lander

A lander is a spacecraft designed to descend from space and touch down on the surface of a planetary body, such as the Moon, a planet, an asteroid, or a comet, with the goal of performing measurements at the site and operating there for an extended period. Unlike orbiters that observe from above or rovers that move across terrain, landers provide in situ data from a fixed position or a short-range deployment.

Key elements of a lander's design include descent and landing systems, such as heat shields, parachutes, retrorockets or thrusters, and landing legs or feet to absorb impact. Systems for navigation, guidance and control enable a gentle touchdown and stable posture. Power is typically provided by solar panels or energy stores, and thermal control keeps instruments within operating temperatures. After landing, instruments may include seismometers, spectrometers, cameras, environmental sensors, drills, and sample-collection devices. Some landers deploy rovers, small stations, or other surface experiments.

Notable landers include the Viking landers on Mars (1976); the Surveyor program for the Moon (1966–1968); the Apollo Lunar Module (Moon, 1969–1972); Huygens on Saturn’s moon Titan (2005); Philae on comet 67P/Churyumov–Gerasimenko (2014); InSight on Mars (2018); and China's Chang'e landers on the Moon (Chang'e 3 in 2013, Chang'e 4 in 2019) as well as Tianwen-1's lander on Mars (2021) with the Zhurong rover. Landers have advanced geology, geophysics, atmosphere studies, and comparative planetology, while confronting challenges such as precise targeting, survivability in harsh environments, and energy management.