Would really NOT want to be on my way to Mars, or back, if one of those CMEs were shot in the ship’s direction.
Or ***on*** Mars. Remember, it has no magnetosphere. I’ve argued that one of the first things we’ll have to engineer when we start a colony will be a global magnetic field.
CMEs are composed primarily of protons and electrons. shielding against these particles is relatively “simple”. Multilayer metal and sometimes plastic shields are already used on spacecraft to protect sensitive electronics and astronauts.