We're a long way from being able to do so in a population-saving way.
Which planets and moons in our solar system could support human life? Apart from the Earth, the answer is none. We may be able to build small colonies on Mars and/or Europa but the difficulty in building sizeable colonies in/on these places would be huge (cost of transport, cost of base building and maintenance, differences in gravity, decreased sunlight, transforming local resources into forms we can more easily use, etc...), the effort would be much better spent securing the life-support mechanisms of our own planet.
Which planets and moons in our solar system could support human life? Apart from the Earth, the answer is none. We may be able to build small colonies on Mars and/or Europa but the difficulty in building sizeable colonies in/on these places would be huge (cost of transport, cost of base building and maintenance, differences in gravity, decreased sunlight, transforming local resources into forms we can more easily use, etc...), the effort would be much better spent securing the life-support mechanisms of our own planet.