A lunar lander or Moon lander is a spacecraft designed to land on the surface of the Moon. As of 2021, the Apollo Lunar Module is the only lunar lander to have ever been used in human spaceflight, completing six lunar landings from 1969 to 1972 during the United States' Apollo Program. The design requirements for these landers depend on factors imposed by the payload, flight rate, propulsive requirements, and configuration constraints. Other important design factors include overall energy requirements, mission duration, the type of mission operations on the lunar surface, and life support system if crewed. The relatively high gravity and lack of lunar atmosphere negates the use of aerobraking, so a lander must use propulsion to decelerate and achieve a soft landing. Several studies indicate the potential for both scientific and technological benefits from sustained lunar surface exploration that would culminate in the utilization of lunar resources, or in the development of the necessary technology to land payloads on other planets in the Solar System. History The Luna program was a series of robotic impactors, flybys, orbiters, and landers flown by the Soviet Union between 1958 and 1976. Luna 9 was the first spacecraft to achieve a soft landing on the Moon on February 3, 1966, after 11 unsuccessful attempts. Three Luna Spacecraft returned lunar soil samples to Earth from 1972 to 1976. Two other Luna spacecraft soft-landed the Lunokhod robotic lunar rover in 1970 and 1973. Luna achieved a total of seven successful soft landings, out of 27 attempts. The United States' Surveyor program first soft-landed Surveyor 1 on June 2, 1966, and successfully soft-landed four more, in a total of seven attempts through January 10, 1968. The Apollo Lunar Module was the lunar lander for the United States' Apollo program. As of 2022, it is the only lunar lander to have ever been used in human spaceflight, completing six lunar landings from 1969 to 1972. The LK lunar module was the lunar lander developed by the Soviet Union as a part of several Soviet crewed lunar programs. Several LK lunar modules were flown without crew in low Earth orbit, but the LK lunar module never flew to the Moon, as the development of the N1 Rocket Launch Vehicle required for the lunar flight suffered setbacks (including several launch failures), and after the first human Moon landings were achieved by the United States, the Soviet Union cancelled