NASA Scientist: Astronauts Could Absolutely Live On Mars Business Insider

The Mars Curiosity rover is three months into its two-year mission to determine if Mars was, or still is, able to support life.
One life-limiting factor to habitability — and critical to a future manned mission to Mars — is the level of radiation, from cosmic rays and solar particles, that gets to the planet’s surface.
To measure this, an instrument onboard the rover called the Radiation Assessment Detector, or “RAD,” has been collecting data on the daily cycles of radiation reaching Curiosity.