To put it bluntly the pessimistic article about manned interplanetary flight in the latest Scientific American magazine
[March issue] has virtually killed the idea of sending humans to Mars because of...cosmic rays...according to its authors.

Cosmic rays, they claim, maybe a "showstopper" for any manned missions to Mars.
The science article states that astronauts living onboard any thinskinned spacecraft
for a year, beyond Earth's magnetosphere, will have one third of their DNA destroyed.

The magazine article goes on to say that hypothesized electostatic or electromagnetic shielding of spacecraft
will be ineffective; even detrimental.
....That heavy/massive shielding will be prohibitive, forcing the costly and necessary increase of additional
propellant, etc, for transplanetary ejection from LEO, etc...

Read the magazine article!...But a warning!...it may leave you depressed or angry if you feel/felt
manned planetary exploration was humanity's salvation or birthright.