A
lander is a
spacecraftA spacecraft is a craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflight carry people on board as...
which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the
landingthumb|right|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...
is called
atmospheric reentryAtmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
and the lander descends as a re-entry vehicle. In these cases landers may employ
aerobrakingAerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...
and
parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are made out of cloth, most commonly nylon....
s to slow down, often with small landing
rocketA rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of a jet of fast moving fluid exhaust from a rocket engine. Chemical rockets create their exhaust by the combustion of rocket propellant...
s which fire just before impact to bring the lander to rest relatively gently. The
Mars PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
mission also used inflatable
airbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
s to cushion the lander's impact.
A
lander is a
spacecraftA spacecraft is a craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflight carry people on board as...
which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the
landingthumb|right|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...
is called
atmospheric reentryAtmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
and the lander descends as a re-entry vehicle. In these cases landers may employ
aerobrakingAerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...
and
parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are made out of cloth, most commonly nylon....
s to slow down, often with small landing
rocketA rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of a jet of fast moving fluid exhaust from a rocket engine. Chemical rockets create their exhaust by the combustion of rocket propellant...
s which fire just before impact to bring the lander to rest relatively gently. The
Mars PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
mission also used inflatable
airbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
s to cushion the lander's impact. When a high velocity impact is planned, the spacecraft is called an impactor.
Several
terrestrial bodiesA terrestrial planet, telluric planet, rocky planet or inner planet is a planet that is primarily composed of silicate rocks. Within the solar system, the terrestrial planets are the closest planets to the Sun...
have been subject of lander and/or impact exploration: among them the planets
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
and
VenusVenus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6...
and the Saturn moon
TitanTitan , or Saturn VI, is the largest moon of Saturn, the only moon known to have a dense atmosphere,
and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
. Of the inner Solar System planets,
MercuryFor the liquid metallic element, see Mercury .Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three...
is the only one yet to be visited by a lander.
Mars
The Soviet Union's
Mars 2The Mars program was a series of Mars unmanned landers and orbiters launched by the Soviet Union in the early 1970s.The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander; they were the first human artifacts to impact the surface of Mars...
lander was the first Earth based mission to reach the surface of Mars in 1973, but communication was lost within a minute after touchdown, which occurred during one of the worst global dust storms since the beginning of telescopic observations of the Red Planet. Three other probes,
Mars 3The Mars program was a series of Mars unmanned landers and orbiters launched by the Soviet Union in the early 1970s.The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander; they were the first human artifacts to touch down on Mars...
, Mars 5, and Mars 6, either crashed or failed to even enter the planet's atmosphere during the 1973 and 1975/76 windows. All four landers were based on the
Luna 9Luna 9 , was an unmanned space mission of the Soviet Union's Luna program. On February 3, 1966 the Luna 9 spacecraft was the first spacecraft to achieve a lunar soft landing and to transmit photographic data to Earth....
lander, and employed an aeroshell-like heat shield during atmospheric entry.
Viking 1 and 2NASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
were launched respectively in August and September 1975, each comprising an orbiter vehicle and a lander. Viking 1 landed in July 1976 and Viking 2 in September 1976. The Viking program ended in May 1983, after both landers had died.
Mars PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
was launched in December 1996 and released the first
roverThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
on
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
, named
Sojourner, in July 1997. It failed in September 1997, probably due to electronics failure caused by the cold temperatures.
Mars Polar LanderMars Polar Lander is one of two exploration vehicles of the NASA Mars Surveyor '98 program. Launched on 3 January 1999, 23 days after its partner, the Mars Climate Orbiter, the mission ended in failure with the loss of both craft in separate incidents...
ceased communication on 3 December 1999, prior to reaching the surface, and is presumed to have crashed.
The European
Beagle 2Beagle 2 was an unsuccessful British landing spacecraft that formed part of the European Space Agency's 2003 Mars Express mission. It is not known for certain whether the lander reached the Martian surface; all contact with it was lost upon its separation from the Mars Express six days before its...
lander deployed successfully from the
Mars ExpressMars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...
spacecraft but the signal confirming a landing which should have come on 25 December 2003 was not received. Indeed no communication was ever established and
Beagle 2 was declared lost on 6 February 2004.
Mars Exploration RoverNASA's Mars Exploration Rover Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers — MER-A Spirit and MER-B Opportunity — to explore the Martian surface and geology....
s
SpiritSpirit, mission designation MER-A , is the first of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully on Mars on 04:35 Ground UTC on January 4, 2004, three weeks before its twin Opportunity landed on the other side of the planet...
and
OpportunityOpportunity, mission designation MER-B , is the second of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully at Meridiani Planum on Mars on January 25, 2004 05:05 Ground UTC , three weeks after its twin Spirit had landed on the other side of the planet...
were launched in June and July 2003. They reached the Martian surface in January 2004 using landers featuring airbags and parachutes to soften impact. , both
roversThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
are still active, having survived more than five years when their design lifetime was three months.
The U.S.
Phoenix spacecraftPhoenix was a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The Phoenix lander descended on Mars on May 25, 2008...
successfully achieved soft landing on the surface of Mars on May 25, 2008, using a combination of parachutes and rocket descent engines.
Lunar
A number of
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
probes, such as some members of the Soviet Luna program and the American
Ranger programThe Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon...
, were hard-impact landers which were not intended to continue providing useful data after their high-speed landings.
The Soviet
Luna 9Luna 9 , was an unmanned space mission of the Soviet Union's Luna program. On February 3, 1966 the Luna 9 spacecraft was the first spacecraft to achieve a lunar soft landing and to transmit photographic data to Earth....
was the first spacecraft to achieve a lunar soft landing and to transmit photographic data to Earth. The American
Surveyor programThe Surveyor Program was a NASA program that, from 1966 through 1968, sent seven robotic spacecraft to the surface of the Moon. Its primary goal was to demonstrate the feasibility of soft landings on the Moon. The program was implemented by NASA's Jet Propulsion Laboratory to prepare for the...
was designed to determine where Apollo could land safely; thus 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
Apollo Lunar ModuleThe Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to achieve the transit from lunar orbit to the surface and back...
s and
Lunakhod landersLunokhod 1 and 2 were a pair of Soviet robotic lunar rovers landed on the Moon in 1970 and 1973, respectively. They were in operation concurrently with the Zond series of flyby missions. The Lunokhod missions were primarily designed to explore the surface and return pictures...
used a
rocketA rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of a jet of fast moving fluid exhaust from a rocket engine. Chemical rockets create their exhaust by the combustion of rocket propellant...
descent engine for a soft landing of astronauts and lunar rovers on the Moon.
The Altair spacecraft, previously known as the "Lunar Surface Access Module" or "LSAM", is the planned lander for
Project ConstellationConstellation is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program are gaining significant experience in operating away from Earth's environment, developing technologies needed for opening the space frontier and conducting fundamental...
. As part of Project Constellation,
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
intends to conduct Moon landings beginning around 2020.
Titan
The
Huygens probeThe Huygens probe, supplied by the European Space Agency and named after the Dutch 17th century astronomer Christiaan Huygens, was an atmospheric entry probe carried to Saturn's moon Titan as part of the Cassini-Huygens mission. The combined Cassini-Huygens spacecraft was launched from Earth on...
, carried to
SaturnSaturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn, along with Jupiter, Uranus and Neptune, is classified as a gas giant...
's
moonA natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. Technically, the term natural satellite could refer to a planet orbiting a star, or a dwarf galaxy orbiting a major galaxy, but it is normally synonymous with moon and used to identify...
TitanTitan , or Saturn VI, is the largest moon of Saturn, the only moon known to have a dense atmosphere,
and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
by the Cassini probe, was specifically designed to survive landing on land and on liquid. It was thoroughly drop-tested to make sure it could withstand impact and continue functioning for at least three minutes. However, due to the low speed impact, it continued providing data for more than two hours after it landed.
Venus
The Soviet Venera program included a number of
VenusVenus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6...
landers, some of which were crushed during descent much as Galileo's Jupiter "lander" and others of which successfully touched down. The Soviet
Vega programThe Vega program were a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,...
also placed two balloons in the Venusian atmosphere.
Comets and asteroids
The Rosetta probe, launched 2 March 2004, is planned to put a lander on
cometA comet is a Small Solar System Body that has coma and is bigger than a meteoroid. When close enough to the Sun, a comet exhibits a visible coma , and sometimes a tail, both because of the effects of solar radiation upon the comet's nucleus...
67P/Churyumov-Gerasimenko67P/Churyumov-Gerasimenko is the designation of a comet with a current orbital period of 6.6 years. It is the destination of the European Space Agency's Rosetta spacecraft mission, launched on March 2, 2004.- Hubble pictures :...
in 2014; due to the extremely low gravity of such bodies, Rosetta's landing system includes a harpoon launcher intended to anchor a cable in the surface and pull it down.
A landing on a similarly small body, the
asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
433 Eros433 Eros is the first discovered Near-Earth asteroid, named after the Greek god of love, Eros . It is an S-type asteroid approximately 34.4×11.2×11.2 km in size, the second-largest near-Earth asteroid after 1036 Ganymed, belonging to the Amors. It is a Mars-crosser asteroid and was the first...
, was performed by the probe
NEAR ShoemakerThe Near Earth Asteroid Rendezvous - Shoemaker , renamed after its launch in honor of planetary scientist Eugene M. Shoemaker, is a robotic space probe designed to study the near-Earth asteroid Eros from close orbit over a period of a year...
despite the fact that NEAR was not originally designed to be capable of landing.
The
Hayabusais an unmanned space mission led by the Japan Aerospace Exploration Agency to return a sample of material from a small near-Earth asteroid named 25143 Itokawa to Earth for further analysis....
probe made several attempts to land on
25143 Itokawa25143 Itokawa is an Apollo and Mars-crosser asteroid. It was the first asteroid to be the target of a sample return mission, the Japanese space probe Hayabusa.-History:...
with mixed success, including a failed attempt to deploy a
roverThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
.
Impactors
Mars Deep Space 2
The
Deep Space 2Deep Space 2 of the NASA New Millennium Program included two highly advanced miniature space probes sent to Mars launched aboard the Mars Polar Lander in January 1999. The probes were named Scott and Amundsen in honor of Robert Falcon Scott and Roald Amundsen, the first explorers to reach the...
impactor probe was to be the first spacecraft to penetrate below the surface of another planet. However the mission failed with the loss of its mother ship,
Mars Polar LanderMars Polar Lander is one of two exploration vehicles of the NASA Mars Surveyor '98 program. Launched on 3 January 1999, 23 days after its partner, the Mars Climate Orbiter, the mission ended in failure with the loss of both craft in separate incidents...
after communication was lost after entry into Mars atmosphere on 3 December 1999.
Deep Impact
Comet Tempel 1 was visited by NASA's
Deep ImpactDeep Impact is an ongoing NASA space probe which was launched on January 12, 2005. It was designed to study the composition of the comet interior of 9P/Tempel, by colliding a section of the spacecraft into the comet. At 5:52 UTC on July 4, 2005, the impactor of the Deep Impact probe successfully...
probe on 4 July 2005. The
impact craterIn the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
formed was approximately 200 m wide and 30-50 m deep, and detected the presence of silicates, carbonates, smectite,
amorphous carbonAmorphous carbon or free, reactive carbon, is an allotrope of carbon that does not have any crystalline structure. As with all glassy materials, some short-range order can be observed...
and polycyclic aromatic hydrocarbons.
See also