 is an international standard for protecting astronauts and spacecraft from space radiation in every phase of a mission. Its scope covers Low Earth Orbit (LEO) operations, lunar missions and surface operations, Mars expeditions and deep space exploration, extravehicular activity (EVA), and emergency radiation events. The standard follows the physics through to operations. It starts with the three radiation sources (galactic cosmic rays, solar particle events and trapped radiation) and moves on to health effects, shielding, monitoring, operational procedures, medical countermeasures and mission planning.
It rests on existing practice rather than replacing it. The applicable documents include the ICRP publications on radiation protection, NASA STD-3001 (Space Flight Human System Standard), ISO 15390 for the galactic cosmic ray environment, and the NCRP reports on space radiation. What the standard adds is a common vocabulary and a set of record formats, so that a dose measured in one agency's dosimeter can be read, audited and compared by another.
The standard is organized into three layers, which the later sections of this chapter follow:
The guiding philosophy is 弘益人間 (Hongik Ingan), "benefit all humanity". In practice this means the protection rules are written for any crew on any mission, not for one national program.
On the ground, the atmosphere and the geomagnetic field filter most of the radiation that comes from space. Outside them, crews face a mixed field of energetic charged particles. Some of these particles are heavy ions that deposit energy along dense tracks in tissue. Because of this, a simple absorbed-dose reading does not describe the biological risk. The standard separates absorbed dose in gray (Gy), equivalent dose in sievert (Sv) and effective dose in Sv, and it requires the LET (linear energy transfer) spectrum so that a quality factor can be determined.
Exposure depends heavily on where the spacecraft is and when. A LEO crew is shielded in part by the geomagnetic field but crosses the trapped-radiation belts. A crew on a lunar or Mars transit loses that shielding and meets the full galactic cosmic ray flux. A sudden solar event can add a large dose in hours. The standard therefore treats radiation as something to be budgeted and managed across a whole mission, not as a hazard that is either present or absent.
The management logic is the ALARA principle (As Low As Reasonably Achievable), applied through three levers:
Every protocol later in this chapter, from EVA time limits to storm-shelter drills, applies one or more of these three levers.
The standard distinguishes three primary sources by physical mechanism and by temporal behavior. The table summarizes the specified characteristics.
| Source | Composition and energy | Temporal behavior | Risk and warning |
|---|---|---|---|
| Galactic cosmic rays (GCR) | ~85% protons, ~14% helium, ~1% HZE particles; hundreds of MeV to hundreds of GeV | Continuous throughout the mission; modulated by the solar cycle (30–50% variation) | High for long-duration missions (>6 months); very high shielding difficulty, with meters of shielding needed for complete protection |
| Solar particle events (SPE) | >90% protons; tens to hundreds of MeV | Hours to days; frequency correlated with the solar cycle | Very high during events, and acute radiation syndrome is possible; warning time from 10 minutes to several hours |
| Trapped radiation (Van Allen belts) | Inner belt: high-energy protons; outer belt: electrons of 0.1–10 MeV | Inner belt very stable; outer belt highly variable | Primary concern for LEO operations |
The inner belt lies at altitudes of roughly 1,000–6,000 km and the outer belt at 13,000–60,000 km. The South Atlantic Anomaly (SAA), centered near 30°S, 60°W, is where the inner belt dips closest to the Earth. An ISS-inclination orbit passes through it five to six times a day, and the SAA contributes 70–80% of an ISS astronaut's dose.
The Phase 1 data format also names secondary radiation (neutrons and spallation products produced as primary particles interact with the spacecraft) and extragalactic gamma-ray bursts. The source-record envelope captures an identifier, an energy spectrum (LET in keV/μm, a particle-type breakdown and a flux-energy distribution) and a temporal envelope. GCR is recorded as steady-state, SPE as event-driven with onset time, peak time and duration, and trapped radiation as orbital, depending on altitude and inclination. A spatial envelope adds heliocentric distance, geomagnetic-cutoff rigidity and shielding-thickness context.
The standard expresses permissible exposure as career limits tied to a 3% Risk of Exposure-Induced Death (REID), so the limit depends on the age and sex of the crew member:
| Age at exposure | Female (mSv) | Male (mSv) |
|---|---|---|
| 25 | 600 | 800 |
| 35 | 900 | 1,000 |
| 45 | 1,100 | 1,200 |
Short-term limits cover 30 days (250 mSv) and one year (500 mSv). The eye lens has a career limit of 2,000 mSv to prevent cataracts. The risk-criterion envelope also carries 30-day and annual organ-dose limits for blood-forming organs, lens and skin, expressed in mGy-equivalent. It adds descriptors for the SPE acute-exposure case, central-nervous-system risk (per NCRP 153) and cardiovascular risk (per NCRP 167). The ICRP-recommended career limits in ICRP 103 differ from the NASA limits, so the standard cross-references them explicitly.
The risk analysis covers cancer, DNA damage, central-nervous-system effects, cardiovascular effects and cataracts. The dose-record envelope is built to feed that analysis. A dose record must carry the following fields:
The LET-spectrum envelope supports the quality-factor step with bins at 0.1, 1, 10, 100 and 1000 keV/μm at minimum, flux resolved by particle type, and depth-resolved spectra. Because the Q-factor models (ICRP 60, ICRP 103, NASA Q(LET) and NCRP-Q) differ for HZE particles above 100 keV/μm, the chosen model must be documented in the record.
Shielding is the third ALARA lever, and the standard treats it in three forms. Passive shielding uses mass: polyethylene, water and multi-layer structures. Active shielding, meaning electromagnetic deflection of charged particles, is described as still under development. The storm shelter is a specially shielded volume sized for SPE protection, at 20–40 g/cm².
The source characteristics explain why the two threats need different answers. SPE protons are comparatively low in energy, so a shelter of that mass thickness is a workable defense against them. GCR particles reach hundreds of MeV to hundreds of GeV, so complete protection would require meters of shielding, which a spacecraft cannot carry. For GCR the realistic goal is to reduce dose rather than to eliminate it, which is why the standard pairs shielding with mission planning and the budget calculation described below.
Shielding is also a data item. The mission-radiation-budget envelope records the shielding configuration as hull mass-thickness per material, the emergency-shelter mass-thickness, and, where applicable, the mass-thickness of regolith berming on a surface habitat. The LET-spectrum envelope records the spectrum at entrance, target and exit for each shielding configuration, which shows how a given configuration changes the particle field.
The shielding configuration can matter in a second way. When primary particles interact with shielding material they produce secondary radiation such as neutrons and spallation products. This is why the source envelope tracks secondary radiation as a source in its own right.
Monitoring combines personal, area and environmental instruments. Personal dosimeters are either passive or active:
Required measurements are absorbed dose (Gy), dose equivalent (Sv), dose rate (mSv/day) and the LET spectrum. Fixed area monitors are installed in all habitable modules and measure dose rate continuously, with an automatic alert when a threshold is exceeded. Environmental monitors track the external radiation environment, particle flux and energy spectrum, and provide real-time SPE detection.
The data-management rules cover the whole path from instrument to crew:
The dosimeter-record envelope catalogues the instrument families the standard recognizes, including TLD, OSL, CR-39 plastic nuclear track detectors, bubble detectors for neutrons, TEPC, silicon-diode arrays, the Liulin spacecraft dosimeter, and the MATROSHKA phantoms. Each record carries a calibration envelope (ISO/IEC 17025), a traceability chain to NIST or PTB primary standards, and the deployment position (intra-vehicular, extra-vehicular or behind shielding). The Phase 2 interface exposes this over HTTP and a stream:
POST /space-radiation/v1/dose-records # submit dose
GET /space-radiation/v1/dose-records/crew/{cid} # crew dose history
POST /space-radiation/v1/dosimeters # register dosimeter
GET /space-radiation/v1/dosimeters/{id}/state # dosimeter state
POST /space-radiation/v1/spe-alerts # SPE alert ingest
WS /space-radiation/v1/state/stream # real-time stream
GET /space-radiation/v1/audit/{id} # audit trailEndpoints that return crew dose records require an operator-medical-officer credential and a crew-protected-data scope (NASA Privacy Act, HIPAA or an equivalent). A dose history is medical data, and the interface treats it as such.
Operational protection is organized around a four-level SPE alert scale. Each level sets a condition and a required action:
| Level | Condition | Action |
|---|---|---|
| Green | Normal | Continue operations |
| Yellow | M-class flare, 2x dose rate | Increase monitoring |
| Orange | X-class flare, SPE predicted | Abort EVA, prepare shelter |
| Red | SPE in progress, >10x dose | Immediate shelter evacuation |
At Red, the shelter response runs in a fixed order:
These numbers tie back to the source physics. The shelter-entry limit exists because warning can be as short as 10 minutes, and the exit criterion reuses the same 2x-background threshold that triggers the active dosimeter alarm. EVA is the most exposed activity, so the protocols combine strict time limits with space-weather monitoring, and Orange stops EVA before the particles arrive. On the planning side the standard calls for solar-cycle optimization and route planning.
The mission-radiation-budget envelope is how planning becomes a record. It is computed before the mission for each crew member from the following inputs:
The result is a cumulative dose for each mission segment, which can be compared against the career and short-term limits in section 1.4.
Medical measures cover four stages. Radioprotectors are given before exposure: antioxidants, and amifostine, which the standard lists as research. Mitigators are used after exposure to support recovery, and the standard names G-CSF and EPO. Treatment of acute radiation syndrome (ARS) is supportive: antiemetics, hydration and general supportive care. Long-term monitoring consists of annual health examinations and cancer screening, since the dominant late risks are cancer, cataracts and cardiovascular and central-nervous-system effects.
The data model keeps this medical follow-up connected to dosimetry. The database requirements call for individual cumulative dose tracking, historical mission data, comparison with models and long-term health correlation. The cumulative record is what lets a flight surgeon judge a crew member's remaining margin against the career limit, and what lets researchers relate delivered dose to later health outcomes. The tracking runs for the whole career, so it follows the individual across missions and operators, and it makes the privacy scope on crew-dose endpoints a design requirement.
The ordering of measures matters. Countermeasures do not replace the first-line controls of time, distance and shielding. They add a layer for the case where those controls were not enough, as during an SPE with a short warning.
The standard names near-term developments for 2025–2030, each aimed at a weakness described above:
The data format is built to absorb such changes without redesign. A new dosimeter type adds a record in the dosimeter envelope with its calibration and deployment position. A new shielding material changes entries in the shielding-configuration envelope. A better SPE forecast arrives through the same SPE-alert ingest. Anything built on the standard stays comparable with older data because every dose record keeps its weighting factors, Q-factor choice and uncertainty.
This chapter set out the logic of WIA-SPACE-009. Radiation comes from three source families with different behavior: GCR is continuous, SPE is sudden, and trapped radiation depends on orbit, with the SAA dominating the LEO dose. The risk to the crew is expressed through age- and sex-dependent career limits (600 to 1,200 mSv at the 3% REID threshold in the table) plus 30-day, annual and organ limits. ALARA, through time, distance and shielding, governs how exposure is reduced. Monitoring turns the environment into dose records, the four-level SPE alert scale turns warnings into actions, and the mission-radiation budget turns planning into numbers. For the machine-readable side, the Phase 1 envelopes define the records, the Phase 2 endpoints (discoverable at /.well-known/wia-space-radiation) move them between missions, dosimeters and ground operators, and the published conformance test suite exercises those endpoints.
The next chapter takes up the first and hardest of the sources, galactic cosmic rays. It looks at where GCR comes from, how its proton, helium and HZE components differ in biological effect, how the 30–50% solar modulation shapes the choice of mission timing, and why the shielding problem for long-duration missions resists the simple mass-based remedies that work against solar protons.