The terraforming scenarios articulate around the increase in temperature and atmospheric density of Mars, which gives it breathable air, liquid water and favorable temperatures. to human and plant life. Three main ideas for how to do that. In the first, giant space mirrors would gravitate around the planet, reflecting sunlight on Mars and heating it. They weigh about 200,000 pounds, too big to be created and thrown from the Earth. The second is to build greenhouse gas plants on the surface of Mars, using them to warm up the Martian climate, in the same way that current fossil fuels cause global warming. The third is perhaps the most extraordinary: capturing large nitrogen-rich asteroids, attaching engines to them and sending them to Mars until they collide with its surface. It is estimated that four of these impacts would be sufficient to create conditions similar to those of the Earth on Mars.