Satellite Power System (SPS) Military Implications HCP/R-4024-11 October 1978 Prepared for: U.S. Department of Energy Office of Energy Research Satellite Power System Project Office Under Contract No. EG-77-C-01-4024 DOE/NASA Satellite Power System Concept Development and Evaluation Program
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HCP/R-4024-11 Dist. Category UC-11,41,60,63, 63a, b, c, e,64,66e, 95f, 97c Satellite Power System (SPS) Military Implications October 1978 Prepared by: Claud N. Bain PRC Energy Analysis Company McLean, Virginia 22102 Prepared for: U.S. Department of Energy Office of Energy Research Satellite Power System Project Office Washington, D.C. 20545 Under Contract No. EG-77-C-01-4024 DOE/NASA Satellite Power System Concept Development and Evaluation Program
NOTICE This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
ACKNOWLEDGEMENTS I wish to acknowledge the helpful reviews by C.E. Bloomquist, M.S. Wei, Peter Cole, Joseph Long, Carl Sandahi, and F.A. Koomanoff and the guidance these reviews provided in establishing the scope of this study. I wish to thank Leonard David and Harry Holloway for contributing appendices. Thanks are also extended to the following individuals for their careful and critical reviews of the draft document and for the comments and recommendations made, several of which have been incorporated. I) Major Grat H. Horn, Jr. U.S. Air Force Energy Management Division Headquarters, United States Air Force 2) Major William C. Ayers U.S. Air Force Tactical Forces 3) LTC Richard L. Kail Office of Assistant Secretary of the Army Installations, Logistics and Financial Management 4) Dr. Walter Warren Director of Aerosciences Aerospace Corporation 5) Dr. Ken Horn Rand Corporation 6) Professor Chih Wu Mechanical Engineering Department U.S. Naval Academy 7) Dr. William A. Shurcliff Harvard University 8) Dr. Barry Smernoff Hudson Institute 9) Dr. Michael Michand U.S. State Department 10) Mr. Leonard David, Director Student Programs, FA AST
PREFACE This paper documents the findings of a survey to determine the military implications of the Satellite Power System and to identify worthwhile study tasks that could be completed during fiscal year 1979.
EXECUTIVE SUMMARY This study was conducted to examine military implications of the NASA Reference Satellite Power System (SPS)* and to identify important military- related study tasks that could be completed during fiscal year 1979. Primary areas of investigation were the potential of the SPS as a weapon, for supporting U.S. military preparedness and for affecting international relations. In addition, the SPS’s relative vulnerability to overt military action, terrorist attacks, and sabotage was considered. The SPS could act as an electronic warfare weapon and, with modification, as a marginally effective energy-beaming weapon. The system could support military preparedness by providing energy for a strong and stable U.S. economy and by providing a powered platform for military systems, system segments, and operations. The SPS would be vulnerable to military action, terrorism and sabotage unless hardened against these attacks by design, security, and a self-defense system. Because space is an international resource, military use of the SPS, even to protect itself, may have an adverse impact on the relations of the United States with other nations. Tasks identified for completion in fiscal year 1979 include (a) a detailed vulnerability study, (b) evaluation of an SPS self-defense system concept, (c) determination of the effect of SPS flexibility to deliver different sized electrical loads on the ability to gain SPS support from individual nations, and (d) investigation of the effect of SPS deployment schedule on obtaining needed agreements, providing security, and controlling risks of armed conflict. A fifth and long-term task would consist of a worldwide survey iaentifying military implications of the SPS that result from the specific requirements of potential SPS power customers. *See table 2.1.
TABLE OF CONTENTS PREFACE v EXECUTIVE SUMMARY vii GLOSSARY xi I. INTRODUCTION I II. SURVEY OF RELEVANT LITERATURE AND RELATED WORK 3 2.1 Weapon and Military Preparedness Implications 3 2.2 Impacts on International Relations 10 2.3 Relative Vulnerability 13 I I I. ANALYSIS AND EVALUATION 15 3.1 Weapon and Military Preparedness Implications 15 3.2 Impacts on International Relations 21 3.3 Relative Vulnerability 22 IV. KEY ISSUES AND GENERAL OBSERVATIONS 25 4.1 Weapon and Military Preparedness Implications 25 4.2 Impacts on International Relations 25 4.3 Relative Vulnerability 26 V. RECOMMENDATIONS 27 5.1 Short-Term Tasks 27 5.2 Long-Term Task 27 VI. REFERENCES 29 VII. BIBLIOGRAPHY 31 APPENDIX A: MILITARY ACTIVITIES IN OUTER SPACE A-1 APPENDIX B: IMPACT OF HOSTILE ENVIRONMENTS ON SPS B-I
GLOSSARY cm centimeter COTV Cargo Orbital Transfer Vehicle DC Direct Current DOD Department of Defense DOE Department of Energy G Gain GEO geostationary earth orbit GHz gigahertz GW gigawatt HLLV Heavy Lift Launch Vehicle Hz hertz kg kilogram km kilometer kW kilowatt LEO low earth orbit m meter mm millimeter MPTS Microwave Power Transmission Subsystem mW milliwatt MW megawatt NACA National Advisory Committee for Aeronautics NASA National Aeronautics and Space Administration OPEC Organization of Petroleum Exporting Countries PLV Personnel Launch Vehicle POTV Personnel Orbital Transfer Vehicle PTS Power Transmission Subsystem RFI/EMI radio frequency interference/electromagnetic interference R&D research and development SPS Satellite Power System W Watt pm micrometer X wavelength
I. INTRODUCTION The U.S. Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) are investigating a potential new source of energy called the Satellite Power System (SPS).—/ The SPS concept involves placing in orbit around the earth satellites equipped with large solar arrays. The arrays collect solar radiation from the sun (approximately 99 percent of the time), which is then converted to electromagnetic radiation and beamed by a transmission system located on the satellites to receiving/conversion stations on the ground. The receiving equipment at the conversion station changes the electromagnetic radiation to electricity that can be fed directly into the utility network. The satellite and receiving antenna/rectifier (rectenna), for the current NASA- reference system using solar cells, and microwave power transmission subsystems are approximately 50 and 100 sq. km in size, respectively. The system is designed so that each rectenna will provide power to the utility grid. The scope of the concept can be placed in perspective by considering that the generating capacity of these satellites would be equal to all the electrical power generated in the United States in 1975. Projected energy demand at the turn of the century, as well as basic economics, indicate that at least 60 satellites will need to be programmed. Such a system is anticipated to have far-reaching impacts on society. The SPS will have many features in common with systems of past and current space programs and will build on the technology that these programs have created. System development, production, and deployment will be costly processes, and SPS relative productiveness will be relied on to place it within the cost feasibility range. Lightweight structures and equipment and reliable operation, made possible by the favorable environment of space and design for the market, may hold the secrets to the needed cost control. If it is believed that the SPS will fulfill its postulated role by becoming a supplier of a significant part of the total energy consumed in the United States at some time during the first half of the twenty- first century, then SPS development, production, and deployed assets are valuable to both civilian and military segments of our nation now and in the forseeable future. Furthermore, if the United States decides to depend on the SPS for so great a part of its total energy supply, the system must be secure. Some believe that the SPS cannot be defended successfully, but that if it could be, this defense would cost more than the SPS.
The investment of materials, effort, and money to fill the energy gap in the time available will be large but finite. Spending a large part of these resources on the development and deployment of a system that is superior from the standpoints of technological, economical, and environmental risks and yet is militarily indefensible actually may be squandering the resources. What is worse, however, is that these resources (and valuable time) then are denied to the alternative ’’runner-up” energy system concept that (though inferior in some respects) is acceptable and militarily defensible. This study has been performed to determine what role, if any, the SPS has in the U.S. military posture. Tasks included the following: • Investigation of the SPS potential as a weapon or other supportive element of U.S. military preparedness; • Investigation of the potential for impacts on international relations; • Investigation of the relative vulnerability to overt military action, terrorist attacks, or sabotage; and • Identification of questions needing further study.
I I. SURVEY OF RELEVANT LITERATURE AND RELATED WORK The survey for unclassified relevant literature and information on related work has included a Defense Documentation Center search, a search of the open literature, and conferences and contacts with representatives of the Department of Energy (DOE), the Department of Defense (DOD), the National Aeronautics and Space Administration (NASA), and industrial organizations and individuals acting in a private capacity. During this survey it was learned that several efforts have included the consideration and documentation of the general topic of military activities in space. Examples include references 3, 4, 5, 6, and 7. However, with the exception of reference 6, no effort has been made to summarize this work because these reports and papers are readily available. Some of the pertinent information contained in reference 6 concerning laws and treaties is summarized by Mr. Leonard David in appendix A. The potential of the Satellite Power System (SPS) to function as a weapon, support U.S. military preparedness, and affect international relations and SPS vulnerability, are discussed in the following paragraphs. 2.1 WEAPON AND MILITARY PREPAREDNESS IMPLICATIONS Civilian space systems, like military space systems, are based on current technology; therefore, the systems provided by NASA and DOD would be expected to have many common features, several of which could implicate the SPS militarily. 8/ In 1958, shortly after the Sputnik launch, NASA- was formed from the old National Advisory Committee for Aeronautics (NACA) and from selected individuals and groups performing DOD space-related work. Projects transferred to NASA included project Vanguard and certain lunar probes and rocket engine programs. The formation of joint committees of NASA and military personnel to pursue common objectives and the free movement of workers (even the astronauts) between military and NASA space projects tend to promote similarities between NASA and military space efforts and equipment. Therefore, it does not seem inappropriate to consider the question of military implications of a civilian space system. 2.1.1 Weapon Implications Use of the SPS as a weapon is a major concern. U.S. citizens as well as foreign governments and their citizens will want to know whether the power transmission beams can operate as weapons and what assurances can be provided that this 5 gigawatts of power will not be used as a weapon. The weapons implication of the NASA reference SPS (table 2.1) is examined.
Table 2.1 Summary of SPS Reference System Concept Generating Capacity • 5 GW DC output per SPS unit at the utility interface Operational Characteristics • Flat solar array with transmitting antenna on one end • Power collection at GEO Energy Conversion • Photovoltaic—single-crystal gallium aluminum arsenide or singlecrystal silicon Power Transmission • Microwave, phased-array transmitting antenna, klystron power amplifiers and slotted waveguide radiating elements Structural Material • Graphite composite Rectenna 2 • Subarray panel with~8 km active element area Space Construction • Construction at GEO Space Transportation • Heavy Lift Launch Vehicle (HLLV)—two-stage, vertical launch, winged, horizontal land-landing, reusable vehicles with 400 metric ton payload to low earth orbit • Personnel Launch Vehicle (PLV)—modified Space Shuttle orbiter with passenger module • Cargo Orbital Transfer Vehicle (COTV)—independent reusable electric- powered vehicle • Personnel Orbital Transfer Vehicle (POTV)—two-stage, reusable chemical fuel vehicle Earth Launch Site • Kennedy Space Center pending further study
2.1.1.1 Microwave Power Transmission Subsystem (MPTS) The MPTS is the transmission subsystem used in the current NASA reference SPS concept. The system, to be constructed and deployed in geostationary earth orbit (GEO), will be powered by a solar cell array having a platform of approximately 55 sq. km. Table 2.2 provides MPTS details from which the following observations can be made: • The system radiates a large amount of power. • Power density at its highest level near the center of the antenna is a relatively low 2.2 W/cm2 (approximately 16 solar constants), from which workers near the antenna can be shielded for short periods of time. (Figure 2.1 is a plot of maximum power density versus distance from the antenna toward the ground receiver.) • There should be no trouble designing spacecraft that can travel in this beam with passengers aboard. Spacecraft or satellites not designed for,this radiation field could overheat when moving slowly through it- resulting in temporary disability or permanent damage to their electronic systems. Two possibilities exist for weapon use. First, the beam could be defocused and noise introduced to render selected communications ineffective (an electronic warfare weapon). Second, the beam could be directed at ground targets or scanned in a manner to follow spacecraft until overheating occurs, and/or until electronic failure disables the craft or produces a mission abort. 2.1.2 U.S. Military Preparedness Implications The energy problem of the DOD was defined in the January 1977 U.S. Navy 9/ Energy Plan— as follows: The most serious and pervasive threat to long-term national stability is the growing world inadequacy of assured energy resources to support world needs. National security depends on maintaining a worldwide balance of the distribution of energy resources. National security objectives can be achieved only if the United States is thoroughly prepared to meet essential industrial and military energy requirements. Attaining these objectives, deterring armed conflict, producing modern weapons systems, and maintaining the overall readiness of the U.S. military are all keyed to uninterrupted energy supplies. - a radiation level as high as 1.5 W/crn is permitted for aircraft. High speed aircraft flying at low altitude are able to dissipate radiation loads several times this value. (In space there is no air flow across spacecraft surfaces to cool them. Therefore, the radiant heat of the beam must be rejected by the use of reflective surfaces and/or absorption and reradiation.)
Table 2.2 Microwave Power Transmission Subsystem Parameters • Frequency = 2.45 GHz • Wavelength = 12.2 cm • Output Power to Power Grid = 5 GW • Transmit Array Size = I km in diameter, 13.4 x 10^ kg mass • Power Radiated from Transmit Array = 6.85 GW • MPTS Efficiency = 61.1 percent • Phase Control System: An active retrodirective array with a pilot beam reference for providing phase conjugation. This system includes: Phase Lock Loop Around Each Tube for Phase Stability and Noise Suppression Double Sideband, Suppressed Carrier Modulation (Two-Pilot Frequencies) Coding of Pilot Beam for Security and Pilot Discrimination Ground Safety Control System (Ground Sensors for Interpreting Beam Shape) Power Density Levels Center of Transmit Antenna = 22 kW/m^ = 2.2 W/cm^ 7 2 Edge of Transmit Antenna = 2.4 kW/m = 240 mW/cm 2 Center of Rectenna = 23 mW/cm 2 Edge of Rectenna = I mW/cm Rectenna Size = 10.0 km x 12.4 km Beam Diameter = 2.8 x IO-Z| rad Pointing Held to + 2.8 x 10”^ raa
Figure 2.1 Power Density at Center of Microwave Beam Versus Distance From the Antenna
The major U.S. military preparedness implications of the SPS result from its ability to supply energy. The embargo on the export of petroleum products to selected countries in October of 1973 by the OPEC nations, and the realization that petroleum is a limited resource, have placed a high national priority on energy and energy-related issues. Objectives have been established to: • Conserve energy; • Increase domestic oil and gas production while reducing the use of oil and gas; • Convert oil and gas electric plants to other fuels, such as coal, hydro, nuclear, solar; • Develop the inexhaustible energy resources; • Reduce oil imports; and • Develop a billion barrel petroleum reserve. The embargo has pointed out to the military the necessity of having a reliable source for each form of energy or fuel that it uses and has caused accelerated energy planning. Military bases, for example, have introduced programs to supply much of their own energy requirements and to reduce their dependence on outside sources. These basic energy availability and use issues implicate the SPS in U.S. military preparedness. Many in the military community who have surveyed the problem believe that the United States will begin to be affected by the fuel shortage by 1985 or 1990; costs are already reducing fuel availability to some of the population. The power expected from the SPS cannot relieve these early shortages directly, but its imminence may encourage a freer flow of oil into the market, thereby keeping a bad situation from becoming intolerable.-^ If the SPS comes on line, its power can begin to be used in the following ways: • Strengthen the civilian/industrial sector, allowing more effective support to the military in the areas of technology, production, and capital; • Free larger quantities of portable fuels required for military mobility (and mobility related stockpiling); Dr. William Shurcliff has pointed out that the encouragement of a freer flow (and use) of oil, with the prospects of an SPS that in fact does not come on line, could hasten and intensify the ultimate energy bind.
• Provide electricity to military ground installations through the utilities; and • Supply markets that will strengthen mutual security bonds and reduce tensions. The current plan is to deploy two 5-GW SPS units each year starting in the year 2000 and running through the year 2030 for a total SPS output of 300 GW. This is equivalent to the 1975 electrical power generating capacity in the United States and from 7.5 to 10.0 percent of the expected U.S. power requirement in 2030. (Other scenarios have projected the SPS deployment rate at two times to approximately four times this rate.) Any growing dependence of the United States on an unfolding and successful SPS for power, coupled with the constant dependence of military preparedness on an economically and industrially strong United States, will implicate the SPS in U.S. military preparedness. However, the implication goes farther; the SPS must be protected by either the U.S. military or a military/quasi-military force in which the United States plays a part commensurate with its potential for loss. 2.1.3 Platform for Weapons The NASA 5-GW SPS reference design is driven by a solar cell array with 2/ an area of approximately 50 sq. km.- This array is supported by a platform that is 10,400 m long, 5,200 m wide, and 470 m thick—a volume of approximately 25 cu km. Materials used in this platform and its design combine for an extremely lightweight structure having the appropriate stiffness for SPS functions. This platform, as well as SPS construction/maintenance facilities and personnel living quarters would seem from a cursory examination to be ideal assets for beginning any necessary SPS military operations. Military housing and work areas could be integrated into the SPS solar array platform by modifying and beefing up structures as required. The array could be extended to supply any added quantities c/ of electricity needed by the military unit. During times of conflict- the array would be a prodigious source of power that could be preempted from the private sector and used to power weapons. The functions of such a military outpost could include security, supply, maintenance, repair, personnel, and training. Security would encompass activities involving the maintenance and use of defensive/offensive equipment needed to protect the SPS. Systems could include c/ - During a national emergency (declared by the president) civil and commercial satellites would be subject to control by the Department of Defense. See appendix A, PRM-23.
visible/infrared/rador sensors for reconnaissance, surveillance, and search/track/- pointing; radiation/particle weapons; projectiles and missiles; communications/com- mand/control; data-handling electronics; and electronic warfare/countermeasures equipment. A recent study by McDonnell Douglas Astronautics Company— investigated the evolutionary development of a space station to support people and equipment engaged in peaceful pursuits. Many of the same problems they encountered would need to be solved in developing and equipping the SPS military outpost. The shuttle transportation system is used to support the McDonnell Douglas space station concept. Major technologies (including surveillance, detection, track, pointing, and laser weapons and missiles) for beginning any needed self-defense system for the SPS and for deploying other weapons at the SPS space site are progressing steadily. However, before an appropriately equipped operational SPS self-defense system can be defined, an understanding of the threat, the output of operational analyses involving this threat, and the feel of experience may need to be combined for an extended operational shakedown of potential system elements. This suggests the possible usefulness of early experience with a system that may supply only modest amounts of power compared to the 5 GW of the NASA reference system. 2.2 IMPACTS ON INTERNATIONAL RELATIONS 2.2.1 SPS Security/Weapons The potential value of the SPS to our industrial capability and national economic system arises from the fact that by 2030 the SPS may be filling a significant part of the U.S. electrical power needs. Any attack on this high-valued asset by a major force would be considered an attack that flies in the face of the U.S. strategic deterrent force. Such an attack could mean that strategic 3/ deterrence had failed- and would lead the United States into decisions and actions involving the very weapons and forces that should have prevented attack but did not. These risks to the SPS and to strategic deterrence might be ameliorated by internationalizing the system and/or by reaching agreements declaring the SPS off-limits for military action. SPS strengthening (which may include a selfdefense system) could be made a part of the SPS to discourage and defend against small, unsophisticated attacks.—In the beginning, it will be difficult to determine —/ Information from the DARPA high-energh-laser space defense program would be helpful in projecting laser weapons capabilities and in defining approaches.
what the extent of any SPS defense system should be. It could start small and expand to fit the need as requirements are developed. At present, space law contains nothing to prevent the United States from stationing parts of its strategic deterrent system (and forces) at the SPS space site, as long as these parts do not include nuclear weapons or weapons of mass destruction.—Growth of a defended SPS may tend to be limited by the fact that as the military capability increases, the value of the already high-valued target becomes even higher. 2.2.2 Agreements/Disputes World communications have progressed to the point that populations in all parts of the world are becoming aware of resources, (such as solar flux, electromagnetic spectrum, and geostationary orbit) and want to share in their exploitation. The elctromagnetic spectrum and the geostationary earth orbit are limited resources. The breadth of the useful electromagnetic spectrum, limited by equipment performance, has increased significantly with the widespread development of ultraviolet, visible, and infrared systems. However, in many regions of the spectrum, particularly the microwave region, bandwidth is a carefully controlled, highly coveted commodity. In the allotment of bandwidth, extreme care is exercised to ensure that the assignment is in the public interest and will not be used in a manner that interferes with equipments on the same band or operating in other bands. For this reason, the use of any frequency/bandwidth used by the SPS will likely need to be cleared through an international organization. The geostationary orbit, because of its special characteristics, is a limited resource (there is only one around the earth). The number of slots available in this orbit for communication satellites, if collisions are to be prevented and occultations and radio interference avoided, has been bounded by the range of 180 3/ to 1800.- The number of satellites now using geosynchronous orbit is large (approximately 100) and growing. This growth in operating systems and the difficulty anticipated in reserving bandwidth for systems that are not scheduled should combine to expedite both the planning of SPS development and deployment schedules and an early determination of bandwidth requirements. The solar flux in space is not a limited resource but a flow of radiation that is continuous. However, the solar flux that can be intercepted in the geostationary orbit may have a practical limit. Figure 2.2 is a projection of the surface of the earth that shows some of the countries which a piece of the GEO path passing through their "extended air space"; the United States is not one of these countries. Satellites to serve the United States need to be placed over South America (where GEO passes over Ecuador, Peru, Colombia, and Brazil) and to the west as shown.
Figure 2.2 Area Over Which Geostationary Orbit Slots Needed To Serve U.S. Power Requirements Are Located NOTES RELATING TO ORBIT ASSIGNMENT: • Geostationary orbit is a limited natural resource--360 • Experts have bracketed number of slots at 180 to 1,800 (problems are mutual interference, collision, eclipse, etc.) • Part of GEO needed by U.S.* for power; approximately one-fourth of orbit, 45-450 slots available (must be shared with other countries of North, Central, and South America) • Other slots may be made available to U.S.* for power export • SPS will share the orbit with communications, navigation, data relay, weather, warning, and conservation satellites * May be a consortium of nations including the U.S. or an international business union satisfying U.S. interests.
To obtain the necessary bandwidth and orbit slots needed for U.S. power, it may be necessary to establish an international organization to design, produce, deploy, and operate an SPS that would provide power to all countries of North, Central and South America. The same organization might be able to create and support any military or civilian force needed to provide SPS protection. This organization could also include countries located in other parts of the world, as long as orbit slots and bandwidth are available on a ’'local” basis and other conditions of any agreements are met.— Most of the world's developing countries are located between 30° N. and 30° S. latitude, the region of the globe that is most easily served by an SPS from GEO. Many of these countries are small and have relatively small power demands. Countries in this region currently do not present a threat to the United States; however, within the time required to deploy the SPS, this situation could change-- particularly if one or more of these countries became allied with a larger country (U.S. adversary) and became a staging area(s) for it. It is also possible that SPS power, once available, could reverse the industrial and economic trends of some of these countries, allowing them to become real and significant partners or adversaries. 2.3 RELATIVE VULNERABILITY The vulnerability of the SPS to disruptive groups or to military forces is believed to be greater than for terrestrial electric power systems. Terrestrial systems are vulnerable to (a) air- and ground-delivered ordinance by military or terrorist groups, (b) military or terrorist groups that could take over operations, and (c) saboteurs within the SPS/utilities and support organizations. The systems are vulnerable at the generating site, in the power distribution system, and in 3/ the lines of supply- for fuel, spare parts, and other operating items. The power distribution and supply systems lend themselves to covert kinds of activity (sometimes part of a larger activity) that can precede open confrontation. The vulnerability of the rectenna site and the distribution system of the SPS is expected to be similar to that of terrestrial systems, except that the supply lines for the SPS do not deliver fuel to the rectenna. "Fuel" is supplied to the rectenna via a beam from the satellite in geosynchronous orbit. Therefore, on the basis of e/ — Several questions needing answers are: Should the organization include only friendly nations, or both friendly and not-so-friendly nations? What about the strategic arms limitations treaties? What part can onsite inspections play? What about questions of technology transfer?
a first-order evaluation, the relative vulnerability of the SPS to that of a terrestrial system reduces to a comparison of the vulnerability of the spaceborne parts of the SPS (and launch sites) to the vulnerability of the terrestrial system’s fuel supply line(s). The spaceborne segment of the SPS will be vulnerable to military attack and to the activities of sabotuers. Vulnerability to terrorist attacks is not likely for some time because such attacks would require the use of either a high-technology space transportation system or sophisticated ground-based equipment capable of destroying a target 36,000 km away. Launch sites are vulnerable in much the same way as the terrestrial power plants except that security probably would be better at the launch sites. There is likely to be at least a nominal effort to harden the satellite components and space transportation units against the hits and explosions of a military attack and the resulting environment. Hardening may be needed against interceptor and satellite killer impacts and explosions, nuclear radiation, high-energy laser and particle weapons, and electronic warfare waged to obstruct the flow of radiation or to compromise and/or gain control of satellite functions. Passive hardening is unlikely to be effective in all these areas; therefore, it is believed that dependable hardening against military attack will necessarily include an active SPS self-defense system unless other assets capable of defending the SPS are available for this function at the time of SPS deployment (see appendix B).
III. ANALYSIS AND EVALUATION Several major military implications were identified during the survey of relevant literature and related work. Results of an analysis of these implications are discussed in the following paragraphs. 3.1 WEAPON AND MILITARY PREPAREDNESS IMPLICATIONS The Satellite Power System (SPS) is designed to provide power for peaceful pursuits. As the SPS grows and is relied on by the United States as one of its prime sources of power, it will become a potential military target. Its significance as a potential target will grow in relation to the increasing power demands that it fills. Issues concerning the SPS as a weapon and/or a base for weapons, and as a source for fuel to the military, will need to be considered when scheduling its development and deployment. 3.1.1 Weapon Considerations As discussed previously, the SPS can be used as an electronic warfare weapon, an energy-beaming weapon, and a powered platform for weapons and weapon system segments. 3.1.1.1 Electronic Warfare Weapon During normal operation of the Microwave Power Transmission Subsystem (MPTS), noise could be introduced to discriminate against or to render ineffective transmissions in selected bands. During hostile periods, the beam could be defocused to affect a larger area; selected communications or other transmissions over an entire hemisphere could be degraded or blocked. Friendly forces having control of the beam could control noise content, beam spread, and times of noise transmissions. Microwave densities, from the defocused microwave beam, though significant when compared with the sensitivities of many microwave receivers, would be tolerable in terms of the levels (short-term and intermittent) that would be detrimental to health and the public welfare. For example, the microwave power from one 5-GW SPS radiated evenly over the projected area of one earth -5 2 hemisphere results in a density of approximately 5 x 10 W/m . 3.1.1.2 Energy-Beaming Weapon The familiarity of the general public with the concepts of high-energy laser (and particle) beams and their frequently cited ability to distribute deadliness and/or destruction has raised the question of the potential use of SPS power beams as weapons. For example, a target in a circular orbit below and 10,000 km from
the SPS traveling in the same direction of the SPS will have a velocity relative to the beam at the point of crossing of 1.16 km/sec (and 5.85 km/sec for a retrograde orbit). From the position of the SPS, these relative velocities represent angular rates of 0.1 16 and 0.585 mrad/sec, respectively. To follow a target of the lower angular rate a beam would have to be rotated about its origin at a rate of 360° in 895 minutes (0.4 degrees per minute), and the higher rate 2.0 degrees per minute. In orbits 1000 km below the SPS, these rates would be 0.36 to 20.7 degrees per minute. The angular rates of maneuvering targets or satellites in retrograde orbits at close range generally would be expected to exceed the track capabilities that could be designed into the MPTS. Targets traveling toward the SPS could be followed at much slower slew rates except at close range when a miss or ”fly-by” is involved (see figure 3.1). The effectiveness of an energybeaming weapon depends on the power in the beam, the beam intensity versus time profile, the angular cross-section of the beam, required beam acceleration and slew rates, and the accuracy to which a target can be tracked and the beam pointed. The tracking/pointing error of a system against a moving target (high information rate required) will usually be significantly greater than the error of that same system against a stationary or nearly stationary target (under mechanically damped low information rate conditions). 3.1.1.2.1 Microwave System The accuracy to which the microwave beam of the reference design can be pointed toward the rectenna site (table 2.1) is considered adequate for a ’’weapon mode" if this accuracy could be maintained during target track. The antenna, a low-density structure, is large and massive but probably could be used to track non maneuvering orbital targets at rates of one or so mrad/sec, provided target detection and/or designation is completed early enough to allow the antenna to be brought on target moving at the appropriate rate without exceeding acceleration limits as established by antenna structural characteristics and figure requirements. Figure tolerances may be as stringent as one tenth the wavelength (+0.1 A = + 1.22 cm) for a frequency of 2.45 GHz. From figure 2.1, it is only after a target has closed to within 12,000 km that irradiance on target is greater than one solar constant. Therefore, use of the microwave system in geostationary orbit (GEO) against earth and near-earth targets does not seem practical. However, at ranges of 4,000 km or less, the rate of temperature rise for highly absorptive targets being irradiated could be significant, causing a damaging heat buildup.
Figure 3.1 Some Examples of Possible Targets That Illustrate the Tracking Problem (Not to Scale)
It would be possible to increase the energy density on target and thus improve weapon capability by equipping the antenna with higher frequency transmitting units to be used during the weapon mode. Figure 3.2 is a plot of gain (G) in peak power on target versus frequency. (Curve is normalized to 2.45 GHz.) Assuming equal efficiency, power on target (using the I-km diameter antenna structure) can be increased by a factor of 100, for example, by increasing the transmitting frequency to 24.50 GHz.— This would reduce beam diameter by a factor of 10, but would decrease figure tolerances, and also decrease the track error allowed by factors of 10. The smaller, higher frequency transmitting units incorporating electronic scan would handle less power and thus would have to be used in greater numbers than the 2.45-GHz units, and the finer figure tolerances would be expected to require a beefed-up antenna structure. The increased number of transmit modules will result in more complex phasing circuits and the refined tracking accuracy will require more sophisticated track circuits and pointing controls. During operation in the weapon mode, power from the array would be switched from the 2.45- GHz klystrons to the higher frequency transmit units. These additions and modifications to the 2.45-GHz MPTS would increase its weight and cost significantly. From the foregoing analysis, it appears that the microwave system operating at 2.45 GHz would be relatively ineffective as an energy-beaming weapon, whereas use of shorter wavelength transmitting units and the large I-km diameter antenna would provide marginally effective results. The cost for either design based on weapon effectiveness probably would be prohibitive, except that with an operating SPS, a large part of the required equipment is already in place. Further study of the weapon potential of the MPTS is needed to identify specifically the feasibility issues and to estimate cost deltas. 3.1.1.2.2 Base for Weapons/Military Operations The SPS satellite’s location at GEO, its size, and the electric power that probably will be available at the site could make it an excellent location for a lookout post and for the deployment of energy-intensive weapons. However, for the lookout function to have greatest value, the satellite must be stationed over the right areas. Stationing such a satellite over the Indian Ocean near the U.S.S.R. or adjacent to other adversary nations without benefit of previous mutual agreements, would likely be provocative. An SPS in GEO used as a base for weapons, Higher frequencies also should oe practical.
Figure 3.2 Power on Target (Gain, a Ratio, Versus Frequency)
weapon system segments, and their integration into military operational scenarios will be a high-value target and vulnerable to attack, except as this vulnerability is reduced by U.S. strategic deterrence and the SPS self-defense system and/or a space defense system of more generalized capabilities. The deterrent concept is good until it fails, but in any case can provide added time, if needed, for selfdefense system development. The SPS structure may not represent an optimum location for some electronic systems because of the RFI/EMI problems that would result from operation of the SPS Power Transmission Subsystem (PTS) and the electric currents associated with the electrical power transmission system that is part of the solar array. The firing of projectiles or launching of missiles from the array platform depending on launch method could impart a velocity delta. Rotational and/or lateral velocities, contributed in this manner, would have to be compensated for by the SPS orientation and station-keeping system. These and other questions concerning the SPS self-protection system and use of the SPS as a platform for other weapons and as a support to U.S. military operations should be investigated in detail to determine technology problems, probable costs, schedules, and values and risks of these weapons and activities to the SPS itself and to international stability. 3.1.2 Preparedness The SPS could be made to contribute to military preparedness by incorporating into its design a weapon mode, by serving as a base for additional weapons and military operations, and by supplying power. The SPS could (1) contribute energy to U.S. activities and industry for a strong and productive economy, (2) provide power to friendly and adversary countries where this promotes U.S. interests and a favorable international stability, (3) supply power to the military, and (4) substitute electricity for portable fuels that then could be released to the U.S. military. The extent to which all these purposes could be served would depend on policy decisions and the SPS’s flexibility to service the variety of demands that make up the potential market for SPS power. In discussions with military representatives regarding military preparedness and SPS defense, the following comments/issues were raised: • The military is concerned about the availability of energy and would use direct SPS power for base operations. The Army may be interested in providing (I) the acreage needed for stable ground power conversion sites and (2) ground security.
• Scheduling early, smaller SPS systems will provide operational experience and allow defense requirements to be worked out incrementally (if defense is possible) before large SPS funding commitments are made. • The DOD should be brought into system planning and development as early as possible to support the identification of defense/mintary related issues and be ready to initiate any R&D required to resolve these issues. 3.2 IMPACTS ON INTERNATIONAL RELATIONS The impacts of the SPS on international relations will be both positive and negative. They will include weapons/military impacts, impacts related to the allotment of the rights to frequency and orbit resources, and impacts that result from large quantities of SPS power being made available for use, export, and control. It is probable that there will be SPS-related disputes to resolve, agreements to forge, and international organizing to do for some time to come. 3.2.1 Weapons Impacts Both the severity of the weapons impacts on international relations and SPS security will be related to the emphasis that is placed on weapons and military activity at the space site. These impacts will be good or bad, depending on the country in question and its own current self-centered interests. Freedom of space as now recognized, just as freedom of the seas, allows property to be escorted and protected as required. This freedom and the limited restrictions (nuclear weapons and weapons of mass destruction in space) should permit the gradual development and deployment of an effective and accepted SPS self-defense system. Weapons that provide a military advantage to the nation(s) in control of the SPS without introducing capabilities that tend toward weapon stability may, through the creation of suspicion, fear, and actual vulnerability to those nations not in control, accelerate the arms race. 3.2.2 Power Export/Power Embargoes The large power production capability of an SPS developed and deployed by the United States will provide a valuable export commodity provided that: • The necessary agreements can be reached ensuring the United States the required frequency, bandwidth, and orbit slots; • The SPS is designed with a flexiblity that allows it to serve export demands; and • The necessary agreements can be reached involving assurances relating to payments, reliability of power delivery (embargoes), and SPS system security (transmitting and receiving sites) between export/import countries.
3.2.3 Internationalization The more logical approach to developing and deploying the SPS from military and security considerations may be to internationalize it from the beginning. Security procedures could then be designed to distribute cost and responsibility among the members of the association of nations formed to exploit the SPS concept. The formation of such an association and the equitable distribution of costs, opportunities, and benefits should facilitate the forging of agreements to obtain needed orbit slots and frequency assignments. When considering the requirements and opportunities for agreements and/or for internationalization of the SPS, several facts stand out. • From figure 2.2 it can be seen that the part of the geosynchronous orbit that is of greatest interest to the United States is approximately one-fourth of the orbit that passes over South America and west of it. • This location is on the other side of the world from the U.S.S.R. and China. Military equipment (and forces) in space protecting SPS and monitoring this region of the world should not cause a maximum level of U.S.S.R./China concern. • Although South and Central American countries would be easy targets, they are not logical U.S. targets. • The U.S.S.R. land mass is one of the least favorable locations with respect to a satellite in geosynchronous orbit for receiving power. The long atmospheric transmission paths and the oblique surface of the earth at this location (relative to a line from GEO) may combine to make SPS service to a large part of Russia marginal. A low earth orbit (LEO) relay SPS may be of more interest to Russia.^/ 3.3 RELATIVE VULNERABILITY Communication satellites located in GEO are considered by some to be vulnerable to direct ascent interceptors and to orbiting satellite killers. The COMSAT’s prime power, control, and electronic systems are also vulnerable to nuclear radiation and to high-energy laser and particle-beam weapons. The SPS, being much larger, is usually considered to be more vulnerable and, like the communication satellite, can be vulnerable to overt military attack in space and on the ground. Actually its size may permit the use of such techniques as redundancy, g/ — The orbits used for this LEO SPS could be selected to satisfy both energy distribution and military objectives.
breakaway structures, placing of decoys of vital aim points at many places on the structure, and other countermeasures to make the SPS less vulnerable than a COMSAT. The large platform of the SPS will also allow the use of larger electronics that are more resistant to radiation such as bipolar devices for some electronics applications instead of the smaller, more vulnerable LSI semiconductor 12/ circuits.— It will also allow some of the more sensitive components to be placed beneath structure to avoid damage due to natural radiation or nuclear radiation from a weapon or test explosion. Hardening against lasers, particle beams, and missiles may be used to control damage and thus require an enemy to come within range of an SPS self-defense system. The SPS transportation system will include the Heavy Lift Launch Vehicle (HLLV), the Personnel Launch Vehicle (PLV) and the Cargo-and Personnel-Orbital-Transfer Vehicles (COTV and POTV). The vulnerability of the personnel vehicles will be a function of vehicle hardening and lifesupport system design, whereas the vulnerability of cargo vehicles will be a function of the hardening techniques used, escort policy/capabilitv, and vehicle velocity (trip duration). For more information concerning the impact of hostile environments on the SPS, see appendix B. The rectenna site is vulnerable to ordinary ground attack but probably can be designed so that its performance degrades gracefully. Vulnerability can be reduced by placing much of the power distribution and heavy power-handling equipment underground at the rectenna site and by closely controlling design and site layout data. Care given to the security aspects of the design (controls and data handling/processing equipment) can reduce the risk of SPS equipment takeover by hostile forces. For the most part terrorist attacks will be limited to ground facilities. Attacks could be launched against the rectenna site, ground-based space transportation facilities, power distribution system, and ground-based supply lines for SPS materials and spares. Terrorist attacks against SPS space assets are conceivable but probably will not be important considerations until equipment such as high-energy laser and/or particle-beam weapons can be acquired by such groups or until earth-space transportation is commonplace. Sabotage of the system is more likely and can occur on the ground or in space. Losses due to sabotage can be controlled through internal security, employee screening, and the enforcement of harsh penalties for sabotage at SPS, utility, and support organizations.
IV. KEY ISSUES AND GENERAL OBSERVATIONS During the study several key issues were identified and observations were made concerning the military implications of the SPS. These are noted in the following paragraphs. 4.1 WEAPON AND MILITARY PREPAREDNESS IMPLICATIONS As a weapon the microwave power transmission subsystem (MPTS) may have some applications as a noise generator in an electronic warfare role. Its applications as an energy-beaming weapon are limited in the current NASA reference system configuration because of the low-power density in the microwave beam and the large massive antenna that would need to be moved to follow the target. A geostationary (GEO) location of the NASA reference system maintains the satellite and any weapons capability stationary over a single spot on earth. Military preparedness will be supported by the SPS in the following ways: • Strengthen the civilian/industrial sector allowing more effective technology, production, and capital support to the military; • Free portable fuels required for military mobility (and stockpiling); • Provide electricity to military ground installations through the utilities; and • Supply markets for electricity and thus strengthen mutual security bonds and reduce tensions. Large, powered, platforms for weapons can be provided by the SPS at several different GEO locations. Weapons or weapon systems segments could include sensors, communications, and laser/particle beam weapons; projectiles/missiles; and electronic warfare and data-handling systems. The platform, reinforced and modified, could be made to provide storage, housing, etc. This additional mass would result in a larger load on the SPS station-keeping system. Each deployment of modestly sized SPS's would provide operational experience and allow any needed SPS defense system to start small and grow to be compatible with risk. In this manner the ability of the SPS to be defended could be determined before making large resource commitments. 4.2 INTERNATIONAL RELATIONS International relations could be affected as a result of: • Disputes between nations with regard to the international agreements that must be made concerning solar flux at GEO, frequency, orbit, power export, security, etc.;
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