Grumman Gulfstream II NASANASA Gulfstream II airplane model. To meet a critical Space Shuttle program requirement, NASA extensively modified six Gulfstream II C 11 aircraft to allow Space Shuttle Astronauts to practice their Shuttle landing procedures. Since a Space Shuttles return from space allowed only one unpowered approach and landing, the astronauts needed repetitive practice landings in the Shuttle Training Aircraft (STA) to ensure safe landings at Kennedy Space Center,