A lander is a spacecraft that descends towards, then comes to rest on the surface of an astronomical body other than Earth. In contrast to an impact probe, which makes a hard landing that damages or destroys the probe upon reaching the surface, a lander makes a soft landing after which the probe remains functional. For bodies with atmospheres, the landing occurs after atmospheric entry. In these cases, landers may employ parachutes and atmospheric entry to slow the probe down to maintain a low terminal velocity. In some cases, small landing rockets will be fired just before impact in order to reduce the lander's velocity on impact. Landing may be accomplished by controlled descent and set down on landing gear, with the possible addition of a post-landing attachment mechanism (such as the mechanism used by Philae) for celestial bodies with low gravity. Some missions (for example, Luna 9 and Mars Pathfinder) used inflatable airbags to cushion the lander's impact rather than utilizing more traditional landing gear. When a high-velocity impact is intentionally planned in order to study the consequences of impact, the spacecraft is called an impactor. Several terrestrial bodies have been subject to lander or impactor exploration. Among them are Earth's Moon; the planets Venus, Mars, and Mercury; Saturn's moon Titan; asteroids; and comets.
Landers
Lunar
Beginning with Luna 2 in 1959, the first few spacecraft to reach the lunar surface were impactors, not landers. They were part of the Soviet Luna program or the American Ranger program. In 1966, the Soviet Luna 9 became the first spacecraft to achieve a lunar soft landing and to transmit photographic data to Earth. The American Surveyor program (1966–1968) was designed to determine where Apollo could land safely. As a result, these robotic missions required soft landers to sample the lunar soil and determine the thickness of the dust layer, which was unknown before Surveyor. The U.S.-crewed Apollo Lunar Modules (1969–1972) with rovers (1971–1972) and late Soviet large robotic landers (1969–), Lunokhods (1970–1973) and sample return missions (1970–1976) used a rocket descent engine for a soft landing of astronauts and lunar rovers on the Moon. The Chinese Chang'e 3 mission and its Yutu ('Jade Rabbit') rover landed on 14 December 2013. In 2019, China's Chang'e 4 mission successfully landed the Yutu-2 rover on the far side of the Moon. Chang'e 5 and Chang'e 6 are designed to be sample return missions. Chang'e 5 and 6 were conducted successfully in 2020 and 2024 respectively. Chang'e 5 mission landed on the Moon on 1 December 2020, China completed the Chang'e 5 mission on 16 December 2020 with the return of approximately 2 kilograms of lunar sample. On 6 September 2019, the lander Vikram on Chandrayaan-2, attempting to land on the lunar south polarregion. Due to software glitch, it lost contact and crashed moments before landing. About 4 years later, on 23 August 2023, the lander Vikram on Chandrayaan-3 successfully touched down on the lunar south pole, close to the crater Manzinus U. This made it the first lander to soft land at the south pole of the Moon. Japan became the fifth country to land a lunar probe on 19 January 2024, by successfully landing its SLIM lander. On 22 February 2024, Intuitive Machine's Odysseus successfully landed on the Moon after taking off on a SpaceX Falcon 9. This was the first successful landing of a privately owned spacecraft on the Moon. China sent Chang'e 6 on 3 May 2024, which conducted the first lunar sample return from Apollo Basin on the far side of the Moon. This is China's second lunar sample return mission, the first was achieved by Chang'e 5 from the lunar near side four years earlier. It also carried the Chinese Jinchan rover to conduct infrared spectroscopy of lunar surface and imaged Chang'e 6 lander on lunar surface. The lander-ascender-rover combination was separated with the orbiter and returner before landing on 1 June 2024 at 22:23 UTC. It landed on the Moon's surface on 1 June 2024. The ascender was launched back to lunar orbit on 3 June 2024 at 23:38 UTC, carrying samples collected by the lander, and later completed another robotic rendezvous and docking in lunar orbit. The sample container was then transferred to the returner, which landed in Inner Mongolia on 25 June 2024, completing China's far side extraterrestrial sample return mission. Planned for 2028, NASA's Artemis IV would be the first crewed lunar landing in over 50 years, utilizing the Orion spacecraft. The planned landing site is the lunar south pole, with the mission lasting for ~30 days with the goal of a sustained lunar presence.
Venus
The Soviet Venera program included a number of Venus landers, some of which were crushed during descent much as Galileo's Jupiter "lander" and others which successfully touched down. Venera 3 in 1966 and Venera 7 in 1970 became the first impact and soft landing on Venus respectively. The Soviet Vega program also placed two balloons in the Venusian atmosphere in 1985, which were the first aerial tools on other planets.
Mars
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