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BRIEFING: Military Satellite History—Part III
by U.S.A.F.'s Space and Missile Center's History Office, Los Angeles Air Force Base

The Space and Missile Systems Center is the birthplace and cradle of military space and the central hub of military space acquisition excellence. SMC’s mission is to deliver unrivaled space and missile systems to the joint warfighter and our nation, producing innovative, affordable, and operationally effective space systems of separate subsystems that could carry out different missions.

We continue our review of military satellite systems and we examine…

Nuclear Surveillance
In addition to reconnaissance and missile warning, SMC and its predecessors have developed satellites to serve a number of other purposes, among which are nuclear surveillance, weather observation, navigation, and communication.

The first space system to accomplish nuclear surveillance was called Vela Hotel—later, simply Vela. Representatives of the Air Force Ballistic Missile Division (AFBMD), the Atomic Energy Commission, and NASA met on December 15, 1960 to initiate a joint program to develop a high-altitude satellite system that could detect nuclear explosions. Its primary purpose was to monitor compliance with the Nuclear Test Ban Treaty then being negotiated in Geneva. During 1961-1962, the Atomic Energy Commission developed detectors and flew experimental versions on Space Systems Division’s Discoverer satellites. SSD issued a contract for the spacecraft to Space Technology Laboratories (later part of TRW) on November 24, 1961.

The first pair of satellites was launched using an Atlas Agena on October 16, 1963, a few days after the Nuclear Test Ban Treaty went into effect two more pairs were launched on July 16, 1964 and July 17, 1965. Six Advanced Vela satellites, containing additional, more sophisticated detectors, were launched in pairs on Titan IIIC vehicles on April 28, 1967, May 23, 1969, and April 8, 1970. (See photos on preceding page.)

The Vela satellites successfully monitored compliance with the Nuclear Test Ban Treaty and provided scientific data on natural sources of space radiation for many years. The least successful of the original satellites operated for 10 times its design lifetime of six months. The last of the advanced Vela satellites was deliberately turned off on September 27, 1984, over 15 years after it had been launched.

Meteorological Systems
Providing the systems with which to conduct military weather observations from space is presently the mission of the Defense Meteorological Satellite Program (DMSP), which maintains a constellation of at least two operational weather satellites in polar orbits about 450 miles above the earth. DMSP satellites now carry primary sensors that provide images of cloud cover over the earth’s surface during both day and night, and they also carry other sensors that provide additional types of data on weather and on the space environment.

The first DMSP satellites were developed by a program office physically located with Space Systems Division but reporting to the National Reconnaissance Office (NRO),27 which needed analyses of cloud cover over Eurasia to plan its photographic reconnaissance.28 The program office awarded a development contract for weather satellites employing television cameras to RCA in 1961.

Block I began with five launch attempts on Scout launch vehicles during 1962 and 1963, all but one of which failed.29 Later Block I launches on Thor Agena and Thor Burner I vehicles were more successful. DMSP Block II and Block III satellites, also launched on Thor Burner I vehicles, provided weather data for tactical applications in Southeast Asia.

Wider military uses for weather data led to an important change in the program’s reporting structure when, on July 1, 1965, it became a program office under Space Systems Division. Development of more capable and more complex satellites also came to fruition with DMSP Block 4 satellites, seven of which were launched during 1966-1969.

Television resolution improved from three to four nautical miles with Blocks I and II to 0.8 to three nautical miles with Block 4, along with many other improvements in the sophistication of secondary sensors. Block 5A satellites introduced the Operational Line Scan (OLS) sensor, which provided images of clouds in both visual and infrared spectra. Television resolution improved to 0.3 nautical miles in daylight.

Three Block 5A, five 5B, and three 5C satellites were launched during 1970-1976 on Thor Burner II launch vehicles. Larger and much more sophisticated Block 5D-1 satellites were also developed during the 1970s, but only five were built.

In 1980, the fifth 5D-1 satellite was lost in a launch failure, and the operational 5D-1 satellites in orbit prematurely ceased to function. From August 1980 to December 1982, when the first Block 5D-2 satellite was successfully launched, meteorological data was supplied to DoD entirely by civilian satellites.

Nine Block 5D-2 satellites were launched during 1982-1997 on Atlas E and Titan II launch vehicles. In 1989, Space Systems Division began the procurement of five Block 5D-3 satellites from General Electric (later acquired by Lockheed Martin). By early 2003, the first of these was scheduled for launch later in the year.

Civilian weather satellites were operated by the National Oceanic and Atmospheric Administration (NOAA). Proposals to merge the civilian and military meteorological systems had been made from time to time since the early 1970s.30 On May 5, 1994, President Clinton issued a presidential decision directive ordering the convergence and eventual merger of the two programs into a new national space-based system for environmental monitoring.

A Tri-Agency Integrated Program Office (IPO) made up of representatives from NOAA, NASA, and DoD would be responsible for carrying out major systems acquisitions, including satellites and launch vehicles. However, NOAA would have overall responsibility for operating the new system, which was soon named the National Polar-orbiting Operational Environmental Satellite System (NPOESS).

A major step in convergence occurred on May 29, 1998, when NOAA’s Satellite Operations Control Center (SOCC) took over satellite control authority as well as actual operational control of the existing DMSP system. The IPO issued competitive contracts to Lockheed Martin and TRW on December 13, 1999 for an early phase of the NPOESS development program called Program Definition and Risk Reduction, and it issued five development contracts for NPOESS sensors during 1997-2001. A flight demonstration satellite known as the NPOESS Preparatory Project (NPP) was scheduled for launch in late 2006. It would be a joint mission involving NASA and the IPO.

Navigation Systems
The world’s first space-based navigation system was called Transit. It was developed by scientists at Johns Hopkins University’s Applied Physics Laboratory in 1958. DoD’s Advanced Research Projects Agency (ARPA) initiated the development program in September 1958 and assigned it to the Navy a year later. The Air Force Ballistic Missile Division launched the Navy’s first Transit satellite on April 13, 1960. The system achieved initial operational capability in 1964 and full operational capability in October 1968.

Transit used three operational satellites to produce signals whose Doppler effects and known positions allowed receivers — primarily ships and submarines — to calculate their positions in two dimensions. Transit established the principle and much of the technology of navigation by satellite and prepared military users to rely on such a system. However, it was too slow for rapidly moving platforms, such as aircraft. Transit’s signals were turned off deliberately in December 1996 because DoD had decided to rely on a newer, faster, and more accurate system.

All of DoD’s navigation and position-finding missions are now performed by the Global Positioning System (GPS). The system consists of 24 operational satellites that broadcast navigation signals to the earth, a control segment that maintains the accuracy of the signals, and user equipment that receives and processes the signals. By processing signals from four satellites, a user set is able to derive the location of each satellite and its distance from each one. From that information, it rapidly derives its own location in three dimensions.

In addition to Transit, GPS had two immediate programmatic ancestors: a technology program called 621B, started by SAMSO in the late 1960s, and a parallel program called Timation, undertaken by the Naval Research Laboratory in the same period. 621B envisioned a constellation of 20 satellites in synchronous inclined orbits, while Timation envisioned a constellation of 21 to 27 satellites in medium altitude orbits. In 1973, elements of the two programs were combined into the GPS concept, which employed the signal structure and frequencies of 621B and medium altitude orbits similar to those proposed for Timation.

Deputy Secretary of Defense William P. Clements authorized the start of a program to “test and evaluate the concepts and costs of an advanced navigation system” on April 17, 1973, and he authorized the start of concept validation for the GPS system on December 22, 1973.

GPS was acquired in the classical three phases:
  • validation
  • development
  • production
During the validation phase, Block I navigation satellites and a prototype control segment were built and deployed, and advanced development models of various types of user equipment were built and tested.

During the development phase, additional Block I satellites were launched to maintain the initial satellite constellation, a qualification model Block II satellite was built and tested, and manufacture of additional Block II satellites was initiated.31 In addition, an operational 31 Block I, Block II, and Block IIA satellites were built by Rockwell International, which sold its aerospace and defense divisions to Boeing in 1997.

In addition, an operational control segment was activated, and prototype user equipment was developed and tested. During the production phase, a full constellation of 24 Block II and IIA (A for advanced) satellites was deployed. User equipment was also produced and put into operation by issuing it to foot soldiers and installing it in ships, submarines, aircraft, and ground vehicles.

The full constellation was completed on March 9, 1994, allowing the system to attain full operational capability in April 1995. SMC began launching the next block of GPS satellites, known as IIR (R for replacement), in 1997.32 The following block of GPS satellites, which incorporated further improvements, was known as Block IIF (F for follow-on). SMC awarded a contract for their production on April 22, 1996.33 By 2003, they were scheduled to be available for launch beginning in 2006.

GPS can support a wide variety of military operations, including aerial rendezvous and refueling, all-weather air drops, instrument landings, mine laying and mine sweeping, anti-submarine warfare, bombing and shelling, photo mapping, range instrumentation, rescue missions, and satellite navigation. GPS is also the focus of a growing civilian market. By 2003, it was widely used commercially, and some of those commercial applications, such as airline navigation, were critical. At one time, the GPS signal available to civil users contained intentional inaccuracies, a condition known as selective availability. At President Clinton’s direction, the intentional inaccuracies were set to zero on May 1, 2000, providing significant improvements in the accuracy available to the system’s civil users.

27 See R. Cargill Hall, A History of the Military Polar Orbiting Meteorological Satellite Program, National Reconnaissance Office, September 2001.

28 Although NASA was developing a National Operational Meteorological Satellite System, the NRO’s director, Under Secretary of the Air Force Joseph V. Charyk, did not believe it would adequately support the NRO’s missions. See note 27 above.

29 The first launch attempt took place on May 23, 1962, but it failed. The first successful launch was the second attempt on August 23, 1962. Later unsuccessful Scout launches took place on February 19, 1963, April 26, 1963, and September 27, 1963. Successful Thor Agena D launches were carried out on January 19, 1964 and June 17, 1964. Block I launches on Thor Burner I rockets took place on January 18, 1965 (failure) and March 18, 1965 (success). Block II launches on Thor Burner I vehicles were on September 9, 1965 (success), January 7, 1966 (failure), and March 30, 1966 (success). The only Block III satellite was launched successfully on May 20, 1965 using a Thor Burner I launch vehicle. See note 27 .

30 The Defense Meteorological Satellite Program was declassified in 1973.

31 Block I, Block II, and Block IIA satellites were built by Rockwell International, which sold its aerospace and defense divisions to Boeing in 1997.

32 The launch of the first IIR satellite on January 15, 1997 failed when the Delta launch vehicle exploded. It was the first failure of a Delta II vehicle and only the second launch failure in the history of the GPS program. The first GPS Block IIR satellite to attain orbit and become operational was launched on July 23, 1997.

33 SMC (then called Space Systems Division) had awarded the contract for Block IIR satellites to General Electric (later part of Lockheed Martin) in 1989. It awarded the contract for Block IIF satellites to Rockwell International (later part of Boeing). See note 31.