Force Enhancement

Force enhancement multiplies combat effectiveness. Space operations contribute directly to the combat effectiveness of our military forces within several mission areas: spacelift, surveillance and reconnaissance, navigation, communications, and meteorology.

Historically, the primary use of United States military space systems has been to support terrestrial forces. From their unique vantage point, satellites can perform and support many military missions more economically, effectively, and efficiently than terrestrial systems. In some cases, satellites are the only feasible means of performing the mission. In addition, the inherent global nature of orbiting satellites makes worldwide support of military operations possible.(18)

The US military relies extensively on space assets for many critical missions. Force enhancement space systems include capabilities that

Provide real-time, survivable, and enduring communications, surveillance, environmental monitoring, navigation, and warning for unified and specified commanders (and their component commanders), the national command authorities, and the intelligence community.

Provide the potential for rapid decision and response actions by the NCA and war-fighting commanders at all levels. Space resources can rapidly distribute information to forces worldwide. Space systems can aid commanders to reduce the time required for observation-orientation-direction-action feedback.

Support national and international space rescue plans.

Provide space environmental and life support capabilities over the full scope of aerospace operations.(19)

Spacelift

Spacelift provides the capability to emplace and replace critical space assets. Spacelift (or launch) operations deliver military space systems to the required operational orbit or location in space. The spacelift mission entails a wide variety of complex activities required to place the satellite into the proper operational orbit.

Spacelift includes preparing the various segments of the space launch vehicle, erecting or stacking the launch vehicle on or near the launchpad, integrating the mission payload(s) with the launch vehicle, conducting a thorough prelaunch checkout of all systems, and conducting the actual operations of countdown, launch, and flight of the space vehicle into orbit.(20) Additional detailed information on various spacelift (launch) vehicles is in chapter 4 of this volume.

Surveillance and Reconnaissance

The following section provides information on two key US space systems that have a long history of success. These systems are only samples of US surveillance and reconnaissance satellite systems. Some of these technologically advanced systems are classified and this volume does not cover them.

Defense Support Program. The Defense Support Program (DSP) is an integral part of the nation's missile warning system operated by the US Air Force Space Command. The satellites report on real-time missile launches, space launches, and nuclear detonations. They have been the spaceborne segment of the North American Aerospace Defense Tactical Warning and Attack Assessment System since 1970.

The vehicle uses infrared detectors that sense the heat from missile plumes against the background of the Earth. The satellite provides secure downlink capabilities to transmit mission data, state-of-health, and other relevant information to the ground data system. The vehicle also provides a secure uplink command receiving, processing, and a distribution capability for both spacecraft and sensor ground-generated commands. The new-generation DSP satellite weighs approximately 5,000 pounds, has a 22-foot diameter, and is 32 feet long with solar paddles deployed. The solar paddles generate 1,485 watts of power. The satellite operates in a geosynchronous orbit, 22,300 nautical miles from Earth. (See annex C for more DSP information.)

Landsat. Landsat is a civil satellite system developed by NASA to provide land, surface, and ocean data. Initially developed in the late 1960s, the primary Landsat mission was to demonstrate the feasibility of multispectral remote sensing from space for practical Earth resources management practical applications. The overall system requirements were acquisition of multispectral images (MSI), collection of data from remotely located ground stations, and production of photographic and digital data in quantities and formats most helpful to potential users.(21) Another requirement was that Landsat take the data in a specific manner: repetitive observations at the same local time, overlapping images, correct locations of images to within two miles, and periodic coverage of each area at least every three weeks.

Currently, data from Landsat is collected at three US ground stations located in California, Alaska, and Maryland. Through bilateral agreements, ground stations located in Canada, Brazil, Argentina, Japan, India, Italy, Australia, Sweden, and South Africa are also receiving data.(22) All data for US consumption is sent to the Goddard Space Flight Center for preprocessing. After preprocessing, the data is transmitted electronically to the Earth Resources Observation System Data Center (EDC) in South Dakota for final processing. The resultant data is then available to users through EDC as photographic imagery or digital data tapes.

Landsat 4 and 5, the second generation of the Landsat series, carry two sensors: a multispectral scanner (MSS) and a thematic mapper (TM). The thematic mapper is a new sensor that has a ground resolution of 30 meters for the visible and near-infrared bands.(23) The MSS records four images of a scene, each covering a ground area of 185 kilometers (km) by 185 km at a nominal ground resolution of 79 meters.(24) The images are produced by reflecting radiance from the Earth's surface to detectors on board the satellite.

Two large applications of Landsat data are mapping land cover and monitoring change, both aquatic and terrestrial. The TM sensor is able to record four times as many radiance levels as the MSS sensor and has better resolution. This enhanced resolution and increased radiance level capability provides greater detail for vegetation absorbance, land/water contrasts, and geological discrimination applications.

The current Landsats take 16 days to cover the Earth (except the poles). Their data is relayed in near real time by using the geostationary Tracking and Data Relay Satellite and the Domestic Communication Satellite systems. This eliminates the need to rely on onboard tape recorders to store data for transmission. As a result, it takes approximately 48 hours from collection of raw sensor data to generation of MSI archival products.(25)

The Landsat program, originally under NASA, has suffered from a lack of a stable home in the competition between programs for funding. The National Space Council shifted the program to the Commerce Department in 1979 in a commercialization plan that would eventually place it under private ownership and operation. That effort brought in smaller revenues than expected and the program languished. If Landsat 4 and 5, launched in 1982 and 1984 respectively, had not exceeded their three-year-design lifetimes, the US would be without a civil Earth observation spacecraft. Landsat 6, scheduled for launch in mid-1992, should operate for five years, during which time Landsat 7 should be launched.

The National Space Council decided in December 1991 to build and operate another Landsat after Landsat 6. Landsat 7 will be comanaged by the Department of Defense and NASA. This would mark the first time the Department of Defense has been involved in management of the civilian imaging system. The impetus for this decision can be attributed to the tactical role MSI data played in the Gulf War (see annex A).

Lawmakers, in deciding on this comanagement approach, considered the possibility that a data gap could harm global change research, national security applications, and market development.(26) The lessons learned concerning MSI data usage during the war will influence the technology for Landsat. Addition of enhanced sensors capable of five-meter stereoscopic images, precise metric data, broad area collection, and a dedicated tracking and data relay antenna would make the Landsat an effective tactical military system for future conflicts.(27)

Navigation Systems

The Global Positioning System is a space-based radio navigation network operated and controlled from Falcon AFB. The Air Force launched the first research and development satellite in February 1978. As of February 1991, the GPS network consisted of six Block I R&D satellites, and 10 Block II operational satellites. This 16-satellite constellation should grow to 21 satellites plus three on-orbit spares by the mid-1990s.

GPS is a navigation system designed to provide US and allied land, sea, and air forces with worldwide, three-dimensional position and velocity information. The system consists of three segments: a space segment of satellites that transmits radio signals, a control segment of ground-based equipment to monitor the satellites and update their signals, and a user equipment segment of devices to passively receive and convert satellite signals into positioning and navigation information.

When fully operational, GPS will provide 24-hour, all-weather, precise positioning and navigation information from satellites circling the Earth every 12 hours and emitting continuous navigation signals. It will also provide such support to civilian users.

The Air Force launches GPS satellites from Cape Canaveral AFS, Florida, using a Delta II launch vehicle. The satellites are put into 11,000 nautical mile circular orbits. The GPS constellation will have six orbital planes with four satellites in each. Satellites will transmit on two different L-band frequencies. The design life of the operational satellites should be seven and one-half years.

The GPS master control station located at Falcon AFB monitors and controls the GPS constellation. Five widely separated monitor stations passively track the satellites and accumulate navigation signals. Three globally dispersed ground antennas act as the two-way communications link between the MCS and the satellites. Through these links, crews in the MCS update the satellites' computers, allowing them to maintain the health and orbit of GPS satellites, monitor and update navigation signals, and synchronize the satellites' atomic clocks.

GPS data aids land, air, and sea vehicles in navigation, precision weapons delivery, photographic mapping, aerial rendezvous and/or refueling, geodetic surveys, range safety and instrumentation, and search and rescue operations. This system provides military users highly accurate, three-dimensional (longitude, latitude, and altitude) position, velocity, and time information. With proper equipment, authorized users can receive the signals and determine their location within tens of feet, velocity within a fraction of a mile per hour, and the time within a millionth of a second. To obtain this information, the user set will automatically select the four most favorably located satellites, lock onto their navigation signals, and compute the position, velocity, and time.

Communications Systems

This section discusses the primary communications satellite systems used by the US Air Force. Communications systems that other services use extensively for specific purposes are not covered in this volume.

Defense Satellite Communications System. The DSCS provides the DOD, the Department of State, and other US government agencies secure, high-capacity communications that a commercial service or military system cannot provide. The Defense Communications Agency manages operational use of the communications capabilities provided by the network of satellites, ensuring proper allocation of frequency and bandwidth to users based upon their requirements.

In the 1960s the DOD began to build a network of satellites for military communications. This program advanced through three phases incorporating improved technology and enhanced capabilities with each phase.

Between June 1966 and June 1968 in Phase I of the program, the Air Force launched 26 small communications satellites, each weighing about 100 pounds. Each satellite had one channel and relayed voice, imagery, computerized digital data, and teletype transmissions. Designers planned for the satellites to last three years. Phase I satellites operated in a circular orbit 20,930 miles above Earth at a speed that nearly kept each satellite over a point on the equator.

DSCS II launched its first satellites in 1971 and is the second generation military communications satellite program. The 3d Satellite Control Squadron currently flies DSCS II satellites from Falcon AFB. DSCS II has increased communications load capability and transmission strength, and double the lifetime expectancy of the Phase I satellites. DSCS II has an attitude control system for orbital repositioning. Ground command can steer the two-dish antennas on DSCS II satellites and can concentrate the antennas' electronic beams on small areas of the Earth's surface for intensified coverage.

The third generation satellite is the DSCS III satellite. These satellites carry multiple-beam antennas to provide flexible coverage and resist jamming. They last twice as long as DSCS II satellites, have six active communications transmitter channels, and carry an integrated propulsion system for maneuverability. The Air Force launched the first DSCS III satellite in 1982. Antenna design for DSCS III allows users to switch between fixed, Earth coverage, and multiple-beam antennas. The latter provides an Earth coverage beam as well as electrically steerable area and narrow-coverage beams. In addition, a steerable transmit dish antenna provides a spot beam with increased radiated power for users with small receivers. In this way, operators can tailor the communications beams to suit the needs of different size user terminals almost anywhere in the world.(28) (See annex A for more information on DSCS's role in Desert Storm.)

NATO III. The NATO III satellite program is a four-satellite constellation. NATO III satellites are geostationary communications satellites designed to provide real-time voice and data links between members of the North Atlantic Treaty Organization (NATO). The program is directed by the NATO Integrated Communications System Operating Agency (NICSCOA), which is located at Supreme Headquarters Allied Powers Europe, Belgium. The AFSCN performs command and control functions on behalf of NICSCOA.(29)

NATO III is a cylindrical, spin-stabilized satellite with a design life of seven years. It is 86 inches in diameter, 110 inches in height, and weighs 783 pounds. Solar arrays cover the sides of the satellite body, and there are thermal shields on the top and bottom. The command and control antenna encircles the vehicle, and three communications antennas are atop the satellite on a despun platform. The communications payload is a repeater providing both narrowbeam and widebeam coverage of the North Atlantic region. This payload provides multiple carrier reception, frequency translation, amplification, and retransmission of X-band signals. The apogee kick motor and two axial thrusters are on the bottom of the vehicle. All electronic equipment, the hydrazine tanks, and radial thrusters are on the main equipment platform in the center of the vehicle. The AFSCN launched the NATO III satellites from the Eastern Test Range aboard Delta boosters between April 1976 and November 1984 and placed the four vehicles in elliptical transfer orbits of approximately 23 degree inclination. At approximately fifth apogee, an apogee kick motor fired, circularizing the orbit and reducing the inclination. NATO III will eventually take on a backup mission when NATO IV becomes operational in the early 1990s.

Fleet Satellite Communications System. The Fleet Satellite Communications System (FLTSATCOM) is a five-satellite constellation. Each satellite has 23 communications channels. The US Navy uses 10 channels for communications among its land, sea, and air forces. The Air Force uses 12 channels as part of the Air Force Satellite Communications System (AFSATCOM) for command and control of nuclear forces. AFSATCOM is not a separate satellite system, but is a functional system imbedded within FLTSATCOM. The last channel is reserved for the NCA.(30)

The ground segment of the system consists of communication terminals on most US Navy ships and submarines, selected Air Force and Navy aircraft, global ground stations, and presidential networks. Individual users acquire and manage these terminals.

The FLTSATCOM satellites launch from Cape Canaveral AFS, aboard Atlas-Centaur rockets. They are three-axis stabilized in geosynchronous orbit approximately 22,250 nautical miles above the equator. The latest version of the FLTSATCOM satellite and its solid propellant apogee kick motor weighs approximately 4,100 pounds. The vehicle's body is approximately 8 feet in diameter and 65 inches high. The parabolic ultra high frequency (UHF) transmit antenna is 16 feet in diameter when extended; ground command deploys the screen portion of the antenna from its folded launch configuration. A 14-foot long, helical UHF receive antenna, 13 inches in diameter, is mounted outside the edge of the transmit antenna. It is also folded to fit inside the Centaur booster fairing during launch and is deployed by separate ground command. (See annex A for more information on FLTSATCOM's role in Desert Storm.)

Two deployable solar array panels, which supply approximately 1,500 watts of power, provide the primary electrical power for the satellite. The span of the deployed solar array panels is 43 feet. In addition, three nickel-cadmium batteries provide power during eclipse operations at the spring and autumnal equinoxes. The design life of the satellite is five years.

Meteorology

The Defense Meteorological Satellite Program has been operational since July 1965. Its military mission is to generate weather data for operational forces worldwide. The Air Force is the DOD executive agent for this program. The Department of Commerce's National Oceanic and Atmospheric Administration furnishes meteorological data to the civilian community.

Satellites in the DMSP meet unique military requirements for worldwide weather information. DMSP satellites provide meteorological data in real time to Air Force, Navy, and Marine Corps tactical ground stations and Navy ships. Through these satellites, military weather forecasters can detect developing patterns of weather and track existing weather systems over remote areas.

Data from these satellites can help identify, locate, and determine the intensity of such severe weather as thunderstorms, hurricanes, and typhoons. Agencies can also use the data to form three-dimensional cloud analyses, which are the basis for computer simulation of various weather conditions.

All of this quickly available information aids the military commander in making decisions. For example, data obtained through this program is especially valuable in supporting the launch, en route, target, and recovery portions of a wide variety of strategic and tactical missions. Air Force Space Command's 6th Space Operations Squadron (SOPS) at Offutt AFB, Nebraska, and Detachment 1 of the 6 SOPS at Fairchild AFB, Washington, provide command and control of DMSP satellites.

Current satellites in the DMSP are designated as the Block 5D-2 integrated spacecraft system because the functions of the launch vehicle's upper stage and the orbital satellite have been integrated into a single system.

This system navigates from lift-off and provides guidance for the spacecraft from booster separation through orbit insertion, as well as electrical power, telemetry, attitude control, and propulsion for the second stage. Block 5D-2 has many improvements over earlier DMSP satellites, including more sensors with increased capability and increased life span. The satellites circle the Earth at an altitude of about 450 NM in a near-polar, Sun-synchronous orbit. Each satellite scans an area 1,600 NM wide and can cover the entire Earth in about 12 hours. Three reaction wheel assemblies, which provide three-axis stabilization, maintain pointing accuracy of the satellites.

The 5D-2 spacecraft has five major sections: a precision mounting platform for sensors and other equipment requiring precise alignment, an equipment support module that encloses the major portion of the electronics, a reaction-control equipment support structure that contains the spent second-stage rocket motor and supports the ascent-phase reaction-control equipment, a solar cell array, and the booster adapter. The Sun-tracking, deployable solar array is covered with 12,500 silicon cells that produce 1,000 watts of power for operating the spacecraft systems. The booster adapter provides electrical interfaces between the satellite and ground test equipment and is the structural interface between the satellite and the booster.

The primary sensor on board the satellite is the operational linescan system that "sees" visible and infrared cloud cover imagery used in analyzing cloud patterns. Also, the spacecraft can carry secondary payload sensors. For example, one sensor measures temperature and moisture; another accurately measures the location and intensity of the aurora to aid radar operations and long-range ground communications in the northern hemisphere, a third measures the precipitating electrons that cause the aurora; a fourth sensor measures X rays, and a fifth sensor measures soil moisture, atmospheric moisture, and sea state.

The normal on-orbit DMSP constellation currently consists of two operational satellites. To date, the DMSP has placed six Block 5D-2 satellites on-orbit. Block 5D-2 satellites are launched on Atlas-E boosters from Vandenberg AFB, California.