Jerrie Cobb, a well known female pilot in the 1950s, testing Gimbal Rig in the Altitude Wind Tunnel, AWT in April 1960. The Gimbal Rig, formally called MASTIF or Multiple Axis Space Test Inertia Facility, was used to train astronauts to control the spin of a tumbling spacecraft. Jerrie Cobb was the first female to pass all three phases of the Mercury Astronaut Program but NASA rules stipulated that only military test pilots could become astronauts and there were no female military test pilots. Jerrie completed this astounding feat in 1961. The MASTIF was installed at the Altitude Wind Tunnel at the Lewis Research Center, now John H. Glenn Research Center. Three tubular aluminum cages could revolve separately or in combination to give roll, pitch and yaw motions at speeds up to 30 revolutions per minute, greater than those expected in actual space flight. Nitrogen-gas jets, attached to the three cages, controlled the motion. NASA engineers built the entire rig inside a test chamber in the research center's old Altitude Wind Tunnel. Geraldyn "Jerrie" M. Cobb (born March 5, 1931) is an American aviator. She was also part of the "Mercury 13," a group of women selected to undergo physiological screening tests at the same time as the original Mercury Seven astronauts, as part of a private, non-NASA program. NASA photograph April 6, 1960.