Gemini 1 was the first mission in NASA's Gemini program. An uncrewed test flight of the Gemini spacecraft, its main objectives were to test the structural integrity of the new spacecraft and modified Titan II launch vehicle. It was also the first test of the new tracking and communication systems for the Gemini program and provided training for the ground support crews for the first crewed missions.
Originally scheduled for launch in December 1963, difficulties in the development of both the spacecraft and its booster caused four months of delay. Gemini 1 was launched from Launch Complex 19 at Cape Kennedy (now Canaveral), Florida on April 8, 1964. The spacecraft stayed attached to the second stage of the rocket. The mission lasted for three orbits while test data were taken, but the spacecraft stayed in space for almost 64 orbits until its orbit decayed due to atmospheric drag. The spacecraft was not intended to be recovered, and holes were drilled through its heat shield to ensure it would not survive re-entry.
Background
Project Gemini was conceived as a bridge between America's single-seat Project Mercury and the three-seat Project Apollo. With a design largely extrapolated from its predecessor,
Its two-person capacity and greater capabilities meant that Gemini would be a substantially heavier spacecraft than Mercury had been — too heavy to be lofted into orbit by Mercury's Atlas rocket. A replacement was needed. The newly developed Titan II ICBM (which had also been tapped by the Air Force for its X-20 spaceplane project) was an attractive replacement. It had a thrust some two and a half times that of the Atlas, a far simpler mechanical construction, and the ability to store propellants indefinitely. Moreover, the Titan II's propellants mixed less violently than those of Atlas meaning a booster explosion, should it happen, would be less violent. This made obsolete the heavy escape tower used in the Mercury program; instead, ejection seats could be used.
Pre-flight
Gemini Spacecraft Number 1 was built specifically for the uncrewed mission. Most internal systems were replaced with dummies and ballast approximating the weight and balance of the crewed spacecraft. In place of the crew couches, two pallets of instruments were installed for the relaying via telemetry of the pressure, vibration, acceleration, temperature, and structural loads experienced during the short flight. A spacecraft heat shield was installed, but four large holes were drilled in it to ensure Gemini 1 was destroyed during reentry.
Inefficient project management threatened to further delay the first Gemini launch, which by November had already been pushed back to February 28, 1964. Gemini Manager Charles Mathews united the several disparate teams into a single Gemini Launch Vehicle Coordination Committee with clearly defined management and communication channels.
The spacecraft achieved orbit five and a half minutes after launch. The launch vehicle had imparted an excess 7 meters (24 feet) per second of velocity to the Gemini 1, placing the spacecraft into an orbit with an apogee of instead of the planned . This lengthened Gemini 1's lifespan from the planned three and a half days to four. and only the first three orbits — lasting four hours and 50 minutes — were part of the flight plan. Gemini 1 and its attached second stage were tracked by the Manned Space Flight Network until they reentered over the South Atlantic, midway between South America and Africa, on April 12, 1964, during their 64th orbit.