— Ch. 1 · Defining Soft And Hard Landings —
Lander (spacecraft).
~4 min read · Ch. 1 of 5
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. When a high-velocity impact is intentionally planned in order to study the consequences of impact, the spacecraft is called an impactor. For bodies with atmospheres, the landing occurs after atmospheric entry. In these cases, landers may employ parachutes to slow them down enough 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. Landing may be accomplished by controlled descent and set down on landing gear, with the possible addition of a post-landing attachment mechanism for celestial bodies with low gravity. Some missions used inflatable airbags to cushion the lander's impact rather than utilizing more traditional landing gear.
The Soviet Lunar Pioneer Era
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 ran from 1966 through 1968 and was designed to determine where Apollo could land safely. 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 operated between 1969 and 1972 with rovers running from 1971 to 1972. Late Soviet large robotic landers known as Lunokhods functioned from 1970 to 1973. Sample return missions occurred between 1970 and 1976 using rocket descent engines for soft landings of astronauts and lunar rovers on the Moon.Modern Lunar Exploration Milestones
The Chinese Chang'e 3 mission and its Yutu rover landed on the 14th of 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 were conducted successfully in 2020 and 2024 respectively. Chang'e 5 mission landed on the Moon on the 1st of December 2020, China completed the Chang'e 5 mission on the 16th of December 2020 with the return of approximately 2 kilograms of lunar sample. On the 6th of September 2019, the lander Vikram on Chandrayaan-2 lost contact and crashed moments before landing due to a software glitch. About four years later, on the 23rd of 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 the 19th of January 2024 by successfully landing its SLIM lander. On the 22nd of February 2024, Intuitive Machine's Odysseus successfully landed on the Moon after taking off on a SpaceX Falcon 9.