Chance of an asteroid hitting Mars is tens or even hundreds times greater than it hitting Earth. Not to mention that Mars has barely any atmosphere, so even a r

Chance of an asteroid hitting Mars is tens or even hundreds times greater than it hitting Earth. Not to mention that Mars has barely any atmosphere, so even a relatively small meteor (5-15 meters across) will be able to penetrate it and cause chaos. If we have to terraform anything, why not first learn to do it here on Earth? Plenty of inhospitable space that we can turn green, no need to go to Mars. Doing that will almost double the amount of living space for the human population. Earth is a big planet. There is also ample space deeper underground. Why not make entire high-tech undergound cities? Doing it will allow us to plan similar projects on Mars, or even some day, on Titan. Conditions underground on very cold planets should be much more "habitable", than those on freezing surface. While we are at it, even the Moon has cave systems where various research can be made and where people can get shelter from radiation.