The Lunar Reconnaissance Orbiter (LRO) is a NASA

robotic spacecraft Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which t ...

currently orbiting the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions to the Moon. Its detailed mapping program is identifying safe landing sites, locating potential resources on the Moon, characterizing the radiation environment, and demonstrating new technologies. Launched on June 18, 2009, in conjunction with the

Lunar Crater Observation and Sensing Satellite The Lunar Crater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the Moon. Launched immedi ...

(LCROSS), as the vanguard of NASA's

Lunar Precursor Robotic Program The Lunar Precursor Robotic Program (LPRP) is a NASA program that uses robotic spacecraft to prepare for future human spaceflight, crewed missions to the Moon. The program gathers data such as lunar radiation, surface imaging, areas of scientific i ...

, LRO was the first United States mission to the Moon in over ten years. LRO and LCROSS were launched as part of the United States's

Vision for Space Exploration The Vision for Space Exploration (VSE) was a plan for space exploration announced on January 14, 2004 by President George W. Bush. It was conceived as a response to the Space Shuttle ''Columbia'' disaster, the state of human spaceflight at NASA, ...

program. The probe has made a 3-D map of the Moon's surface at 100-meter resolution and 98.2% coverage (excluding polar areas in deep shadow), including 0.5-meter resolution images of Apollo landing sites. The first images from LRO were published on July 2, 2009, showing a region in the lunar highlands south of

Mare Nubium Mare Nubium (Latin ''nūbium'', the "sea of clouds") is a lunar mare in the Nubium basin on the Moon's near side. The mare is located just to the southeast of Oceanus Procellarum. Formation The basin containing Mare Nubium is believed to ...

(''Sea of Clouds''). The total cost of the mission is reported as US$583 million, of which $504 million pertains to the main LRO probe and $79 million to the LCROSS satellite. LRO has enough fuel to continue operations until at least 2026.

Mission

Developed at NASA's

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C., in Greenbelt, Maryland, United States. Established on May 1, 1959, as NASA's first space flight center, GSFC ...

, LRO is a large () and sophisticated spacecraft. Its mission duration was planned for one year, but has since been extended numerous times after review by NASA. After completing a preliminary design review in February 2006 and a critical design review in November 2006, the LRO was shipped from Goddard to

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the sta ...

on February 11, 2009. Launch was planned for October 2008, but this slid to April as the spacecraft underwent testing in a thermal vacuum chamber. Launch was rescheduled for June 17, 2009, because of the delay in a priority military launch, and happened one day later, on June 18. The one-day delay was to allow the Space Shuttle ''Endeavour'' a chance to lift off for mission STS-127 following a hydrogen fuel leak that canceled an earlier planned launch. Areas of investigation include selenodetic global

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

; the lunar

polar region The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitu ...

s, including possible

water ice Water ice may refer to: *Ice formed by water (as opposed to other substances) *In ice climbing, ice made from flowing water (as opposed to ice from precipitation) *The alternate term for various similar frozen fruit-flavoured desserts: ** Italian ic ...

deposits and the lighting environment; characterization of deep space

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

in lunar orbit; and high-resolution mapping, at a maximum resolution of , to assist in the selection and characterization of future landing sites. In addition, LRO has provided images and precise locations of landers and equipment from previous and current lunar missions, including the Apollo sites. In 2024, it confirmed the highly accurate landing site of the first successful Japanese SLIM soft landing.

Instruments

The orbiter carries a complement of six instruments and one technology demonstration: ; Cosmic Ray Telescope for the Effects of Radiation (CRaTER) : The primary goal of the Cosmic Ray Telescope for the Effects of Radiation is to measure and characterize local energy transfer by charged particles in lunar orbit and its biological impacts. ;

Diviner Diviner, also referred to as the Diviner Lunar Radiometer Experiment (DLRE), is an infrared radiometer aboard NASA's Lunar Reconnaissance Orbiter, part of the Lunar Precursor Robotic Program which is studying the Moon. It has been used to create t ...

: The Diviner Lunar Radiometer Experiment measures lunar surface thermal emission to provide information for future surface operations and exploration. ; Lyman-Alpha Mapping Project (LAMP) : The

Lyman-Alpha Lyman-alpha, typically denoted by Ly-α or Lyα, is a spectral line of hydrogen (or, more generally, of any one-electron atom) in the Lyman series. It is emitted when the atomic electron transitions from an ''n'' = 2 orbital to the gro ...

Mapping Project peers into permanently shadowed craters in search of water ice, using

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

light generated by stars as well as the hydrogen atoms that are thinly spread throughout the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

. ; Lunar Exploration Neutron Detector (LEND) : The Lunar Exploration Neutron Detector provides measurements, creates maps, and detects possible near-surface water ice deposits. ; Lunar Orbiter Laser Altimeter (LOLA) : The Lunar Orbiter Laser Altimeter investigation provides a precise global lunar topographic model and geodetic grid. ; Lunar Reconnaissance Orbiter Camera (LROC) ''Narrow Angle Camera (NAC)'': The Lunar Reconnaissance Orbiter Camera addresses the measurement requirements of landing site certification and polar illumination. LROC comprises a pair of narrow-angle cameras (NAC) and a single wide-angle camera (WAC). The two Narrow Angle Cameras feature a Cassegrain ( Ritchey-Chretien) primary optics at f/3.59, with primary mirror diameter of 19.5 cm, using push-broom imaging. At its original altitude of about 50 km, each NAC images pixels about 0.5-meter across, and the swath, which is 5064 pixels wide, is about 2.5 km across. The orbit was raised in 2011 to be elliptical, reducing the resolution in parts of the orbit to 2.0 m/px.: LROC has flown several times over the historic

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

lunar landing A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959. In 1969 Apollo 11 was the first cr ...

sites at altitude. The

Lunar Roving Vehicle The Lunar Roving Vehicle (LRV) is a Battery electric vehicle, battery-powered four-wheeled Rover (space exploration), rover used on the Moon in the last three missions of the American Apollo program (Apollo 15, 15, Apollo 16, 16, and Apollo 17 ...

s and

Lunar Module The Apollo Lunar Module (LM ), 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 s ...

descent stages and their respective shadows are clearly visible, along with other equipment previously left on the Moon. ; Lunar Reconnaissance Orbiter Camera (LROC) ''Wide Angle Camera (WAC)'': The WAC provides visible and UV images at a scale of 100 meters/pixel in seven color bands over a 60 km swath. Image format is 1024 x 1024 pixels, with a field of view of 92° (monochrome), 61° (visible light), and 59° in the UV. ; Mini-RF : The Miniature Radio Frequency radar demonstrated new lightweight

synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or 3D reconstruction, three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target regi ...

(SAR) and communications technologies and located potential water-ice.

Names to the Moon

Prior to the LRO's launch,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

gave members of the public the opportunity to have their names placed in a microchip on the LRO. The deadline for this opportunity was July 31, 2008. About 1.6 million names were submitted.

Mission progress

Goddard Spaceflight Center Laser Ranging Facility

Animation of Lunar Reconnaissance Orbiter trajectory around Earth

Animation of Lunar Reconnaissance Orbiter trajectory

On June 23, 2009, the Lunar Reconnaissance Orbiter entered into orbit around the Moon after a four-and-a-half-day journey from the Earth. When launched, the spacecraft was aimed at a point ahead of the Moon's position. A mid-course correction was required during the trip in order for the spacecraft to correctly enter Lunar orbit. Once the spacecraft reached the

far side of the Moon The far side of the Moon is the hemisphere of the Moon that is facing away from Earth, the opposite hemisphere is the near side. It always has the same surface oriented away from Earth because of synchronous rotation in the Moon's orbit. C ...

, its rocket motor was fired in order for it to be captured by the Moon's gravity into an elliptical lunar orbit. A series of four rocket burns over the next four days put the satellite into its commissioning phase orbit where each instrument was brought online and tested. On September 15, 2009, the spacecraft started its primary mission by orbiting the Moon at about for one year. After completing its one-year exploration phase, in September 2010, LRO was handed over to NASA's

Science Mission Directorate The Science Mission Directorate (SMD) of the National Aeronautics and Space Administration (NASA) is one of the six directorates that constitute NASA. Its responsibility is to define and direct research into scientific questions of interest, shari ...

to continue the science phase of the mission. It would continue in its 50 km circular orbit, but eventually would be transitioned into a fuel-conserving "quasi-frozen" elliptical orbit for the remainder of the mission. NASA's LCROSS mission culminated with two lunar impacts at 11:31 and 11:36 UTC on October 9. The goal of the impact was the search for water in the

Cabeus crater Cabeus is a lunar impact crater that is located about from the south pole of the Moon. At this location the crater is seen obliquely from Earth, and it is almost perpetually in deep shadow due to lack of sunlight. Hence, not much detail can be ...

near the Moon's south pole, and preliminary results indicated the presence of both water and

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

, an ion related to water. On January 4, 2011, the Mini-RF instrument team for the Lunar Reconnaissance Orbiter (LRO) found that the Mini-RF radar transmitter had suffered an anomaly. Mini-RF has suspended normal operations. Despite being unable to transmit, the instrument is being used to collect

bistatic radar Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called ...

observations using radar transmissions from the Earth. The Mini-RF instrument has already met its science mission success criteria by collecting more than 400 strips of radar data since September 2010. In January 2013, NASA tested one-way laser communication with LRO by sending an image of the ''

Mona Lisa The ''Mona Lisa'' is a half-length portrait painting by the Italian artist Leonardo da Vinci. Considered an archetypal masterpiece of the Italian Renaissance, it has been described as "the best known, the most visited, the most written about, ...

'' to the Lunar Orbiter Laser Altimeter (LOLA) instrument on LRO from the Next Generation Satellite Laser Ranging (NGSLR) station at NASA's

in Greenbelt, Maryland. In May 2015, LRO's orbit was altered to fly above the Moon's south pole, allowing higher resolution data to be obtained from the Lunar Orbiter Laser Altimeter (LOLA) and Diviner instruments over the permanently shadowed craters there. In 2019, LRO found the crash site of Indian moon lander Vikram. In 2020, software was tested to use star trackers instead of the Miniature Inertial Measurement Unit that had been turned off in 2018 (as it was degrading). LRO and the

Chandrayaan-2 Chandrayaan-2 (; from Sanskrit: , "Moon" and , "craft, vehicle") is the second lunar exploration mission developed by the Indian Space Research Organisation (ISRO) after Chandrayaan-1. It consists of a lunar orbiter, the ''Vikram'' lunar l ...

orbiter were expected to come dangerously close to each other on 20 October 2021 at 05:45 UTC over the Lunar North pole. Chandrayaan-2 orbiter performed a

collision avoidance In transportation, collision avoidance is the maintenance of systems and practices designed to prevent vehicles (such as aircraft, motor vehicles, ships, cranes and trains) from colliding with each other. They perceive the environment with sensors ...

manoeuvre at 14:52 UTC on 18 October 2021 to avert the possible conjunction event.

Results

On August 21, 2009, the spacecraft, along with the

Chandrayaan-1 Chandrayaan-1 (; from Sanskrit: , "Moon" and , "craft, vehicle") was the first Indian lunar probe under the Chandrayaan programme. It was launched by the Indian Space Research Organisation (ISRO) in October 2008, and operated until August 200 ...

orbiter, attempted to perform a

experiment to detect the presence of water ice on the lunar surface, but the test was unsuccessful. On December 17, 2010, a topographic map of the Moon based on data gathered by the LOLA instrument was released to the public. This is the most accurate topographic map of the Moon to date. It will continue to be updated as more data is acquired. On March 15, 2011, the final set of data from the exploration phase of the mission was released to the NASA

Planetary Data System The Planetary Data System (PDS) is a distributed data system that NASA uses to archive data collected by Solar System missions. The PDS is an active archive that makes available well documented, peer reviewed planetary data to the research commun ...

. The spacecraft's seven instruments delivered more than 192 terabytes of data. LRO has already collected as much data as all other planetary missions combined. This volume of data is possible because the Moon is so close, LRO has its own dedicated ground station, and it doesn't have to share time on the

Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA' ...

. Among the latest products is a global map with a resolution of from the Lunar Reconnaissance Orbiter Camera (LROC). In March 2015, the LROC team reported having imaged the location of an impact whose flash was observed from Earth on March 17, 2013. The team found the crater by going back to images taken in the first year or two and comparing them to images taken after the impact, called temporal pairs. The images revealed splotches, small areas whose reflectance is markedly different from that of the surrounding terrain, presumably from disruption of the surface by recent impacts. By September 2015, LROC had imaged nearly three-fourths of the lunar surface at high resolution, revealing more than 3,000

lobate scarp The geology of solar terrestrial planets mainly deals with the geology, geological aspects of the four terrestrial planets of the Solar System – Mercury (planet), Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres (dwa ...

s. Their global distribution and orientation suggests that the faults are created as the Moon shrinks, with influence by gravitational tidal forces from Earth. In March 2016, the LROC team reported the use of 14,092 NAC temporal pairs to discover over 47,000 new splotches on the Moon. In July 2024, the analysis of the radar data obtained by LRO confirmed the presence of an underground cave on the Moon accessible from the surface. The cave is said to be about 45 metres wide and at least 80 metres long, and present in the

Mare Tranquillitatis Mare Tranquillitatis (Latin for Sea of Tranquillity or Sea of Tranquility) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It contains Tranquility Base, the first location on another celestial body to be visited by huma ...

(Sea of Tranquility), the ancient lava plain where the

Apollo 11 Apollo 11 was a spaceflight conducted from July 16 to 24, 1969, by the United States and launched by NASA. It marked the first time that humans Moon landing, landed on the Moon. Commander Neil Armstrong and Lunar Module pilot Buzz Aldrin l ...

astronauts

Neil Armstrong Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aerospace engineering, aeronautical engineer who, in 1969, became the Apollo 11#Lunar surface operations, first person to walk on the Moon. He was al ...

and

Buzz Aldrin Buzz Aldrin ( ; born Edwin Eugene Aldrin Jr.; January 20, 1930) is an American former astronaut, engineer and fighter pilot. He made three extravehicular activity, spacewalks as pilot of the 1966 Gemini 12 mission, and was the Lunar Module Eag ...

first set foot on the Moon. The mission maintains a full list of publications with science results on its website.

Gallery

File:LRO FirstImage.jpg, First LRO image (June 30, 2009) File:Apollo11-LRO-March2012.jpg,

landing site File:Apollo 12 LRO.jpg,

Apollo 12 Apollo 12 (November 14–24, 1969) was the sixth crewed flight in the United States Apollo program and the second to land on the Moon. It was launched on November 14, 1969, by NASA from the Kennedy Space Center in Florida. Commander Charles ...

and

Surveyor 3 Surveyor 3 is the third lander of the American uncrewed Surveyor program sent to explore the surface of the Moon in 1967 and the second to successfully land. It was the first mission to carry a surface-soil sampling-scoop. Surveyor 3 was vis ...

landing site File:LRO Apollo14.jpg,

Apollo 14 Apollo 14 (January 31February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to Moon landing, land on the Moon, and the first to land in the Geology of the Moon#Highlands, lunar highlands. It was the las ...

landing site File:LRO Apollo15.jpg,

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a longer stay on the Moon and a greate ...

landing site File:LRO Apollo16.jpg,

Apollo 16 Apollo 16 (April 1627, 1972) was the tenth human spaceflight, crewed mission in the United States Apollo program, Apollo space program, administered by NASA, and the fifth and penultimate to Moon landing, land on the Moon. It was the second o ...

landing site File:LRO Apollo17.jpg,

Apollo 17 Apollo 17 (December 7–19, 1972) was the eleventh and final mission of NASA's Apollo program, the sixth and most recent time humans have set foot on the Moon. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on the Moon, ...

landing site File:Apollo 17 LM Challenger LRO.png, Close up of

''Challenger'' descent stage File:390497main surveyor1 enlarged.jpg,

Surveyor 1 Surveyor 1 was the first lunar soft-lander in the uncrewed Surveyor program of the National Aeronautics and Space Administration (NASA, United States). This lunar soft-lander gathered data about the lunar surface that would be needed for the c ...

landing site File:LROviewsLADEEorbitingMOON-20140114.jpg, LRO views

LADEE The Lunar Atmosphere and Dust Environment Explorer (LADEE; ) was a NASA lunar exploration and technology demonstration mission. It was launched on a Minotaur V rocket from the Mid-Atlantic Regional Spaceport on September 7, 2013. During its s ...

at a distance of File:LRO Chang'e 4, first look.png,

Chang'e 4 Chang'e 4 (; ) is a robotic spacecraft mission in the Chinese Lunar Exploration Program of the CNSA. It made a soft landing on the far side of the Moon, the first spacecraft to do so, on 3 January 2019. A communication relay satellite, , w ...

landing site File:14284-Moon-Maskelyne-LRO-20141012.jpg, LRO view of

irregular mare patch An irregular mare patch also known as an IMP, is a smooth, rounded, slightly mounded area, generally about 500 meters wide, occurring in the lunar maria.Wood, Charles. "Strange Little IMPs." ''Sky and Telescope,'' February 2015 issue. Discovery ...

, an extremely young terrain File:Earthrise over Compton crater -LRO full res - edit1.jpg, Earthrise over Compton crater The Moon The Moon is Earth's only natural satellite. It orbits around Earth at an average distance of (; about 30 times Earth's diameter). The Moon rotates, with a rotation period ( lunar day) that is synchronized to its orbital period ( lunar ...

Mission

Instruments

Names to the Moon

Mission progress

Results

Gallery

See also

References

External links