venus...

so the heat shield can make venus a possible place to be. after some transformation,venus can be a better place than mars.

more...

so it is possible a make a heat shield for earth with some billions dollars. it is quite cheap in my opinion. all you need is black smoke rockets. it will last some years since it is in space.  

smoky rockets...

carbon particles from smoky rockets can provide a heat shield when the sun become too strong. firing rockets in orbit would be a simple task.