A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.[3]
In 1969 Apollo 11 was the first crewed mission to land on the Moon.[4] There were six crewed landings between 1969 and 1972, and numerous uncrewed landings. All crewed missions to the Moon were conducted by the Apollo program, with the last departing the lunar surface in December 1972. After Luna 24 in 1976 there were no soft landings on the Moon until Chang'e 3 in 2013. All soft landings took place on the near side of the Moon until January 2019, when Chang'e 4 made the first landing on the far side of the Moon.[5]
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Six government space agencies, Interkosmos, NASA, CNSA, ISRO, JAXA and ESA, have reached the Moon with uncrewed missions. Three private/commercial missions, Beresheet (hard landing), Hakuto-R (hard landing), and Odysseus (soft landing) have also reached the lunar surface (see #Commercial landings). The Soviet Union (Interkosmos), the United States (NASA), China (CNSA), India (ISRO),[6] and Japan (JAXA)[7] are the only five nations to have successfully achieved soft landings.
The Soviet Union performed the first hard Moon landing – "hard" meaning the spacecraft intentionally crashes into the Moon at high speeds – with the Luna 2 spacecraft in 1959, a feat the U.S. duplicated in 1962 with Ranger 4.
Following their initial hard landings on the Moon, sixteen Soviet, U.S., Chinese and Indian spacecraft have used braking rockets (retrorockets) to make soft landings and perform scientific operations on the lunar surface. In 1966 the Soviet Union accomplished the first soft landings and took the first pictures from the lunar surface during the Luna 9 and Luna 13 missions. The U.S. followed with five Surveyor soft landings. China's ongoing "Chang'e" program has landed 4 times since 2013, achieving robotic soil sample return and the first landing on the far side of the Moon.
On 23 August 2023, ISRO successfully landed its Chandrayaan-3 module in the lunar south pole region, making India the fourth nation to successfully complete a soft landing on the Moon.[8] Chandrayaan-3 saw a successful soft landing of its Vikram lander and Pragyan rover at 6.04 pm IST (1234 GMT), marking the first uncrewed soft landing in the little-explored region.[9]
On 19 January 2024, JAXA successfully landed its SLIM lander, making Japan the fifth nation to successfully complete a soft landing.[10]
Two organizations have attempted but failed to achieve soft landings: Israeli private space agency SpaceIL with their Beresheet spacecraft (2019), and Japanese company ispace's Hakuto-R Mission 1 (2023).
On 22 February 2024, Intuitive Machine's Odysseus successfully landed on the Moon after taking off on a SpaceX Falcon 9 liftoff on 15 February 2024 in a mission between NASA, SpaceX, and Intuitive Machines, marking the United States' first soft unmanned Moon landing in over 50 years. This event marked the first successful landing of a privately owned spacecraft on the Moon.[11][12]
A total of twelve astronauts have landed on the Moon. This was accomplished with two pilot-astronauts flying a Lunar Module on each of six NASA missions. The missions spanned a 41-month period starting 20 July 1969, beginning with Neil Armstrong and Buzz Aldrin on Apollo 11, and ending on 14 December 1972 with Gene Cernan and Harrison Schmitt on Apollo 17. Cernan was the last man to step off the lunar surface.
All Apollo lunar missions had a third crew member who remained on board the command module.
To get to the Moon, a spacecraft must first leave Earth's gravity well; currently, the only practical means is a rocket. Unlike airborne vehicles such as balloons and jets, a rocket can continue accelerating in the vacuum outside the atmosphere.
Upon approach of the target moon, a spacecraft will be drawn ever closer to its surface at increasing speeds due to gravity. In order to land intact it must decelerate to less than about 160 kilometres per hour (100 mph) and be ruggedized to withstand a "hard landing" impact, or it must decelerate to negligible speed at contact for a "soft landing" (the only option for humans). The first three attempts by the U.S. to perform a successful hard Moon landing with a ruggedized seismometer package in 1962 all failed.[13] The Soviets first achieved the milestone of a hard lunar landing with a ruggedized camera in 1966, followed only months later by the first uncrewed soft lunar landing by the U.S.
The speed of a crash landing on its surface is typically between 70 and 100% of the escape velocity of the target moon, and thus this is the total velocity which must be shed from the target moon's gravitational attraction for a soft landing to occur. For Earth's Moon, the escape velocity is 2.38 kilometres per second (1.48 mi/s).[14] The change in velocity (referred to as a delta-v) is usually provided by a landing rocket, which must be carried into space by the original launch vehicle as part of the overall spacecraft. An exception is the soft moon landing on Titan carried out by the Huygens probe in 2005. As the moon with the thickest atmosphere, landings on Titan may be accomplished by using atmospheric entry techniques that are generally lighter in weight than a rocket with equivalent capability.
The Soviets succeeded in making the first crash landing on the Moon in 1959.[15] Crash landings[16] may occur because of malfunctions in a spacecraft, or they can be deliberately arranged for vehicles which do not have an onboard landing rocket. There have been many such Moon crashes, often with their flight path controlled to impact at precise locations on the lunar surface. For example, during the Apollo program the S-IVB third stage of the Saturn V rocket as well as the spent ascent stage of the Lunar Module were deliberately crashed on the Moon several times to provide impacts registering as a moonquake on seismometers that had been left on the lunar surface. Such crashes were instrumental in mapping the internal structure of the Moon.
To return to Earth, the escape velocity of the Moon must be overcome for the spacecraft to escape the gravity well of the Moon. Rockets must be used to leave the Moon and return to space. Upon reaching Earth, atmospheric entry techniques are used to absorb the kinetic energy of a returning spacecraft and reduce its speed for safe landing. These functions greatly complicate a moon landing mission and lead to many additional operational considerations. Any moon departure rocket must first be carried to the Moon's surface by a moon landing rocket, increasing the latter's required size. The Moon departure rocket, larger moon landing rocket and any Earth atmosphere entry equipment such as heat shields and parachutes must in turn be lifted by the original launch vehicle, greatly increasing its size by a significant and almost prohibitive degree.
The political context of the 1960s helps to parse both the United States and Soviet Union's efforts to land spacecraft, and eventually humans, on the Moon. World War II had introduced many new and deadly innovations including blitzkrieg-style surprise attacks used in the invasion of Poland and Finland, as well as in the attack on Pearl Harbor; the V-2 rocket, a ballistic missile which killed thousands in attacks on London and Antwerp; and the atom bomb, which killed hundreds of thousands in the atomic bombings of Hiroshima and Nagasaki. In the 1950s, tensions mounted between the two ideologically opposed superpowers of the United States and the Soviet Union that had emerged as victors in the conflict, particularly after the development by both countries of the hydrogen bomb.
On 4 October 1957, the Soviet Union launched Sputnik 1 as the first artificial satellite to orbit the Earth and so initiated the Space Race. This unexpected event was a source of pride to the Soviets and shock to the U.S., who could now potentially be surprise attacked by nuclear-tipped Soviet rockets in under 30 minutes.[17] The craft was also barely visible to the naked eye as the steady beeping of the radio beacon aboard Sputnik 1 as it passed overhead every 96 minutes, which was widely viewed on both sides[18] as effective propaganda to Third World countries demonstrating the technological superiority of the Soviet political system compared to that of the U.S. This perception was reinforced by a string of subsequent rapid-fire Soviet space achievements. In 1959, the R-7 rocket was used to launch the first escape from Earth's gravity into a solar orbit, the first crash impact onto the surface of the Moon, and the first photography of the never-before-seen far side of the Moon. These were the Luna 1, Luna 2, and Luna 3 spacecraft.
The U.S. response to these Soviet achievements was to greatly accelerate previously existing military space and missile projects and to create a civilian space agency, NASA. Military efforts were initiated to develop and produce mass quantities of intercontinental ballistic missiles (ICBMs) that would bridge the so-called missile gap and enable a policy of deterrence to nuclear war with the Soviets known as mutual assured destruction or MAD. These newly developed missiles were made available to civilians of NASA for various projects (which would have the added benefit of demonstrating the payload, guidance accuracy and reliabilities of U.S. ICBMs to the Soviets).
After the fall of the Soviet Union in 1991, historical records were released to allow the true accounting of Soviet lunar efforts. Unlike the U.S. tradition of assigning a particular mission name in advance of a launch, the Soviets assigned a public "Luna" mission number only if a launch resulted in a spacecraft going beyond Earth orbit. The policy had the effect of hiding Soviet Moon mission failures from public view. If the attempt failed in Earth orbit before departing for the Moon, it was frequently (but not always) given a "Sputnik" or "Cosmos" Earth-orbit mission number to hide its purpose. Launch explosions were not acknowledged at all.
The U.S. was not able to reach the Moon with the Pioneer and Ranger programs, with fifteen consecutive U.S. uncrewed lunar missions from 1958 to 1964 failing their primary photographic missions.[19][20] However, Rangers 4 and 6 successfully repeated the Soviet lunar impacts as part of their secondary missions.[21][22]
Three U.S. missions[13][21][23] in 1962 attempted to hard land small seismometer packages released by the main Ranger spacecraft. These surface packages were to use retrorockets to survive landing, unlike the parent vehicle, which was designed to deliberately crash onto the surface. The final three Ranger probes performed successful high altitude lunar reconnaissance photography missions during intentional crash impacts between 2.62 and 2.68 kilometres per second (9,400 and 9,600 km/h).[24][25][26]