Want to go to Mars? Better leave when the Sun is active to minimize galactic radiation poisoning

If the idea of sending humans to Mars is a romantic one, the reality of it is a bucket of cold water.

Going to Mars is hard. Something like half of all missions have failed for one reason or another, but adding humans into the mix makes things far harder. We inconveniently need air and water and food, for one thing, but we also need the environment to be safe.

Radiation is a direct threat to that.

In this case I mean subatomic particles zipping around space at extremely high velocities. These...