Spacecraft call signs are radio

call signs In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a Identifier, unique identifier for a transmitter station. A call sign can be fo ...

used for communication in

crewed spaceflight Human spaceflight (also referred to as manned spaceflight or crewed spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be ...

. These are not formalized or regulated to the same degree as other equivalent forms of transportation, like aircraft. The three nations currently launching crewed space missions use different methods to identify the ground and space radio stations; the United States uses either the names given to the space vehicles or else the project name and mission number. Russia traditionally assigns code names as call signs to individual

cosmonaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs, human spaceflight program to serve as a commander or crew member of a spa ...

s, more in the manner of aviator call signs, rather than to the spacecraft. The only continuity in call signs for spacecraft has been the issuance of "ISS"-suffixed (or "-1SS", for its visual similarity) call signs by various countries in the Amateur Radio service as a citizen of their country has been assigned there. The first Amateur Radio call sign assigned to the International Space Station was NA1SS by the United States. OR4ISS (Belgium), GB1SS (UK), DP0ISS (Germany), and RS0ISS (Russia) are examples of others, but are not all-inclusive of others also issued.

United States

In America's first crewed space program

Project Mercury Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Un ...

, the astronauts named their individual spacecraft. These names each consisted of a significant word followed by the number 7 (representing the seven original astronauts) and were used as the call signs by the capsule communicators (CAPCOMs). In

Project Gemini Project Gemini () was the second United States human spaceflight program to fly. Conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early development, Gemini was conceived in 1961 and ...

, the astronauts were not officially permitted to name their two-man spacecraft, which was identified by "Gemini" followed by the mission number (3 through 12). A notable exception was that

Gus Grissom Virgil Ivan "Gus" Grissom (April 3, 1926 – January 27, 1967) was an American engineer and pilot in the United States Air Force, as well as one of the original Mercury Seven selected by the NASA, National Aeronautics and Space Administration fo ...

named his Gemini 3 spacecraft ''Molly Brown'' after the '' Titanic'' survivor, as a joke based on his experience with his ''Liberty Bell 7'' capsule sinking. This name was used as a call sign by CAPCOM L. Gordon Cooper, without NASA's approval. Starting with the second Gemini flight,

Gemini 4 Gemini 4 (officially Gemini IV) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was the second crewed spaceflight in NASA's Project Gemini, occurring in June 1965. It was the tenth crewed American spaceflight (in ...

, NASA used the Lyndon B. Johnson Space Center (JSC) to house the flight control center. The call sign for this facility was ''

Houston Houston ( ) is the List of cities in Texas by population, most populous city in the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the county seat, seat of ...

''. The

Christopher C. Kraft Jr. Mission Control Center NASA's Christopher C. Kraft Jr. Mission Control Center (MCC-H, initially called Integrated Mission Control Center, or IMCC), also known by its radio callsign, ''Houston'', is the facility at the Lyndon B. Johnson Space Center in Houston, Texa ...

, the current flight control facility at JSC, also uses ''Houston'' as its call sign. The practice of using the mission number continued through the first two flights of the

Project Apollo The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...

crewed lunar landing program,

Apollo 7 Apollo 7 (October 11–22, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test ...

and

Apollo 8 Apollo 8 (December 21–27, 1968) was the first crewed spacecraft to leave Sphere of influence (astrodynamics), Earth's gravitational sphere of influence, and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times ...

. But all remaining Apollo missions included two crewed spacecraft ( Command/Service Module (CSM) 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 ...

(LM)) on each flight, which required the use of separate call signs for each vehicle when they flew independently of each other. For this reason, NASA permitted the three-man crews to name both crafts for each of their missions, and these names were used as the call signs. A temporary exception to this was on the first Moon landing,

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 ...

: since the first Moon landing site was in the Sea of Tranquillity, the call sign ''Tranquillity Base'' was used while the LM was on the lunar surface. Before and after the independent flight of the LM, the mission number was used as the call sign. The Apollo call signs were: For project

Skylab Skylab was the United States' first space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three trios of astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Skylab was constructe ...

, the practice returned to using the mission name as the spacecraft call sign, since the Skylab station was left uncrewed while the shuttle vehicle (an Apollo CSM) carried a crew to it or back to Earth. The six

Space Shuttle The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. ...

orbiters were given individual names (they also had letter-and-number callsigns) by NASA, which were used as the call signs: ''

Enterprise Enterprise (or the archaic spelling Enterprize) may refer to: Business and economics Brands and enterprises * Enterprise GP Holdings, an energy holding company * Enterprise plc, a UK civil engineering and maintenance company * Enterpris ...

'' (OV-101, which was not fitted for spaceflight), '' Columbia'' (OV-102), '' Challenger'' (OV-099), ''

Discovery Discovery may refer to: * Discovery (observation), observing or finding something unknown * Discovery (fiction), a character's learning something unknown * Discovery (law), a process in courts of law relating to evidence Discovery, The Discovery ...

'' (OV-103), ''

Atlantis Atlantis () is a fictional island mentioned in Plato's works '' Timaeus'' and ''Critias'' as part of an allegory on the hubris of nations. In the story, Atlantis is described as a naval empire that ruled all Western parts of the known world ...

'' (OV-104), and '' Endeavour'' (OV-105). Of these, ''Columbia'', ''Challenger'', and ''Endeavour'' had served as call-signs of Apollo spacecraft.

SpaceX Space Exploration Technologies Corp., commonly referred to as SpaceX, is an America, American space technology company headquartered at the SpaceX Starbase, Starbase development site in Starbase, Texas. Since its founding in 2002, the compa ...

Crew Dragon Dragon 2 is a class of partially reusable spacecraft developed, manufactured, and operated by the American space company SpaceX for flights to the International Space Station (ISS) and private spaceflight missions. The spacecraft, which consi ...

capsules use two calls signs. ''Dragon'' is used as a generic call sign, particularly if the capsule has not been named. The name of the spacecraft is also used as a call sign. The name and call sign of each Crew Dragon, as given by the crew of the spacecraft's initial mission, is: ''Endeavour'', which was named for the space shuttle ''Endeavour'', had previously served as call signs for both an Apollo spacecraft and the spacecraft's namesake shuttle. The name ''Freedom'' honors '' Freedom 7'', the space capsule used by

Alan Shepard Alan Bartlett Shepard Jr. (November 18, 1923 – July 21, 1998) was an American astronaut. In 1961, he became the second person and the first American to travel into space and, in 1971, he became the List of Apollo astronauts#Apollo astr ...

's Mercury Redstone 3, the first United States

human spaceflight Human spaceflight (also referred to as manned spaceflight or crewed spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be ...

mission. The call sign ''SpaceX'' is used by the Crew Operations and Resources Engineer (CORE) (the SpaceX equivalent of the CAPCOM in Houston) at SpaceX Mission Control (MCC-X) in Hawthorne,

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Boeing Starliner The Boeing Starliner (or CST-100) is a spacecraft designed to transport crew to and from the International Space Station (ISS) and other low-Earth-orbit destinations. Developed by Boeing under NASA's Commercial Crew Program (CCP), it consists o ...

capsules use the generic call sign ''Starliner''. The only named Starliner capsule, Starliner Spacecraft 3, was named ''Calypso'' by

Boeing Crewed Flight Test Boeing Crew Flight Test (Boe-CFT) was the first crewed mission of the Boeing Starliner capsule. Launched on 5 June 2024, the mission flew a crew of two NASA astronauts, Barry Wilmore, Barry E. Wilmore and Sunita Williams, from Cape Canaveral Sp ...

pilot Sunita Williams and can use that name as an alternate call sign. As Boeing Mission Control (MCC-CST) is located at the Johnson Space Center, the standard JSC call sign ''Houston'' is used.

Russia (including the former Soviet Union)

The

spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...

of the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

were not individually named, nor are those of

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

today. Only the general type of spacecraft, for example, "Vostok," "Soyuz," or "Soyuz-T" is publicly announced after launch, usually followed by the number of the flight of that type of spacecraft. The Soviet and now Russian call signs are more nearly code words, and so are not disclosed before launch. Each is given to a particular

who commands a spacecraft, generally staying as his or her designation from spacecraft to spacecraft. The other crew members use the same call sign with a number of their rank in the chain of command suffixed. Russian popular journalism refers to the crew by the plural of the call sign (for example, "the Fotons"). ''Kedr'', meaning "cedar," was the call sign of

Yuri Gagarin Yuri Alekseyevich Gagarin; Gagarin's first name is sometimes transliterated as ''Yuriy'', ''Youri'', or ''Yury''. (9 March 1934 – 27 March 1968) was a Soviet pilot and cosmonaut who, aboard the first successful Human spaceflight, crewed sp ...

, the first man in space. It would have disclosed nothing to a listener concerning the momentousness of the flight. The rest of the call signs of the Vostok series were the names of birds. Pavel Popovich and Andriyan Nikolayev's call signs in their joint flight in ''Vostok-3'' and ''Vostok-4'', ''Sokol'' ("falcon") and ''Berkut'' ("golden eagle"), were widely popularized by Soviet media. The call sign of the launch facility itself for Vostok was nearly a code word: ''Zarya'', meaning "dawn". Early

Soyuz Soyuz is a transliteration of the Cyrillic text Союз (Russian language, Russian and Ukrainian language, Ukrainian, 'Union'). It can refer to any union, such as a trade union (''profsoyuz'') or the Soviet Union, Union of Soviet Socialist Republi ...

flights intent on practicing docking procedures were given call signs elaborating on the first few letters of an alphabet. Soyuz 4, which had the call sign ''Amur'', docked with Soyuz 5, called ''Baikal'' - the names derived from a railway project of that era, intending to link those two geographical features. Soyuz 6 was given a call sign equivalent to "Antaeus," which referred to the largest aircraft of the era, the Antonov 22. Its mission in a group flight was to film the intended docking of Soyuz 7 (called ''Buran'', which means "snowstorm") with Soyuz 8, called ''Granit'' ("granite") - standard Soviet military call signs. The equivalent for the letter ''A'' was ''Aktif'', meaning "Active"; it would be inappropriate for the mission of Soyuz 6. Later Soyuz flights to the

Salyut The ''Salyut'' programme (, , meaning "salute" or "fireworks") was the first space station programme, undertaken by the Soviet Union. It involved a series of four crewed scientific research space stations and two crewed military reconnaissa ...

space stations and

Mir ''Mir'' (, ; ) was a space station operated in low Earth orbit from 1986 to 2001, first by the Soviet Union and later by the Russia, Russian Federation. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to ...

had less noteworthy call signs: ''Foton'', meaning "photon", etc. In contrast to the naming conventions applied by the Soviet Union and now Russia, most American space flights, with the exception of those of

and early

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 ...

flights, have had their spacecraft officially named. Calls to ground facilities by radiotelephone use the name of the spacecraft (e.g., "The ''Eagle'' has landed") as the call sign.

International Space Station

The call sign of the International Space Station was Alpha, now ''Station''. When different space missions and different control centers work together in joint operations, for example when a Dragon capsule docks to the ISS, NASA connects all communication channels using what is known as the Big Loop. When communicating on the Big Loop, one can hear the call signs ''Dragon'', ''Starliner'', ''SpaceX'', ''Houston'' and ''Station'' at any given time. The following Call signs are available for use on the ISS: * RUSSIAN: RS0ISS * USA: NA1SS * EUROPEAN: DP0ISS, OR4ISS, IR0ISS The following callsigns are called when the crew needs to contact one of the field centers on the ground what ever segment they are in when performing experiments: * Houston: As in Mission Control Houston at the

in Houston Texas * Huntsville: As in the

Payload Operations and Integration Center The Payload Operations and Integration Center (POIC), part of the Huntsville Operations Support Center (HOSC), callsign Huntsville, or the Payload Operations Center, is a National Aeronautics and Space Administration (NASA) facility located at th ...

in Huntsville Alabama * Moscow: As in Mission Control Moscow at the

RKA Mission Control Center The RKA Mission Control CenterRKA (): Russian space agency (, ). (), also known by its acronym TsUP () or by its radio callsign Mission Control Moscow, is the mission control center of Roscosmos. It is located in Korolyov, Moscow Oblast, on ...

in Korolyov Russia outside of

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

* Munich: As in the Columbus Control Centre located at ESA Headquarters in Munich Germany * Saint Hubert: Rarely used as in Mobile Servicing System Control and Training Center at CSA Headquarters in Saint Hubert Quebec * Tsukuba: As in the Space Station Integration and Promotion Center at

JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...

Headquarters

Tsukuba Space Center The Tsukuba Space Center (TKSC) also known by its radio Call sign, callsign Tsukuba, is the operations facility and headquarters for the Japan Aerospace Exploration Agency (JAXA) located in Tsukuba Science City in Ibaraki Prefecture. The facil ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

* Hawthorne: As in the

Dragon A dragon is a Magic (supernatural), magical legendary creature that appears in the folklore of multiple cultures worldwide. Beliefs about dragons vary considerably through regions, but European dragon, dragons in Western cultures since the Hi ...

Control Center at

Headquarters in

Hawthorne, California Hawthorne is a city in southwestern Los Angeles County, California. It is part of a seventeen-city subregion of the Los Angeles metropolitan area commonly known as the South Bay (Los Angeles County), South Bay. As of the 2020 United States cens ...

References

{{Reflist Call signs

Call sign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally as ...