"Our measurements provide crucial information for human missions to Mars," said Dr.
Two forms of radiation pose potential health risks to astronauts: a chronic low dose of galactic cosmic rays (GCRs) and the possibility of short-term exposures to the solar energetic particles (SEPs) associated with solar flares and coronal mass ejections. The radiation on Mars is much harsher than on Earth for two reasons: Mars lacks a global magnetic field and the Martian atmosphere is much thinner than Earth's, providing little shielding to the surface.
This environmental factor poses a challenge for future human exploration of Mars and is also important in understanding both geological and potential biological evolution on Mars. Both GCRs and SEPs interact with the atmosphere and, if energetic enough, penetrate into the Martian soil, or regolith, where they produce secondary particles that contribute to the complex radiation environment on the Martian surface, which is unlike anything on Earth.
"The RAD surface radiation data show an average GCR dose equivalent rate of 0.67 millisieverts per day from
According to RAD data, most mission radiation exposure will be during outbound and return travel, when astronauts will be exposed to the radiation environment in interplanetary space, shielded only by the spacecraft itself. The total dose during just the transit phases of a Mars mission would be approximately 0.66 Sv for a round trip with current propulsion systems and during similar solar activity. A 500-day mission on the surface would bring the total exposure to around 1 Sv.
Long-term population studies have shown that exposure to radiation increases a person's lifetime cancer risk; exposure to a dose of 1 Sv is associated with a five percent increase in fatal cancer risk. Although
SwRI, together with
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