Tucson recently was the scene of a space invasion, with former astronauts, space artists, scientists, fiction writers and space geeks here for the eighth edition of Spacefest.
Kara Sircy of Knoxville, Tennessee, the daughter of a former Space Shuttle contractor and space "fan girl."
James Hansen, a history professor at Auburn University in Alabama and author of the only authorized biography of Neil Armstrong, "First Man."
Nicole Stott, a two-time astronaut and now a space artist.
Riki Goss, a 10-year-old from Santa Barbara, California, who is interested in the mysteries of space.
Emily Carney of St. Petersburg, Florida, an author and founder of the Facebook group Space Hipsters.