Here's a quick analysis for planning and realism purposes for manned exploration of Jupiter's Galilean satellites:
Satellite | Daily radiation rate (Sv) | Yearly rate (Sv) | Single-year limit | 5-year cumulative limit | Mild sickness | LD 10/30 | LD 35/30 | LD 50/30 | LD 60/30 | LD 100/14 | LD 100/7 | LD 100/2
Io | 36 | 13149 | 2 min | 4 min | 20 min | 40 min | 1.33h | 2 h | 2.67h | 4 h | 6.67h | 33.33h
Europa | 5 | 1972 | 13.33 min | 26.66 min | 2.22h | 4.44h | 8.89h | 13.33h | 17.78h | 26.67h | 44.44h | -
Ganymede | 0.08 | 29.22 | 15h | 30h | 6.25d | 12.5d | 25d | 37.5d | 50d | 75d | - | -
Callisto | 0.0001 | 0.037 | 1.37y | 2.74y | - | - | - | - | - | - | - | -The single year limit is 50 mSv, while the maximum 5-year cumulative exposure is 100 mSv (or 20 mSv per year). LD stands for Lethal Dose, LD x/y means "x" percent of individuals die within "y" days. LD 50/30 thus means half of people exposed at this level of radiation would die within 30 days. Some values have been omitted as the time required to reach the lethal dose level exceeds the time for lower lethal dose rates to be achieved or, in the case of Callisto, because it would simply be unreachable with the low radiation rate observed.
A few observations point to the obvious:
Astronauts on Io would experience fierce radiation flux, reaching their maximum cumulative radiation dose accepted by various safety regulations for a period of 5 years in only 4 minutes outside on the surface!!! Europa isn't much better, with less than half an hour of exposure. Ganymede is also a fierce environment, despite radiation being much less intense than at Io. With minimal shielding, Callisto would provide a safe working environment no worse than a nuclear power plant or research facility.
For shielding purposes to limit exposure to below regulatory levels for 5-year periods, the number of halving thickness of shielding material stands as follows:
Satellite | Number of shielding layers | Liquid water thickness
Io | 20 | 3.6 m |
Europa | 17 | 3.06 m
Ganymede | 11 | 1.98 m
Callisto | 1 | 18 cmAs ice is less dense than water, about 10% more would be required.
I'll spare the details of what would happen to the exposed crews, you can read for yourself at Wikipedia!
Io | 36 | 13149 | 2 min | 4 min | 20 min | 40 min | 1.33h | 2 h | 2.67h | 4 h | 6.67h | 33.33h
Europa | 5 | 1972 | 13.33 min | 26.66 min | 2.22h | 4.44h | 8.89h | 13.33h | 17.78h | 26.67h | 44.44h | -
Ganymede | 0.08 | 29.22 | 15h | 30h | 6.25d | 12.5d | 25d | 37.5d | 50d | 75d | - | -
Callisto | 0.0001 | 0.037 | 1.37y | 2.74y | - | - | - | - | - | - | - | -
A few observations point to the obvious:
Astronauts on Io would experience fierce radiation flux, reaching their maximum cumulative radiation dose accepted by various safety regulations for a period of 5 years in only 4 minutes outside on the surface!!! Europa isn't much better, with less than half an hour of exposure. Ganymede is also a fierce environment, despite radiation being much less intense than at Io. With minimal shielding, Callisto would provide a safe working environment no worse than a nuclear power plant or research facility.
For shielding purposes to limit exposure to below regulatory levels for 5-year periods, the number of halving thickness of shielding material stands as follows:
Io | 20 | 3.6 m |
Europa | 17 | 3.06 m
Ganymede | 11 | 1.98 m
Callisto | 1 | 18 cm
I'll spare the details of what would happen to the exposed crews, you can read for yourself at Wikipedia!