they are just so far away from us, even a distance of 1 lightyear is too much for manned space missions. as everyone knows only light, which has no mass, can travel the speed of light.
also there's the wait calculation, go too early and u'd still arrive there earlier 1000 years later with better technology
awesome song m8, i hope u put this on youtube i am sure ppl will like it
also, if we r talking about simple lifeform like bacteria, maybe we don't need to travel as far