Forbes Earlier today, the Maven mission announced their first science results, and what we found was a tremendous confirmation of what we expected, along with some incredibly precise details... by Ethan Siegel
'Water was abundant and active on Mars for the first few hundred million years of the Solar System, with oceans, rivers, rains and more.
'However, at some point less than a billion years after Mars formed, its global magnetic field ceased to be, removing the planet’s main source of protection from the solar wind.
'As measured at the top of Mars’ atmosphere, the solar wind — fast moving particles that are mostly protons — strikes the red planet at about 1,000,000 mph (447,000 m/s, or about 0.15% the speed of light), an incredibly fast rate.
'The particles it collides with wind up moving so quickly that they have enough energy to escape from Mars’ gravity; Mars presently loses about 100 grams (a quarter of a pound) of atmosphere every second.
'If there was life on the surface of Mars early on, the atmospheric changes were gradual enough that we have reason to believe it could have evolved to find a suitable niche where it may survive even to the present day.
'If we decided to terraform Mars by artificially creating a dense atmosphere, it would survive for many millions of years today before we needed to replenish it.'