Measurements from Curiosity’s Radiation Assessment Detector (RAD) show radiation levels on the surface of Mars aren’t as intense as originally thought, meaning extended human visits on Mars just became more feasible!
According to Space.com, a round trip journey of 380 days, coupled with a 500 day stay on the red planet, would result in an exposure of 1.01 Sieverts (a measurement of the absorption of radiation) from Galactic Cosmic Rays and Solar Energetic Particles.
Humans on the surface of the Earth are typically exposed to just a few thousandths of a Sievert every year, so that 880 day trip to Mars would produce about a 5% increase in risk of cancer over a lifetime.
However, 1.01 Sieverts may be low due to the Sun’s 11-year peak scattering the Galactic Cosmic Rays and resulting in less exposure. Since NASA intends to send humans to Mars in the mid-2030’s, and the Sun will once again peak in 2035, that may line up perfectly.