• 
  Michio Kaku

  Himself - Theoretical Physicist
• 
  Gene Kranz

  Himself - NASA Flight Controller
• 
  Jim Lovell

  Himself - Astronaut
• 
  Story Musgrave

  Himself - Astronaut
• 
  Bill Nye

  Himself - CEO Planetary Society
• 
  John M. Logsdon

  Himself - Professor George Washington University
• 
  Marcia Smith

  Herself - Space Journalist
• 
  Lamar Smith

  Himself - Congressman

• 
  Norman Augustine

  Himself - Chairman Review of Human Spaceflight Committee
• 
  Mark Sirangelo

  Himself - Vice President, Sierra Nevada Corporation
• 
  Michelle Stellhorn

  Herself - School Teacher
• 
  Jeff Greason

  Himself - Founder, XCOR Aerospace
• 
  Jeff Bingham

  Himself - Congressional Staff
• 
  Neil deGrasse Tyson

  Self - Astrophysicist
• 
  Robert Zubrin

  Self - Astronautical Engineer

• 
  Dale Myers

  Self
• 
  Rick Tumlinson

  Self - Space Activist
• 
  John Vilja

  Self
• 
  James Muncy

  Self