Radiation from cosmic rays is too high.
A group of researchers has published data from a dosimeter installed on board the ExoMars mission probe of the Trace Gas Orbiter (TGO) spacecraft. The measurements were taken during transit and in the high elliptical orbit of Mars, the article says.
The Lyulin-MO dosimetric telescope to measure the radiation situation was launched on board the ExoMars orbiting satellite in 2016. The first results of data on charged particle fluxes, dose rates, linear energy transfer (LET) spectra and estimates of dose equivalent velocities in interplanetary space showed that a person during a mission to Mars can receive about 0.66 sievert of radiation - a dose close to lethal.
Most of the radiation (95%) comes from cosmic rays, and only 5% from the sun. That is, for a year of flight to the Red Planet, the astronaut will receive 73 roentgen radiation. For example, on board the ISS, astronauts receive about 0.3 sievert per year.
“During a six-month flight to Mars and back, astronauts will accumulate at least 60% of the maximum radiation dose for the entire space career of a person, if the flight is carried out during a decrease in solar activity,” the researchers conclude.
GRIGORY PUSHKAREV