Mars Without Biology: Three Paths to Warmth express
Mars is an icy desert with an average temperature of minus 60. To warm it without biology, scientists propose three approaches with a single idea: create a thick heat-trapping blanket.
First, deploy transparent film-blankets over bases. They let sunlight in but keep heat from escaping, allowing us to harvest water from the soil and grow plants. Second, launch giant mirrors into orbit. They would direct extra sunlight onto the ice caps to vaporize frozen carbon dioxide. Third, directly thicken the planet's gas blanket by adding carbon dioxide and other heat-retaining substances to the atmosphere.
Mars already has a thin blanket of sparse air. Doubling its density could raise temperatures by tens of degrees — like a glass of water under a blanket, slow but unstoppable. And Martian soil is rich in gases: start the heating, and they'll release on their own, amplifying the effect. A single city-sized mirror could trigger a chain reaction. For now, it's all being tested on Earth: for example, baking plastic for domes straight from local air and soil. Small investments today keep alive the chance to someday wrap the Red Planet in warmth.
Carbon dioxide on Mars freezes out of the atmosphere and falls as frost — much like the dry ice used to create fog at concerts.
In classic science fiction, such as Kim Stanley Robinson's 'Mars Trilogy', people deploy giant mirrors in orbit to melt the polar caps and build an atmosphere.