Department of the Navy History in Space
As a result of World War II, the United States, its allies, and its adversaries realized a number of profound technological capabilities (nuclear weapons, radar, electronic navigation, weapon guidance, long-range rockets (V-2), proximity fuzes, and so on) that would affect warfare forever. Yet by modern standards, the Department of Defense (DOD) in general and the Navy in particular had many deficiencies, including the following:
Long-haul wireless communications were limited to the high-frequency (HF) band and were often not available as a result of little-understood changes in the environment;
Navigation was inaccurate and uncertain—even when the Navy’s Long Range Navigation (LORAN) system was available, inaccuracies were generally in the range of 1 to 2 miles;
Environmental knowledge (regarding winds, wave height, cloud cover, storms, temperature, and sea conditions) was limited to the local area of an observer, and forecasting capabilities were limited or nonexistent;
Except for HF transmissions, the ability to track and identify beyond-line-of-sight (BLOS) targets or transmitters did not exist;
Weapon delivery accuracy was appallingly poor, being limited by the lack of precise knowledge of the geolocations of both the weapon release platform and the target;
Target surveillance and identification were limited to the questionable capabilities of reconnaissance aircraft whose survival over enemy terrain was tenuous;
Surface-to-surface rockets had a maximum range of about 200 miles and an apogee of about 60 miles, used single-stage nongimbaled engines, delivered a unitary payload, and were highly unreliable in their performance; and
The ability to identify and locate the site of a clandestine detonation of a nuclear weapon was rudimentary.
Few knowledgeable military officers of the post-World War II era would have disagreed with the foregoing list of shortfalls in military capabilities. While the senior leadership of the Navy had no game plan for overcoming these deficiencies, there was a faith, best expressed in Vannevar Bush’s book Endless Horizons,1 that broad investment in basic research would generate discoveries that would lead to the development of new technologies to ameliorate this list of deficiencies.
The Navy, more than any other Service, embarked on a systematic program of investment in and support of basic research in its own in-house laboratories (primarily the Naval Research Laboratory (NRL)), in universities, in university-associated contract research centers (such as the Applied Physics Laboratory (APL) at Johns Hopkins University, the Applied Research Laboratory at Pennsylvania State University, and the Scripps Institution of Oceanography), and in selected industrial research centers.
Modern space-based capabilities have largely served to resolve the list of post-World War II deficiencies listed above. Almost all of the modern space-based capabilities available to the DOD and the Navy are traceable to early investments in basic research made by the Navy and other DOD Services in the decades after the war.
Many vectors drove NRL’s interests in the use of space platforms. The Navy came out of World War II with communications systems that were dependent on the vagaries of HF propagation. As early as 1927, NRL developed an intense interest in attaining an understanding of the factors that described the behavior of the ionosphere. By 1937, NRL had established a small group to develop sounding rockets that could carry research instruments above the atmosphere. Much of that work was quiescent, but not forgotten, during the war years.
At the end of World War II, the U.S. Army captured a factory near Niedersachswerfen in Germany containing enough parts of the Vergeltungswaffe (the vengeance weapon, or V-2) to allow the reconstruction of about 100 V-2 rockets. These were shipped to the Army’s White Sands Missile Range (WSMR) in New Mexico where the Army had the mission of developing long-range tactical missiles. If the Army was going to fly these missiles in space, it needed to obtain a better understanding of the environment above the atmosphere. By early 1946, NRL had established a group with responsibility to investigate the physical phenomena in, and the properties of, the upper atmosphere with a view to supplying
knowledge to influence the course of future military operations. As NRL was the most competent group in the country in the area of above-atmosphere instrumentation, the Army group at WSMR turned to NRL for support, and a synergistic union between the two resulted.
Although the V-2 was an unreliable rocket, it could lift scientific payloads of 500 kg approximately 150 km above Earth. NRL teams led by Herbert Friedman and Richard Tousey were able to undertake landmark research that established the effect of solar x-rays on the ionosphere and established the nature of the solar ultraviolet spectra.
Through the late 1940s and early years of the 1950s, the NRL-WSMR team continued its work with ever more impressive results. However, it was clear that the supply of V-2 rockets was dwindling. Beginning in the late 1940s, personnel in NRL’s Rocket Sonde Research Branch began the design of a new rocket designed to support NRL’s upper-atmosphere research program. NRL’s first rocket was called Viking. Unlike the V-2, which was not steerable, Viking had a gimbaled engine, allowing it to be steered. After the normal early developmental problems, Viking became routinely available for research purposes.
Although the Viking could deliver a scientific payload to greater altitudes than the V-2 could, its real advantage was its steerable engine. The jump from a single-stage steerable rocket to a multistage steerable rocket was, conceptually at least, a straightforward engineering challenge. Once a multistage-steerable-rocket capability was available, the placement of a satellite in orbit would be possible. By 1954, as a result of developments at NRL and at the Army’s Redstone Arsenal in Alabama, the conceptual pathway to placing research packages into satellite orbits was clear.
In the summer of 1954, members of the International Scientific Radio Union recommended that as part of the activities scheduled for the International Geophysical Year (IGY)—1957/1958—artificial satellites be launched for use as research platforms. On July 29, 1955, the White House announced that, in support of the IGY, the United States intended to launch “small earth circling satellites.”2 At the time of this announcement, a high-level committee known as the Steward Committee was convened by the Assistant Secretary of Defense. The Steward Committee was charged with deciding who in fact would be assigned responsibility for the first satellite launch.
The Air Force might have been a contender for this assignment, but its major personnel talent was committed to the development of the Atlas rocket, which was slated to become the launch vehicle for an intercontinental ballistic missile and, by congressional guidance, had to take precedence over support of a scien-
James C. Hagerty, Press Secretary to the President. 1955. “Presidential Press Briefing,” The White House, Washington, D.C., July 29. Available online at <http://www.eisenhower.archives.gov/dl/IGY/StatementbyHagertyJuly291955.pdf> or at <http://www.hq.nasa.gov/office/pao/History/sputnik/17.html>. Accessed May 4, 2004.
tific rocket project. That left two available rocket design groups: one was at NRL and the other, led by Wernher von Braun, was at the Army’s Redstone Arsenal.
The Army proposed the Orbiter, some of whose components already had been under development with funds provided by the Office of Naval Research (ONR). Plans for the Orbiter called for a multistage rocket that could put a 5 lb satellite into orbit. The NRL proposal was for a three-stage rocket using a Viking-based design for the first two stages and a newly designed upper stage that could deliver a 40 lb scientific payload into orbit. The NRL proposal also included a virtually ready-to-go radar tracking system, called Minitrack, that already had been developed to provide tracking for the Viking project.
After considerable internal debate, the Steward Committee selected the NRL approach, and on September 9, 1955, NRL won stewardship of the satellite program, which became known as Project Vanguard. NRL’s basic tasking was to build a satellite launch vehicle,3 place one satellite in orbit, verify its orbital path, and accomplish one scientific objective, all before the end of the IGY.
After suffering numerous highly visible failures (in part in an effort to catch up with the Soviet launch of Sputnik), the NRL team on March 17, 1958, delivered a 3 1/2 lb satellite into an orbital trajectory. Although Project Vanguard suffered every public relations calamity conceivable, it represented an astounding achievement. In just 2 1/2 years, NRL took an all-paper design to a successfully launched satellite. The legacy of the Project Vanguard rocket design would be traceable through several National Aeronautics and Space Administration (NASA) and Air Force vehicles, including the Delta, on which Vanguard is the second stage.
The activities of this period eventually brought the United States into the era of manned spaceflight. The Minitrack system would become the basis of all DOD satellite tracking, including the advanced and comprehensive Naval Space Surveillance System (NAVSPASUR). (See Box A.1 for additional detail on NRL’s development of satellite tracking systems.) The existence of NAVSPASUR also proved crucial to the development and monitoring of the Global Positioning System (GPS) constellation. In addition to these accomplishments, the Vanguard I satellite provided data that enabled improved calculations of Earth’s shape and of the periodic variations of the density of the upper atmosphere.
Several weeks after the Vanguard launch, President Eisenhower set in motion actions that would lead to the formation of NASA. Personnel from NRL, the Army Ballistic Missile Agency, the Air Force Cambridge Research Laboratory, and the Jet Propulsion Laboratory were transferred into the nascent NASA organization. A draft of NRL personnel with experience in rocket design constituted the largest portion of NASA’s initial technical staff.
Surprising the nation in the late 1950s was the Soviet Union’s launch, on October 4, 1957, of the Sputnik satellite. The U.S. Navy, through the almost immediate response of the Naval Research Laboratory (NRL), started receiving data and tracking Sputnik by its third orbit, fewer than 5 hours after its launch, using the NRL’s radio array at Hybla Valley, Virginia. NRL soon brought its Vanguard Minitrack satellite tracking system online and used it to provide additional higher-precision tracking data for Sputnik.1 Sputnik orbital measurements were also collected by the Applied Physics Laboratory of Johns Hopkins University and led to the use of measurements of the Doppler shift of Sputnik’s radio signal, enabling a greatly improved tracking calculation. The use of Doppler-shift monitoring and tracking later led to the concept of the Transit series of navigation satellites.2
Although the formation of NASA left NRL without in-house rocket design capabilities, NRL still had a highly competent satellite design group and a strong research staff with impressive qualifications for undertaking exo-atmospheric research programs. By 1962, NRL demonstrated the launch of multiple satellites with a single rocket. After this seminal event, the launches of classified satellites often were piggybacked on launches of NRL research satellites. One particularly successful program developed electronic-intelligence-gathering satellites (called GRAB, for Galactic Radiation and Background), as described in Box A.2. These
The nation’s first successful electronic intelligence (ELINT) satellite was proposed by the Naval Research Laboratory (NRL) in the spring of 1958. Named GRAB, for Galactic Radiation and Background, its first launch was approved by President Eisenhower in May 1960, four days after a Central Intelligence Agency U-2 aircraft was lost on a reconnaissance mission over Soviet territory—thus initiating an urgent need to develop continual unmanned surveillance from space. Taking advantage of NRL’s multiple-launch capability, the GRAB satellite launch also carried the Navy’s third Transit satellite and the Navy’s SOLRAD satellite—developed to measure solar radiation.
launches were so successful that during the 1960s and 1970s classified satellite programs and associated staff grew to the point of dominating NRL’s space activities.
By 1960, Sputnik, Vanguard, and several other satellites had been placed in orbit. Although much of the necessary technology had not yet matured sufficiently to allow the implementation of space systems, a broad general understanding of their future role had begun to evolve in the DOD, in the intelligence community, in the nation’s science community, and in many civil agencies within the U.S. government. This time period witnessed the development of many new space capabilities, including the following:
The ability, demonstrated by NRL, to communicate with in-flight sounding rockets established that communications satellites would be feasible.
Imagery retrieved from NRL cameras launched on pre-1960 sounding rockets indicated the potential for satellite imagery.
Early NRL satellite launches demonstrated the feasibility of launching multiple independent packages from a single launch—indicating the potential for developing intercontinental ballistic missiles with multiply targeted independent reentry vehicles.
Although the Vanguard satellite was ridiculed for its small size and multiple launch failures before finally being placed in orbit, it provided a vast amount of data on the actual shape of Earth. These data were in turn used to achieve a significant improvement in the delivery accuracy of intercontinental ballistic missiles.
Early NRL efforts on the readout of telemetry and sensor data indicated that if space-based sensors were specifically configured to intercept signals from hostile radars or communications transmitters, tremendous increases in intelligence-gathering capabilities and emitter-location capabilities could be achieved. Thus, the limitations of surface- and aircraft-based sensors could be eliminated.
The satellite tracking networks developed in support of Project Vanguard and the development under ONR sponsorship of reliable, stable, and highly accurate atomic clocks and hydrogen masers implied that if such clocks could be
space-qualified, ultraprecise space-based navigation systems (such as GPS) might ultimately be deployed.
The performance of Earth-orientated sensors in early NRL and APL tests, and particularly by the Television and Infrared Observation Satellite (TIROS) funded by the Advanced Research Projects Agency (ARPA), indicated that weather and sea-surface conditions could be observed worldwide with considerable accuracy and precision and that space-sensor-derived data could provide significantly improved weather and ocean forecasting capabilities. These activities were first consolidated into NASA and eventually became one of the core operations of the National Oceanic and Atmospheric Administration (NOAA).
Sensors used in early NRL sounding rocket experiments to detect x-rays and solar radiation were also used to validate that space-based sensors could provide an improved capability to globally detect nuclear explosions. The Defense Advanced Research Projects Agency (DARPA) and NRL later collaborated on the early deployment of the Vela Hotel satellites,7 whose measurements enabled the U.S. government to determine that there was a high probability that clandestine nuclear tests in space could be detected and thus that the United States could verify compliance with a nuclear test ban treaty with the Soviet Union.
During the decades after 1960, there was an explosive growth in the overall national funding for space-related systems. As computer capabilities, sensor performance, clock accuracies, optical system resolution, communications capabilities, and the thrust of launch vehicles grew, so did the performance of systems that were launched. From the standpoint of senior naval officials, the performance of such systems was impressive. Yet, faced with the problems of conducting the Vietnam War and competing with the Soviet Union’s development of an open-ocean surface and submarine fleet, the performance of space systems in the 1960s through the 1980s was not great enough to command a significant priority in the Navy’s budgetary allocations.
INTELLIGENCE, SURVEILLANCE, AND RECONNAISSANCE
When it was available, imagery derived from space-based sensors was quickly found to be of tactical use to the Services. Unfortunately, when imagery was not available for technical or priority reasons or both, it often took weeks to months before Navy or other Service requests for imagery were satisfied. Satellite imagery was the domain of the intelligence community, whose highest priorities in those decades were driven by considerations of nuclear exchanges between
the United States and the Soviet Union. In that period the support of military operations definitely had low priority in the eyes of those who controlled the tasking of imaging satellites. As a consequence, Services including the Navy had little desire to provide budgetary (or even personnel) support for such activities.
A similar problem existed with respect to satellites that were designed either to intercept hostile communications or to geolocate radars associated with hostile surface-to-air missiles (broadly classified as electronic intelligence (ELINT) systems). Although the computers of that era could not perform near-real-time analyses of the data, the real delay was inherent in the operation of the era’s ELINT satellites. At the time, all satellite-derived intelligence data were forwarded to the National Security Agency (NSA) where they were processed and evaluated by NSA’s analytical staff. Data that could be associated with nuclear warfare had first priority; data related to the support of military operations were a distant second priority.
Until the early 1980s, the latency of space-derived ELINT data could be days to weeks. As a consequence, the Navy’s concepts of operations did not have a strong dependence on the availability of such data. Although both NRL and certain naval commands were heavily involved in space-based programs related to the gathering of ELINT from space-based sensors, the Navy as a whole was not sufficiently impressed with system output to be willing to provide major personnel or budgetary support for these programs. Nonetheless, NRL continued to develop space-based intelligence systems relying on funding supplied from outside the Navy (see Box A.3).
The Navy’s limited involvement in such programs had a negative feedback effect. Owing in part to the long lead times for developing new satellite systems (often 5 to 15 years), as new generations of equipment were designed and procured the Navy’s small amount of up-front monetary and personnel support led to a lack of early priority for Navy and naval requirements. In addition, the less responsive the acquisition community became to Navy requirements, the less interest the Navy showed in the development and use of future systems.
ENVIRONMENTAL SENSING AND GEODESY
The first movie of a hurricane taken from overhead was recorded in 1954 by NRL.8 Since that time, the Navy has developed a significant number of scientific and environmental sensors and satellites, including the following: SOLRAD, the Solar Radiation satellite; Geosat, the Navy’s Geodetic Satellite; and, most recently, Coriolis—launched through the Space Test Program (STP), this satellite carries the NRL-built WindSat wind-speed and wind-direction measurement sen-
In a sense, the Naval Research Laboratory (NRL) became a victim of its own success. Beginning in 1960, the nation’s investment in space-based systems expanded tremendously. The expansion was far beyond anything that an organization even as large as NRL could cope with. Although NRL developed and launched some 80 satellites in the four decades between 1960 and 2000, the number was only 1 or 2 percent of the total national effort. NRL’s expertise in sensor technology and scientific research caused the expertise of its staff to be sought out and funded by a long list of non-Navy organizations (the Air Force, Army, Missile Defense Agency, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, National Security Agency, National Reconnaissance Office (NRO), National Science Foundation, predecessors of the National Geospatial-Intelligence Agency, and others). The support that NRL received from all of these non-Navy organizations was sufficient to allow it to build up a large and very competent staff.
Through the early 1980s, NRL’s largest effort was in support of the development of classified prototype surveillance satellites. These developments were indeed successful, to the degree that the sponsoring agency (NRO) decided to go into serial production of such satellites. Since NRL was a research laboratory and not a manufacturing facility, the production of the next generation of satellites was transferred to an industrial organization. This transfer left many members of the NRL staff without sponsor support and necessitated a rather traumatic drawdown in the number of NRL personnel available to manage the development, acquisition, and launch of full satellite systems. The difficulty was that the Navy (through the Office of Naval Research) only provided funds to cover NRL’s basic research activities. In the past three decades, no Navy funds have been provided to NRL to develop and launch new satellite systems. As a consequence, NRL’s ability to develop and deploy satellite systems that offer the Navy new warfighting capabilities has diminished by a significant amount.
sor.9 The operation of this latter sensor system is coordinated with NASA, NOAA, and the Air Force. SOLRAD was used to provide measurements of the Sun to help with predicting radio transmission performance and to help understand other scientific issues. The concepts underlying Geosat and its forerunners began after the Navy’s Moon Bounce program showed that accurate ranging data (in this case the Earth-Moon distance) could be measured. This led NRL scientists to determine that similar radar, looking at the ocean surface from orbit, could accu-
rately determine the ocean surface height.10 Satellites supporting these altimetry measurements included Seasat, which carried a radar altimeter built by APL, and the current Geosat system, also built by APL. These altimetry satellites provide insights into ocean surface topography, currents, and eddies that are important for submarine-launched ballistic missiles and other submarine operations, landings, and Special Forces operations.
The Defense Meteorological Satellite Program (DMSP) carries NRL’s Special Sensing Microwave/Imager (SSM/I) sensors and the follow-on SSM/IS, which measures sea ice, precipitation, atmospheric winds, and surface winds. The current generation of surface-monitoring sensors, the WindSat sensor built by NRL, adds to the prior measurements by providing data on wind speed and direction. These wind data have proven important to many naval operations and are now included in plans for NOAA’s next generation of polar-orbiting environmental satellites.
Early geodetic work (modeling of Earth’s surface height and gravitational field) was done by both the Army Map Service and the U.S. Naval Observatory using precision measurements of the motion of Earth’s natural satellite, the Moon. This approach, while improving geodesy significantly over earlier terrestrial techniques, still left surface-height uncertainties on the order of kilometers. With the advent of satellites orbiting close to Earth (hundreds of miles in altitude), more and higher-precision geodesy data were collected. The APL Transit satellite, the first satellite designed to provide accurate positioning data, enabled significant increases in geodetic accuracy, eventually reducing the uncertainties to the 10 m range.11 Later, launch of the GPS satellites, with their resident high-precision clocks and advanced ground-monitoring systems, brought geodetic measurement accuracies on the order of millimeters, enabling small ground movements such as continental drift and small movements along faults to be measured. These data, in combination with laser altimeter data provided by the Geosat satellites, enable accurate calculation of Earth’s surface profile as well as its gravitational field profile. The gravimetric data in particular have been useful to the Navy in support of the submarine-launched ballistic missile system.
From the 1960s through the 1980s, the Navy expressed intense interest in the acquisition of satellites to provide environmental data. In this area, NOAA, NASA, and the Air Force had requirements congruent with those of the Navy, and to the degree that contemporary technology permitted, many but not all Navy needs were satisfied by the satellites acquired and operated by NOAA. To meet the Services’ special environmental sensing needs, particularly to determine
cloud-free areas for optical imaging satellites, the DMSP was established under the direction of the Air Force. Thus, there was no strong need for additional Navy funding in the area of space systems that supported the needs of the weather forecasting community.
The “O” in NOAA stands for Oceanic, but it is the “A” standing for Atmospheric that has historically dominated the organization’s activities. Early environmental satellites, fielded to provide worldwide synoptic information on sea-surface temperatures and radar images of the sea surface, were developed and supported by NASA. Although the data from NASA oceanographic satellites were designed for the national scientific community, the Navy was a massive consumer and user of the derived information. Further advances in the performance of oceanographic satellite sensors will require space-based active sources (radar and lasers) to measure ocean wave heights and to measure near-surface winds and humidity. Neither NASA nor NOAA has shown recent budgetary enthusiasm for investments in active space-based environmental sensors. Since 1994 NOAA has been the designated National Executive Agent for environmental satellites;12 thus, the Navy can only submit requests to the interagency steering group of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) satellites to bring about what the Naval Oceanographic Office believes to be necessary and desirable improvements in the performance of active space-based environmental sensors.
Beginning in the 1960s, the Navy, along with the rest of the DOD and the commercial communications industry, was intensely interested in the development of communications satellites whose potential had been demonstrated by early NRL rocket studies. In the following decades, the DOD’s investment in satellite communications systems was large, but it was dwarfed by worldwide commercial investments and developments in this area. Although the Navy’s investments in this same area were robust, they tended to be specific to Navy needs for systems with antennas suitable for shipboard use. These activities included support (and even acquisition) of several satellite communications systems, such as the Fleet Satellite (FLTSAT) communications system, UHF (ultrahigh frequency) Follow-on (UFO), and the extremely high frequency (EHF) packages on UFO.
The Navy recognized fairly early on that satellite communications to submarines would require the use of very small antennas. This need, as well as others, led to the Navy’s support for the development of EHF-band communications satellites. The Navy worked with the Massachusetts Institute of Technology Lin-
coln Laboratory in the 1960s to explore the feasibility of providing EHF satellite communications; this work led to the development and demonstration of the Lincoln Experimental Satellite series.
In 1974 the DOD allowed the Air Force to fund the entire development of a radiation-hardened DOD EHF communications satellite constellation (later named MILSTAR, for Military Strategic, Tactical, and Relay Satellite) in exchange for the Air Force’s being designated the lead Service for EHF communications. Even though the Air Force was developing MILSTAR, the Navy, through the Lincoln Laboratory, developed and deployed Fleet EHF Packages (FEPs) as test packages on the final four FLTSAT satellites as well as on the initial four UFO satellites.13 This action assured the Navy of timely access to EHF communications without reliance on the developing MILSTAR program.
Just after the 1970 removal of DOD restrictions against Navy development of operational satellite systems, the Navy obtained DOD authorization to develop FLTSAT to provide the fleet with global support for tactical communications. FLTSAT satellites were initially procured in 1972 through the Air Force, with the NRL developing and providing the Fleet Broadcast Processor (FBP)—a system that provided a large margin of jam resistance and one that continues to be used on the UFO and other UHF satellites.14
As a result of the uncertainties and delays in the acquisition of the FLTSAT satellites, the Navy was permitted, beginning in 1976, to lease UHF satellite communications from commercial sources. The first FLTSAT satellite was finally launched in 1978. As other Services and agencies began using FLTSAT and its reliability was proven, the Navy sought and received permission to purchase additional satellites on a “turnkey” basis.15 This program, called Leasat, entered operation in 1984. Based on the successes and demonstrated economy of these UHF programs, the Navy was assigned the responsibility for acquiring UFO as well as for developing the next-generation UHF system, the Mobile User Objective System (MUOS).
By the 1990s the DOD recognized that Service-unique satellite communications systems were undesirable. At a minimum, the DOD decided that all space communications systems needed to be joint and to satisfy the communications needs of all Services. Although the Navy has continued to invest resources in the development of MUOS and other satellite communications systems, these efforts are no longer dominated by Navy needs and requirements.
POSITION, NAVIGATION, AND TIMING
In the area of space-based navigational systems, the development of the necessary technology took place before senior Navy leadership could appreciate its significance. Leading these navigation efforts, ARPA provided funding for the first Navy satellite navigation system, Transit (further described in Box A.4). The
The Navy’s ballistic missile submarines had a critical need for precise location updates in order to meet their operational goals. The Navy, through the Applied Physics Laboratory (APL) at Johns Hopkins University, invented and developed Transit—the world’s first satellite navigation system—to meet that need.
There had been no navigation program at APL before the initiation of Transit. The Transit concept was developed after APL tracked the Soviet Sputnik “surprise” of October 4, 1957. The tracking of the Sputnik satellite by William Guier, a researcher at APL, led him to recognize that the measured Doppler shift of a satellite’s radio signal could be used to accurately track the satellite. Guier and George Weiffenbach, also at APL, tracked Sputnik by this method and improved the orbit predictions over the next 6 months. This capability led Frank McClure, then also at APL, to recognize that “you could use the Doppler effect to compute your location on the ground.”1
On March 18, 1958, McClure’s concept was described in detail in a memorandum.2 The Transit concept was briefed to a special subcommittee of the presidential science advisory committee headed by Herbert York, who had visited APL earlier. York later became head of the Advanced Research Projects Agency (ARPA) and approved ARPA’s providing initial funding for Transit. Later funding was provided by the Navy: the Transit program was then funded and managed through the Navy’s Strategic Programs Office, allowing it to proceed with a minimum of red tape. “There were no constraints put upon us,” observed Weiffenbach. “The only question I ever heard from them was, ‘do you need more money?’”
On September 17, 1959, the first Transit satellite was launched. Unfortunately it did not achieve orbit, owing to a booster malfunction. The second launch, on April 13, 1960, was successful, and it demonstrated the key features needed for an operational system. After 10 launches of progressively refined prototype satellites, the Transit satellite system became operational in 1964 and remained so until 1996. This system provided accurate navigational information throughout the Cold War years to the most covert component of the ballistic missile triad, submarines. Transit went on to be used on a large number of naval and commercial ships as well as extensive numbers of land-based systems.3
capabilities of the present-day GPS system are an outgrowth of NRL work in the 1960s and early 1970s on Transit and Timation (TIMe/navigATION), the first satellite to utilize on-orbit atomic clocks, and NRL’s continuing support to NAVSPASUR; Aerospace Corporation’s work on the downlink signal structure; ONR’s continued support of the development of highly stable atomic clocks that were made space-qualified by NRL; and the microelectronics revolution that allowed the design of compact GPS receivers. These and other Navy efforts in support of GPS are listed in Box A.5.
In the 1970s the Navy had neither GPS guided weapons nor plans to acquire such capabilities. In effect, the Navy withdrew its support of further development
The Naval Research Laboratory (NRL), mainly through the efforts of a talented radio engineer, Roger Easton, developed and demonstrated the core concepts of the current Global Positioning System (GPS). Based on NRL’s efforts, a low-cost, low-risk path to the operational capability for GPS was provided. The key features of NRL’s efforts were as follows:
of space-based navigational capabilities and the development of the GPS system was assigned by the DOD to the Air Force and its lead laboratory at Aerospace Corporation. NRL and the Navy retained some responsibility for the continued development of ever more precise space-qualified clocks that will be inserted into future generations of GPS satellites.
As described above, NRL early on proved the effectiveness of its Minitrack satellite tracking system. For many years Minitrack was also used by NASA as its
In addition, NRL engineers provided the Air Force and its contractors, Aerospace Corporation and Rockwell International, a detailed NTS-2 operations plan as a means of ensuring that those involved in the developing Air Force GPS program understood the designs, expected performance, and operation of NTS-2.6 NRL then engaged frequently with the Rockwell and Air Force engineers during GPS’s early operational phases. The launch in 1978 of the first NDS satellite, by Rockwell, demonstrated that a successful transition of skills and information had taken place.
primary satellite tracking system. The Transit Network (TRAnet) and Operational Network (OPnet) were developed to support the tracking and monitoring needs of Transit and other satellites and remained in use into the 1990s.
The NAVSPASUR system, developed by NRL, has been a key to the nation’s ability to track almost all objects in Earth orbit that are larger then about 10 cm in diameter. Being an active radar system (one currently based on radio-frequency transmit and receive arrays positioned in a line across the entire southern United States), it detects all orbital objects, not only active (transmitting) satellites. NAVSPASUR was initiated in 1958 as Minitrack and was commissioned as an operational naval command in February 1961. Data processing is done, as it has been since the early 1960s, at the Space Surveillance Processing Center in Dahlgren, Virginia.16 This system has been very productive in keeping the United States aware of almost all large objects orbiting Earth, producing an average of 160,000 observations per day.17 NAVSPASUR is still highly effective, and while responsibility for the system was transferred to the Air Force in 2003, the Air Force has retained the Navy’s Dahlgren facility to continue its support of NAVSPASUR operation.
One additional ramification of NAVSPASUR was that, with the addition in 1960 of the second radio array site in Texas, the NAVSPASUR system was found to be in need of a means to coordinate the high-precision clocks on which the facilities rely. This timing coordination need then led to the concept of a space-based common time and became one of the drivers for the Navy’s Timation program.18