let's watch chris cassidy in space. >> i'm going to go out on a limb here. so please join me in the barber shop. this is how we cut hair in space. have you the standard hair trimmer, the hair would go all over the place. so we need to connect it to a vacuum cleaner, which is right here. then we're ready to cut hair. what do you think so far? should i stop here? that's pretty close to what luca has going on now, but not quite. nasa wants it completely smooth on the top, so i still have one more step to do. what if he does this every day? it kind of hurts. >> luca is the italian? >> yes. >> so he's on the space station now? >> yes. >> was that his gd idea to do that? >> totally chris' idea. people have always accused chris of he and luca looking alike, so it is sort of to make luca feel at home. this is the story i was told. chris decided, shucks, i look like you anyway, we may as well become twins. >> how long do they stay up there? >> they are there six months at a time. luca now is about halfway through chris' tenure. chris came up halfway through chris hat

give up never slow down ♪ ♪ never grow old never ever die young ♪ >> astronaut and navy commander chris cassidynnedy's words. >> i am talking about genuine peace, the kind of peace that makes life on earth worth living, the kind that enables men and nations. >> to grow and to hope and build a better life for their children. >> today the historian david mccullough reminded this crowd what was important about john f. kennedy. >> he knew words mattered. his words changed lives. his words changed history. >> and about that last man we just heard from, the organizers of this event today were wise enough to invite one of the wisest men in our nation to speak here today, the great historian and author david mccullough. after the public ceremony, we met inside the book depository building to talk about dallas, about john f. kennedy and the course of history. >> i think the three things that i would value most, not just from my point of view but from the point of view of the country and the history of the country, are his use of language, his use of words to move us, to lift us like lincoln did and fran

this is really about what's happening right now, so we were lucky enough to get commander chris cassidyor us on the international space station and there he is floating in zero gravity with a coin with kennedy's head on it and talking about how kennedy's call to go to space in 1961 really has impacted his desire to be an astronaut and all of our space exploration efforts, so drawing that thread between when kennedy was alive up until today is really kind of the point of the site. you're right, the personal stories are what make it, so i think human and fascinating. >> what is the one story that stands out the most? >> that is a really good question. i'm going to give you a cop out. i hate to do it, but individual stories are so wonderful, we got a chance to go to main to interview president obama's inaugural poet and he talks about how he feels a connection to robert frost, kennedys nag really a poet. there are so many stories individually. if you visit the site, you'll see as they begin to build up and you see more and more, the best part really is them in total and the diversity of vo