WIA-SPACE-009 is the Space Radiation Protection Standard, version 1.0, published on 2025-01-26 and classed as Space Safety / Radiation Protection. The Phase 3 protocol document, which this chapter follows, treats radiation exposure as a managed operational budget rather than a hazard to be endured. The protocols give the crew, the ground team and the medical officer one shared vocabulary for deciding when to work, when to shelter, when to treat and when to document an exception.
Phase 3 defines six protocols. Each one answers a different question that arises at a different point in a mission.
| Protocol | Question it answers |
|---|---|
| Shielding design | How much material, of what kind, between the crew and the environment? |
| SPE shelter | What do we do when a solar particle event is predicted or in progress? |
| Real-time monitoring | How do we know the dose rate has changed, and who is told? |
| Medical countermeasure | What is given before, during and after exposure, and what is tracked for life? |
| Verification | Do the measured doses match the plan, and can we prove it? |
| Crew-protection deviation | How is a mission allowed to exceed its risk criterion, and at what cost in oversight? |
The standard states its philosophy as 弘益人間 (Hongik Ingan), "Benefit All Humanity". In practice this means the protocols are written so that any operator can adopt them. Thresholds are expressed as multiples of background dose rate, as time limits and as areal densities, so they stay meaningful across different vehicles and habitats.
Crews in low Earth orbit work partly inside the protection of Earth's magnetic field. Crews bound for the Moon or Mars leave much of that protection behind. They fly through a continuous background of galactic cosmic rays and face the occasional burst of solar energetic particles, and they usually do so in cabins whose walls were sized for structural and thermal reasons first. The standard's response is to make radiation a planning input from the very beginning of a mission, not a late safety check.
The mission-planning protocol sets out three groups of decisions:
The dose budget ties everything together. Shielding mass, EVA hours, shelter occupancy and medical readiness are all traded against it. The verification and deviation protocols later in this chapter also compare outcomes with this budget.
The standard separates the radiation environment into components because each one calls for a different defence.
Information about these environments reaches a vehicle from several sources. The standard names NOAA and ESA alerts, the SWPC GOES proton feed, an Antarctic neutron monitor and the vehicle's own onboard particle detector. Redundancy across ground and onboard sources lets the monitoring protocol cross-check an alert instead of trusting a single feed.
The standard handles risk on two time scales. Acute effects follow a large dose delivered in a short period, as in a severe SPE. Late effects accumulate across a career. The protocols tie both to measured dose, expressed in grays (Gy) for the acute thresholds.
Acute radiation syndrome (ARS). Diagnosis relies on three observations: the onset time of symptoms such as nausea and vomiting, a dose estimate from dosimeters, and a lymphocyte count from a blood test where the facility exists. The treatment sequence escalates with dose:
Late effects. Post-mission medical monitoring covers a lifetime cancer-screening commitment under the NASA Lifetime Surveillance of Astronaut Health programme. It also covers cardiovascular, central nervous system and cataract surveillance per NCRP 153 and 167. The pre-mission pharmaceutical set targets the bone, cardiovascular and cognitive risk envelopes.
Each crew member's career dose is updated after every mission and kept with a full audit trail per NASA NPR 1441.1G. This running record is what turns individual exposures into an individualised lifetime risk figure. It is also the figure that has to be recalculated whenever a deviation exceeds the normal risk criterion.
The standard's shielding requirements are written as areal density, meaning mass per unit area, because attenuation depends on the amount of material traversed and not on the wall's geometric thickness. Three tiers apply to a habitat:
Materials are prioritised in this order: hydrogen-rich materials first, then multi-layer structures, then low-Z materials, because they minimise secondary radiation. The reference data are:
| Material | Density (g/cm³) | Hydrogen content | Application |
|---|---|---|---|
| Polyethylene | 0.92 | 14% | Dedicated shielding layers |
| Water | 1.0 | 11% | Multi-purpose (life support + shielding) |
| Aluminum | 2.7 | 0% | Structural (baseline) |
| Boron composite | 1.8-2.5 | Varies | Neutron capture |
The design protocol refines this table. Polyethylene appears at 0.93 g/cm³ in the HZETRN analyses that show the best GCR attenuation per gram of mass. Aluminium remains the primary structural shield. Stored water counts as shielding wherever the operator can repurpose its mass. For surface habitats, regolith berming has a density envelope of 1.7 to 2.5 g/cm³ depending on lunar or Martian composition. A cislunar or Mars-transit cabin typically falls within 20 to 40 g/cm², and a storm shelter above 40 g/cm². The final design is verified by Monte Carlo transport, using FLUKA, Geant4, PHITS or MCNP6 with HZE extensions.
Storm shelter. The shelter must give 20 to 40 g/cm² of effective thickness and hold every crew member for at least 72 hours without resupply. It sits in the central area with maximum shielding, and any crew location must be able to reach it within 15 minutes. Its life support has to be complete: oxygen, CO₂ removal, temperature control, food and water, waste management and communications.
EVA suit. The current EMU provides only about 0.1 to 0.2 g/cm². The enhancement targets are 0.5 g/cm² over the torso to protect critical organs, a helmet of enhanced polycarbonate with hydrogen gel, and flexible joints made from a polyethylene fibre weave.
The real-time monitoring protocol uses two classes of dosimeter. Active dosimeters are polled at a cadence of 1 to 60 seconds. Passive dosimeters are read at the end of the mission. Dose rate from the active instruments is trended continuously, and anomalies are detected as a z-score deviation from the trailing 24-hour mean:
z = (current_dose_rate - mean_24h) / stddev_24h
anomaly if |z| exceeds the operator-configured threshold
An anomaly is checked against external feeds (the GOES proton feed, the Antarctic neutron monitor and the onboard particle detector) so the crew can tell a real environmental change from an instrument fault. Alerts escalate according to an operator-configurable threshold matrix, and the medical officer is notified when a threshold is crossed or an anomaly is detected. The standard's default alert levels are:
| Level | Condition | Action |
|---|---|---|
| Green | Normal | Continue operations |
| Yellow | M-class flare or dose rate 2x background | Increase monitoring, review EVA |
| Orange | X-class flare or SPE predicted | Abort EVA, prepare shelter |
| Red | SPE in progress, dose rate above 10x background | Immediate shelter evacuation |
Verification. Measurements are useful only if the instruments are trusted. Before flight, TLDs are checked against pre- and post-irradiation references, OSL dosimeters are bleached and given a dose curve, and CR-39 is calibrated for etch rate. In flight, active and passive instruments are intercompared: TEPC, TLD, CR-39 and silicon diode. After flight, a dose reconstruction combines all dosimeter classes. A cumulative dose that deviates from the mission budget by more than 20% triggers a root-cause investigation under ISO/IEC 17025 §7.10. The final step is the crew career-dose update, with the audit trail described in 6.4.
The operational protocols turn the alert levels into concrete procedures. The pre-EVA go/no-go decision rests on a 48-hour review of the solar activity forecast and on the current radiation environment. The decision criteria are:
GO only if all conditions hold:
- no M-class or larger flare in the past 24 hours
- no active region with high flare probability
- background dose rate within normal range
- SAA passage timing acceptable (ISS)
During the EVA, the crew wears a personal dosimeter that is monitored continuously, and ground teams watch the environment independently. Time limits are enforced: 8 hours for a single EVA, 16 hours per week, and a mission total set by the dose budget. Abort criteria are an SPE warning, a dose rate more than five times background, or a cumulative dose approaching the daily limit. After the EVA, the dosimeter is read and recorded, the crew's health is assessed, and the cumulative dose is updated.
SPE response. The shelter sequence is: receive the alert, stop non-essential activity, enter the shelter (target under 15 minutes), close and verify the hatch, monitor with internal and external dosimeters, and communicate with the ground. Occupancy lasts until the dose rate returns below twice background. Inside the shelter, the crew minimises movement to conserve energy, monitors health, keeps communications open and provides psychological support. Exit follows its own checks: verification of post-event flux, comparison of cumulative dose with the SPE budget, and a medical-officer assessment. The event is documented per ISS-IRD or the operator's equivalent.
Deviation. Sometimes mission requirements, such as an emergency contingency or an off-nominal trajectory, force the crew past the normal risk criterion. The deviation protocol permits this only with heavy oversight:
The standard divides pharmacological defence by timing. Radioprotectors are given before exposure to prevent or reduce cellular damage. The standard names amifostine (WR-2721), which is FDA-approved but carries significant side effects, and antioxidants such as vitamin C, vitamin E, selenium and N-acetylcysteine. They are administered before high-risk activities, for example an EVA during a period of elevated risk. Radiation mitigators are given after exposure to limit the progression of damage. The primary agents are G-CSF for bone marrow recovery, EPO for red blood cell production and TPO for platelet production. The administration window is within 24 to 48 hours of a significant exposure, meaning more than 1 Gy.
The medical-countermeasure protocol, aligned with NASA HRP-47065, adds three layers:
The pharmaceutical inventory completes the picture. It must contain antiemetics (ondansetron, metoclopramide), growth factors (G-CSF, EPO), broad-spectrum antibiotics, analgesics, IV fluids and electrolytes, and antioxidants. Packaging is radiation-shielded and temperature-controlled, and expiration dates are monitored. Mars missions require a shelf life of at least three years, which in effect makes pharmacy logistics a radiation-protection concern.
The standard is candid about where current practice falls short. Those gaps point to likely areas of development:
The standard's own compatibility promise gives these developments a place to land. Within the 1.x line, hosts may add optional fields and new envelopes but must not remove existing ones, so new countermeasures or materials can be introduced without breaking existing deployments.
This chapter followed the Phase 3 protocols in the order a mission experiences them. Shielding is designed in areal density, with hydrogen-rich materials, multi-layer construction and a verified Monte Carlo model. Monitoring turns dosimeter readings into a four-level alert scheme (Green, Yellow, Orange and Red) that drives EVA aborts and shelter entry. Treatment thresholds at 1, 2 and 4 Gy connect dose to clinical action. Verification checks the whole chain against the dose budget, with a 20% deviation triggering root-cause investigation. A formal deviation protocol exists for the rare cases where the risk criterion must be exceeded.
On the engineering side, the Phase 3 document also asks every host to emit structured audit lines carrying a trace identifier, which Phase 2 returns as the X-WIA-Trace-Id response header. It optionally lets a host advertise its supported capabilities at a well-known path. Both are conveniences shared with other WIA standards and are not specific to radiation protection.
The protocols specify what must happen and which thresholds apply, but they do not say how the signals travel between vehicles, ground stations, medical records and partner agencies. That question belongs to Phase 4, the integration layer that connects these protocol exchanges to the wider ecosystem. The next chapter turns to it, examining how dosimetry, alerts and medical records are exchanged across organisational boundaries.