How many orbiters did NASA originally plan to build for the Space Shuttle program? Didn't 20+ launches per year seem like too much for a fleet of four orbiters? - Quora
Space Shuttle - FlightGear wiki
Space Shuttle Atlantis - Simple English Wikipedia, the free encyclopedia
Space Shuttle - Wikipedia
Space Shuttle - FlightGear wiki
NASA - Launch and Landing
Launch of Space Shuttle Atlantis on STS-125 Mission | Flickr
Space Shuttle - FlightGear wiki
Slim Shuttle - Kerbal Space Program Wiki
Space Shuttle Discovery - Wikipedia
Space Shuttle - Wikiwand
File:Space Shuttle Discovery on Display.jpg - Wikimedia Commons
NASA salvages old space shuttle parts for the ISS | Engadget