There could be no exchange program because it takes 1000's of years to get to the nearest system with Sentient Alien life. It would require a spaceship built by all of HumanKind and would have a tiny crew of 3-4 who would have to be in hypersleep the whole journey. There is no Zeta-Retculi and there is no exchange program and for any Sentient Alien race to send astronauts here still takes 1000's of years for them to get here.
"Trust me I know what I'm doing" Detective Sledge Hammer