6555th Aerospace Test Group


The 6555th Aerospace Test Group is an inactive United States Air Force unit. It was last assigned to the Eastern Space and Missile Center and stationed at Patrick AFB, Florida. It was inactivated on 1 October 1990.
Prior to the activation of the Air Force Space Command, the unit was responsible for the development of USAF missiles, both tactical surface-to-surface; CIM-10 Bomarc Interceptor; SM-62 Snark Intercontinental Cruise Missile; Intercontinental ballistic missile and heavy launch rockets used for military for satellite deployment. The unit played a key role in the civilian NASA Project Mercury, Project Gemini and Project Apollo manned space programs along with military Space Shuttle flights.
The mission of the unit today is performed by the 45th Space Wing.

History

Activated in December 1950, replacing 550th Guided Missiles Wing. the 6555th had a distinguished career launching and/or managing ballistic missiles, space launch vehicles and payloads for the Ballistic Systems Division, the Space Systems Division and the Space & Missile Systems Organization. As a Wing or a Group, the 6555th earned ten Air Force Outstanding Unit Awards between 21 December 1959 and October 1990.
In the 1950s, the unit had several designation changes and organizational realignments. As launches of winged missiles continued, the Wing gained two new units the 1st and 69th Pilotless Bomber Squadrons in October 1951 and January 1952. Thereafter, the 6555th focused most of its efforts on assembling, testing and launching B-61 Matador missiles so the 1st and 69th Pilotless Bomber Squadrons would be prepared for operations in Europe. The 6555th Guided Missile Wing became the 6555th Guided Missile Group on 1 March 1953, and the 1st and 69th Pilotless Bomber Squadrons were reassigned to Tactical Air Command on 15 January 1954. Since TAC agreed to train all other B-61 Matador squadrons at TAC's own school at Orlando AFB, Florida, the 6555th Guided Missile Group was little more than a squadron when the 69th completed its field training in the summer of 1954.
The 6555th Guided Missile Group was discontinued on 7 September 1954. The 6555th Guided Missile Squadron was allowed to survive as a B-61 Matador research and development testing unit, and it was reassigned to AFMTC Headquarters on 7 September 1954. The 6555th Guided Missiles Squadron became the 6555th Guided Missile Group on 15 August 1959, and it was reassigned to the Air Force Ballistic Missile Division on 21 December 1959. Concurrent with its reassignment, the Group picked up the resources of the Air Force Ballistic Missile Division's Assistant Commander for Missile Tests.
At the beginning of 1971, the 6555th Aerospace Test Group consisted of a commander's office and three divisions. Though the Test Group's launch operations revolved around the Atlas and Titan III systems divisions in the early 1970s, the Group established its Space Transportation System Division on 1 July 1974 to ensure the Defense Department's Shuttle requirements were factored into future Shuttle operations at the Kennedy Space Center.
On 1 November 1975, the Test Group reorganized its Atlas and Titan III launch vehicle agencies under a new division, the Space Launch Vehicle Systems Division. On the same date, the Atlas Satellite Launch Systems Branch and the Titan III Space Satellite Systems Launch Operations Branch were consolidated under the newly created Satellite Systems Division. The changes were directed by the 6595th Aerospace Test Wing Commander to combine booster operations under one division chief and payload operations under another division chief. In the same vein, the IUS Operations Branch was placed under the Space Launch Vehicle Systems Division when that branch was formed on 1 July 1977. Following the final Atlas-Agena launch on 6 April 1978, the Space Launch Vehicle Systems Division and the Satellite Systems Division shifted their respective attentions from Atlas-Agena operations on Complex 13 to Atlas-Centaur boosters and payloads designated for Defense Department missions on Complex 36.
On 1 October 1979, the Group was transferred to the 45th Space Wing's immediate predecessor, the Eastern Space and Missile Center. The unit was inactivated on 1 October 1990 when Air Force Space Command inactivated the provisional unit and merged the organization with ESMC. Most of the 6555th's resources were reorganized as the 1st Space Launch Squadron under ESMC and two Combined Task Forces serving AFSPC and Air Force Systems Command.
Ultimately, the last vestiges of the 6555th were inactivated on 1 July 1992 as Air Force Systems Command and Air Force Logistics Command merged to form Air Force Materiel Command. Today, the mission of the unit is performed by the 45th Operations Group and the 45th Launch Group components of the 45th Space Wing.

Weapons and missile development

Postwar era

Between 1946 and 1950, the Group's predecessor units, the 1st Experimental Guided Missiles Group and 550th Guided Missiles Wing, tested a variety of glided bombs and tactical missiles. They also developed QB-17 drone aircraft for use in atomic bomb testing, and later as targets for anti-aircraft missiles. The 550th GMW also launched the first rockets from the Joint Long Range Proving Ground at Cape Canaveral, Florida in 1950.
Aerodynamic or "winged" missile testing dominated the activities of the 6555th for most of the 1950s. The decade witnessed the introduction of the B-61 Matador, SM-62 Snark, IM-99 Bomarc, XSM-64 Navaho and TM-76 Mace aerodynamic missiles, among which the Matador, with over 280 launches to its credit, stood out as the most-launched missile of its era. The Matador was also the 6555th's first full-fledged weapon system program and its initial deployment overseas included military launch crews trained at Cape Canaveral AFS.
The Air Force ballistic missile program had its origins in studies and projects initiated by the Army Air Corps immediately after World War II. Faced with growing evidence of the Soviet Union's development of thermonuclear weapons and ballistic missile technology in 1953, the Air Force established the Western Development Division in Los Angeles to carry out that task.
The 6555th's role in ballistic missile development ended with the Minuteman III flight test program in 1970, but Minuteman and Titan missile tests continued under SAC and the 6595th Aerospace Test Wing at Vandenberg Air Force Base.

Space launch operations

The Air Force's interest in artificial satellites—and hence, space operations—was sparked by discussions with the Navy shortly after the end of World War II. At Major General Curtis E. LeMay's request, the Douglas Aircraft Company's RAND group provided The Pentagon with a 321-page study in May 1946 on the feasibility of satellites for military reconnaissance, weather surveillance, communications and missile navigation.
The Soviets' successful launch of Sputnik I on 4 October 1957 came as a shock to the American public, but the military implications of that capability came into even sharper focus as much heavier payloads were orbited from the Soviet Union in the months and years that followed. Galvanized into action by the Soviet Union's achievements, the U.S. Department of Defense set high priorities on the development of military satellite systems. It also created the Advanced Research Projects Agency on 7 February 1958 to supervise all U.S. military space efforts. The Air Force drew up a manned military space system development plan in April 1958, and it also volunteered to carry out the U.S. man-in-space mission. Though much of the plan was incorporated in later manned space efforts, President Dwight Eisenhower rejected the Air Force's offer to lead the effort. Instead, he called on Congress to establish a civilian space agency, and the National Aeronautics and Space Act was passed by Congress in July 1958.
Since the Air Research and Development Command was destined to serve the Air Force and two non-Air Force clients in space, effective coordination among the agencies was crucial to the early success of the space mission. Before the 6555th absorbed the Air Force Ballistic Missile Division's resources at the Cape in December 1959, most of the Air Force's participation in the Cape's space launch operations was managed by the WS-315A Project Division under the Air Force Ballistic Missile Division's Assistant Commander for Missile Tests. The WS-315A Project Division was redesignated the Space Project Division on 16 November 1959, and it became the Space Projects Division under the 6555th Test Wing on 15 February 1960.
Following the establishment of Air Force Systems Command, the 6555th's Test Directorate and Operations Directorate were transformed into the Space Programs Office and the Ballistic Missiles Office on 17 April 1961. Under that reorganization, the old Atlas Project Office's resources were divided roughly in half to create an Atlas Booster Branch and an Atlas Weapons Branch. The Atlas Booster Branch was placed under the Space Programs Office. The old Atlas Operations Division became the new Atlas Weapons Branch's Operations Section, and the new Atlas Weapons Branch was placed under the Ballistic Missiles Office. The Space Projects Division became the Space Projects Branch under the Space Programs Office on 17 April, and its Thor Booster Branch was removed and set up as a separate branch under the Space Programs Office.

Thor-Able (1958–1961)

The division had jurisdiction over Complex 17 and three missile assembly buildings. It supported a total of 10 Air Force-sponsored Thor-Able, Thor-Able I and Thor-Able II space launches from Pad 17A before the end of 1959. The division also supported NASA's Pioneer 1 and Pioneer 2 missions, which were launched by Douglas from Pad 17A on 11 October and 8 November 1958, and NASA's Explorer 6 mission, which was launched by Douglas from Pad 17A on 7 August 1959. Under the 6555th Test Wing, the Space Projects Division managed five Thor-Able-Star missions for the Army, the Navy and ARPA in 1960. It also monitored Douglas' preparation and launch of two Thor-Able boosters for NASA's Pioneer 5 deep space mission to Venus in March 1960 and its TIROS-1 weather satellite mission in April 1960.

Atlas (Atlas-Agena, Atlas-Centaur, Atlas-Project Mercury) (1959–1965)

1961 proved to be a very busy year for the 6555th and its space launch contractors. Following its first two unmanned Project Mercury capsule launches for NASA in September 1959 and July 1960, Convair launched Atlas-D boosters on three successful Project Mercury flights from Complex 14 in 1961. The Douglas Aircraft Company launched three Transit navigation satellite missions from Pad 17B for the U.S. Navy, and it provided booster support for two Project Explorer missions and one TIROS mission that were launched from Pad 17A in 1961. Aeroneutronic and the Blue Scout Branch's Operations Section launched a total of six space vehicles from pads 18A and 18B in 1961. NASA Associate Administrator Robert C. Seamans, Jr. signed a joint NASA/ARDC agreement on 30 January 1961 concerning the Air Force's participation in the RM-81 Agena B Launch Vehicle Program, and the 6555th's participation in the Centaur program was settled with NASA under a joint memorandum of agreement in April 1961.
The Air Force Ballistic Missile Division procured the ATLAS boosters required by the program, and it provided operational, administrative and technical support for those launch vehicles. NASA's Jet Propulsion Laboratory and the Goddard Space Flight Center provided the spacecraft. The Launch Operations Directorate's Test Support Office acted as NASA's formal point of contact for all agencies involved in the Agena B program on the Eastern Test Range, but the 6555th was responsible for supervising the Air Force contractors who provided the boosters for the Agena B. While many tests were observed jointly by NASA and Air Force representatives, NASA was responsible for the spacecraft, Lockheed was responsible for the Agena B, Convair was responsible for the Atlas-D booster, and the 6555th was responsible for the readiness of the entire launch vehicle. Ultimately, NASA's Operations and Test Director had overall responsibility for the countdown, but he received direct inputs from the 6555th's Test Controller concerning the vehicle's status on launch day.
The 6555th was also allowed to assign Air Force supervisors to Convair's processing teams while they were working on Atlas-D boosters for the Atlas-Centaur R&D test flights. In instances where NASA's Launch Operations Directorate wanted procedures added to Convair's Atlas-D checklists, the 6555th integrated those items. NASA also agreed to coordinate Centaur test documentation with the 6555th. To avoid duplication of effort, NASA and the Air Force agreed to share "a large number of facilities" for the Centaur, Agena-B and Project Mercury efforts. Since NASA planned to use the Centaur's facilities first, the Air Force secured a promise from NASA to coordinate its Centaur facility and equipment modifications with the 6555th before the changes were made. The 6555th agreed to make an officer available as a consultant to NASA's Launch Director during Atlas-Centaur launch operations.
In 1962, Air Force contractors and the Atlas Space Branch supported three Ranger program and two Mariner program missions from Complex 12, and they supported the first three manned orbital Mercury-Atlas missions, which were launched from Complex 14. All those NASA missions were launched by contractors, but the Air Force implemented plans in the last half of 1962 to establish an Atlas-Agena B USAF launch capability. The division's Project Mercury support mission ended following the last Mercury flight in May 1963, but the unit still supported DOD operations on Complex 13. It picked up Atlas-Agena B Target Vehicle operations for Project Gemini shortly thereafter.

Titan II (Thor-Titan, Titan-Project Gemini)(1961–1966)

Thor-Titan Branch formed in 1961 by re-designation of Thor Booster Branch. On 10 September 1962, the Wing established the SLV-V Division to handle the Titan III program separately, and it transferred Titan III personnel from the Thor/Titan Branch to the new division before renaming it the SLV-V/X-20 Division on 1 October 1962. The Thor/Titan Branch became the SLV II/IV Division on 1 October 1962, but it was split up to form two new divisions—the SLV II Division – on 20 May 1963.
Though Complex 17 supported seven other NASA missions in 1964 and 1965, the two-part ASSET program quickly became the SLV-II Division's principal interest after the first Project ASSET launch on 18 September 1963. Under one part of the ASSET flight test program at the Cape, the second, third, and sixth hypervelocity vehicles were launched from Pad 17B on 24 March 1964, 22 July 1964 and 23 February 1965. Those flights were designed to gather data on the ability of materials and structures to handle the pressures and temperatures of atmospheric reentry. Though the flight on 24 March failed to meet its test objectives due to a malfunction in the Thor rocket's upper stage, the other two flights were successful, and the vehicle launched on 22 July was recovered. Under the other part of the ASSET flight testing, two nonrecoverable delta wing glide vehicles were launched from Pad 17B on 27 October and 8 December 1964. Both missions were designed to obtain data on "panel flutter" under high heating conditions and information of the vehicles' "unsteady aerodynamics" over a broad range of hypersonic speeds. Both flights were successful, and the final ASSET flight on 23 February 1965 completed the ASSET program.
The Air Force had no further use for Thor rocket facilities at Cape Canaveral after the ASSET program was completed, so the Space Systems Division directed the 6555th to turn over its SLV-II facilities to NASA for the civilian agency's Thor-Delta program. In accordance with Air Force Eastern Test Range procedures, the 6555th returned the facilities to the Range in April 1965, and the Air Force Eastern Test Range transferred them to NASA's Kennedy Space Center in May 1965.
The 6555th's Titan-Gemini Division lasted considerably longer than its SLV-II Division. The division exercised technical test control over the Titan II GLV launch vehicle, but the Martin Company launched the booster. Martin launched the first unmanned Gemini-Titan GLV mission from Complex 19 on 8 April 1964, and the flight succeeded in placing an unmanned 7,000-pound Gemini 1 capsule into low earth orbit on that date. The first manned Gemini mission was launched from Complex 19 on 23 March 1965, and it met all of its test objectives. Nine more pairs of astronauts were boosted into orbit aboard Gemini-Titan GLV launch vehicles in 1965 and 1966, and seven Atlas-Agena target vehicles were launched from Complex 14 in support of six Project Gemini missions. Following the last highly successful Gemini-Titan GLV flight in November 1966, the Gemini Launch Vehicle Division completed its mission and began transferring personnel to other Air Force bases or to other agencies under the 6555th Aerospace Test Wing. As overall manager for Project Gemini, NASA was understandably proud of its role in the highly successful effort, but the Air Force and its contractors planned, built and launched all the Titan II GLV space boosters associated with Project Gemini.

Titan IIIA/C (1961–1982)

NASA's plans for the Saturn heavy-lift rocket program were already underway in 1961, and the agency saw no need for a military heavyweight space booster for low earth orbit, geosynchronous orbit or deep space missions. Consequently, NASA resisted the Air Force's first attempts to secure funding for the Titan III initiative, and the Air Force had to work long and hard to prepare its case for the Titan III.
It was decided that the Titan III would be developed exclusively for Department of Defense heavy-lift orbital missions after 1965. Following that concession, initial funding for the Titan III contractual effort was granted on 11 December 1961, and Space Systems Division's new 624A Systems Program Office began managing the Titan III program four days later. Initially the Titan III was planned for use in the X-20 Dyna Soar manned space glider which could be boosted into orbit, maneuvered, and piloted back to earth. Plans for the program called for two unmanned and eight manned Titan IIIC space flights with manned glider landings at Edwards Air Force Base. At Secretary McNamara's request, it was stopped by president Lyndon B. Johnson in December 1963 before any space flights were flown.
Though Titan III Complex 41 extended across the Cape Canaveral boundary into NASA's territory on Merritt Island, all property within Complex 41's security fence and along the access road to the site was considered part of the Air Force's Titan III program. Put simply, NASA had jurisdiction over the Merritt Island Launch Area, the Saturn rocket program and Saturn rocket facilities on Merritt Island and Cape Canaveral. The Air Force had jurisdiction over Cape Canaveral, the Titan III program and all Titan III facilities, including Complex 41. Though the Air Force Eastern Test Range and its contractors continued to provide range support for all of NASA's launch vehicle programs on Merritt Island and Cape Canaveral, the Saturn rocket and Titan III rocket programs were pursued as distinctly separate NASA and Air Force launch efforts.
Martin launched the first Titan IIIA from Complex 20 on 1 September 1964, and three more TITAN IIIA flights were completed before the first TITAN IIIC was launched from Complex 40 on a successful mission on 18 June 1965. Following the fourth and final TITAN IIIA launch on 6 May 1965, Complex 20 was deactivated and returned to the Air Force Eastern Test Range in September 1965. Complex 41 was turned over to the Titan III Division's Operations Branch for beneficial occupancy on 18 June 1965, and the facility was accepted by the Air Force in December 1965. The first Titan IIIC lifted off Pad 41 on 21 December. The flight met most of its test objectives, including the successful release of the LES-3 and LES-4 communications satellites and the OSCAR IV amateur radio satellite. Two more Titan IIIC missions were launched from Complex 41 on 16 June and 26 August 1966. The first of those flights included the successful release of seven Initial Defense Communications Satellite Program satellites and one gravity gradient satellite, but the second flight ended after the Titan IIIC's payload fairing broke up approximately 79 seconds after launch.
Another Titan IIIC was launched from Complex 40 on 3 November 1966, and it boosted a modified Gemini 2 spacecraft and three secondary satellites into orbit during a largely successful experimental mission on that date. Since the Air Force intended to use Complex 40 for its Manned Orbiting Laboratory flights. The MOL was cancelled in June 1969.
Complex 41 eventually supported all the Titan IIIC missions launched from the Cape between the beginning of 1967 and the end of the decade. It was used by Titan IIIC rockets for a Project Viking simulator mission and a Project Helios solar mission in 1974, two NASA Project Viking missions to Mars in 1975, another Project Helios mission in 1976, and two NASA Voyager program missions to the outer planets in 1977.
A Defense Support Program mission had just been launched from Complex 40 on 6 November 1970, but the payload failed to achieve proper orbit. The next Titan IIIC vehicle and its DSP payload were assembled and checked out for a launch on 5 May 1971. The launch on 5 May was successful, and the payload was placed in a synchronous earth orbit as planned. That flight marked the 16th Titan IIIC mission in the 6555th Test Group's history.
On 2 November 1971, the Air Force and its contractors launched the first two Phase II Defense Satellite Communications Program satellites into near synchronous equatorial orbits from Complex 40. That Titan IIIC mission was successful, and it marked the first in a series of classified flights destined to replace Phase I DSCP satellites that had been launched from the Cape between 16 June 1966 and 14 June 1968. On 1 March 1972, a Titan IIIC carrying a 1,800-pound DSP satellite was launched successfully from Complex 40. Eight days later, a Titan IIIC core vehicle arrived via C-5A Galaxy aircraft, and it was erected at the VIB on 16 March 1972. It was launched successfully on 12 June 1973.
Titan IIIC launches continued throughout the 1970s when Launch Vehicle C-37 and a twin-DSCS payload. The Launch CST was run on 12 November 1979. Regarding the launch itself, there was one unscheduled five-minute hold during C-37's launch countdown on 20 November. The countdown resumed without further incident, and the Titan IIIC lifted off Complex 40 on the 20th at 2110:00 Eastern Standard Time. Both Phase II DSCS communications satellites were placed in their proper near synchronous orbits, and the mission was a complete success. The last vehicle launched under the Titan IIIC program was Launch Vehicle C-38. It arrived at the Cape on 24 October 1979, and it was the last of 36 Titan IIICs launched from the Cape between 18 June 1965 and the evening of 6 March 1982. After two years of testing, storage and retesting, C-38 was launched on a classified mission on 6 March 1982 at 1425:00 Eastern Standard Time. The flight marked the end of an era at the Cape.
Complex 41 was refurbished for the Titan IV program during the last half of the 1980s, but its first Titan IV launch did not take place until 14 June 1989—almost 12 years after it was used to launch the Voyager program missions to the outer planets.

Titan 34D (1980–1989)

As the last Titan IIIC thundered skyward, Martin Marietta and the Test Group were completing their second year of preparations for the Titan 34D's first launch. The effort began in earnest when the first Titan 34D core vehicle arrived at the Cape in March 1980. Baseline CSTs were completed in September 1980, and, apart from a brief roundtrip ride to the SMAB on 11 November, the core vehicle remained in storage at the VIB until 18 May 1981.
The core vehicle was accepted in August 1981, and it was moved to the SMAB on 18 January 1982. The Titan 34D's operational IUS arrived at the Cape on 22 December 1981. It was taken to the SMAB, and its assembly was completed there on 8 June 1982. Though the IUS' preplanned acceptance testing was completed on 19 August, its formal acceptance was delayed pending additional tests required by Space Division. The IUS was mated to the launch vehicle on 1 September 1982, and it was mated to the vehicle's DSCS II/III payload on 29 September. Acceptance testing was completed on 2 October, and the vehicle was prepared for launch.
Launch Vehicle D-01's first Launch CST was aborted on 20 October 1982, but its second Launch CST was completed successfully on 21 October. The countdown was picked up smoothly on 29 October at 2055Z, and the first TITAN 34D lifted off Complex 40 at 0405:01Z on 30 October 1982. The Titan's flight was virtually flawless, and the IUS placed both DSCS satellites into near-perfect equatorial orbits. With the completion of this first highly successful launch operation, the Cape moved solidly into the Titan 34D era.
All Titan 34D launch operations at Vandenberg and the Cape were suspended following the Titan 34D-9 launch failure in April 1986, but it would be wrong to conclude that the suspension allowed the 6555th Aerospace Test Group and the Air Force's Titan contractors to lapse into a period of inactivity. On the contrary, the space launch recovery effort and TITAN IV program initiatives kept the Test Group's agenda full. The Test Group supervised the initial recovery effort at the Cape. As part of that program, a Non-Destructive Testing X-Ray facility was constructed in the ITL Area for the purpose of inspecting Titan solid rockets for flaws in propellant, restrictors, insulation and podding compounds. Construction of the NDT facility began on 1 October 1986, and solid rocket motor testing was conducted there as part of the Titan 34D recovery effort from 23 December 1986 through 12 June 1987.
The last Titan 34D launched from the Cape had an extensive processing history between the time it first arrived at the Cape and the time it was erected for the final time on Transporter No. 3 in Cell No. 1 on 13 December 1988. The transtage was erected on the core vehicle on 28 March 1989. The Acceptance CST was completed successfully on 23 June 1989. Core Vehicle D-2 was moved to the SMAB for solid rocket mating on 2 July, and Launch Vehicle D-2 was moved out to Complex 40 on 5 July 1989. The vehicle was mated to a classified payload and prepared for launch. Though the first Launch CST failed on 21 August, the Launch CST on 27 August was completely successful. A balky Mobile Service Tower delayed pre-launch activities on 4 September, but a 22-minute-long user hold brought operations up to speed at T minus 30 minutes. After the countdown resumed at 0524Z, it proceeded without incident to vehicle lift-off at 0554:01Z on 4 September 1989.

Titan IV (1988–1990)

As TITAN 34D launch operations continued, the first Titan IV liquid rocket engines were installed on the Titan IV "pathfinder" vehicle at the end of January 1988, shortly before the core vehicle was erected in the VIB. Four Titan IV solid rocket motor segments were received at the SMAB by the middle of February 1988, and two electrical functional tests were conducted in early March. As "bugs" were worked out of various systems, the core vehicle had its first successful CST on 11 May 1988. The vehicle was moved to the SMAB around the middle of May. Following a successful mate with two five-segment stacks of solid rocket motor segments, the pathfinder vehicle was moved out to Complex 41 on Saturday, 21 May. The first Titan IV vehicle supported a classified mission. Its launch had been scheduled for 7 June 1989, but the lift-off was pushed to 14 June due to a range timing generator problem and a computer malfunction. The countdown was picked up at 0254Z on 14 June. Two unscheduled holds were called to let the launch team catch up on checklist items that were behind schedule, and another hold was called for a high temperature reading on the vehicle's S-Band transmitter. Following the last unscheduled hold, the countdown proceeded uneventfully, and the Titan IV lifted off Complex 41 at 1318:01Z on 14 June 1989.

Navstar Global Positioning System and development of the Delta II (1978–1990)

The Navstar Global Positioning System program opened up a whole new field for space support operations at the Cape in the 1980s: the launching of satellites to provide highly accurate three-dimensional ground, sea and air navigation. The U.S. Navy and Air Force began the effort in the early 1960s with a series of studies and experiments dealing with the feasibility of using satellite-generated radio signals to improve the effectiveness of military navigation. After ten years of extensive research, the services concluded that Defense Department requirements would be best served by a single, highly precise, satellite-based Global Positioning System. In December 1973, the Defense Navigation Satellite System entered its concept validation phase.
The technology necessary to field the GPS was confirmed during that phase, and four advanced development model Block I Navstar satellites were launched on converted SM-65F Atlas boosters from Vandenberg's Space Launch Complex 3 between 22 February and 11 December 1978. Two more Block I satellites were launched on converted SM-65F Atlas boosters from Vandenberg Complex 3 on 9 February and 26 April 1980. By the end of 1980, the Navstar GPS constellation was arranged in two orbital planes of three satellites each, orbiting Earth at an altitude of approximately 10,900 nautical miles. Following the GPS development phase in the early 1980s, the Air Force planned to procure and deploy a constellation of 24 Block II GPS satellites via Space Shuttle launches by the end of 1987. Funding cuts in 1980 and 1981 reduced the planned constellation to 18 Block II satellites and added a year to their deployment, but the program continued to move ahead.
A Block I replenishment satellite was launched on a converted SM-65E Atlas booster from Vandenberg Complex 3 on 18 December 1981. Unfortunately, a hot gas generator on one of the Atlas booster's main engines failed shortly after lift-off, and the vehicle crashed about 150 yards from the pad. The next replenishment satellite launch was postponed while Atlas engines were refurbished and test-fired in 1982, but the mission was finally launched successfully from Vandenberg Complex 3 on 14 July 1983. The satellite replaced Navstar I in the 240-degree orbital plane of the GPS constellation. The last three Block I satellite missions were launched on converted SM-65E Atlas boosters from Complex 3 on 13 June 1984, 8 September 1984 and 8 October 1985. All three launches were successful, and the satellites performed as planned. Testing of the first Block II satellite was well underway in 1985, but the Navstar II satellite program was already markedly behind schedule. By the fall of 1985, the first Block II mission had to be rescheduled from October 1986 to January 1987.
Following the Space Shuttle Challenger disaster in January 1986, the GPS Program Office replanned the first eight Block II satellites for flights on the new Delta II expendable Medium Launch Vehicle in lieu of the Space Shuttle. Space Division awarded the Medium Launch Vehicle contract to McDonnell-Douglas Astronautics Company on 21 January 1987. However, unlike earlier commercial arrangements, the company would no longer be under contract to NASA. Under the new Commercial Expendable Launch Vehicle program encouraged by president Ronald Reagan since 1983, McDonnell-Douglas would be responsible for producing, marketing and launching its commercial Delta IIs. The Air Force would be responsible for ensuring safety and environmental standards for commercial as well as military launches, but McDonnell-Douglas would have greater responsibility in meeting those standards. Both launch pads would be equipped to handle commercial and Defense Department missions. McDonnell-Douglas and its subcontractors were soon hard at work preparing the pads for the new Delta II vehicles.
Like the Titan and Atlas lines of launch vehicles, the Delta II line was built on major components supplied by several different contractors. McDonnell-Douglas built the basic core vehicle and supplied fairing materials at its plant in Huntington Beach, California, but it shipped them to another plant in Pueblo, Colorado for further assembly and/or match ups with other contractors' components. Rocketdyne provided the Delta's main engine, and Aerojet supplied the vehicle's second stage engine. Delco supplied the inertial guidance system, and Morton Thiokol built the strap-on solid rocket motors used for the basic Model 6925 Delta II vehicle. The first and second stages were transported to the Horizontal Processing Facility in Area 55 for destruct system installation. Following processing at the HPF, both stages were moved to Complex 17 and erected. At Complex 17, the entire process came together to create a complete Delta II launch vehicle.
Unfortunately, trouble loomed from a different quarter in July 1988: McDonnell-Douglas ran into trouble getting some fiber optic equipment it ordered for Pad 17A, and the first Delta II launch was rescheduled from 13 October 1988 to 8 December 1988. Following additional delays and pre-launch tests, the countdown was begun on 12 February 1989, but it was scrubbed at 1827Z due to excessive high altitude winds. The countdown was picked up again on 14 February, and lift-off was recorded at 1829:59.988Z on 14 February 1989. The first Delta II placed the first Navstar II GPS payload into the proper transfer orbit. The mission was a success.
Following the first Navstar II GPS mission on 14 February 1989, the GPS Program Office hoped to have five Navstar II satellites in orbit by the end of September, but only three of those spacecraft had been launched by that time. Since twelve Block II satellites would be needed to give the GPS constellation its first worldwide two-dimensional navigation capability, planners estimated that capability could not be achieved before the spring of 1991. In point of fact, six more Navstar II satellites were launched over the next year.
Iraq's invasion of Kuwait in August 1990 provided additional incentive for McDonnell-Douglas and the Air Force to rise to the challenge. Navstar II-9 lifted off on 1 October 1990, and it was placed in orbit over the Middle East. The satellite's on-orbit testing program was completed in record time, and Navstar II-9 was turned over to Air Force Space Command on 24 October 1990. Navstar II-10 was launched successfully on 26 November 1990. With II-10 in operation, the GPS network provided two-dimensional coordinates with an average accuracy of 4.5 meters during Operation Desert Storm. The Navstar system's three-dimensional accuracy averaged 8.3 meters during the war. The GPS Program Office hoped to launch five Block IIA Navstar spacecraft by October 1991, but component problems associated with the new design caused lengthy delays. Only two Block IIA missions were launched by October 1991, but five more Block IIA launches were completed by the end of 1992. The constellation was well on its way to full operational status by the beginning of 1993.

Space Shuttle military missions

The 6555th Aerospace Test Group established its Space Transportation System Division on 1 July 1974. The division was created to ensure that Defense Department requirements were included in plans for future Space Shuttle operations at the NASA Kennedy Space Center.
As two of its earliest accomplishments, the division got NASA to agree to the Defense Department's requirement for vertical payload installations at the Shuttle launch pad and a secure conference area in the Firing Room of the Shuttle Launch Control Center. The division continued to serve as an intermediary between KSC and the Defense Department payload community. The division not only gave the payload community a better understanding of schedule and contractual constraints affecting KSC ground operations, it also gathered a more detailed set of requirements from military payload programs to help NASA support those programs.
The division also helped the 6595th Space Test Group develop requirements for a Shuttle Launch Processing System at Vandenberg Air Force Base. The division also provided selection criteria and background information to help the Space and Missile Systems Organization select its Shuttle payload integration contractor. Martin Marietta was awarded the Shuttle payload integration contract on 15 September 1977.
As preparations for military space shuttle operations continued, the STS Division identified and analyzed many problems associated with "factory-to-pad" processing of military payloads. The division's findings helped justify the need for an off-line Shuttle Payload Integration Facility, and they convinced the AFSC Commander to approve the SMAB's west bay as the site for the SPIF in January 1979. As work on the SPIF got underway, the 6555th Aerospace Test Group formed the STS/IUS Site Activation Team in September 1981 to address problems associated with the first IUS processed aboard the Shuttle. The STS Division and the Satellite Systems Division were consolidated to form the Spacecraft Division on 1 November 1983.
The first military Space Shuttle mission, STS-4, was launched from Pad 39A at 1500Z on 27 June 1982. Military space missions also accounted for part or all of 14 out of 37 Shuttle flights launched from the Cape between August 1984 and July 1992. While many details of those missions are not releasable, some features of Shuttle payload ground processing operations and range support requirements can be summarized for what might be termed a "typical" military space mission.
One process common to many military Shuttle missions was the preparation of the Inertial Upper Stage. Though the ultimate destination of the IUS was mission-specific, the IUS was processed in one of two basic assembly/checkout flows. Before either process began, the Inertial Upper Stage's structural assemblies, avionics and flight batteries were received at hangars E and H and placed in various storage areas at the Cape. At the appropriate time, all vehicle elements were transferred to the SMAB, where they were assembled and checked out. Following power up checks and functional testing, the military IUS was cleaned and transferred to the SPIF. For civilian missions, IUSs entered a different assembly/checkout flow at this point in the process. They were sent directly to NASA's Vertical Processing Facility on Merritt Island.