Manned Space Flight Network
Encyclopedia
The Manned Space Flight Network (abbreviated MSFN, pronounced "misfin") was a set of tracking stations built to support the American space efforts of Mercury
, Gemini
, Apollo and Skylab
. There were two other space communication networks at this time, the Spacecraft Tracking and Data Acquisition Network
(STADAN) for tracking unmanned satellites in low Earth orbit, and the Deep Space Network
(DSN) for tracking more distant unmanned missions. After the end of Skylab, the MSFN and STADAN were merged to form the Spaceflight Data Tracking Network (STDN). STDN was in turn replaced by the satellite-based Tracking and Data Relay Satellite System
(TDRSS), being used .
s (LEO) is quite different from tracking deep space missions. Deep space missions are visible for long periods of time from a large portion of the Earth's surface, and so require few stations (the DSN uses only three). These few stations, however, require the use of huge antennas and ultra-sensitive receivers in order to cope with the very weak signals. Low earth orbit missions, on the other hand, are only visible from a small fraction of the Earth's surface at a time, and the satellites move overhead very quickly, which necessitates the use of a large number of tracking stations, spread all over the world. The antennas required for LEO tracking and communication are not required to be as large as those used for deep space, but they must be able to track quickly.
These differing requirements have led NASA
to build a number of independent tracking networks, each optimized for its own mission. Prior to the mid 80's, when the Tracking and Data Relay Satellite System
(TDRSS) satellites became operational, NASA used several networks of ground based antennas in order to track and communicate with Earth orbiting spacecraft. For the Mercury
, Gemini
, and Apollo missions, these were the primary means of communication, with the Deep Space Network
(DSN) being assigned a supporting/backup role.
's 1963 Mercury flight
were:
The network expanded for Project Gemini
's longer flights which included rendezvous operations involving two spacecraft. A move toward increased computerization and decreased voice support for Gemini made a more centralized network possible with fewer primary stations and more secondary stations, although those major facilities were better equipped. Some Mercury stations were dropped; many were supplemented with new hardware.
To meet these requirements, the MSFN used a combination of resources. A Jet Propulsion Laboratory
(JPL) system called "Unified S-Band
", or USB, was selected for Apollo communications, which allowed tracking, ranging, telemetry, and voice to all use the same S band
transmitter. Near-Earth tracking was provided by upgrading the same networks used for Mercury and Gemini. New large antennas for the lunar phase were constructed explicitly for the MSFN, with Deep Space Network
(DSN) large antennas used for backup and critical mission phases.
(DSN) also contributed to the communication and tracking of Apollo missions to the Moon
, although primary responsibility remained with the Manned Space Flight Network (MSFN). The DSN designed the MSFN stations for lunar communication and provided a second antenna at each MSFN site (the MSFN sites were near the DSN sites for just this reason). Two antennas at each site were needed since the beam widths which the large antennas required were too small to encompass both the lunar orbiter and the lander at the same time. DSN also supplied some larger antennas as needed, in particular for television broadcasts from the Moon, and emergency communications such as Apollo 13.
From a NASA
report describing how the DSN and MSFN cooperated for Apollo:
The details of this cooperation and operation are available in a two-volume technical report from JPL.
(DSN) and the Tracking and Data Relay Satellite System
(TDRSS). The DSN, as the name implies, tracks probes in deep space (more than 10000 miles (16,093.4 km) from Earth), while TDRSS is used to communicate with satellites in low earth orbit. TDRSS uses a network of 10 geostationary communication satellites, and a single ground station at White Sands Test Facility
.
After Apollo, the MSFN no longer needed the large antennas that had been used for lunar communication, which were eventually given over to the DSN. In 1985, the antenna at Honeysuckle Creek Tracking Station
was moved to the Canberra Deep Space Communication Complex
(CDSCC) DSN site, and the antenna at Fresnedillas was moved to the existing Robledo DSN location. The Goldstone Deep Space Communications Complex
antenna is still in its original location.
Project Mercury
In January 1960 NASA awarded Western Electric Company a contract for the Mercury tracking network. The value of the contract was over $33 million. Also in January, McDonnell delivered the first production-type Mercury spacecraft, less than a year after award of the formal contract. On February 12,...
, Gemini
Project Gemini
Project Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini was conducted between projects Mercury and Apollo, with ten manned flights occurring in 1965 and 1966....
, Apollo and Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...
. There were two other space communication networks at this time, the Spacecraft Tracking and Data Acquisition Network
Spacecraft Tracking and Data Acquisition Network
The Spacecraft Tracking and Data Network was established by NASA to satisfy the requirement for long-duration, highly-available space-to-ground communications...
(STADAN) for tracking unmanned satellites in low Earth orbit, and the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN) for tracking more distant unmanned missions. After the end of Skylab, the MSFN and STADAN were merged to form the Spaceflight Data Tracking Network (STDN). STDN was in turn replaced by the satellite-based Tracking and Data Relay Satellite System
Tracking and Data Relay Satellite System
The Tracking and Data Relay Satellite System is a network of American communications satellites and ground stations used by NASA for space communications. The system was designed to replace an existing network of ground stations that had supported all of NASA's manned flight missions...
(TDRSS), being used .
Orbital vs. deep space tracking
Tracking vehicles in low Earth orbitLow Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
s (LEO) is quite different from tracking deep space missions. Deep space missions are visible for long periods of time from a large portion of the Earth's surface, and so require few stations (the DSN uses only three). These few stations, however, require the use of huge antennas and ultra-sensitive receivers in order to cope with the very weak signals. Low earth orbit missions, on the other hand, are only visible from a small fraction of the Earth's surface at a time, and the satellites move overhead very quickly, which necessitates the use of a large number of tracking stations, spread all over the world. The antennas required for LEO tracking and communication are not required to be as large as those used for deep space, but they must be able to track quickly.
These differing requirements have led NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
to build a number of independent tracking networks, each optimized for its own mission. Prior to the mid 80's, when the Tracking and Data Relay Satellite System
Tracking and Data Relay Satellite System
The Tracking and Data Relay Satellite System is a network of American communications satellites and ground stations used by NASA for space communications. The system was designed to replace an existing network of ground stations that had supported all of NASA's manned flight missions...
(TDRSS) satellites became operational, NASA used several networks of ground based antennas in order to track and communicate with Earth orbiting spacecraft. For the Mercury
Project Mercury
In January 1960 NASA awarded Western Electric Company a contract for the Mercury tracking network. The value of the contract was over $33 million. Also in January, McDonnell delivered the first production-type Mercury spacecraft, less than a year after award of the formal contract. On February 12,...
, Gemini
Project Gemini
Project Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini was conducted between projects Mercury and Apollo, with ten manned flights occurring in 1965 and 1966....
, and Apollo missions, these were the primary means of communication, with the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN) being assigned a supporting/backup role.
Mercury MSFN stations
The Manned Space Flight Network (MSFN) stations during Gordon CooperGordon Cooper
Leroy Gordon Cooper, Jr. , also known as Gordon Cooper, was an American aeronautical engineer, test pilot and NASA astronaut. Cooper was one of the seven original astronauts in Project Mercury, the first manned space effort by the United States...
's 1963 Mercury flight
Mercury-Atlas 9
Mercury-Atlas 9 was the final manned space mission of the U.S. Mercury program, launched on May 15, 1963 from Launch Complex 14 at Cape Canaveral, Florida. The spacecraft, named Faith 7, completed 22 Earth orbits before splashing down in the Pacific Ocean, piloted by astronaut Gordon Cooper, then...
were:
- Canton Island
- Eglin AFB, Florida
- Goldstone (GDS)Goldstone Deep Space Communications ComplexThe Goldstone Deep Space Communications Complex — commonly called the Goldstone Observatory — is located in California's Mojave Desert. Operated by ITT Corporation for the Jet Propulsion Laboratory, its main purpose is to track and communicate with space missions. It includes the Pioneer...
- Grand Canary Island (CAN)
- Guaymas, Mexico (GYM): The station was about six miles east of Empalme, Sonora, adjacent to Mexican Federal Highway No. 15. Personnel resided in or near Guaymas, about 12 miles west of the station. Originally built in 1960–1961 as a Mercury tracking station, it was modified for successive US manned space programs through Apollo 13. Major equipment was the 30-foot antenna USB system, VHF telemetry, data processing and recording equipment. NASA discontinued its use on November 30, 1970.
- Kano, Nigeria (KAN)
- Kauai, Hawaii (HAW)
- Mercury Control Center (CNV)
- Muchea, Australia
- South Texas
- White Sands, New Mexico
- Woomera, Australia
- Zanzibar (ZAN)
- Indian Ocean ship (IOS)
- Pacific Ocean ship
The network expanded for Project Gemini
Project Gemini
Project Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini was conducted between projects Mercury and Apollo, with ten manned flights occurring in 1965 and 1966....
's longer flights which included rendezvous operations involving two spacecraft. A move toward increased computerization and decreased voice support for Gemini made a more centralized network possible with fewer primary stations and more secondary stations, although those major facilities were better equipped. Some Mercury stations were dropped; many were supplemented with new hardware.
The Apollo missions
The Manned Space Flight Network (MSFN) during the Apollo era was also known as the Apollo Network. From a NASA technical report on the history of the MSFN:
The technical facts of life were these: the radars
of the Mercury and Gemini Networks obviously could not track
two spacecraft orbiting the Moon a quarter-million miles
away: neither could the small MSFN telemetry antennas hope
to pick out the telemetry and voice messages in the weak
signals arriving from the vicinity of the Moon. Translated
into network hardware terms, Apollo would require at least
the following changes in the MSFN:
- A range and range rate tracking system, such as GRARR or the JPL range and range rate system, would have to be incorporated to accurately track the distant spacecraft while it was out of radar range.
- Large dish antennas with high gains, such as the 26-m paraboloids employed in STADAN and the DSN, would have to be added to the MSFN to track and communicate at lunar distances.
- Extant MSFN stations could not properly monitor the very critical mission phases when the spacecraft was inserted into its lunar trajectory and when it plunged into the narrow reentry corridor on the return trip. The result was that the MSFN had to be extended with ships, aircraft, and additional land sites.
- Small paraboloidal antennas would have to be added at some MSFN sites to communicate with the Apollo spacecraft while it was still below the horizon for the 26-m dishes (below about 16,000 km) but beyond the range of the Gemini telemetry antennas.
- The communication traffic during the Apollo missions would be several times that planned for Gemini. NASCOM lines would have to be augmented.
To meet these requirements, the MSFN used a combination of resources. A Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
(JPL) system called "Unified S-Band
Unified S-Band
The Unified S-band system was a tracking and communication system developed for the Apollo program by NASA and the Jet Propulsion Laboratory . It operated in the S band portion of the microwave spectrum, combining voice communications, television, telemetry, command, tracking and ranging into a...
", or USB, was selected for Apollo communications, which allowed tracking, ranging, telemetry, and voice to all use the same S band
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...
transmitter. Near-Earth tracking was provided by upgrading the same networks used for Mercury and Gemini. New large antennas for the lunar phase were constructed explicitly for the MSFN, with Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN) large antennas used for backup and critical mission phases.
DSN support during Apollo
Although normally tasked with tracking unmanned spacecraft, the Deep Space NetworkDeep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN) also contributed to the communication and tracking of Apollo missions to the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, although primary responsibility remained with the Manned Space Flight Network (MSFN). The DSN designed the MSFN stations for lunar communication and provided a second antenna at each MSFN site (the MSFN sites were near the DSN sites for just this reason). Two antennas at each site were needed since the beam widths which the large antennas required were too small to encompass both the lunar orbiter and the lander at the same time. DSN also supplied some larger antennas as needed, in particular for television broadcasts from the Moon, and emergency communications such as Apollo 13.
From a NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
report describing how the DSN and MSFN cooperated for Apollo:
Another critical step in the
evolution of the Apollo Network came in 1965 with the advent
of the DSN Wing concept. Originally, the participation of
DSN 26-m antennas during an Apollo Mission was to be limited
to a backup role. This was one reason why the MSFN 26-m
sites were collocated with the DSN sites at Goldstone, Madrid,
and Canberra. However, the presence of two, well-separated
spacecraft during lunar operations stimulated the rethinking
of the tracking and communication problem. One thought was
to add a dual S-band RF system to each of the three 26-m
MSGN antennas, leaving the nearby DSN 26-m antennas still in
a backup role. Calculations showed, though, that a 26-m
antenna pattern centered on the landed Lunar Module would
suffer a 9-to-12 db loss at the lunar horizon, making tracking
and data acquisition of the orbiting Command Service
Module difficult, perhaps impossible. It made sense to
use both the MSFN and DSN antennas simultaneously during the
all-important lunar operations. JPL was naturally reluctant
to compromise the objectives of its many unmanned spacecraft
by turning three of its DSN stations over to the MSFN for
long periods. How could the goals of both Apollo and deep
space exploration be achieved without building a third 26-m
antenna at each of the three sites or undercutting planetary
science missions?
The solution came in early 1965 at a meeting at NASA
Headquarters, when Eberhardt Rechtin suggested what is now
known as the "wing concept". The wing approach involves
constructing a new section or "wing" to the main building at
each of the three involved DSN sites. The wing would include
a MSFN control room and the necessary interface equipment
to accomplish the following:
i. Permit tracking and two-way data transfer with either
spacecraft during lunar operations.
2. Permit tracking and two-way data transfer with the
combined spacecraft during the flight to the Moon
3. Provide backup for the collocated MSFN site passive
track (spacecraft to ground RF links) of the Apollo
spacecraft during trans-lunar and trans-earth phases.
With this arrangement, the DSN station could be quickly
switched from a deep-space mission to Apollo and back again.
GSFC personnel would operate the MSFN equipment completely
independently of DSN personnel. Deep space missions would
not be compromised nearly as much as if the entire station's
equipment and personnel were turned over to Apollo for several
weeks.
The details of this cooperation and operation are available in a two-volume technical report from JPL.
Current communication with earth-orbiting spacecraft
, two different networks are used - the Deep Space NetworkDeep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN) and the Tracking and Data Relay Satellite System
Tracking and Data Relay Satellite System
The Tracking and Data Relay Satellite System is a network of American communications satellites and ground stations used by NASA for space communications. The system was designed to replace an existing network of ground stations that had supported all of NASA's manned flight missions...
(TDRSS). The DSN, as the name implies, tracks probes in deep space (more than 10000 miles (16,093.4 km) from Earth), while TDRSS is used to communicate with satellites in low earth orbit. TDRSS uses a network of 10 geostationary communication satellites, and a single ground station at White Sands Test Facility
White Sands Test Facility
White Sands Test Facility is a U.S. government rocket engine test facility and a resource for testing and evaluating potentially hazardous materials, space flight components, and rocket propulsion systems. NASA established WSTF on the White Sands Missile Range in 1963...
.
After Apollo, the MSFN no longer needed the large antennas that had been used for lunar communication, which were eventually given over to the DSN. In 1985, the antenna at Honeysuckle Creek Tracking Station
Honeysuckle Creek Tracking Station
Honeysuckle Creek was a NASA tracking station near Canberra, Australia, which played an important role in supporting Project Apollo. The station was opened in 1967 and closed in 1981....
was moved to the Canberra Deep Space Communication Complex
Canberra Deep Space Communication Complex
The Canberra Deep Space Communication Complex is a ground station that is located in Australia at Tidbinbilla in the Paddys River valley, about half an hour's drive out of Canberra in the Australian Capital Territory. The complex is part of the Deep Space Network run by NASA's Jet Propulsion...
(CDSCC) DSN site, and the antenna at Fresnedillas was moved to the existing Robledo DSN location. The Goldstone Deep Space Communications Complex
Goldstone Deep Space Communications Complex
The Goldstone Deep Space Communications Complex — commonly called the Goldstone Observatory — is located in California's Mojave Desert. Operated by ITT Corporation for the Jet Propulsion Laboratory, its main purpose is to track and communicate with space missions. It includes the Pioneer...
antenna is still in its original location.