Near-Earth object focused on asteroids and short-period comets. CNEOS even restricts its definition of NECs to short-period comets—, 107 such objects have been discovered. , only 20 comets have been observed to pass within of Earth, including 10 which are or have been short-period comets. Two of these comets, Halley's Comet and 73P/Schwassmann–Wachmann, have been observed during multiple close approaches. The closest observed approach was 0.0151 AU (5.88 LD) for Lexell's Comet on July 1, 1770. After an orbit change due to a close approach of Jupiter in 1779, this object is no longer a NEC. The closest approach ever observed for
Earth orbit rendezvous and Gemini 7 rendezvoused in orbit in 1965, but without Agena. Next, Gemini 8 successfully docked with the Agena on March 16, 1966. The Agena-Gemini rendezvous also achieved other objectives in later Gemini launches, including docked orbital maneuvering (Gemini 10 and Gemini 11), inspection of the abandoned Gemini 8 ATV (Gemini 10) and space walks (Gemini 12). The EOR proposal for Apollo consisted of using a series of small rockets half the size of a Saturn V to put different components of a spacecraft to go to the Moon in orbit around the Earth, then assemble them in orbit. Experiments