Martian air has a partial pressure of CO 2 of 0.71 kPa, compared to 0.031 kPa on Earth.The Martian atmosphere is 95% carbon dioxide, 3% nitrogen, 1.6% argon, and traces of other gases including oxygen totaling less than 0.4%.Since terraforming cannot be expected as a near-term solution, habitable structures on Mars would need to be constructed with pressure vessels similar to spacecraft, capable of containing a pressure between 30 and 100 kPa. The atmospheric pressure on Mars is far below the Armstrong limit at which people can survive without pressure suits.Due to the lack of a magnetosphere, solar particle events and cosmic rays can easily reach the Martian surface.Mars's orbit is more eccentric than Earth's, increasing temperature and solar constant variations.Also, year-round dust storms on Mars may block sunlight for weeks at a time. The maximum solar irradiance on Mars is about 590 W/m 2 compared to about 1000 W/m 2 at the Earth's surface.
However, due to the much thinner atmosphere, a higher fraction of the solar energy reaches the surface.