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117-682: The Apollo Lunar Module ( LM / ˈ l ɛ m / ), originally designated the Lunar Excursion Module ( LEM ), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program . It was the first crewed spacecraft to operate exclusively in the airless vacuum of space, and remains the only crewed vehicle to land anywhere beyond Earth. Structurally and aerodynamically incapable of flight through Earth's atmosphere,
234-525: A Saturn IB . This was originally planned for April 1967, to be followed by the first crewed flight later that year. But the LM's development problems had been underestimated, and LM-1's flight was delayed until January 22, 1968, as Apollo 5 . At that time, LM-2 was held in reserve in case the LM-1 flight failed, which did not happen. LM-3 now became the first crewed LM, again to be flown in low Earth orbit to test all
351-417: A partial success occurs when a spacecraft lands intact on the Moon but its in-situ operations is compromised as a result of the landing process for any reason. Landing on any Solar System body comes with challenges unique to that body. The Moon has relatively high gravity compared to that of asteroids or comets—and some other planetary satellites —and no significant atmosphere. Practically, this means that
468-616: A throttleable Descent Propulsion System (DPS) engine with four hypergolic propellant tanks. A continuous-wave Doppler radar antenna was mounted by the engine heat shield on the bottom surface, to send altitude and rate of descent data to the guidance system and pilot display during the landing. Almost all external surfaces, except for the top, platform, ladder, descent engine and heat shield, were covered in amber, dark (reddish) amber, black, silver, and yellow aluminized Kapton foil blankets for thermal insulation. The number 1 (front) landing leg had an attached platform (informally known as
585-605: A Reaction Control System (RCS) for attitude and translation control, which consisted of sixteen hypergolic thrusters similar to those used on the Service Module, mounted in four quads, with their own propellant supply. A forward extravehicular activity hatch provided access to and from the lunar surface, while an overhead hatch and docking port provided access to and from the Command Module. Internal equipment included an environmental control (life support) system;
702-543: A Saturn V, the telescope was mounted on a hinged arm and controlled from inside the MDA. Only the octagonal shape of the telescope container, solar panels and the Apollo Telescope Mount name were kept, though there was no longer any association with the LM. The Apollo LM Truck (also known as Lunar Payload Module) was a stand-alone LM descent stage intended to deliver up to 11,000 pounds (5.0 t) of payload to
819-487: A VHF communications system with two antennas for communication with the Command Module; a unified S-band system and steerable parabolic dish antenna for communication with Earth; an extravehicular activity antenna resembling a miniature parasol which relayed communications from antennas on the astronauts' Portable Life Support Systems through the LM; primary (PGNCS) and backup (AGS) guidance and navigation systems; an Alignment Optical Telescope for visually determining
936-656: A biopic of Neil Armstrong . Lunar lander A lunar lander or Moon lander is a spacecraft designed to land on the surface of the Moon . As of 2024, the Apollo Lunar Module is the only lunar lander to have ever been used in human spaceflight, completing six lunar landings from 1969 to 1972 during the United States' Apollo Program . Several robotic landers have reached the surface, and some have returned samples to Earth. The design requirements for these landers depend on factors imposed by
1053-485: A brief hop off the lunar surface. The Apollo Lunar Module was the lunar lander for the United States' Apollo program . As of 2024, it is the only crewed lunar lander. The Apollo program completed six successful lunar soft-landings from 1969 until 1972; a seventh lunar landing attempt by the Apollo program was aborted when Apollo 13 's service module suffered explosive venting from its oxygen tanks. The LK lunar module
1170-601: A crewed command and service module , named the Apollo Telescope Mission (ATM). This idea was later transferred to the original wet workshop design for the Skylab orbital workshop and renamed the Apollo Telescope Mount to be docked on a side port of the workshop's multiple docking adapter (MDA). When Skylab changed to a "dry workshop" design pre-fabricated on the ground and launched on
1287-639: A dramatization of that mission starring Tom Hanks , Kevin Bacon , and Bill Paxton , was filmed using realistic spacecraft interior reconstructions of the Aquarius and the Command Module Odyssey . In 2013 in the television show Arrested Development , a fictionalized version of Howard is depicted as having the Apollo 11 "LEM" in his office, which his character claims was used to fake the 1969 moon landing . The development and construction of
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#17327880191931404-586: A follow-up robotic lander named Beresheet 2 . India's Chandrayaan Programme conducted an unsuccessful robotic lunar soft-landing attempt on 6 September 2019 as part of its Chandrayaan-2 spacecraft with the lander crashing on the Moon's surface. On 23 August 2023, the program's follow-up Chandrayaan-3 lander achieved India's first robotic soft-landing and later conducted a brief hop on 3 September 2023 to test technologies required for Indian lunar sample return mission called Chandrayaan-4 . Japan's ispace (not to be confused with China's i-Space ) attempted
1521-590: A generic two-body model ) of the actual minimum distance to the Sun using the full dynamical model . Precise predictions of perihelion passage require numerical integration . The two images below show the orbits, orbital nodes , and positions of perihelion (q) and aphelion (Q) for the planets of the Solar System as seen from above the northern pole of Earth's ecliptic plane , which is coplanar with Earth's orbital plane . The planets travel counterclockwise around
1638-409: A lifeboat to provide life support and propulsion to keep the crew alive for the trip home, when their CSM was disabled by an oxygen tank explosion en route to the Moon. The six landed descent stages remain at their landing sites; their corresponding ascent stages crashed into the Moon following use. One ascent stage (Apollo 10's Snoopy ) was discarded in a heliocentric orbit after its descent stage
1755-516: A lunar soft-landing by its Hakuto-R Mission 1 robotic lander on 25 April 2023. The attempt was unsuccessful and the lander crashed into the lunar surface. The company has plans for another landing attempt in 2024. Russia's Luna-Glob program, the successor program to the Soviet Union's Luna program , launched the Luna 25 lunar lander on 10 August 2023; the probe's intended destination was near
1872-401: A much stricter range of between −40 and 50 °C (−40 and 122 °F), and human comfort requires a range of 20 to 24 °C (68 to 75 °F). This means that the lander must cool and heat its instruments or crew compartment. The length of the lunar night makes it difficult to use solar electric power to heat the instruments, and nuclear heaters are often used. Achieving a soft landing
1989-426: A near-vertical position, allowing the crew to look forward and down to see the lunar surface for the first time. Astronauts flew Apollo spacecraft manually only during the lunar approach. The final landing phase began about 2,000 feet (0.61 km) uprange of the targeted landing site. At this point, manual control was enabled for the commander, who had enough propellant to hover for up to two minutes to survey where
2106-523: A second, forward docking port, allowing the LEM crew to take an active role in docking with the CSM. As the program continued, there were numerous redesigns to save weight, improve safety, and fix problems. First to go were the heavy cockpit windows and the seats; the astronauts would stand while flying the LEM, supported by a cable and pulley system, with smaller triangular windows giving them sufficient visibility of
2223-424: A similar method. Airbag methods are not typical. For example, NASA's Surveyor 1 probe, launched around the same time as Luna 9, did not use an airbag for final touchdown. Instead, after it arrested its velocity at an altitude of 3.4m it simply fell to the lunar surface. To accommodate the fall the spacecraft was equipped with crushable components that would soften the blow and keep the payload safe. More recently,
2340-525: A story published in 1998, thus appearing before perinigricon and aponigricon (from Latin) in the scientific literature in 2002. The suffixes shown below may be added to prefixes peri- or apo- to form unique names of apsides for the orbiting bodies of the indicated host/ (primary) system. However, only for the Earth, Moon and Sun systems are the unique suffixes commonly used. Exoplanet studies commonly use -astron , but typically, for other host systems
2457-564: A suit-puncture hazard to the astronauts, as the probes tended to break off and protrude upwards from the surface.) Equipment for the lunar exploration was carried in the Modular Equipment Stowage Assembly (MESA), a drawer mounted on a hinged panel dropping out of the lefthand forward compartment. Besides the astronaut's surface excavation tools and sample collection boxes, the MESA contained a television camera with
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#17327880191932574-403: A tripod; as the commander opened the MESA by pulling on a lanyard while descending the ladder, the camera was automatically activated to send the first pictures of the astronauts on the surface back to Earth. A United States flag for the astronauts to erect on the surface was carried in a container mounted on the ladder of each landing mission. The Early Apollo Surface Experiments Package (later
2691-468: Is -gee , so the apsides' names are apogee and perigee . For the Sun, the suffix is -helion , so the names are aphelion and perihelion . According to Newton's laws of motion , all periodic orbits are ellipses. The barycenter of the two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass,
2808-435: Is 236 years early, less accurately shows Eris coming to perihelion in 2260. 4 Vesta came to perihelion on 26 December 2021, but using a two-body solution at an epoch of July 2021 less accurately shows Vesta came to perihelion on 25 December 2021. Trans-Neptunian objects discovered when 80+ AU from the Sun need dozens of observations over multiple years to well constrain their orbits because they move very slowly against
2925-473: Is currently about 1.016 71 AU or 152,097,700 km (94,509,100 mi). The dates of perihelion and aphelion change over time due to precession and other orbital factors, which follow cyclical patterns known as Milankovitch cycles . In the short term, such dates can vary up to 2 days from one year to another. This significant variation is due to the presence of the Moon: while the Earth–Moon barycenter
3042-482: Is in contrast to a small asteroid, in which "landing" is more often called "docking" and is a matter of rendezvous and matching velocity more than slowing a rapid descent. Since rocketry is used for descent and landing, the Moon's gravity necessitates the use of more fuel than is needed for asteroid landing. Indeed, one of the central design constraints for the Apollo program's Moon landing was mass (as more mass requires more fuel to land) required to land and take off from
3159-432: Is moving on a stable orbit around the Sun, the position of the Earth's center which is on average about 4,700 kilometres (2,900 mi) from the barycenter, could be shifted in any direction from it—and this affects the timing of the actual closest approach between the Sun's and the Earth's centers (which in turn defines the timing of perihelion in a given year). Because of the increased distance at aphelion, only 93.55% of
3276-452: Is the farthest or nearest point in the orbit of a planetary body about its primary body . The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values . Apsides pertaining to orbits around the Sun have distinct names to differentiate themselves from other apsides; these names are aphelion for the farthest and perihelion for
3393-428: Is the overarching goal of any lunar lander, and distinguishes landers from impactors, which were the first type of spacecraft to reach the surface of the Moon. All lunar landers require rocket engines for descent. Orbital speed around the Moon can, depending on altitude, exceed 1500 m/s. Spacecraft on impact trajectories can have speeds well in excess of that. In the vacuum the only way to decelerate from that speed
3510-401: Is to use a rocket engine. The stages of landing can include: Lunar landings typically end with the engine shutting down when the lander is several feet above the lunar surface. The idea is that engine exhaust and lunar regolith can cause problems if they were to be kicked back from the surface to the spacecraft, and thus the engines cut off just before touchdown. Engineers must ensure that
3627-514: The Apollo Lunar Surface Experiments Package ), was carried in the opposite compartment behind the LM. An external compartment on the right front panel carried a deployable S-band antenna which, when opened looked like an inverted umbrella on a tripod. This was not used on the first landing due to time constraints, and the fact that acceptable communications were being received using the LM's S-band antenna, but
Apollo Lunar Module - Misplaced Pages Continue
3744-483: The First Point of Aries not in terms of days and hours, but rather as an angle of orbital displacement, the so-called longitude of the periapsis (also called longitude of the pericenter). For the orbit of the Earth, this is called the longitude of perihelion , and in 2000 it was about 282.895°; by 2010, this had advanced by a small fraction of a degree to about 283.067°, i.e. a mean increase of 62" per year. For
3861-571: The Galactic Center respectively. The suffix -jove is occasionally used for Jupiter, but -saturnium has very rarely been used in the last 50 years for Saturn. The -gee form is also used as a generic closest-approach-to "any planet" term—instead of applying it only to Earth. During the Apollo program , the terms pericynthion and apocynthion were used when referring to orbiting the Moon ; they reference Cynthia, an alternative name for
3978-606: The Lunar Landing Research Vehicle (LLRV), which used a gimbal-mounted vertical jet engine to counter five-sixths of its weight to simulate the Moon's gravity, in addition to its own hydrogen peroxide thrusters to simulate the LM's descent engine and attitude control. Successful testing of two LLRV prototypes at the Dryden Flight Research Center led in 1966 to three production Lunar Landing Training Vehicles (LLTV) which along with
4095-549: The Lunokhod robotic lunar rover in 1970 and 1973. Luna achieved a total of seven successful soft-landings out of 27 landing attempts. The United States' Surveyor program first soft-landed Surveyor 1 on June 2, 1966, this initial success was followed by four additional successful soft-landings, the last occurring on January 10, 1968. The Surveyor program achieved a total of five successful soft landings out of seven landing attempts through January 10, 1968. Surveyor 6 even did
4212-688: The S-IVB third stage of the Saturn V rocket. There it remained through Earth parking orbit and the trans-lunar injection (TLI) rocket burn to send the craft toward the Moon. Soon after TLI, the SLA opened; the CSM performed a maneuver whereby it separated, turned around, came back to dock with the Lunar Module, and extracted it from the S-IVB. During the flight to the Moon, the docking hatches were opened and
4329-624: The United States , the Soviet Union cancelled both the N1 Rocket and the LK Lunar Module programs without any further development. The Chinese Lunar Exploration Program (also known as the Chang'e project) includes robotic lander, rover, and sample-return components; the program realized an initial successful lunar soft-landing with the Chang'e 3 spacecraft on 14 December 2013. As of 2023,
4446-463: The comets , and the asteroids of the Solar System . There are two apsides in any elliptic orbit . The name for each apsis is created from the prefixes ap- , apo- (from ἀπ(ό) , (ap(o)-) 'away from') for the farthest or peri- (from περί (peri-) 'near') for the closest point to the primary body , with a suffix that describes the primary body. The suffix for Earth
4563-472: The command module Columbia splashed down in the Pacific Ocean, completing President John F. Kennedy's goal : "...before this decade is out, of landing a man on the Moon and returning him safely to the Earth". This was followed by landings by Apollo 12 (LM-6 Intrepid ) and Apollo 14 (LM-8 Antares ). In April 1970, the Apollo 13 LM-7 Aquarius played an unexpected role in saving the lives of
4680-404: The payload , flight rate, propulsive requirements, and configuration constraints. Other important design factors include overall energy requirements, mission duration, the type of mission operations on the lunar surface, and life support system if crewed. The relatively high gravity (higher than all known asteroids, but lower than all Solar System planets) and lack of lunar atmosphere negates
4797-428: The precession of the axes .) The dates and times of the perihelions and aphelions for several past and future years are listed in the following table: The following table shows the distances of the planets and dwarf planets from the Sun at their perihelion and aphelion. These formulae characterize the pericenter and apocenter of an orbit: While, in accordance with Kepler's laws of planetary motion (based on
Apollo Lunar Module - Misplaced Pages Continue
4914-407: The two-stage Lunar Module was ferried to lunar orbit attached to the Apollo command and service module (CSM), about twice its mass. Its crew of two flew the Lunar Module from lunar orbit to the Moon's surface. During takeoff, the spent descent stage was used as a launch pad for the ascent stage which then flew back to the command module , after which it was also discarded. Overseen by Grumman ,
5031-411: The "porch") in front of the ascent stage's extravehicular activity hatch and a ladder, which the astronauts used to ascend and descend between the cabin to the surface. The landing pad of each leg incorporated a 67-inch-long (1.7 m) surface contact sensor probe, which signaled the commander to switch off the descent engine. (The probe was omitted from the number 1 leg of every landing mission, to avoid
5148-562: The 5th country to soft land on the moon. In January 2024, the first mission of the NASA-funded CLPS program, Peregrine Mission One , suffered a fuel leak several hours after launch, resulting in losing the ability to maintain attitude control and charge its battery, thereby preventing it from reaching lunar orbit and precluding a landing attempt. The probe subsequently burnt up in Earth's atmosphere. The second CLPS probe Odysseus landed successfully on 22 February 2024 on
5265-492: The 67-inch (170 cm) probes touched the surface. During Apollo 11 Neil Armstrong however touched down very gently by firing the engine until touchdown; some later crews shut down the engine before touchdown and felt noticeable bumps on landing, with greater compression of the landing struts. Perilune An apsis (from Ancient Greek ἁψίς ( hapsís ) 'arch, vault'; pl. apsides / ˈ æ p s ɪ ˌ d iː z / AP -sih-deez )
5382-468: The CLEP has achieved three successful soft-landings out of three landing attempts, namely Chang'e 3 , Chang'e 4 and Chang'e 5 . Chang'e 4 made history by making humanity's first ever soft-landing on the far side of the moon. Israel's SpaceIL attempted a robotic lunar landing by its Beresheet lander on 4 April 2019; the attempt failed. As of 2023, SpaceIL has plans for another soft-landing attempt using
5499-399: The CSM and docked to transfer the crew and rock samples. Having completed its job, the ascent stage was separated. The Apollo 10 ascent stage engine was fired until its fuel was used up, sending it past the Moon into a heliocentric orbit . The Apollo 11 ascent stage was left in lunar orbit to eventually crash; all subsequent ascent stages (except for Apollo 13) were intentionally steered into
5616-416: The CSM, flying independently. The commander operated the flight controls and engine throttle, while the Lunar Module pilot operated other spacecraft systems and kept the commander informed about systems status and navigational information. After the command module pilot visually inspected the landing gear , the LM was withdrawn to a safe distance, then rotated until the descent engine was pointed forward into
5733-582: The Chinese Chang'e 3 lander used a similar technique, falling 4m after its engine shut down. Perhaps the most famous lunar landers, those of the Apollo Program , were robust enough to handle the drop once their contact probes detected that landing was imminent. The landing gear was designed to withstand landings with engine cut-out at up to 10 feet (3.0 m) of height, though it was intended for descent engine shutdown to commence when one of
5850-526: The Earth reaches perihelion in early January, approximately 14 days after the December solstice . At perihelion, the Earth's center is about 0.983 29 astronomical units (AU) or 147,098,070 km (91,402,500 mi) from the Sun's center. In contrast, the Earth reaches aphelion currently in early July, approximately 14 days after the June solstice . The aphelion distance between the Earth's and Sun's centers
5967-434: The Earth's distance from the Sun. In the northern hemisphere, summer occurs at the same time as aphelion, when solar radiation is lowest. Despite this, summers in the northern hemisphere are on average 2.3 °C (4 °F) warmer than in the southern hemisphere, because the northern hemisphere contains larger land masses, which are easier to heat than the seas. Perihelion and aphelion do however have an indirect effect on
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#17327880191936084-584: The Greek Moon goddess Artemis . More recently, during the Artemis program , the terms perilune and apolune have been used. Regarding black holes, the term peribothron was first used in a 1976 paper by J. Frank and M. J. Rees, who credit W. R. Stoeger for suggesting creating a term using the greek word for pit: "bothron". The terms perimelasma and apomelasma (from a Greek root) were used by physicist and science-fiction author Geoffrey A. Landis in
6201-588: The LLRV's were used to train the astronauts at the Houston Manned Spacecraft Center. This aircraft proved fairly dangerous to fly, as three of the five were destroyed in crashes. It was equipped with a rocket-powered ejection seat, so in each case the pilot survived, including the first man to walk on the Moon, Neil Armstrong . LM-1 was built to make the first uncrewed flight for propulsion systems testing, launched into low Earth orbit atop
6318-469: The LM's development was plagued with problems that delayed its first uncrewed flight by about ten months and its first crewed flight by about three months. Regardless, the LM became the most reliable component of the Apollo–Saturn space vehicle . The total cost of the LM for development and the units produced was $ 21.65 billion in 2016 dollars, adjusting from a nominal total of $ 2.29 billion using
6435-413: The Lunar Module pilot entered the LM to power up temporarily and test all systems except propulsion. The Lunar Module pilot performed the role of an engineering officer, monitoring the systems of both spacecraft. After achieving a lunar parking orbit, the commander and LM pilot entered and powered up the LM, replaced the hatches and docking equipment, unfolded and locked its landing legs, and separated from
6552-557: The Moon for an uncrewed landing. This technique was intended to deliver equipment and supplies to a permanent crewed lunar base . As originally proposed, it would be launched on a Saturn V with a full Apollo crew to accompany it to lunar orbit and guide it to a landing next to the base; then the base crew would unload the "truck" while the orbiting crew returned to Earth. In later AAP plans, the LPM would have been delivered by an uncrewed lunar ferry vehicle. The 1995 Ron Howard film Apollo 13 ,
6669-501: The Moon to obtain readings from seismometers placed on the surface. The Lunar Module (originally designated the Lunar Excursion Module, known by the acronym LEM) was designed after NASA chose to reach the Moon via Lunar Orbit Rendezvous (LOR) instead of the direct ascent or Earth Orbit Rendezvous (EOR) methods. Both direct ascent and EOR would have involved landing a much heavier, complete Apollo spacecraft on
6786-462: The Moon, marking the United States' first unmanned lunar soft-landing in over 50 years. This mission is the first private -NASA partnership to land on the Moon and the first landing using cryogenic propellants . However, the mission experienced some anomalies, including tipping-over on one side on the lunar surface; an off-nominal initial lunar orbit, a non-functioning landing LIDAR instrument, and apparently low communication bandwidth . Later it
6903-399: The Moon. The lunar thermal environment is influenced by the length of the lunar day. Temperatures can swing between approximately −250 to 120 °C (−418.0 to 248.0 °F) (lunar night to lunar day). These extremes occur for fourteen Earth days each, so thermal control systems must be designed to handle long periods of extreme cold or heat. Most spacecraft instruments must be kept within
7020-519: The Moon. Once the decision had been made to proceed using LOR, it became necessary to produce a separate craft capable of reaching the lunar surface and ascending back to lunar orbit. In July 1962, eleven firms were invited to submit proposals for the LEM. Nine companies responded in September, answering 20 questions posed by the NASA RFP in a 60-page limited technical proposal. Grumman was awarded
7137-514: The NASA New Start Inflation Indices. Ten lunar modules were launched into space. Of these, six were landed by humans on the Moon from 1969 to 1972. The first two flown were tests in low Earth orbit : Apollo 5 , without a crew; and Apollo 9 with a crew. A third test flight in low lunar orbit was Apollo 10 , a dress rehearsal for the first landing, conducted on Apollo 11 . The Apollo 13 lunar module functioned as
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#17327880191937254-513: The South pole-Aitken basin on the lunar far side at 22:23 UTC on 1 June 2024. After the completion of sample collection and the placement of the sample on the ascender by the probe's robotic drill and robotic arm, the ascender successfully took off from atop the lander portion of the probe at 23:38 UTC on 3 June 2024. The ascender docked with the Chang'e 6 service module (the orbiter) in lunar orbit at 06:48 UTC on 6 June 2024 and subsequently completed
7371-404: The Sun and for each planet, the blue part of their orbit travels north of the ecliptic plane, the pink part travels south, and dots mark perihelion (green) and aphelion (orange). The first image (below-left) features the inner planets, situated outward from the Sun as Mercury, Venus, Earth, and Mars. The reference Earth-orbit is colored yellow and represents the orbital plane of reference . At
7488-452: The Sun. The words are formed from the prefixes peri- (Greek: περί , near) and apo- (Greek: ἀπό , away from), affixed to the Greek word for the Sun, ( ἥλιος , or hēlíos ). Various related terms are used for other celestial objects . The suffixes -gee , -helion , -astron and -galacticon are frequently used in the astronomical literature when referring to the Earth, Sun, stars, and
7605-438: The abbreviation as ( / l ɛ m / ) instead of the letters "L-M". Comparing landing on the Moon to "a hovering operation", Gus Grissom said in 1963 that although most early astronauts were fighter pilots, "now we're wondering if the pilot making this first moon landing shouldn't be a highly experienced helicopter pilot". To allow astronauts to learn lunar landing techniques, NASA contracted Bell Aerosystems in 1964 to build
7722-415: The atmospheres of the bodies on which they landed to slow their descent using parachutes, reducing the amount of fuel they were required to carry. This in turn allowed larger payloads to be landed on these bodies for a given amount of fuel. For example, the 900-kg Curiosity rover was landed on Mars by a craft having a mass (at the time of Mars atmospheric entry) of 2400 kg, of which only 390 kg
7839-452: The cabin. The return payload included the lunar rock and soil samples collected by the crew (as much as 238 pounds (108 kg) on Apollo 17), plus their exposed photographic film . The descent stage's primary job was to support a powered landing and surface extravehicular activity. When the excursion was over, it served as the launch pad for the ascent stage. Its octagonal shape was supported by four folding landing gear legs, and contained
7956-408: The computer to slow the craft's forward and vertical velocity to near zero. Control was exercised with a combination of engine throttling and attitude thrusters, guided by the computer with the aid of landing radar. During braking, the LM descended to about 10,000 feet (3.0 km), then, in the final approach phase, down to about 700 feet (210 m). During final approach, the vehicle pitched over to
8073-400: The computer was taking the craft and make any necessary corrections. If necessary, landing could have been aborted at almost any time by jettisoning the descent stage and firing the ascent engine to climb back into orbit for an emergency return to the CSM. Finally, one or more of three 67.2-inch (1.71 m) probes extending from footpads on the legs of the lander touched the surface, activating
8190-422: The conservation of angular momentum ) and the conservation of energy, these two quantities are constant for a given orbit: where: Note that for conversion from heights above the surface to distances between an orbit and its primary, the radius of the central body has to be added, and conversely. The arithmetic mean of the two limiting distances is the length of the semi-major axis a . The geometric mean of
8307-474: The contact indicator light which signaled the commander to shut off the descent engine, allowing the LM to settle onto the surface. On touchdown, the probes would be bent as much as 180 degrees, or even break off. The original design used the probes on all four legs, but starting with the first landing (LM-5 on Apollo 11), the one at the ladder was removed out of concern that the bent probe after landing might puncture an astronaut's suit as he descended or stepped off
8424-471: The contract officially on November 7, 1962. Grumman had begun lunar orbit rendezvous studies in the late 1950s and again in 1961. The contract cost was expected to be around $ 350 million. There were initially four major subcontractors: Bell Aerosystems ( ascent engine ), Hamilton Standard (environmental control systems), Marquardt (reaction control system) and Rocketdyne ( descent engine ). The Primary Guidance, Navigation and Control System (PGNCS)
8541-513: The descent propellant tanks were enlarged. A waste storage tank was added to the descent stage, with plumbing from the ascent stage. These upgrades allowed stays of up to 75 hours on the Moon. The Lunar Roving Vehicle was folded up and carried in Quadrant 1 of the descent stage. It was deployed by the astronauts after landing, allowing them to explore large areas and return a greater variety of lunar samples. Weights given here are an average for
8658-502: The designers compromised on four landing legs. In June 1966, the name was changed to Lunar Module (LM), eliminating the word excursion . According to George Low , Manager of the Apollo Spacecraft Program Office, this was because NASA was afraid that the word excursion might lend a frivolous note to Apollo. Despite the name change, the astronauts and other NASA and Grumman personnel continued to pronounce
8775-409: The direction of travel. A 30-second descent orbit insertion burn was performed to reduce speed and drop the LM's perilune to within about 50,000 feet (15 km) of the surface, about 260 nautical miles (480 km) uprange of the landing site. As the craft approached perilune, the descent engine was started again to begin powered descent. During this time, the crew flew on their backs, depending on
8892-409: The distance of the line that joins the nearest and farthest points across an orbit; it also refers simply to the extreme range of an object orbiting a host body (see top figure; see third figure). In orbital mechanics , the apsides technically refer to the distance measured between the barycenter of the 2-body system and the center of mass of the orbiting body. However, in the case of a spacecraft ,
9009-400: The extended missions. [REDACTED] One proposed Apollo application was an orbital solar telescope constructed from a surplus LM with its descent engine replaced with a telescope controlled from the ascent stage cabin, the landing legs removed and four "windmill" solar panels extending from the descent stage quadrants. This would have been launched on an uncrewed Saturn IB, and docked with
9126-405: The extreme range—from the closest approach (perihelion) to farthest point (aphelion)—of several orbiting celestial bodies of the Solar System : the planets, the known dwarf planets, including Ceres , and Halley's Comet . The length of the horizontal bars correspond to the extreme range of the orbit of the indicated body around the Sun. These extreme distances (between perihelion and aphelion) are
9243-412: The final approach. The CSM would then raise its perilune back to the normal 60 nautical miles (110 km). The Extended Lunar Module (ELM) used on the final three "J-class missions" — Apollo 15 , 16 , and 17 — was upgraded to land larger payloads and stay longer on the lunar surface. The descent engine thrust was increased by the addition of a 10-inch (250 mm) extension to the engine bell, and
9360-401: The generic suffix, -apsis , is used instead. The perihelion (q) and aphelion (Q) are the nearest and farthest points respectively of a body's direct orbit around the Sun . Comparing osculating elements at a specific epoch to those at a different epoch will generate differences. The time-of-perihelion-passage as one of six osculating elements is not an exact prediction (other than for
9477-422: The ladder. The original extravehicular activity plan, up through at least 1966, was for only one astronaut to leave the LM while the other remained inside "to maintain communications". Communications were eventually deemed to be reliable enough to allow both crew members to walk on the surface, leaving the spacecraft to be only remotely attended by Mission Control. Beginning with Apollo 14 , extra LM propellant
9594-562: The landing site. Later, the redundant forward docking port was removed, which meant the Command Pilot gave up active control of the docking to the Command Module Pilot; he could still see the approaching CSM through a small overhead window. Egress while wearing bulky extra-vehicular activity spacesuits was eased by a simpler forward hatch (32 in × 32 in or 810 mm × 810 mm). The configuration
9711-468: The last four landing missions by using the Service Module engine to perform the initial descent orbit insertion burn 22 hours before the LM separated from the CSM, a practice begun on Apollo 14. This meant that the complete spacecraft, including the CSM, orbited the Moon with a 9.1-nautical-mile (16.9 km) perilune, enabling the LM to begin its powered descent from that altitude with a full load of descent stage propellant, leaving more reserve propellant for
9828-411: The lightest possible configuration. But as any particular leg would have to carry the weight of the vehicle if it landed at a significant angle, this was also the least stable configuration if one of the legs were damaged during landing. The next landing gear design iteration had five legs and was the most stable configuration for landing on an unknown terrain. That configuration, however, was too heavy and
9945-465: The lines of apsides of the orbits of various objects around a host body. Distances of selected bodies of the Solar System from the Sun. The left and right edges of each bar correspond to the perihelion and aphelion of the body, respectively, hence long bars denote high orbital eccentricity . The radius of the Sun is 0.7 million km, and the radius of Jupiter (the largest planet) is 0.07 million km, both too small to resolve on this image. Currently,
10062-408: The lunar landing, practicing all phases of the mission except powered descent initiation through takeoff. The LM descended to 47,400 feet (9.0 mi; 14.4 km) above the lunar surface, then jettisoned the descent stage and used its ascent engine to return to the CSM. The first crewed lunar landing occurred on July 20, 1969, in the Apollo 11 LM-5 Eagle . Four days later, the Apollo 11 crew in
10179-403: The lunar module is dramatized in the 1998 miniseries From the Earth to the Moon episode entitled "Spider" . This is in reference to LM-3, used on Apollo 9, which the crew named Spider after its spidery appearance. The unused LM-13 stood in during the teleplay to depict LM-3 and LM-5, Eagle , used by Apollo 11. The Apollo 11 Lunar Module Eagle is depicted in the 2018 film First Man ,
10296-462: The lunar south pole, but on 19 August 2023 the lander crashed on the Moon's surface. Japan's Smart Lander for Investigating Moon made a successful lunar landing with wrong attitude, bleak signal bandwidth and even after losing one of its engines during descent but within 100 m (330 ft) of its landing spot on 19 January 2024. It carried two small LEV rovers on board deployed sepqrately, just before SLIM's touchdown. It's landing made Japan
10413-431: The main aim of its mission. China launched Chang'e 6 from China's Hainan Island on 3 May 2024; this mission seeks to conduct the first lunar sample return from the far side of the Moon . This is China's second lunar sample return mission, the first was successfully completed by Chang'e 5 when it returned 1.731 kg of lunar near side material to the Earth on 16 December 2020. The Chang'e 6 lander successfully landed in
10530-413: The nearest point in the solar orbit. The Moon 's two apsides are the farthest point, apogee , and the nearest point, perigee , of its orbit around the host Earth . Earth's two apsides are the farthest point, aphelion , and the nearest point, perihelion , of its orbit around the host Sun. The terms aphelion and perihelion apply in the same way to the orbits of Jupiter and the other planets ,
10647-594: The only method of descent and landing that can provide sufficient thrust with current technology is based on chemical rockets . In addition, the Moon has a long solar day . Landers will be in direct sunlight for more than two weeks at a time, and then in complete darkness for another two weeks. This causes significant problems for thermal control. As of 2019, space probes have landed on all three bodies other than Earth that have solid surfaces and atmospheres thick enough to make aerobraking possible: Mars , Venus , and Saturn's moon Titan . These probes were able to leverage
10764-503: The orbit of the Earth around the Sun, the time of apsis is often expressed in terms of a time relative to seasons, since this determines the contribution of the elliptical orbit to seasonal variations. The variation of the seasons is primarily controlled by the annual cycle of the elevation angle of the Sun, which is a result of the tilt of the axis of the Earth measured from the plane of the ecliptic . The Earth's eccentricity and other orbital elements are not constant, but vary slowly due to
10881-403: The original pre-ELM spec vehicles. For specific weights for each mission, see the individual mission articles. The ascent stage contained the crew cabin with instrument panels and flight controls. It contained its own Ascent Propulsion System (APS) engine and two hypergolic propellant tanks for return to lunar orbit and rendezvous with the Apollo command and service module . It also contained
10998-588: The perihelion passage. For example, using an epoch of 1996, Comet Hale–Bopp shows perihelion on 1 April 1997. Using an epoch of 2008 shows a less accurate perihelion date of 30 March 1997. Short-period comets can be even more sensitive to the epoch selected. Using an epoch of 2005 shows 101P/Chernykh coming to perihelion on 25 December 2005, but using an epoch of 2012 produces a less accurate unperturbed perihelion date of 20 January 2006. Numerical integration shows dwarf planet Eris will come to perihelion around December 2257. Using an epoch of 2021, which
11115-409: The perturbing effects of the planets and other objects in the solar system (Milankovitch cycles). On a very long time scale, the dates of the perihelion and of the aphelion progress through the seasons, and they make one complete cycle in 22,000 to 26,000 years. There is a corresponding movement of the position of the stars as seen from Earth, called the apsidal precession . (This is closely related to
11232-504: The radiation from the Sun falls on a given area of Earth's surface as does at perihelion, but this does not account for the seasons , which result instead from the tilt of Earth's axis of 23.4° away from perpendicular to the plane of Earth's orbit. Indeed, at both perihelion and aphelion it is summer in one hemisphere while it is winter in the other one. Winter falls on the hemisphere where sunlight strikes least directly, and summer falls where sunlight strikes most directly, regardless of
11349-417: The seasons: because Earth's orbital speed is minimum at aphelion and maximum at perihelion, the planet takes longer to orbit from June solstice to September equinox than it does from December solstice to March equinox. Therefore, summer in the northern hemisphere lasts slightly longer (93 days) than summer in the southern hemisphere (89 days). Astronomers commonly express the timing of perihelion relative to
11466-401: The smaller mass is negligible (e.g., for satellites), then the orbital parameters are independent of the smaller mass. When used as a suffix—that is, -apsis —the term can refer to the two distances from the primary body to the orbiting body when the latter is located: 1) at the periapsis point, or 2) at the apoapsis point (compare both graphics, second figure). The line of apsides denotes
11583-409: The spacecraft orientation; rendezvous radar with its own steerable dish antenna; and a system for active thermal control. Electrical storage batteries, cooling water, and breathing oxygen were stored in amounts sufficient for a lunar surface stay of 48 hours initially, extended to 75 hours for the later missions. During rest periods while parked on the Moon, the crew would sleep on hammocks slung across
11700-472: The systems, and practice the separation, rendezvous, and docking planned for Apollo 8 in December 1968. But again, last-minute problems delayed its flight until Apollo 9 on March 3, 1969. A second, higher Earth orbit crewed practice flight had been planned to follow LM-3, but this was cancelled to keep the program timeline on track. Apollo 10 launched on May 18, 1969, using LM-4 for a "dress rehearsal" for
11817-466: The table; they are added as their initial robotic and/or crewed landers are launched from Earth. The term landing attempt as used here includes any mission that was launched with the intent to land on the Moon, including all missions which failed to reach lunar orbit for any reason. A landing attempt by a spacecraft is classified as full success if it lands intact on the Moon and is situated in its designed orientation/attitude and fully functional, while
11934-415: The terms are commonly used to refer to the orbital altitude of the spacecraft above the surface of the central body (assuming a constant, standard reference radius). The words "pericenter" and "apocenter" are often seen, although periapsis/apoapsis are preferred in technical usage. The words perihelion and aphelion were coined by Johannes Kepler to describe the orbital motions of the planets around
12051-751: The three astronauts after an oxygen tank in the service module ruptured, disabling the CSM. Aquarius served as a "lifeboat" for the astronauts during their return to Earth. Its descent stage engine was used to replace the crippled CSM Service Propulsion System engine, and its batteries supplied power for the trip home and recharged the Command Module's batteries critical for reentry. The astronauts splashed down safely on April 17, 1970. The LM's systems, designed to support two astronauts for 45 hours (including two depressurization and repressurization cycles, causing loss of oxygen supply), actually stretched to support three astronauts for 90 hours (without pressurization cycles and loss of oxygen). Hover times were maximized on
12168-412: The time of vernal equinox, the Earth is at the bottom of the figure. The second image (below-right) shows the outer planets, being Jupiter, Saturn, Uranus, and Neptune. The orbital nodes are the two end points of the "line of nodes" where a planet's tilted orbit intersects the plane of reference; here they may be 'seen' as the points where the blue section of an orbit meets the pink. The chart shows
12285-548: The transfer of the sample container to the Earth rentry module at 07:24 UTC on the same day. The orbiter then left lunar orbit on 20 June 2024 with the returner, which landed in Inner Mongolia on 25 June 2024, completing China's lunar far side sample return mission. The following table details the success rates of past and on-going lunar soft-landing attempts by robotic and crewed lunar-landing programs. Landing programs which have not launched any probes are not included in
12402-491: The two distances is the length of the semi-minor axis b . The geometric mean of the two limiting speeds is which is the speed of a body in a circular orbit whose radius is a {\displaystyle a} . Orbital elements such as the time of perihelion passage are defined at the epoch chosen using an unperturbed two-body solution that does not account for the n-body problem . To get an accurate time of perihelion passage you need to use an epoch close to
12519-539: The use of aerobraking , so a lander must use propulsion to decelerate and achieve a soft landing . The Luna program was a series of robotic impactors, flybys, orbiters, and landers flown by the Soviet Union between 1958 and 1976. Luna 9 was the first spacecraft to achieve a soft landing on the Moon on February 3, 1966, after 11 unsuccessful attempts. Three Luna Spacecraft returned lunar soil samples to Earth from 1972 to 1976. Two other Luna spacecraft soft-landed
12636-481: The vehicle is protected enough to ensure that the fall without thrust does not cause damage. The first soft lunar landing, performed by the Soviet Luna 9 probe, was achieved by first slowing the spacecraft to a suitable speed and altitude, then ejecting a payload containing the scientific experiments. The payload was stopped on the lunar surface using airbags, which provided cushioning as it fell. Luna 13 used
12753-416: Was chiefly designed by Grumman aerospace engineer Thomas J. Kelly . The first LEM design looked like a smaller version of the Apollo command and service module (a cone-shaped cabin atop a cylindrical propulsion section) with folding legs. The second design invoked the idea of a helicopter cockpit with large curved windows and seats, to improve the astronauts' visibility for hover and landing. This also included
12870-710: Was developed by the MIT Instrumentation Laboratory ; the Apollo Guidance Computer was manufactured by Raytheon (a similar guidance system was used in the command module ). A backup navigation tool, the Abort Guidance System (AGS), was developed by TRW . The landing gear was manufactured by Héroux . The Apollo Lunar Module was assembled in a Grumman factory in Bethpage, New York . The Apollo Lunar Module
12987-473: Was discarded in lunar orbit. The other three LMs were destroyed during controlled re-entry in the Earth's atmosphere: the four stages of Apollo 5 and Apollo 9 each re-entered separately, while Apollo 13's Aquarius re-entered as a unit. At launch, the lunar module sat directly beneath the command and service module (CSM) with legs folded, inside the Spacecraft-to-LM adapter (SLA) attached to
13104-714: Was frozen in April 1963, when the ascent and descent engine designs were decided. In addition to Rocketdyne, a parallel program for the descent engine was ordered from Space Technology Laboratories (TRW) in July 1963, and by January 1965 the Rocketdyne contract was cancelled. Power was initially to be produced by fuel cells built by Pratt and Whitney similar to the CSM, but in March 1965 these were discarded in favor of an all-battery design. The initial design had three landing legs,
13221-432: Was fuel. In comparison, the much lighter (292 kg) Surveyor 3 landed on the Moon in 1967 using nearly 700 kg of fuel. The lack of an atmosphere, however, removes the need for a Moon lander to have a heat shield and also allows aerodynamics to be disregarded when designing the craft. Although it has much less gravity than Earth, the Moon has sufficiently high gravity that descent must be slowed considerably. This
13338-409: Was made available for the powered descent and landing, by using the CSM engine to achieve the 50,000-foot (15 km) perilune. After the spacecraft undocked, the CSM raised and circularized its orbit for the remainder of the mission. When ready to leave the Moon, the LM's ascent engine fired, leaving the descent stage on the Moon's surface. After a few course correction burns, the LM rendezvoused with
13455-404: Was revealed that, though it landed successfully, one of the lander's legs broke upon landing and it tilted up on other side, 18° due to landing on a slope, but the lander survived and payloads are functioning as expected. EagleCam was not ejected prior to landing. It was later ejected on 28 February but was partially failure as it returned all types of data, except post IM-1 landing images that were
13572-545: Was the lunar lander developed by the Soviet Union as a part of several Soviet crewed lunar programs . Several LK lunar modules were flown without crew in low Earth orbit , but the LK lunar module never flew to the Moon, as the development of the N1 Rocket Launch Vehicle required for the lunar flight suffered setbacks (including several launch failures), and after the first human Moon landings were achieved by
13689-602: Was used on Apollo 12 and 14. A hand-pulled Modular Equipment Transporter (MET), similar in appearance to a golf cart, was carried on Apollo 13 and 14 to facilitate carrying the tools and samples on extended moonwalks. On the extended missions ( Apollo 15 and later), the antenna and TV camera were mounted on the Lunar Roving Vehicle , which was carried folded up and mounted on an external panel. Compartments also contained replacement Portable Life Support System (PLSS) batteries and extra lithium hydroxide canisters on
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