> While it is true that the solar wind has stripped Mars of much of its original atmosphere (due to the lack of the planet's magnetic field), and that any man-made atmosphere on Mars would eventually be dissipated by the solar wind - the speed at which this occurs is measured over geological time frames - on the scale of tens, if not hundreds of millions of years. If humanity were to create an artificial, life-conducive atmosphere on Mars, any atmospheric output due to economic activity (CO2 + other gases) would easily exceed any atmospheric losses. Thus, the atmosphere would be stable.

From ... https://www.reddit.com/r/SpaceX/wiki/faq/mars#wiki_what_will...