Here's the thing about traveling to other planets.
We can get to a planet that's 20 light years away, and have it so from the astronaut's perspective only a few months have passed. But from Earth's perspective, more than 20 years will have passed. So it is realistic to travel to other planets, but not in a manner where the astronaut can make the return trip in our lifetimes.
Unless there's some way to cheat relativity that hasn't been discovered yet. I suppose I can't prove it's impossible but I'm not holding my breath.