Enceladus Atmosphere

Oops, i mean nearby stars, of course. Sorry

I thought that was probably what you meant... just checking.

The biggest problem with terraforming planets around other stars is that the nearest star to ours is still 4.2 light years away. Traveling that distance within anyone's lifetime (either manned or unmanned) is going to be tough with the current laws of physics

Well, travel times are a problem indeed. And even if you assume resasonably high speeds of 0.1 to 0.2c, it will still take decades or centuries, depending on your target. Furthermore, the next star system is Alpha Centauri, a trinary star system, hence no good place for planets to form. Thus, stars with habitable/terraformable planets will be further away.

The work-around wound be either 'freezing' the crew (which would probably be risky), or vastly increasing the lifespan of the crew (which would be risky as well due to psychological factors).