Retired U.S. Navy flight surgeon and NASA astronaut Captain Jerry Linenger talks about the awe and peril of space travel. He spent five months on the Russian Space station Mir and wrote about the account in his book, Off the Planet: Surviving Five Perilous Months Aboard the Space Station Mir." He described the Mir as "six school buses all hooked together." During his time there, he says, he and fellow crew members had numerous brushes with death, lacked adequate supplies and battled constant system failures. Linenger's new book is Letters from Mir: An Astronaut's Letters to His Son.