Heat should help add atmosphere to some degree. Solid co2 could gasify and some frozen water could enter the atmosphere.
If you can heat the planet up, you can start redirecting comets or asteroids rich in water ice and frozen CO2 into it to get a thicker atmosphere.
I'm looking for the day where 1000 Starships pull a million ton ice asteroid into Mars in order to thicken its atmosphere.
A million tons of ice would add more or less the water content of a medium-small fishing pond on the whole planet (or a cube with 100 meter sides).
The order of magnitude of would require stripping Ceres of it's mantle.
> Mere dozens of such Starship launches would be needed to substantially increase net insolation on Mars and begin raising the temperature, without the emplacement of any surface infrastructure.
Heating sounds like a good step, but aren't the major challenges a lack of atmosphere and magnetosphere? Having one without the others seems a bit useless to me. What am I missing?