Space Weather Scale for Solar Radiation Storms
Category |
Effect |
Physical measure |
Average Frequency | |
S 5 |
Extreme |
Biological: unavoidable, high radiation hazard to astronauts on EVA (extravehicular activity); high radiation levels to passengers and crew in commercial jets at high latitudes (approximately 100 chest x-rays). Satellite operations: loss of some satellites, memory impacts cause loss of control, serious noise in image data, star-trackers unable to locate sources; permanent damage to solar panels. Other systems: No HF (high frequency) communications possible in the polar regions, and position errors make navigation operations extremely difficult. |
105 (Flux level of >10 MeV particles (ions)*) |
Fewer than 1 per cycle (Number of events when flux level was met — events may last longer than one day) |
S 4 |
Severe |
Biological: unavoidable radiation hazard to astronauts on EVA; elevated radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 10 chest x-rays). Satellite operations: memory device problems, noise on imaging systems, star-trackers cause orientation problems, and solar panels degraded. Other systems: blackout of HF radiocommunications through the polar cap and increased navigation errors over several days. |
104 |
3 per cycle |
S 3 |
Strong |
Biological: radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in commercial jets at high latitudes receive low-level radiation (approximately 1 chest x-ray). Satellite operations: likely single-event upsets, noise in imaging systems, permanent damage to exposed components/detectors, and decrease of solar panel currents. Other systems: degraded HF radio propagation through the polar cap and navigation position errors. |
103 |
10 per cycle |
S 2 |
Moderate |
Biological: none. Satellite operations: infrequent single-event upsets. Other systems: small effects on HF propagation through the polar cap and navigation at the polar cap impacted. |
102 |
25 per cycle |
S 1 |
Minor |
Biological: none. Satellite operations: none. Other systems: minor impacts on HF radio in the polar regions. |
10 |
50 per cycle |
* Flux levels are 5-minute averages. Flux in particles · s-1 · ster-1 · cm-2 Table from the National Oceanic and Atmospheric Administration
** These events can last more than one day.
