If future Mars colonizers want to survive without pressure suits, they’ll need to generate a denser atmosphere. One way to achieve this could be to bombard the Red Planet with water-rich asteroids.

Depending on whom you talk to, terraforming could take anywhere from ... The lack of gravity may cause humans on Mars to evolve differently than on Earth. Mars has one-third the gravity of Earth ...

Mars may be the most Earth-like of the other planets in our Solar System, but it's still an inhospitably cold desert world with a thin and unbreathable atmosphere. If humans are ever going to ...