Effects of radiation, from solar flares and coronal mass ejections (CMEs):

- Makes aurorae (air glows, like fluorescent lamps)
- Health danger to astronauts
- Ages spacecraft electronics (two satellites failed after the 1989 March 9 flare)
- Charges up spacecraft, causing electrical problems
- Charges up high-voltage power lines, caused Hydro Quebec blackout (1989)
- Makes Earth's ionosphere (uppermost atmosphere) reflective, doing weird things to 
radio transmission and cell phones: local taxi drivers may become unable to talk 
to their dispatcher, but able to talk to the one in Kansas city.

Types of radiation:
- charged particles (protons, electrons, alpha particles [helium nuclei])
- neutrons
- ionizing electromagnetic radiation: gamma rays and X-rays.

All are so energetic, they ionize matter, including your cells.

Radiation doses:

0.1 rem: normal sea-level dose, from cosmic rays and natural radioactivity in rocks
About twice as much: normal dose for Denver, "the mile-high city"
There is also a corresponding increase in skin cancer and leukemia (blood cancer)

1 rem: typical dose from crossing Earth's radiation belts, e.g. by Apollo astronauts;
	also the maximum yearly dose allowed for nuclear plant workers.

40 rem: typical dose for a 2.5-year Mars expedition, outside of Earth's magnetosphere.
	But the body can heal itself over time: this level of radiation
	elevates the risk of cancer of about 1% per year, about as much as
	smoking for this length of time.

75-200 rem within 30 days:
	Body can't repair cell damage fast enough.
	Radiation sickness results: vomiting, fatigue, hair loss.
Can also cause birth defects in later children, and cancer in later life.

500 rem, promptly: fatal dose

Large CMEs (e.g., the one that hit 2 weeks after the Apollo 16 mission) can have 
> 2000 rems/hour.

=> Definitely want a "storm shelter" inside a Mars-bound spacecraft!
Best shielding: water!  (Little secondary radiation.)

Therefore, build the wash-water tank with a cavity in the middle, so you can duck inside!