This is an unflown Gemini personnel parachute. These nylon parachutes would be used only in aborts and emergencies where the astronauts had to eject from the capsules. They were located at the right rear of each astronaut's backboard and their risers were attached to the astronaut's personal harness. After the astronaut had ejected from the capsule, a drogue mortar fired at or below 5,700 feet altitude, which separated the backboard/seat from the astronaut and deployed the parachute.
Northrop Ventura made this parachute in 1965. In 1971, McDonnell Douglas Astronautics Company in St. Louis transferred many leftover artifacts from the Gemini program to the Smithsonian on behalf of the National Aeronautics and Space Administration, including this parachute. The former McDonnell Aircraft Corporation had manufactured the Gemini spacecraft.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.