MILITARY GROUND CONTROL CENTERS, UNITED STATES

Military Ground Control Centers

Most people have the perspective of military operations centers typified by the 1980s movie ”War Games” (1). They expect to visit facilities such as Colorado’s Cheyenne Mountain Complex (2) and see vast, darkened underground chambers ringed with immense display screens supported by powerful computers and occupied by legions of console operators. Although an attempt was made in the mid-1990s to ”spruce up” Cheyenne Mountain Complex and other military space facilities, the fact is that military operations centers are mostly filled with rather antiquated equipment and present a decidedly unmodern appearance. Anyone who has flown on a military aircraft would understand the less than spectacular ambiance and would feel right at home in the military’s space operations centers.
Current military space operations centers grew out of 1950s and early 1960s facilities and missions — some of those missions were quite different from those of today. The military is quite conservative when it comes to innovation and modernization. And nowhere is this more evident than in space operations. The watchword is evolutionary, not revolutionary. Thus, a facility, and even its hardware, has often been adapted from a previous mission in the same facility. Because the old mission, often critical to national security, must continue as new missions are brought on, old hardware and procedures are replaced only when new technologies and hardware are well proven. Similarly, organizations responsible for military space missions tend to be adapted from older, often quite different missions and organizations. In recent years, this is particularly evident in the U.S. Air Force’s space organizations that are steadily being evolved out of and in a way that mimics air operations. Organizations such as the Air Force Space Command’s 50th Space Wing, the operator of much of the Service’s on-orbit satellites, is organized exactly as a flying wing, complete with the assumption of a unit name. As this article unfolds, the reader should keep this conservatism and legacy in mind.
The U.S. military currently maintains ground control centers for three related missions: early warning, space surveillance/space control, and on-orbit satellite operations. Early warning and space surveillance/space control evolved from the North American Air Defense mission developed jointly by the United States and Canada in the 1950s, culminating in the construction of the North American Air Defense Command (NORAD) Combat Operations Center (COC) in the early 1960s (2). On-orbit satellite operations centers have a different pedigree. Shrouded in secrecy during most of the Cold War, these facilities began as control centers for the United States space-based intelligence collection mission. As such, they were originally developed and largely operated by the still secretive National Reconnaissance Office (NRO) (3). To understand current military operations centers, it is necessary to understand the history of these missions and organizations.


History

North American Air Defense Command (NORAD). NORAD is the consolidated United States-Canada organization responsible for the defense of North America (2). Its key command and control center is contained in the Cheyenne Mountain Complex south of Colorado Springs, Colorado. NORAD originated in the early 1950s as a response to the development of the Soviet atomic bomb in 1949 and their TU-4 bomber designed to deliver these weapons. By the mid-1950s, the Soviet Union had thermonuclear weapons and a jet-powered bomber. In 1954, the United States established a Continental Air Defense Command with a concrete-block Command Operations Center (COC) at Ent Air Force Base in Colorado Springs, Colorado. When the Soviet intercontinental ballistic missile (ICBM) was demonstrated in the late 1950s, the perceived levels of threat in both the United States and Canada escalated and the Ent AFB above-ground facilities were considered extremely vulnerable to attack. In 1958, the U.S. and Canadian governments formally established NORAD to meet this air and missile threat. It was soon decided to build a much more survivable NORAD Combat Operations Center (COC). By the early 1960s, the Cheyenne Mountain site south of Colorado
Springs had been selected for an underground NORAD COC, and construction began in 1961 (2). Ironically, by the time the facility was completed in 1965, ICBM accuracy had progressed to the point where it is doubtful that the Cheyenne Mountain facility could survive any concerted nuclear attack (Fig. 1).
By the mid-1960s, the NORAD COC was fully operational in a series of buildings more than 1000 feet underground. The facility was designed to withstand the effects of a nuclear detonation and operate for more than a month without outside contact. Its initial mission was to use complex computer systems (which have been upgraded many times since the mid-1960s) to collect and assess data from early warning radar sensors in the United States, Canada, and other locations for potential air or missile attack on North America. By the addition of satellite missile warning sensors in the early 1970s, this data was augmented with space-based missile attack sensors.
By the mid-1960s, growing concern over Soviet Union space activities led the United States Government to include an integrated Space Defense Center as part of NORAD and as a third mission (with air and missile attack) for the NORAD COC. The Space Defense Center’s function was and remains today to identify and track all man-made objects in space using inputs from missile warning radars and a dedicated set of space-track radars and optical space-track sensors.
In the mid-1980s, the United States embarked on its Strategic Defense Initiative (SDI) to develop technologies that could be applied to an effective national and global missile defense system. This initiative was highly controversial and had as its core many sensor and weapon concepts, which would be based in space. The Canadian Government had expressed in the 1980s and continued to express into the 2000s considerable concern with the arms control implications of missile defense and military activities in space. As a consequence, the role of NORAD as joint United States-Canada organizations in either missile defense or what is now known as space control is uncertain. Thus, most U.S. space control activities are now concentrated in a separate United States Space Command (USSPACECOM).
The Cheyenne Mountain Operations Center is the heart of the missile warning and space track functions that support NORAD and the U.S. SPACE COMMAND, respectively. Figure courtesy USAF Space Command. Picture can be found at http:// www.spacecom.mil/images/cmdctr-4.gif. This figure is available in full color at http:// www.mrw.interscience.wiley.com/esst.
Figure 1. The Cheyenne Mountain Operations Center is the heart of the missile warning and space track functions that support NORAD and the U.S. SPACE COMMAND, respectively. Figure courtesy USAF Space Command.

United States Space Command

To understand the current United States command and control of space capabilities, one must understand the basic structure of U.S. military command. U.S. military operations are carried out through a “unified” command structure, as mandated by the Goldwater-Nichols Act of 1986 (4). Responsibility for combat or other operations devolve from the U.S. President through his Secretary of Defense to the Joint Chiefs of Staff (JCS). Composed of the Service Chiefs of the U.S. Army, Navy, Marines, and Air Force, as well as a Chairman and Vice-Chairman, the JCS control U.S. military forces through a series of Unified Commands, led by Combatant Commanders. Most Unified Commands are “regional” in that they have responsibility for geographic regions such as the Pacific and Indian Ocean rims—in this case the responsibility of the U.S. Pacific Command or “PACOM.” There are also three ”global commands”—the U.S. Strategic Command, responsible for nuclear war planning, the U.S. Transportation Command, responsible for global mobility, and the U.S. Space Command (USSPACECOM) responsible for space capability support for other commands, space control, and recently computer network defense and attack. The Commander of the U.S. Space Command controls and conducts space operations through forces provided by the military services. The U.S. Strategic Command and U.S. Space Command are scheduled to merge on 1 October 2002 (5).
The U.S. military services (Air Force, Army, Navy, Marines) are not responsible for military operations. Rather they train, organize and equip forces, which they provide to the various unified commanders. Thus, now there exists a U.S. Army, U.S. Navy, and U.S. Air Force Space Command to provide CINC-SPACE with trained organized and equipped space forces.
The intensive focus on U.S. President Reagan’s Strategic Defense Initiative (SDI) for missile defense announced on 23 March 1983 led the U.S. Department of Defense to establish a Unified Space Command on 23 September 1985. As noted before, the Canadian government had serious reservations about the U.S.
SDI and associated issues. Thus, NORAD and the USSPACECOM remain separate entities. However, since its inception, the USSPACECOM and NORAD have been dually commanded by a single U.S. Air Force four-star general. This results in a rather complex command relationship and numerous opportunities for confusion as to roles and missions. In addition, from 1990 to 2002, this Air Force general has been ”triple-hatted” as the Commander of the U.S. Air Force Space Command. This arrangement again changed with the assignment of a separate four-star Air Force General to command the Air Force Space Command on 19 April 2002. This reorganization was a result of the findings of the Space Commission Study completed in 2001 (6).
A new Combatant Command, the United States Northern Command, will be initiated in late 2002. It will assume responsibility for homeland defense of the United States. Its Commander will probably retain ”dual hat” Command of this U.S. Northern Command and NORAD—unless the two Commands are formally merged by international agreement between Canada and the United States (7). At the same time, as noted before, the space and information operations responsibilities of the U.S. Space Command will devolve onto a separate Combatant Commander who will assume these and current responsibilities of the nuclear war-fighting U.S. Strategic Command.
U.S. Air Force, Army, and Naval Space Commands. Throughout the history of the U.S. military space program, the U.S. Air Force has remained a central player. Thus, its composition for training, organizing, and equipping military space forces must perforce initiate any discussion of Service programs. In the 1960s, the Air Force’s Systems Command, then the research, development, and test and evaluation command, developed space systems. More discussion of this Command and its activities will follow. Because most space capabilities during the 1960s were ”experimental,” the operational Air Force played a little role in space system operations. The notable exception was NORAD’s U.S. component, the Continental Air Defense Command (CONAD) which operated the space surveillance and missile warning system from its NORAD Combat Operations Center in Cheyenne Mountain, Colorado (8). The functions of CONAD were later assigned to the Air Force’s newly named ADCOM, and CONAD was disestablished (9).
In the 1970s, NORAD’s air defense mission had withered to less than 25% of its levels in the 1960s. As a result, ADCOM was disestablished as a major Air Force command in 1980. Because the Air Force traditionally assigned space systems functionally to the command or agency with the greatest need, space capabilities had, by the late 1970s, become scattered to many different organizations. Air Force Systems Command retained control of communications satellites, and the Strategic Air Command managed meteorological satellite products. However, the late 1970s saw a resurgence in military space interest. Spearheaded by the Secretary of the Air Force, a variety of efforts were kicked off in the late 1970s to bring focus to the diverse Air Force space efforts. A major impetus for this restructuring was the promise of NASA’s Space Shuttle as a revolutionary, and then assumed, sole future space access system and the imminent deployment of the Global Positioning System (GPS). The pressure accelerated in the early 1980s when President Ronald Reagan focused on a defense and corresponding space buildup. Thus, the Air Force formed its Air Force Space Command in September 1982 to consolidate its operational efforts. Initially, this command was linked with the Systems Command’s development center (”Space Division”) through a ”dual-hatted” three-star general officer who served as Air Force Space Division Commander and Air Force Space Command Vice-Commander.
Today, the Air Force Space Command (AFSPC) operates most of the nation’s military space infrastructure, controlling through its operations centers the space tracking and space surveillance systems, meteorological satellites, many military communications satellites, early warning satellites, and navigation satellites (GPS). It also acquired operations of the nation’s ICBMs in the late 1980s. AFSPC has more than 35,000 personnel and ”owns” more than 60 operational satellites along with the nation’s military space launch capabilities and ranges, and satellite control network (10). However, it does not operate a national reconnaissance system—that remains the responsibility of the National Reconnaissance Office (NRO) to be discussed later. Unlike the Air Force, the U.S. Army developed its current space organization through its long-standing missile defense mission. The Army’s current space command was created as the U.S. Army Space and Missile Defense Command (SMDC) on 1 October 1997 (11). Although the Command began in 1947 when the Army created the first program office for ballistic missile defense, SMDC today amalgamates its missile defense research and development functions and its space development and operations activities. Unlike the Air Force, both development and operational programs are contained in the same organization. Key to the Army’s space efforts was its pioneering effort to apply national intelligence capabilities managed by the NRO to tactical uses. Since 1973, the Army Space Program Office has overseen the Army’s ”Tactical Exploitation of National Capabilities” or “TENCAP” Army Space Command (ARSPACE), a subordinate command of SMDC, serves today as the Army’s operational component of the U.S. Space Command (analogous to the Air Force Space Command). It does operational space planning and oversees the Defense Satellite Communications System (DSCS) Operations Centers (ground facilities for the central wideband military communications system; the Air Force Space Command operates the satellites through its satellite operations facility at Schriever Air Force Base, Colorado). The Army Space Command also explores the feasibility of off-the-shelf technology in the space program, such as the lightweight GPS receiver used during Operation Desert Shield/Desert Storm in 1991-1992.
The U.S. Navy also established a Naval Space Command on 1 October 1983 (12). It is the naval component of the U.S. Space Command. It has about 300 military and civilian personnel at the Naval Surface Warfare Center in Dahlgren, Virginia, and it operates the Naval Space Surveillance Center. Along with the Air Force Space Surveillance Network and other inputs received from missile tracking radars, it provides data to the U.S Space Command’s Space Control Center in Cheyenne Mountain, Colorado, from which the United States derives its current space situational awareness. The Naval Space Command also operates the Navy’s communications satellite systems, the Fleet Satellite Communications System (FLTSATCOM) and its new Ultra-High-Frequency Follow-On (”UFO”) system. The Naval Space Command operates the alternate space control center, a backup for the U.S. Space Command’s Space Control Center (SCC) in Cheyenne Mountain, Colorado Springs, Colorado. The U.S. Navy announced a reorganization in 2002; its Space Command will be subsumed under a new Naval Network Warfare Command (13).
USAF Space and Missile Systems Center (SMC). The Space and Missile Systems Center traces its ancestry back to the Western Development Division (WDD). WDD was activated in July 1954 and was redesignated as the Air Force Ballistic Missile Division (AFBMD) in June 1957 (14). Its initial Commander was General Bernard A. Schriever—essentially the ”father” of the U.S. military space program. The original mission of the organization was to develop intercontinental ballistic missiles (ICBMs) for the Air Force, but responsibility for developing the first military satellite system was added in February 1956. The ICBM mission remained with AFBMD and its successors through the decades that followed, but the Department of Defense (DOD) reassigned the space mission several times before settling on a final pattern. In February 1958, the DOD activated the Advanced Research Projects Agency (ARPA) and placed it in charge of all DOD space programs during their research and development phases. In September 1959, ARPA lost its dominant role, and the DOD divided responsibility for developing military satellites among the three services. The Army was to develop communication satellites; the Navy, navigation satellites; and the Air Force (i.e., AFBMD), reconnaissance and surveillance satellites. The Air Force was also to develop and launch all military space boosters. This arrangement continued until March 1961, when the DOD gave the Air Force (AFBMD) a near monopoly on the development of all military space systems, ending the role of the Army and the Navy except under exceptional circumstances. The final policy change occurred in September 1970. The DOD declared that the Air Force would remain responsible for developing, producing, and launching space boosters and for developing, producing, and deploying satellite systems for missile warning and for surveillance of enemy nuclear delivery capabilities. However, all three military departments would have the right to submit proposals for development of satellite systems for other purposes, and DOD would decide whether to approve those proposals. In theory, this decision gave considerable leeway to the Army and the Navy and eroded the Air Force space monopoly to a considerable degree. In practice, however, the Air Force has continued to develop most of the satellite systems used by the DOD. This arrangement has undergone further change again as a result of the 2001 Space Commission Study.
As the importance of space systems increased, space and missile functions were separated in April 1961, when AFBMD was inactivated and replaced by the Ballistic Systems Division (BSD) and the Space Systems Division (SSD). In July 1967, the space and missile functions were reconsolidated to save money in the Space and Missile Systems Organization (SAMSO). Space and missile functions were separated again in October 1979, when SAMSO was divided into the Space Division and the Ballistic Missile Office. In March 1989, SD and BMO were renamed Space Systems Division (SSD) and Ballistic Systems Division (BSD). Due to the end of the Cold War and the subsequent demise of the Soviet Union, there was a significant decrease in mission programs. Consequently, BSD (which again was renamed the Ballistic Missile Organization) was realigned under SSD. Finally, in July 1992, SSD was renamed the Space and Missile Systems Center (SMC), and BMO was formally inactivated in September 1993; thus space and missile development went full circle in four decades back to a single organization responsible for both space and missile programs (14).
As the organizational structure of SMC has changed, so has the structure of its field units. Beginning in the 1950s, SMC’s predecessors acquired units that controlled DOD satellites in orbit, conducted satellite and R&D missile launches, and operated the launch ranges on the East and West Coasts. The satellite control function was originally performed by the 6594th Test Group, created in 1959, and later performed by the Air Force Satellite Control Facility, which replaced the Test Group in 1965. Test wings at both Vandenberg AFB, California, and Cape Canaveral AFS, Florida, performed launch activities. Then, to reduce costs, President Carter directed that the eastern and western launch ranges be redes-ignated the Eastern and Western Space and Missile Centers (ESMC and WSMC) under the control of the Space and Missile Test Organization (SAMTO), created in 1979. When the Air Force Space Command (AFSPC) was created, responsibility for operational command of military space systems passed from the test and development community to an operational organization. This resulted in the dissolution of SAMTO, and responsibility for the ESMC and WSMC was transferred to the new operational command. Even though the responsibility for space launch and on-orbit satellite operations diminished, SMC remains an important part of the development and acquisition of all military space systems. This importance was recently restated when the 2001 Space Commission Study recommended the transfer of SMC from the Air Force’s Material Command to the Air Force Space Command (6).


National Reconnaissance Office (NRO)

In the late 1950s, considerable creative turmoil occurred in the organization of U.S. national security space programs. As a result of this turmoil, late in 1960, the Department of Defense created the National Reconnaissance Office (NRO) to work satellite reconnaissance programs. Although nominally attached to the Air Force, usually through its Director holding a senior Air Force civilian position (e.g., Undersecretary of the Air Force), the NRO is part of the intelligence community and not under direct control of the Air Force and its leadership.
In 1994, the NRO’s existence, as well as details and data from the initial CORONA program, were declassified. The NRO continues to develop and operate the nation’s reconnaissance satellites, still under classified conditions and largely separate from other national security systems.

Missions

Today’s military use of space is divided into four main areas: (1) space force enhancement—the use of space capabilities to support terrestrial land, maritime, and air operations; (2) space operations—the necessary capabilities and systems to launch, operate, and, if necessary, deorbit military space systems; (3) space control—systems and functions to obtain space situational awareness (space surveillance), protect friendly use of space assets, deny enemy use of these assets and if, necessary, negate hostile space systems and capabilities; and (4) space force application—using systems that fly through space (ICBMs) or operate in space (in the future such systems as the Space-Based Laser, or SBL, under development by the USAF) to deliver lethal force to land, maritime, or air targets. For the purpose of this article, ground operations centers are considered part of the second function, space operations. But these centers support space force enhancement and space control. Organizationally, these operations centers may be further divided into those for early warning of missile attack; those for ”tactical” space force enhancements systems such as the communications, navigation, intelligence and reconnaissance, and weather; and finally, those for the space surveillance portion of space control.
Space Force Enhancement: Missile Warning. The current missile warning system—the Defense Support Program (DSP) and its follow-on, the Space-Based InfraRed System (SBIRS), grew out of one of the three original 1959 satellite programs of the Air Force’s Western Development Division’s Military Satellite System—the Missile Detection Alarm System (MIDAS). MIDAS was aimed at developing a satellite that would carry an infrared sensor to detect hostile ICBM launches. After an initial failure, the first MIDAS satellite was successfully launched in May 1960 (14). The current Defense Support Program (DSP) began operations in the early 1970s. It consists of a number of (DSP) satellites in geosynchronous Earth orbit (GEO), ground operations centers, and missile warning centers. DSP provides a critical part of current ”dual phenomenology” requirements to provide at least two unambiguous, independent ways to assess an attack against North America (Fig. 2). The other means are NORAD’s ground-based early warning radars.
DSP is operated a little differently from other U.S. military satellite systems in that its satellite bus operation can be completely separate from the sensor mission operations. The 50th Space Wing’s 1st Satellite Operations Squadron at Schriever Air Force Base, Colorado, can perform the former command and control support. This function uses the Air Force Satellite Control Network (AFSCN) for transmitting command and control information and is essentially global. The latter, which can include both satellite operations and warning sensor functions, is done through dedicated operations centers and antennae. The primary site for this function is the 21st Space Wing’s 2nd Satellite Warning Squadron at Buckley Air National Guard Base, near Denver, Colorado. Routine operations use the dedicated systems. But when a satellite is in critical stages of operations or maneuvers, the more flexible, global, AFSCN system is used.
The Air Force Space Command-operated Defense Support Program (DSP) satellites are a key part of North America's early warning systems. Figure courtesy USAF Space Command. Picture can be found at http://www.peterson.af.mil/hqafspc/library/ FactSheets/FactSheets.asp?FactChoice — 6. This figure is available in full color at http:// www.mrw.interscience.wiley.com/esst.
Figure 2. The Air Force Space Command-operated Defense Support Program (DSP) satellites are a key part of North America’s early warning systems. Figure courtesy USAF Space Command.
The missile warning system is undergoing a major upgrade, which will enable much better missile warning, as well as make a comprehensive theater and national missile defense feasible. The Space Based Infrared System (SBIRS) is a planned constellation of high- and low-altitude satellites that has a consolidated, common ground system built to meet U.S. surveillance needs through the next two to three decades. SBIRS, which will replace the 29-year-old DSP system, is designed to support multiple missions, including missile warning and detection, missile defense, technical intelligence, and battle space characterization. The system includes two major components, SBIRS High and Low (Fig. 3).
SBIRS High, scheduled for initial deployment in 2004, will employ satellites in geosynchronous orbit as well as hosted payloads in highly elliptical orbits. The SBIRS consolidated ground system will be developed in three increments phased to support DSP continental U.S. processing consolidation and the SBIRS High and SBIRS Low constellation deployments. The SBIRS Mission Control Station is located in a new facility located at Buckley Air National Guard Base in Colorado.
The SBIRS Low constellation of low-altitude satellites, which will perform midcourse tracking, is planned for initial deployment in 2006. At this point, SBIRS Low is planned as a primary part of comprehensive missile defense. However, its detailed ground facilities and operations have not yet been set.
The Space-Based Infrared System (SBIRS) program will provide the nation with critical missile defense and warning capability well into the twenty-first century. Figure courtesy USAF Space and Missile Systems Center. Picture can be found at http:// www.losangeles.af.mil/SMC/PA/Fact_Sheets/SBIRS.htm. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 3. The Space-Based Infrared System (SBIRS) program will provide the nation with critical missile defense and warning capability well into the twenty-first century. Figure courtesy USAF Space and Missile Systems Center.
Missile warning functional operations—into which DSP and missile warning radars and in the future SBIRS will feed, are the responsibility of the United States Space Command and NORAD. The heart of these operations is in the Cheyenne Mountain Operations Center, Colorado Springs, Colorado. The Center collects data from a worldwide system of satellites, radars, and other sensors and processes that information to support critical NORAD and U.S. Space Command missions. For the NORAD mission, the Cheyenne Mountain Operations Center provides warning of ballistic missile or air attacks against North America, assists the air sovereignty mission for the United States and Canada, and, if necessary, is the focal point for air defense operations to counter enemy bombers or cruise missiles. In support of the U.S. Space Command mission, the Cheyenne Mountain Operations Center provides a day-to-day picture of precisely what is in space and where it is located. The Cheyenne Mountain Operations Center also supports space operations, providing critical information such as collision avoidance data for Space Shuttle flights and troubleshooting satellite interference problems.
Cheyenne Mountain Operations Center (CMOC). Cheyenne Mountain operations are conducted by six centers staffed 24 hours a day, 365 days a year. The centers are the Command Center, the Air Defense Operations Center, the Missile Warning Center, the Space Control Center, the Combined Intelligence Watch Center, and the Systems Center (Fig. 4).
The Command Center is the heart of operations in Cheyenne Mountain. In this center, the Command Director and his crew serve as the NORAD and U.S. Space Command Commander in Chief’s direct representative for monitoring, processing, and interpreting missile, space, or air events that could have operational impacts on our forces or capabilities or could be potential threats to North America or U.S. and allied forces overseas. The Command Center is linked directly to the National Command Authorities of both the United States and
The Cheyenne Mountain Combat Operations Center (COC) is protected by a series of massive steel doors embedded in reinforced concrete located in a tunnel more than a thousand feet underground. Figure courtesy Cheyenne Mountain Operations Center. Picture can be found at http://www.cheyennemountain.af.mil. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 4. The Cheyenne Mountain Combat Operations Center (COC) is protected by a series of massive steel doors embedded in reinforced concrete located in a tunnel more than a thousand feet underground. Figure courtesy Cheyenne Mountain Operations Center.
Canada as well as to regional command centers. When required, the Command Director must consult directly with the NORAD and U.S. Space Command Commander in Chief for time-critical assessments of missile, air, and space events to ensure that the Commander in Chief’s response and direction are properly conveyed and executed.
The CMOC comprises the largest and most complex command and control network in the world. The system uses satellites, microwave radio routes, and fiber optic links to transmit and receive vital communications. Two blast-hardened microwave antennae and two underground coaxial cables transmit the bulk of electronic information. Most of this information is data sent from the worldwide space surveillance and warning network directly to computers inside the Mountain. Redundant and survivable communications hot lines connect the Command Center to the Pentagon, White House, U.S. Strategic Command, Canadian Forces Headquarters in Ottawa, other aerospace defense system command posts, and major military centers around the world.
With respect to space operations and systems, the primary user of space-based warning data is the Missile Warning Center. It uses a worldwide sensor and communications network to provide warning of missile attacks, either long or short range, launched against North America or North American forces overseas. The Missile Warning Center is divided into ”strategic” and ”theater” sections. The strategic section focuses on information regarding missile launches anywhere on Earth that are detected by the strategic missile warning system and could be a potential threat to Canada or the United States. The theater section focuses on short-range missile launches processed by a Theater Event System that monitors missile launches in areas or theaters that could threaten U.S./allied forces, such as when Iraqi SCUD missiles threatened coalition troops in Operation Desert Storm. Cheyenne Mountain’s capabilities to provide timely and accurate warning and cueing for defensive systems such as the Patriot batteries have improved considerably since Desert Storm and continue to improve as new computer and communications systems are added to the Cheyenne Mountain Operations Center (15).
Another key user and driver for space-based data is the Space Control Center. Its detailed functions are to be discussed later. It supports the space control missions of space surveillance and protection of our assets in space. This center was formed in March 1994 through the combination of the Space Surveillance Center and Space Defensive Operations Center. The Space Control Center’s primary objective in performing the surveillance mission is to detect, track, identify, and catalog all man-made objects in space. The Center maintains a current computerized catalog of all orbiting space objects, charts objects, charts present positions, plots future orbital paths, and forecasts times and general locations for significant objects reentering Earth’s atmosphere. Since 1957, more than 24,000 space objects have been cataloged; many of them have since reentered the atmosphere. Currently, there are about 8000 on-orbit objects being tracked by the Space Control Center. The Center’s protection mission is accomplished by compiling information on possible hostile threats that could directly or indirectly threaten U.S./allied space assets. This information is then analyzed to determine the effects/impacts of these threats to our assets in space, so that timely warning and countermeasure recommendations can be made. A good example of this mission is our constant protection of the Space Shuttle while in orbit, by providing collision avoidance information to NASA (15). Combined Intelligence Watch Center. There are more than 1100 military and civilian personnel working in the Mountain. Although Cheyenne Mountain would probably not survive a direct hit from today’s accurate and high-yield nuclear weapons, it could survive a lower yield nuclear and conventional weapons impact. It is also well protected against other actions such as sabotage and terrorism. It is self-sustaining, capable of providing its own power, water, air, and food for up to 800 people for 30 days.
Space Force Enhancement: Meteorological Satellites. The Defense Meteorological Satellite Program (DMSP) was originally the DOD weather observation system. It is currently composed of two satellites placed in Sun-synchronous orbits 450 nautical miles above Earth. The Air Force’s Space Systems Division began developing weather satellites and associated ground stations and terminals during the 1960s (16). The existence of a military weather system was classified secret until 1973. Since that time, all elements of the system have been upgraded several times: the current system is the military’s sixth generation. As for many other initially classified systems, DMSP developed its ground and space operations system as a ”stovepipe,” largely separate from other satellite systems (Fig. 5).
Currently, DMSP Block 5D-2 satellites provide cloud imaging over Earth’s surface during both day and night. The satellite also carries a number of additional weather and space environment (”space weather”) sensors. The visible and infrared sensors collect images of global cloud distribution across a 3000-km swath during both daytime and nighttime conditions. The microwave imager and sounders (SSMIS) are capable of recording ocean wind speed, ice age and density,water content in soils, and other scientifically useful data. The SSMIS covers only half the swath width of the infrared and visible sensors. This coverage limitation results in full coverage of Earth’s polar regions above 60°, twice daily, and the equatorial region, daily. The space environmental sensors record along-track plasma densities, velocities, composition, and drifts.
The Defense Meteorological Satellite Program (DMSP) has been collecting weather data for U.S. military operations for almost four decades. At all times, two operational DMSP satellites are in polar orbit at about 458 nautical miles (nominal). The primary weather sensor on DMSP is the Operational Linescan System which provides continuous visual and infrared imagery of cloud cover over an area 1600 nautical miles wide. Figure courtesy USAF Space Command. Picture can be found at http://www. peterson.af.mil/hqafspc/Library/FactSheets/FactSheets.asp?FactChoice — 4. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 5. The Defense Meteorological Satellite Program (DMSP) has been collecting weather data for U.S. military operations for almost four decades. At all times, two operational DMSP satellites are in polar orbit at about 458 nautical miles (nominal). The primary weather sensor on DMSP is the Operational Linescan System which provides continuous visual and infrared imagery of cloud cover over an area 1600 nautical miles wide.
The Block 5-D system was originally operated as part of the Air Force’s 50th Space Wing as the 6th Space Operations Squadron at Offutt Air Force Base, Nebraska; satellite control stations are situated at Loring Air Force Base, Maine, and Fairchild AFB, Washington. DMSP could also be operated through the AFSCN for early-orbit checkout and satellite emergencies. However, as part of civilian and military meteorological satellite consolidation begun in 1994, DMSP is now operated through the National Oceanic and Atmospheric Administration’s (NOAA) Suitland, Maryland, operations center, and the Loring, Maine, uplink-downlink site is closed.
The DMSP spacecraft operates in two modes. It can directly downlink data to tactical terminals ( IV Series Transportable Terminals, AN/SMQ-11 Shipboard Receiving Terminals, and Rapid Deployment Information Tactical Terminals—RDITs). The Tactical Terminals receive DMSP mission data in real time. Alternatively, data may be stored on board the satellite on tape recorders for ”store and forward” downlink primarily to the Fairchild ground station and retransmission to users including Air Force Global Weather Central (AFGWC) and the Navy Fleet Numerical Meteorological Oceanography Center (FNMOC).
AFGWC, located at Offutt Air Force Base in Omaha, Nebraska, is the primary strategic user and distributor of DMSP satellite data destined for the Air Force and Army. FNMOC, located at Monterey, California, distributes DMSP data to the Navy and Marine Corps. Although neither AFGWC nor FNOC are DMSP agencies, both receive and process DMSP data in combination with meteorological, solar-geophysical, and oceanographic observations from other sources. They disseminate such environmental information in various forms to the DOD and other governmental agencies, as required.
A 1994 U.S. White House decision mandated convergence of DMSP with NOAA’s Polar-Orbiting Operational Environmental Satellite (POES) program. The goal of the converged program is to reduce the cost of acquiring and operating polar orbiting operational environmental satellites, while continuing to satisfy U.S. military, civil, and national security requirements. As part of this goal, the converged program will incorporate appropriate aspects of both DMSP and NASA’s Earth Observing System. The converged system on-orbit architecture will consist of three low Earth orbiting satellites versus the current four satellites (two civilian and two military). The orbits of the three satellites will be evenly spaced throughout the day to provide timely data refresh. The nominal equatorial crossing times of the satellites will be 5:30, 9:30, and 1:30 (17). Space Force Enhancement: Navigation. The U.S. Navigation mission is executed by the Global Positioning System (GPS). This program, due to its status as an essential ”global utility,” is arguably the military’s most significant space program. GPS grew out of two predecessors—an Air Force technology program started in the late 1960s, 621B, and a parallel U.S. Naval Research Laboratory program called Timation (16). 621B proposed a constellation of about 20 inclined geosynchronous satellites, and Timation suggested a constellation of 21 to 27 satellites in a medium altitude Earth orbit (MEO). Elements of both programs were combined in 1973 to create the initial GPS concept. This initial concept would employ the signal structure and frequencies of 621B and the MEO orbits of the Timation proposal (Fig. 6).
The GPS program began in 1973, and it was acquired in three phases— validation, development, and production. Ironically, the USAF was a reluctant program manager and had to be repeatedly forced to proceed with system development. 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, and Block II satellites were tested and began deployment. In addition, an operational control segment was activated under the Air Force Space Command’s 50th Space Wing at Falcon (now Schriever) Air Force Base, Colorado (18). During the production phase, a full constellation of 24 Block II and IIA satellites was deployed, and user equipment was produced and put into the field. The full constellation of Block II and IIA satellites completed in March 1994 allowed the system to attain full operational capability in April 1995.
The CONTROL segment is comprised of five monitor stations located in Hawaii, Kwajalein, Ascension Island, Diego Garcia, and Colorado Springs, three ground antennae located at Ascension Island, Diego Garcia, and Kwajalein), and a master control station (MCS) located at Schriever AFB in Colorado. All monitor stations except Hawaii and Colorado (Schriever) are equipped with ground antennae for communications with the GPS satellites. The monitor stations passively track all GPS satellites in view and collect ranging data from each satellite. This information is passed on to the MCS where the satellite orbital parameter data (ephemeris) and clock parameters are estimated and predicted. The MCS periodically uploads the updated ephemeris and clock data to each satellite for retransmission in the navigation. The USER segment consists of antennae and receiver-processors that provide positioning, velocity, and precise timing to the user.
The Navstar Global Positioning System (GPS) is a constellation of orbiting satellites that provides navigational data to military and civilian users all over the world. The system is operated and controlled by members of the 50th Space Wing, located at Schriever AFB, Colorado. Figure courtesy USAF Space Command. Picture can be found at http://www.peterson.af.mil/hqafspc/Library/FactSheets/FactSheets.asp7FactChoice — 9. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 6. The Navstar Global Positioning System (GPS) is a constellation of orbiting satellites that provides navigational data to military and civilian users all over the world. The system is operated and controlled by members of the 50th Space Wing, located at Schriever AFB, Colorado. Figure courtesy USAF Space Command.
The GPS system’s importance to global commercial and civil uses was recognized during the 1990s. GPS provides precise positions for military, civil, and commercial purposes worldwide, but it may be even more important as the ”global clock.” As a means of ”time-transfer,” users everywhere rely on GPS to time everything precisely, from communications circuits to bank transactions, to within a few billionths of a second. To see how important this is, consider what happened when a real error occurred in 1996. A satellite controller at the Air Force’s GPS control center accidentally put a bad time into just one of GPS’s 24 satellites. The bad time was broadcast for only six seconds before automatic systems detected it and shut the satellite signal down. Nonetheless, more than 100 of the 800-plus cellular telephone networks on the U.S. East Coast—which rely on precise GPS-provided timing to work—failed. Some took hours and even days to recover. GPS directly produces several tens of billions of dollar revenue for the United States yearly—indirectly it produces many times this amount.
In recognition of the criticality of GPS as a global utility, the U.S. government has implemented a number of important upgrades and initiatives following a March 1996 White House decision. In 1999, the United States decided to remove the deliberate signal degradation (”Selective Availability”), which limited nongovernmental users to considerably worse signal performance. In addition, the U.S. Department of Defense has officially taken on modernization of the GPS system to provide additional precise signals for civil and commercial users in the second ”military” frequency and to provide a third civil frequency. Moreover, military users will now have a separate, more protected signal structure within the two original GPS bands. These upgrades are to be implemented on 12 of the current block of GPS IIR satellites and future IIF. Finally, a new GPS system development, GPS III will launch late in the decade to provide greatly improved signal structure and strength. In recognition of the importance of the timing function, the U.S. Naval Observatory has placed an alternate master clock time standard at Schriever Air Force Base, and the GPS program is building a protected alternate master control station at Vandenberg Air Force Base, California. Space Force Enhancement: Communications. Communications support is one of the most long-standing and critical systems supporting war fighters from and through space. Despite the rapid growth in fiber-based communications, military support is usually required in locations where ground-based fiber links are unavailable or have been cut. Thus, military satellite communications systems (MILSATCOM) remain the heart of national security communications networks.
Before delving into individual system operating concepts, it is necessary to understand the overarching DOD approach to communications. The top-level architecture is contained in the U.S. Department of Defense Information Systems Network (DISN), which is the responsibility of the Defense Information Systems Agency (DISA), part of the Office of the Secretary of Defense. DISN prescribes a global network integrating Defense Communications System assets,
MILSATCOM, Commercial SATCOM initiatives (which now include the troubled IRIDIUM system), leased telecommunications systems, dedicated DOD Service and Defense Agency networks, and mobile/deployed networks, such as the consolidated worldwide enterprise level telecommunications infrastructure, for example, that provides the end-to-end information transfer component of what’s known as the ”Defense Information Infrastructure” (DII) (19). The DISN provides rapid information access ”to allow any warrior to perform any mission, anytime, any place in the world, based on information needs” (19). DISA provides top-level policy and architecture support and is the primary route for providing commercial communications support to war fighters. Conversely, MILSATCOM operation and support, subject to DISA policy guidance, is provided through the United States Space Command and its components.
Various satellite communications systems have been developed. The first of these, the Initial Communications Satellite Program (IDCSP), began in 1962. It consisted of small, 100-pound satellites launched in clusters. A total of 26 such satellites were placed in orbit between June 1966 and June 1968 (16). It was superseded by the more sophisticated Defense Satellite Communications System, Phase II (DSCS II). The first two DSCS II satellites were put into GEO orbit in November 1973, and a total of 16 were built and launched during the life of the program; the final launch was in 1989. DSCS II and its successor DSCS III use super-high-frequency (SHF) transponders.
The U.S. Air Force began launching DSCS III satellites in 1982. DSCS III has more flexible coverage than DSCS II and provides increased power, which can be tailored to suit the needs of different site user terminals. There is an expected economic payoff from the operation of the DSCS III satellites; they are expected to have a useful lifetime twice that of the DSCS II satellites. DSCS III can also be used to disseminate emergency action and force direction messages to nuclear capable forces. The system can provide worldwide secure voice and high data rate communications. The system is also designed to resist jamming (20).
As in many other military systems, DSCS III separates satellite system (bus) operations from payload operations. Air Force Space Command units operate the DSCS bus, the 50th Space Wing’s 3rd Space Operations Squadron at Schriever Air Force Base, Colorado, and the 5th Space Operations Squadron at Onizuka Air Force Base, California. Conversely, the payloads are operated by Army Space Command crews at the major communications uplink and downlink sites in the United States and overseas. Allocation of communications channels shifted in 1998 from the Joint Staff in the Pentagon to the United States Space Command’s Space Operations Center (SPOC) at Peterson AFB, Colorado.
The U.S. Navy has also invested heavily in space-based communications systems. During the 1960s, the military saw the need to transmit data to much smaller terminals than those required by the DSCS VHF system. In February 1969, Lincoln Laboratory’s Tactical Communications Satellite (TACSAT I) was launched and proved the feasibility of communications with small tactical terminals in the UHF band. This paved the way for the Navy’s Fleet Satellite Communications System (FLTSATCOM). The U.S. Navy conducted overall management, and the Air Force managed the system acquisition. Between February 1978 and September 1989, eight FLTSATCOMs were built and launched. However, only six became fully operational in orbit. The Navy supplemented its FLTSATCOM system during this period and the 1990s with leased commercial UHF satellite services (16).
The Navy began replacing its UHF satellite constellation during the early 1990s with a constellation of customized Hughes 601 spacecraft known as the UHF-Follow-On (UFO) satellites (Fig. 7). So, yes, the U.S. DOD does have a not-so-secret fleet of UFOs! These satellites were purchased in a novel ”services in orbit” contract that needed minimal government oversight. Nine UFO satellites were successfully launched from 1993-1999.
In March 1996, the U.S. Navy ordered a high-speed, high-power global broadcast system (GBS) to be added to its future UFO satellites. This GBS package provides the military equivalent of ”direct broadcast TV.” It is revolutionizing the dissemination of high-capacity data ranging from intelligence imagery to ”quality-of-life” television for forward-deployed forces (21).
 The first UHF F/O was launched 25 March 1993. The Atlas II rocket booster malfunctioned, placing the spacecraft in a dangerously low orbit after efforts by the 3rd Space Operations Squadron, Schriever AFB, Colorado. Each UFO satellite will possess 39 UHF communications channels (a 70% increase over Fleet Satellites). Figure courtesy USAF Space and Missile Systems Center. Picture can be found at http://www.au.af.mil/ au/awc/awcgate/usspc-fs/space.htm. This figure is available in full color at http://www. mrw.interscience.wiley.com/esst.
Figure 7. The first UHF F/O was launched 25 March 1993. The Atlas II rocket booster malfunctioned, placing the spacecraft in a dangerously low orbit after efforts by the 3rd Space Operations Squadron, Schriever AFB, Colorado. Each UFO satellite will possess 39 UHF communications channels (a 70% increase over Fleet Satellites).
The FLTSATCOM systems, as well as the UFO satellites, were originally operated by the Air Force Space Command in concert with other military communications systems. However, in 1999, the eight on-orbit UFO satellites were transferred from the Air Force to the Naval Space Command’s Naval Satellite Operations Center (NAVSOC) in Dahlgren, Virginia. Also in 1999, the Chief of Naval Operations transferred control of the Navy’s commercial satellite services from its research and development command, the Space and Naval Warfare Systems Command, to the Naval Space Command (22).
NAVSOC provides ”one-stop shopping” for operational satellite intelligence and communications to deployed U.S. Navy and Marine forces worldwide. In addition, the Navy maintains its own space surveillance capability and sensors as part of the Naval Space Command and its support to the United States Space Command.
To provide additional tactical communications support, the U.S. Department of Defense agreed in late 1999 to continue commercial operations of the troubled Iridium, low Earth orbit network of 70-plus linked communications satellites. In this sense, the U.S. military became an anchor-tenant for the global handheld communications system, which was unable to compete successfully with the burgeoning fiber-optic and cellular services available worldwide. However, the U.S. military’s unique requirements for communications in remote, particularly Arctic areas, make this a cost-effective approach to maintaining secure connectivity to deployed forces.
In addition to the long-haul DSCS and commercial satellite users and tactical users of FLTSATCOM and the UFO, there is a third group of users—nuclear-capable forces. These users require extremely high reliability and only very low data rates, as well as very high survivability. Initially, the Air Force provided this capability through its Air Force Satellite Communications System (AFSATCOM). It is carried as an additional payload on FLTSATCOM and other DOD spacecraft. It became operational with both user terminals and satellites in the late 1970s.
Replacement of AFSATCOM began in 1994 with the successful launch and checkout of the first MILSTAR I satellite. MILSTAR is a worldwide, survivable, highly jam-resistant communications satellite system that enables the U.S. President and his Secretary of Defense to communicate with tactical and strategic nuclear forces (Fig. 8). MILSTAR II was initiated in 1993; it will provide protected, medium data rate, secure communications capabilities. To date a total of five spacecraft have been launched and are operational. The last of them was launched on 15 January 2002. A launch of the seventh MILSTAR satellite is scheduled for 4 November 2002. If successful, this will make a constellation with a total of six MILSTAR spacecraft in orbit (23).
MILSTAR is another program operated independently of other satellite systems. It includes both tactical terminals and a central dedicated control capability at Schriever AFB, Colorado, under the 50th Space Wing’s 4th Space Operations Squadron. A reserve satellite operations squadron at Vandenberg AFB, California, provides backup master control.
Space-Based Reconnaissance. Intelligence uses of space are the responsibility of the National Reconnaissance Office (NRO) as discussed before. The details of these satellite’s operations and facilities remain classified. However,most of them use dedicated, system-specific command and control and data distribution systems and sites.
Milstar is a joint service satellite communications system that provides secure, jam-resistant, worldwide communications to meet essential wartime requirements for high priority military users. The multisatellite constellation will link command authorities with a wide variety of resources, including ships, submarines, aircraft, and ground stations. Figure courtesy USAF Space Command. Picture can be found at http://www.peter-son.af.mil/hqafspc/Library/FactSheets/FactSheets.asp?FactChoice — 14. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 8. Milstar is a joint service satellite communications system that provides secure, jam-resistant, worldwide communications to meet essential wartime requirements for high priority military users. The multisatellite constellation will link command authorities with a wide variety of resources, including ships, submarines, aircraft, and ground stations. Figure courtesy USAF Space Command.
Space Operations. The second major military space function includes all of those efforts and facilities needed to launch military systems into space, control them while in orbit, deorbit or decommission them when their missions are complete, and distribute mission data. For this discussion, we will focus on the second part of these activities—operating satellites in orbit. As discussed previously, U.S. military satellite operations are a combination of system-specific dedicated command and control systems and use of the DOD-wide common satellite control network known as the Air Force Satellite Control Network (AFSCN).
The AFSCN tracks DOD satellites, receives and processes telemetry and in some cases data transmitted by them, and sends commands to them. At its peak in the mid-1990s, the AFSCN consisted of two control nodes, two scheduling facilities (one at each node), nine remote tracking sites, and communications links connecting them. As we enter a new century, the scheduling and control node at Onizuka AFB, California, is being phased out, and all activities are to be concentrated at Schriever AFB, Colorado, under the command of the Air Force Space Command’s 50th Space Wing. One of the remote tracking sites, at the Seychelles, Indian Ocean, was also shut down in the late 1990s.
The common user element of the AFSCN was originally activated to support the Discoverer program of the late 1950s and early 1960s. An interim satellite control facility was initially established in Palo Alto, California, in January 1959.
By June 1960, a permanent control center had been established in Sunnyvale, California. It was originally named the Satellite Test Annex. Since then, it has been renamed numerous times, and finally, it is called the Onizuka Air Force base in honor of Air Force astronaut Ellison Onizuka killed in the 1986 Challenger Space Shuttle explosion. It was generally known as the ”Blue Cube” because it was very visible from nearby freeways as a large, blue-painted, windowless building. Tracking facilities were established at nine different locations between 1959 and 1961 to complement the Sunnyvale control center (16).
Due in large part to the Sunnyvale facility’s location near major public thoroughfares and its unfortunate placement near three active fault lines, concern grew during the 1970s about its vulnerability as a single node failure point. Thus, a second control center was added—the Consolidated Space Operations Center (CSOC) located in what is now known as Schriever AFB. The Secretary of Defense authorized CSOC in 1979. Originally, it was to consist of two parts—a satellite operations complex (SOC) for on-orbit satellite control and a Shuttle Operations Planning Center (SOPC) for planning and controlling DOD Space Shuttle missions. However, after the Challenger accident and cancellation of DOD Space Shuttle use, the SOPC was itself canceled in 1987. The CSOC began operations in 1989 and was turned over to the Air Force Space Command after initial operational test and evaluation in 1993. The Onizuka site is in the process of being phased out, and most of its functions are now transferred to an enlarged facility at Schriever AFB. In the late 1990s, the U.S. Navy’s independent satellite control facilities were merged with the AFSCN, which now serves as the DOD’s sole common user satellite control network.
The AFSCN remains an impressive capability. However, despite continued upgrades for improved automation and reliability, it remains a manpower-intensive system requiring more than 1000 contractor and government people to maintain and operate it.
The biggest challenge facing the AFSCN today is in satellite control frequencies. The AFSCN uses a U.S. military-unique frequency structure called the Space-Ground Link System or SGLS. This frequency structure was designed in the 1950s to provide a robust, jam-resistant uplink and downlink capability. It uses 20 separate channels for uplink between 1.75 and 1.85 GHZ. Similarly, SGLS uses 20 downlink channels around 2.3 GHZ. However, as pressure grows on the overall frequency spectrum and because the U.S. military does not have global assignment of these frequencies, it is faced with an increasingly urgent necessity to transition to other satellite control frequencies or approaches. For the long-term, space-to-space options similar to those used in NASA’s Tracking and Data Relay Satellite System (TDRSS) appear most desirable. For the interim, the U.S. military is considering transiting to the Unified S-band system used by NASA.
Space Control and Satellite Tracking. Space control is the third major U.S. military mission area. It consists of four elements: (1) space surveillance to provide critical space situational awareness; (2) protection methods to ensure that U.S., allied and commercial systems vital to U.S. national security operations are not interfered with; (3) preventive means to ensure that adversaries do not use U.S. systems such as the GPS to assist in their military operations, and finally; (4) negation means to deny adversaries use of their own space systems for aggression. Currently, almost all U.S. work focuses on the surveillance and protection aspects of space control.
The United States Space Command holds overall responsibility for space control operations. Central to this function is the Space Control Center (SCC) in Cheyenne Mountain, Colorado. Its primary function is to maintain tracking data on all objects in orbit and to determine if threats exist to national security space operations. The SCC is manned jointly by U.S. Space Command personnel who maintain overall responsibility for identifying threats to U.S. and allied space systems and Air Force Space Command’s 21st Space Wing 1st Command and Control Squadron that provides tasking to the Space Surveillance Network’s sensors. The U.S. Navy Space Command operates the Alternate Space Control Center in Dahlgren, Virginia.
Space Control and Satellite Tracking—The Space Surveillance Network.
Space surveillance involves detecting, tracking, cataloging, and identifying man-made objects orbiting Earth. These objects include active/inactive satellites, spent rocket bodies, or fragmentation debris. Space surveillance accomplishes the following:
- predicts when and where a decaying space object will reenter Earth’s atmosphere;
- prevents a returning space object, which to radar looks like a missile, from triggering a false alarm in missile-attack warning sensors of the U.S. and other countries;
- charts the present position of space objects and plots their anticipated orbital paths;
- detects new man-made objects in space;
- produces a running catalog of man-made space objects;
- determines which country owns a reentering space object;
- informs NASA whether or not objects may interfere with the Space Shuttle and International Space Station.
The command accomplishes these tasks through its Space Surveillance Network (SSN) of U.S. Army, Navy, and Air Force operated ground-based radars and optical sensors at 25 sites worldwide (Fig. 9).
The SSN has been tracking space objects since 1957 when the Soviets opened the Space Age by launching Sputnik I. Since then, the SSN has tracked more than 24,500 space objects orbiting Earth; two thirds of these have reentered Earth’s atmosphere and disintegrated or impacted Earth (24). SSN Sensors. Due to network capacity limitations (number of sensors, location, availability), the SSN uses a ”predictive” technique to monitor space objects, that is, it spot-checks them rather than tracking them continually. Following is a brief description of each type of sensor.
Phased-array radars can maintain tracks on multiple satellites simultaneously and scan large areas of space in a fraction of a second. These radars have no moving mechanical parts to limit the speed of the radar scan—the radar energy is steered electronically (Fig. 10).
 The Space Surveillance Network is a worldwide network of ground- and space-based sensors that has radar and ground stations located on every continent. Figure courtesy USAF Air University. Picture can be found at http://www.au.af.mil/au/ awc/awcgate/usspc-fs/space.htm. This figure is available in full color at http://www.mrw. interscience.wiley.com/esst.
Figure 9. The Space Surveillance Network is a worldwide network of ground- and space-based sensors that has radar and ground stations located on every continent. Figure courtesy USAF Air University.
Conventional radars use immobile detection and tracking antennae. The detection antenna transmits radar energy into space in the shape of a large fan. When a satellite intersects the fan, the energy is reflected back to the antenna, triggering the tracking antenna. The tracking antenna, then, locks its narrow beam of energy on the target and follows it to establish orbital data (Fig. 11).
The Ground-Based Electro-Optical Deep Space Surveillance System (GEODSS) consists of three telescope sensors linked to a video camera (Fig. 12). The video cameras feed their space pictures into a nearby computer, which drives a display scope. The image is transposed into electrical impulses and recorded on magnetic tape. This is the same process used by video cameras. Thus, the image can be recorded and analyzed in real time (24).
In 1998, the Air Force Space Command began using the missile defense experimental spacecraft “MSX” to explore the use of space-based space surveillance sensors. This has been a very successful experiment in detecting and tracking geosynchronous (GEO) orbiting satellites. Since its initial use, the MSX sensor has succeeded in lowering the number of “lost” satellites in GEO by more than a factor of 2.
Combined, these sensors make up to 80,000 satellite observations each day. This enormous amount of data comes from SSN sites in Maui, Hawaii; Eglin, Florida; Thule, Greenland; and Diego Garcia, Indian Ocean. The data is transmitted directly to the SCC via satellite, ground wire, microwave, and telephone. All available methods of communication are used to ensure that a backup is readily available, if necessary.
The Space Surveillance Network is composed in part of ground-based radars, like this precision acquisition vehicle entry and phased array warning system (PAVE PAWS), which detects and tracks sea-launched and intercontinental ballistic missiles. Their secondary mission is to track objects in space. Figure courtesy USAF Space Command. Picture can be found at http://www.peterson.af.mil/hqafspc/library/FactSheets/ FactSheets.asp?FactChoice —15. This figure is available in full color at http://www.mrw. interscience.wiley.com/esst.
Figure 10. The Space Surveillance Network is composed in part of ground-based radars, like this precision acquisition vehicle entry and phased array warning system (PAVE PAWS), which detects and tracks sea-launched and intercontinental ballistic missiles. Their secondary mission is to track objects in space.
Space Control Center (SCC). The SCC in Cheyenne Mountain Air Station is the terminus for the SSN’s abundant flow of information. The SCC houses large, powerful computers to process SSN information and accomplish the space surveillance and space control missions.
The NAVSPACECOM provides the site and personnel for the Alternate SCC (ASCC). The ASCC would take over all operations in the event the SCC could not function. This backup capability is exercised frequently.
Orbital Space Debris. USSPACECOM tracks about 8000 man-made space objects, baseball-size and larger, that orbit Earth. The space objects consist of active/inactive satellites, spent rocket bodies, or fragmentation. About 7% are operational satellites, 15% are rocket bodies, and about 78% are fragmented and inactive satellites; the rest are debris. USSPACECOM is primarily interested in the active satellites but also tracks space debris. The SSN tracks space objects, which are as small as 10 cm in diameter (baseball size) or larger.
PIKE, a Remote Tracking Station at Schriever AFB, Colorado, looks like a giant golf ball to casual observers. PIKE is operated by the 22nd Space Operations Squadron. Figure courtesy USAF Space Command. Picture can be found at http:// www.peterson.af.mil/hqafspc/Library/almanac/pg12/almanac_12.htm. This figure is available in full color at http://www.mrw.interscience.wiley.com/esst.
Figure 11. PIKE, a Remote Tracking Station at Schriever AFB, Colorado, looks like a giant golf ball to casual observers. PIKE is operated by the 22nd Space Operations Squadron.
GEODSS sites play a vital role in tracking deep space objects. More than 2500 objects, including geostationary communications satellites, are in deep space orbits more than 3000 miles from Earth. Three operational GEODSS sites report to the 18th Space Surveillance Squadron, Edwards AFB, California; Socorro, Natingham; Maui, Hawaii; and Diego Garcia, British Indian Ocean Territories. Figure courtesy USAF Space Command. Picture can be found at http://www.peterson.af.mil/hqafspc/Library/Fact-Sheets/FactSheets.asp?FactChoice — 8. This figure is available in full color at http:// www.mrw.interscience.wiley.com/esst.
Figure 12. GEODSS sites play a vital role in tracking deep space objects. More than 2500 objects, including geostationary communications satellites, are in deep space orbits more than 3000 miles from Earth. Three operational GEODSS sites report to the 18th Space Surveillance Squadron, Edwards AFB, California; Socorro, Natingham; Maui, Hawaii; and Diego Garcia, British Indian Ocean Territories.
Although 8000 space objects seems like a large number, in the 800-km orbital belt, there are normally only three or four items in an area roughly equivalent to the airspace over the continental U.S. up to an altitude of 30,000 feet. Therefore, the probability of collision between objects is very small (24).
During the 23 March 2001 reentry of the Russian MIR space station, the SSN proved its worth as the only worldwide sensor network capable of monitoring the MIR’s precise location and configuration nearly continuously. Space Control—Protection, Denial, and Negation. Although space surveillance is the basis of all space control functions, the uniquely military functions of protecting U.S. and other friendly satellites from hostile interference, denial of use of friendly satellite systems such as GPS, and negation of hostile space capabilities are uniquely military functions. During the 1990s, there have been a number of hostile interferences with communications satellites. The best known was the apparent deliberate jamming of a Tongan-leased Chinese communications satellite by Indonesia. The latter had claimed the same GEO operating slot and frequency usage. The U.S. Department of Defense focused in 1999 on a broad area review of space control and concluded that effective space surveillance was key but that far more attention was also needed in the areas of protection and denial.
To date, little is possible in the realm of satellite protection. The Space Control Center attempts to fuse information on potential satellite attacks based on reports from satellite operators, intelligence information, and satellite users. However, this data is often not timely enough to provide effective protection of satellite systems. A related satellite protection initiative is to increase force protection of satellite ground facilities and communications links. As for most military systems in the early twenty-first century, these facilities are increasingly vulnerable to terrorist attack. As military reliance on these space systems grows, their physical protection will take on new urgency.
Related to protection of space capabilities is the ability to deny an adversary use of friendly military and commercial systems. Key among these capabilities is the Global Positioning System. As previously outlined, the system is capable of encrypting its high accuracy data—that which could be used by a hostile group for precise guidance of a munition—and only providing degraded publicly available data. In 1998, the U.S. government decided to remove this degradation. However, it reserves the right to reactivate the degradation in the event of hostilities. Currently, the GPS degradation must be implemented globally at the direction of the satellite control element at Schriever Air Force Base, Colorado. However, the Department of Defense has been directed to develop means to limit degradation to local crisis areas and is actively pursuing a variety of means to do so.
Another denial capability is to prohibit hostile nations or groups from receiving commercial or other space-based imagery, which could be of military use during crisis or conflict. Currently, this is accomplished through ”shutter-control” agreements with commercial and foreign entities licensed to use U.S. produced systems or components—which is most of those currently available. However, as more and diverse groups develop space-based imaging and other surveillance capabilities, it will become impossible to control access to high quality imagery and other surveillance products. This will drive governments to develop more active means of denial.
Negation of on-orbit space systems remains a politically sensitive topic. In the 1970s, the Soviet Union developed an antisatellite weapon (ASAT). In the early 1980s, the United States tested its own antisatellite system—an air-launched miniature homing vehicle (MV-ASAT) which would crash into the target satellite. During its brief life as a prototype operational system, command and control for the system was done through the SCC’s predecessor, the Space Defense Operations Center (SPADOC) within Cheyenne Mountain. Both the Soviet and U.S. operational ASATs have been discontinued. However, the United States has publicly stated that it is pursuing negation capabilities and reserves the right to deploy them should the military and world situation so warrant. As for the MV-ASAT, command and control for such future systems would devolve through the U.S. Space Command’s Space Control Center through the service component actually operating the weapon system.
One of the most likely near-term negation systems is the ground-based laser. Both the United States and the former Soviet Union have developed ground-based lasers capable of damaging LEO satellites. The Mid-Infra Red Advanced Chemical Laser (MIRACL) at the White Sands Missile Range—operated by the U.S. Army Space and Missile Defense Command, the U.S. Army service component of the U.S. Space Command—retains a contingency ASAT capability (25). Other nations such as China are believed to be actively pursuing ground-based laser ASAT systems.

Future Directions

As we enter the twenty-first century, there is considerable uncertainty about the direction of future military use of space, both in the United States and throughout the world. Today, the United States stands alone in having a substantial military space organization and infrastructure. However, Russia has retained much of its former Soviet space potential and has shown signs of revitalizing its military space organization and capabilities. Several countries within the European Community—particularly France—have a close relationship between their civil space effort and a growing military use of space. China and India both have growing space access and use capabilities and have devoted increasing portions of these efforts toward national security missions. Smaller nations, such as Israel and even Chile, have developed and launched military space systems.
It is difficult to predict the future direction of military space, but several trends are apparent. In the area of space operations, there are two emerging trends. First is the growing need to maintain continuous contact with space systems. For GEO systems, this is relatively straightforward because a ground antenna at the subsatellite point can maintain a 24-hour a day lock on the satellite. However, these links are vulnerable to both ground attack and electronic interference (jamming). The problem is much more difficult for LEO and MEO satellites which do not stay in continuous view of a ground station and rely on a network of ground sites situated around the world. Correspondingly, they are in contact only a few hours a day—usually for only a few minutes at a time as they rise and fall from the field of view of each station. Thus, considerable effort is focused on developing continuous satellite contact through space-to-space communications links. Such capabilities have long been embodied in NASA’s TDRSS. However, future military space-based satellite control systems must be cognizant of the potential for hostile interference. For this reason, the military is looking at two approaches. The first relies on using radio frequencies, which cannot be propagated effectively through the atmosphere—thus, the satellite-to-satellite links are not susceptible to ground-based interference. Alternately, space-to-space communications may be via very narrowband laser cross-links— making it very difficult for an adversary to enter or jam the communications link.
Another potential trend in space operations is the likely emergence of fully reusable space access systems. The U.S. DOD refers to such systems as ”space-planes.” Affordability is a concern, but fully reusable space access systems would allow aircraft-sortie-like access to space. If this capability were realized, key military space systems might no longer be permanently stationed in space but would be put in place during a crisis or conflict and potentially recovered after their mission was completed. For permanently stationed space systems such as GPS, reusable sortie access to space would allow these systems to be much more easily repaired or upgraded or replaced in orbit. Today, it will take more than 10 years to replace the existing GPS system fully with a system currently being built to add new military and civilian frequency service. With reusable space access and reconfigurable space systems, this change might be accomplished in a few months versus a decade or more. The emergence of the reusable space plane would thus offer a complete revolution in space operations. This revolution may not be far off, but it will take renewed investment in “X-vehicles” by NASA that has lately been quick to eliminate such high-risk programs.
Space Control may also be revolutionized by two new developments. The first is the emergence of “microsatellite” technologies. In recent years, a number of groups around the world began constructing very sophisticated space systems weighing 100 kilograms or less. These so-called ”microsatellites” can perform many of the scientific functions formerly requiring satellites weighing thousands of kilograms. Microsatellites not only weigh less, they cost less, too. Typical system development costs are in the few millions of dollars versus hundreds of millions for a comparable conventionally sized satellite. Of course a cheap satellite is of less appeal if it still costs a large fraction of $100 million to launch, as is the case currently. Here, too, a revolution is occurring. Although fully reusable launch vehicles are a decade or more away, microsatellites have been able to take advantage of ”free” space on larger launch vehicles. This has been particularly true of the European Ariane launcher—which since the late 1980s has had available space for a number of microsatellites weighing up to about 50 kilograms. The newer Ariane V can launch up to eight secondary microsatellites into GEO transfer orbits on each launch. Typical costs for putting a microsatellite into orbit as a secondary payload are about $1 million. Thus, not only are low-cost microsatellites feasible, they are ”cheap” to launch into LEO orbits and higher orbits as well.
Currently, the most advanced microsatellite development group is the UK’s University of Surrey Space Centre. This group has constructed and launched more than 20 small and microsatellite class payloads—most as secondary pay-loads. Particularly interesting have been the successful efforts of the Surrey concern to transfer microsatellite capability to nations not normally associated with space programs such as Chile, Thailand, Malaysia, and Korea. Recently, the Surrey Space Centre has developed the next iteration of smaller, equally capable satellites—testing their SNAP-1 “nanosatellite” weighing about 5 kilograms. Although this system costs a few hundred thousand dollars to construct, it is no toy. It is three-axis stabilized and contains a propulsion system and a camera, which is used to take very good images of the primary and secondary payloads alongside of which it was launched.
The microsatellite and nanosatellite revolution is interesting from a scientific perspective, but it is even more significant in its implications for military use of space and space control. It places the ability to access space, inspect objects in space, and even interfere with other objects within the reach of most nations. This greatly complicates all aspects of space control—particularly space surveillance and space system protection. Because the current space surveillance system, of which the U.S. capability is most advanced, is a “tracking” system which looks for a satellite where it’s supposed to be, it is not well suited to detect a satellite that operates in a non-Keplerian fashion. A system that searches large areas of space is needed. Furthermore, particularly the “nanosatellites” are very near the limit of detectability—particularly at higher orbits—for today’s surveillance systems. Thus, the challenge for space control systems of the future is to detect and keep tabs on a large number of very small objects, which might be maneuvering frequently. The solution to this problem appears to be space-based optical and infrared surveillance systems.
Currently, only the Air Force’s MSX satellite conducts space-based surveillance operations. It operates only in a tasked track mode, although it can, in principle, search the entire GEO belt. However, it is a research and development satellite that is expected to fail in the near future. Microsatellite technology does, however, offer a means to put in place a low-cost, all-sky, comprehensive search. The Canadian microsatellite-based Near-Earth Surveillance System (NESS) proposes a 50-kilogram surveillance satellite capable of searching large parts of the sky down to a limiting magnitude of about 19. This would detect a nano-satellite out to GEO altitudes.
The emergence of many nations that have microsatellite and nanosatellite technology will change greatly the current approach to space surveillance. Conversely, the same microsatellite technology offers near real-time, all-sky, space surveillance.
The emergence of easy-to-maneuver microsatellites further presses the case for space-to-space continuous communications links. For LEO satellites, as discussed before, this may take the form of a TDRSS-type system. However, continuous space contact might be maintained with a LEO satellite through one of the new multisatellite communications systems such as the LEO Iridium constellation.
Space Force Application. No nation currently uses space to apply military force—other than the significant exception of long-range ballistic missiles—but this situation may soon change. The United States is developing various concepts for space-based missile defense systems. As the offensive missile defense threat grows, as many believe it will, pressure for a global missile defense versus simply a national or theater missile defense will also grow. These global missile defenses might be based on a constellation of space-based laser platforms or could consist of dozens to thousands of small interceptor missiles in orbit. Conversely, some advocate replacing nuclear-armed ballistic missiles with precision nonnuclear weapons launched on need into or through space to their targets. The United States Space Command was merged with United States Strategic Command on 1 October 2002. This combined Command assumed current space and strategic nuclear deterrence missions of its two component commands and also global strike and information operations missions. The latter two missions almost certainly would involve space capabilities (5).
It is unclear how these future force application missions might be controlled. However, several aspects of this control are worth noting. First, they would probably be coupled with real-time targeting systems, also based in space, to track their missile or other moving air, maritime, or ground targets. The U.S. Space-Based Infrared System (SBIRS) now under construction is one such system. The proposed Discover II system, which was under development before it was cancelled in 2000, would have used several dozen space-based radar satellites to track moving targets on the ground. In addition to these real-time surveillance and tracking systems, a command and control system that had very high fidelity and rapid response would also be needed. Engagements in and through space occur on timescales of seconds, so it is unlikely that a future command and control system would use human operators for conducting detailed engagements—there is simply insufficient time for human reactions to meet the requirements. Conversely, future force application systems would undoubtedly require “man-in-the-loop”—not as noted before to conduct the engagement, but to enable the system and set operational parameters (limitations) at the beginning of a crisis or engagement. Moreover, for reasons of survivability—particularly for critical strategic systems such as missile defenses, the command and control system would undoubtedly be “distributed,” rather than confined to a single or small number of potentially vulnerable nodes.
Other future missions may also emerge. In recent years, there have been growing calls and concerns about the threat of natural objects striking the earth—comets and asteroids. A large asteroid strike is generally deemed responsible for wiping out the dinosaurs — along with most other large animals — 65 million years ago. And small asteroids have apparently struck the earth with explosive power comparable to a nuclear weapon several times a century. It is uncertain what might be done about these threats, but most agree that a comprehensive all-space surveillance system is needed to catalog potential threats and track objects as they move close to Earth. This capability is similar to that needed for controlling and monitoring the growing constellations of man-made satellites and almost certainly will be an adjunct mission of any military space-based space surveillance system. Should a threatening asteroid or comet be detected, there have been various proposals to divert the threat. Many of these proposals include the use of a nuclear weapon exploded in the vicinity of the threat to deflect or destroy it. This would invariably require international cooperation but could also include various military capabilities and systems such as launch and space intercept systems.
The possibility of growing national security reliance on space has raised, at least in the United States, the potential need for a military service, separate from today’s army, navy, and air force. Russia has recently established such a separate space service adding credibility to these proposals. The U.S. Congress sponsored a high-level commission in 1999 to study this possibility. Donald Rumsfeld, who was subsequently appointed U.S. Secretary of Defense, chaired it. The commission recommended that a separate space service was not appropriate at the current time but was likely to emerge in the decades ahead. ”Space Commission” Changes. The charge of the aforementioned commission was to ”Assess the organization and management of space activities that support U.S. national security interests” (26). After nearly a year of deliberation and interviews with nearly every senior member of every organization within the U.S. government responsible for some aspect of space development and operations, the Commission’s findings resulted in some significant changes in the DOD’s structure for spacecraft and space launch life-cycle system oversight and management. Their overarching findings were that it was ”in the U.S. national interest to
- promote the peaceful use of space;
- use the nation’s potential in space to support its domestic, economic, diplomatic and national security objectives;
- develop and deploy the means to deter and defend against hostile acts directed at U.S. space assets and against the uses of space hostile to U.S. interests” (26).
The Commission further recommended a full review and revision of the nation’s space policy. Ultimately the commission recommended that the policy provide unambiguous direction to all branches of government to ensure that space systems developed address the needs of the military to deter and defend against evolving threats to its forces, allies, and other international interests. The commission further identifies the changes that will have to be made to make this possible. They include revolutionary use of space for collecting and disseminating intelligence to facilitate effective planning and resolution of national crises; development of an international legal and regulatory environment for space issues that ensures U.S. national security interests and enhances commercial competitiveness and effective exploitation of space for civil purposes; and finally, the commission recommended renewed investment by the government and commercial sector in leading edge, truly revolutionary, technologies to ensure that the United States can master operations in space and continue to compete on the open market. Of particular interest to the DOD were the recommendations the commission made with regard to the structure of the military’s organizations involved with acquisition and operation for and in space.
From the commission’s research and through the many interviews they held, the commission quickly realized that the Intelligence Community and the Department of Defense ”are not yet arranged or focused to meet the national security space needs of the 21st century” (26). In response to this shortcoming, the commission concluded that the numerous space activities throughout the Defense and Intelligence Communities should be merged and have chains of command, lines of communications, and policies adjusted to ensure improved accountability and responsibility. To this end, the DOD has initiated several notable changes in its management structure for space.
In April 2002, the U.S. Air Force Space Command (AFSPC) was assigned its own four-star commander. This change will ensure that AFSPC has the necessary autonomy to assert authority appropriately over its new organization. As the newly appointed executive agent for space, AFSPC is now the leader for cradle to grave development and deployment of military space systems. In support of this designation as executive agent for space, responsibility for SMC has been transferred from the Air Force Material Command to AFSPC. The net result of the changes made is yet to be realized; however, this indicate the first time that one organization has been responsible for military space systems. This, along with their recommendation to consolidate budgeting for space programs, will ensure that the DOD is able to address the requirements of its forces and ensure that U.S. national security interests are appropriately addressed.

Summary

Most space programs throughout the world emerged from national security programs. Generally, national security use of space for communications, surveillance, and other information is the first practicable use for space that a nation sees. This was true, particularly for the United States. National security use of space continues to be the lion’s share of U.S. government space investment. Although there is a growing trend to rely on commercial and dual use civil and military space infrastructure—particularly for space launch support, unique military space control and operations facilities are here to stay. As various nations, probably led by the United States, make even more use of space for national security, these unique military operations facilities will evolve considerably. They are likely to become much more ”distributed.” They will increasingly rely on space-based elements such as space-based space surveillance systems and space-relayed command and control systems. It is even possible, if not likely, that we will see national security space forces emerge separate from terrestrial armies, navies, and air forces.

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