NASA Contractor Report 3349 Satellite Power System Salvage and Disposal Alternatives CONTRACT NAS8-33783 NOVEMBER 1980
Digitized by the Space Studies Institute - ssi.org
NASA Contractor Report 3349 Satellite Power System Salvage and Disposal Alternatives ECON, Incorporated Princeton, Netv Jersey Prepared for Marshall Space Flight Center under Contract NAS8-33783 National Aeronautics and Space Administration Scientific and Technical Information Branch 1980
This report is submitted in fulfillment of the requirements of Contract No. NAS8-33783. It provides a "first-cut" assessment of the salvage and disposal alternatives for both the demonstration and full-size SPS satellites. The ECON study manager for this study has been Dr. George A. Hazelrigg, Jr. Mr. Joel S. Greenberg also contributed to the study. The Marshall Space Flight Center’s contracting officers technical representative was Mr. Georg F. Von Tiesenhausen. FOREWORD
TABLE OF CONTENTS List of Figures v List of Tables vi 1. Introduction 1 1.1 Background 2 1.2 Approach 4 1.3 Results 9 1.4 Conclusions and Recommendations 13 1.5 Backup Documentation 15 2. A Post-2000 Mission Model 16 2.1 The Period 2000 to 2030 22 2.2 The Post-2030 Time Period 26 3. SPS Demonstration Satellite Salvage Alternatives 28 3.1 Growth to Full-Scale Satellite 33 3.2 Demonstration Satellite Use as a Power Supply for Non-SPS Space Activities 37 3.3 Power Supply for a Laser Orbit-to-Orbit Transportation System 46 3.4 Source of Space-Based Materials 49 4. Full-Scale Satellite Salvage Alternatives 50 4.1 Salvage for SPS Reuse 50 4.2 Power Supply for Non-SPS Space Activities 52 4.3 Power Supply for a Laser Orbit-to-Orbit Transportation Systems 53 4.4 Power Supply for Laser-Propelled Aircraft 54 4.5 Asteroid Capture and Mining 57 4.6 Source of Space-Based Materials 59 4.7 Miscellaneous Salvage Uses 60 4.8 Continued Use 61 5. SPS Salvage Value 64 5.1 SPS Demonstration Satellite Salvage Value 64 5.2 Full-Scale SPS Satellite Salvage Value 66 5.3 Programmatic Implications 68
6. SPS Disposal 71 6.1 Disposal Alternatives 71 6.2 Disposal Costs 78 Appendix A Supporting Data for Value of the Demonstration Satellite Used as a Power Source for Other Activities 80
LIST OF FIGURES Figure Page 1.1 Reference Satellite Configuration 2 1.2 Salvageable SPS Mass and Generation Capacity 5 2.1 Geostationary Satellites—To Date and Planned 19 2.2 Potential Space Activity Levels, 1980-2060 21 2.3 Historical and Projected Growth of Spacecraft Power and Lifetime 25 3.1 SPS Demonstration Satellite in Final Phases of Construction 29 3.2 Full-Scale Operational SPS Satellite Configuration 30 3.3 Salvage Value--Growth to Full-Scale Satellite 34 3.4 Present Value of Demonstration Satellite When Used as an Initial Element in a Full-Scale Satellite 38 3.5 Supply & Demand for Power from Demonstration SPS Satellite 39 3.6 Salvage Value--SPS Demonstration Satellite Used as a Source of Power and Other Subsystems for Other Activities 40 3.7 Salvage Value of the SPS Demonstration Satellite When Used as a Source of Power for Other Activities 45 3.8 Salvage Value of SPS Demonstration Satellite When Used as a Source of Power and Other Subsystems for Other Activities 45 3.9 LEO to GEO Traffic Growth 48 4.1 Continued Use SPS Salvage Value 62 4.2 The Decision to Decommission an SPS Satellite 63 5.1 Summary of Demonstration and Full-Scale Satellite Salvage Applications 65 5.2 Programmatic Implication of Demonstration Satellite Salvage Value 69 6.1 Lagrangian Points in the Earth-Moon System 73 6.2 EOTV Configuration 76 6.3 Alternative Trajectory Modes 77
LIST OF TABLES Table Page 1.1 Reference Satellite Characteristics 3 1.2 SPS Satellite and Rectenna Salvage Value 10 1.3 Disposal Options and Costs 13 2.1 Traffic to Support GEO Platforms 26 3.1 Demonstration Satellite Cost Structure 31 3.2 Mass Properties of Full-Scale and Demonstration SPS Satellites 32 4.1 Current Oceanic Air Traffic 55 4.2 Characteristics of Amor and Apollo Asteriods 58 4.3 Value of SPS Satellite Materials--GaAs, CR=2 60
1. INTRODUCTION SPS system cost and trade studies conducted to date have, by and large, assumed a 30-year satellite life with zero net salvage value at the end of that time. Many factors make this assumption inappropriate: 1. The SPS satellite represents a very large source of power in geosynchronous orbit that might be put to many uses, such as: • Power for other space-based platforms, satellites, habitats, manufacturing facilities, bases, etc. • Power for laser transportation systems including geocentric space, earth escape and laser-powered aircraft • Power for a large, low-thrust space transportation system for missions such as asteriod recovery • Power for space-based science such as particle physics. 2. The SPS satellite represents a large supply of subsystems and components for use in other space activities such as: • Spares and materials for other SPS satellites • Solar arrays and other components for non-SPS satellites. 3. The SPS satellite represents a fairly large source of raw materials located in geosynchronous orbit that might be recovered and put to use either in space or returned to earth for reuse. The first SPS satellite will approach the end of its useful life around the year 2030; some 30 years sooner, the SPS demonstration satellite will have served its initial purpose. The demonstration satellite represents a somewhat similar, albeit considerably smaller, resource. To the extent to which there develops a demand for energy, SPS-like subsystems and raw materials in space, one can expect that SPS will derive some salvage value. If, on the other hand, no such demand develops, the SPS satellite will have to be removed from geosynchronous orbit (GEO), either for storage and
possible later salvage use or for permanent disposal. In this case it is important to have estimates of the cost of SPS satellite disposal. The objectives of this study are to find potential salvage uses for both the SPS demonstration and full-scale satellites, to determine the satellite salvage values for each potential use, to prioritize these uses in order to determine likely salvage value per satellite as a fraction of satellite capital cost and to determine the cost of disposal for unsalvaged satellites or portions thereof. 1.1 Background The salvage uses and values and disposal costs estimated in this study are based on the Rockwell International SPS satellite configuration and development program. The basic satellite configuration is shown in Figure 1.1 and its major pnysical characteristics are provided in Table 1.1. The satellite uses gallium aluminum arsenide solar cells with a concentration ratio of 2 and a graphite composite structure. FIGURE 1.1 REFERENCE SATELLITE CONFIGURATION
The development and implementation program for this satellite calls for deployment of a geosynchronous demonstration satellite, with a power generation capability of 335 MW at beginning of life, early in the year 1999. Shortly thereafter, the demonstration satellite is grown into a full-scale satellite with a generation capability (in space) of 9.53 GW (8.92 GW' power into the microwave antenna). The first full-scale SPS satellite becomes operational late in the year 2000. Following the first full-scale SPS, the reference program calls for bringing two 5 GW systems on line each year, beginning in the year 2001, until a total of 60 systems, 300 GW capacity, are installed. TABLE 1.1 REFERENCE SATELLITE CHARACTERISTICS*
Using the above program plan, the demonstration satellite becomes available for salvage early in the year 2000 and full-scale SPS satellites become available for salvage at the rate of two per year beginning late in the year 2030. Concurrent with the full-scale satellites, the rectenna also becomes available for salvage, it is possible that the rectenna will be used for a subsequent SPS if the program continues. If this is the case, some amount of refurbishment may be necessary and/or desirable, thus allowing evolutionary changes in the satellite portion of the system, such as beam power density, beam shape and size, frequency and polarization. In any event, rectenna reuse may be considered to be a salvage use. Figure 1.2 shows the amount of SPS materials which will have become available for salvage as a function of time. The utilization of geosynchronous orbit in the post-2000 time period is likely to be quite intense. Thus it is likely that any structures or satellites that are placed in this orbit will have to be removed upon completion of their useful life. Accordingly, any unsalvaged SPS-related structures, facilities or satellites will have to be disposed of at the end of their useful life. 1.2 Approach It is clear from Figure 1.2 that all salvage and disposal activities will occur in the post-2000 time period. Salvage or disposal of the demonstration satellite will occur somewhere in the 2000 to 2010 time period; salvage or disposal of full-scale satellites will begin sometime after 2030 and continue at least through 2060. In order to make any estimates of salvage uses and salvage values, it is necessary to place the potential salvage activities into the context of a space program. Thus it is necessary first to establish a mission model for the period 2000 to 2060 as a basis for analysis. Obviously any such mission model will suffer from major uncertainties and, in the end, one can identify only certain long-term trends without becoming specific about particular missions.
CALENDAR YEAR (a) CUMULATIVE SALVAGEABLE MASS (b) CUMULATIVE SALVAGEABLE GENERATION CAPACITY FIGURE 1.2 SALVAGEABLE SPS MASS AND GENERATION CAPACITY
The generic trends which one can identify today that are likely to carry over into the 21st century include mainly an '’industrialization" of §pace; that is, a gradual transition from government-funded activities primarily of a research nature to activities promoted and conducted in the private sector because they are profitable. It is likely that these activities will be encouraged by significant reductions in the cost of space-based activities resulting from a transition to the Space Shuttle and more advanced space transportation systems, and by the introduction and proliferation of multipurpose platforms. Much of the activity in space in the post-2000 time period will take place in geosynchronous orbit. This activity is likely to generate a considerable amount of low earth orbit (LEO) to GEO traffic, independent of SPS. There is also likely to be considerable other geocentric traffic, however, including LEO to GEO, GEO to GEO and lunar traffic, as well as earth escape traffic. Within the context of these space activities, potential salvage uses for both the SPS demonstration satellite and full-scale SPS satellites were identified and evaluated. It is not clear today that the SPS demonstration will be a success; that is, that upon completion of the demonstration satellite project, it will be found desirable to proceed with construction of full-scale SPS satellites as planned. (If it were known today that the demonstration would be successful, it would be unnecessary.) Thus salvage uses of the demonstration satellite need to recognize that there may or may not be a continuing SPS program. On the other hand, salvage of full-scale SPS satellites will occur only if there is an SPS program and, consequently, the salvage uses for full-scale SPS satellites are appropriately identified in the context of a space program which includes SPS. Such a program clearly requires a space transportation system that can inexpensively transport large amounts of materials to geocentric space, and it includes
capabilities in large space structures, space-based construction, manned LEO and GEO facilities, and so on. These capabilities infer such space-based activities as space manufacturing, the utilization of large applications platforms, lunar exploration and exploitation, and physics and astronomy. The above space-based activities lead to identification of the following potential salvage uses: Demonstration Satellite • Growth into full-scale SPS satellite (Rockwell International reference program plan, applicable only if the demonstration is successful) • Use as a source of power for other space activities such as GEO platforms, a manufacturing base or an electric orbit transfer vehicle • Use as a power supply for a laser space transportation system • Use as a source of raw material. Full-Scale SPS Satellites • Use as spares and materials for other SPS satellites • Use as a power supply and platform for other space activities such as platforms, a manufacturing base, a lunar base or space habitats • Use as. a power supply for laser transportation systems including geocentric space, especially LEO to GEO, earth escape and aircraft on oceanic routes • Use as a power supply to recover Amor and Apollo asteriods • Use as a power supply for a high-energy, high-vacuum physics laboratory in space. Next, the salvage value of the SPS satellites was estimated for most of the above potential uses. In all cases the salvage value is taken to be the present value of the cost savings afforded by the salvage use referenced to the initial operation date of the salvaged article. The discount rate used throughout this study is a real (i.e., inflationary effects removed) rate of 4 percent. Thus, the salvage values presented represent the effective amount by which the capital cost
of the satellite is reduced because it will provide a positive net salvage value. The present value of SPS revenue requirements, reflected in the SPS charge rates, may accordingly be reduced by this amount. For example, if it is found that the salvage value of an SPS satellite is equal to ten percent of the capital cost of the satellite, then the annual capital carrying charge for the satellite, for purposes of comparison to alternative systems, may be reduced by ten percent. Any SPS satellites or portions thereof which are not salvaged will, in all likelihood, have to be removed from geosynchronous orbit. An objective of this study is to estimate SPS satellite disposal costs. To do this a number of disposal alternatives were identified, the velocity requirements for each were estimated and then the costs of each were determined. SPS disposal costs include four major cost categories: cost of propellant, cost of transporting the propellant to GEO, cost of modifying the SPS satellite as necessary (mainly installation of thrusters, tankage and controls) and the cost of mission operations. Cost estimates provided are based on the assumption that the satellite is disposed of intact. Wherever possible cost estimates used in this study were derived from the * SPS Concept Definition Study performed by Rockwell International, and are in 1977 dollars, consistent with this report. Thus while these cost estimates contain considerable uncertainty, the variation in estimates of salvage value and disposal costs are likely to approximate the variations in satellite captial costs. Hence the estimates provided can be taken to be relatively firm when viewed in comparison to the capital cost estimates. Satellite Power Systems (SPS) Concept Definition Study, System Engineering, Part 2 (Cost and Programmatics, Rockwell International Report No. SSD 79- 0010-2-2, March 1979.
1.3 Results Discussion of the results is appropriately divided into four parts: salvage value for potential salvage uses of the demonstration satellite, salvage value for potential salvage uses of full-scale SPS satellites, salvage value of rectennae and disposal costs for the demonstration and full-scale satellites. The major study results are summarized in Table 1.2. Two principal salvage uses for the demonstration satellite are apparent: growth to a full-scale satellite and use as a power supply for a laser space• transportation system. Obviously, the former use applies only if the demonstration program is a success; that is, if it is found desirable to continue the SPS program beyond the demonstration phase. If this salvage use is implemented, the salvage value of the demonstration satellite is about 80 percent of the on-orbit cost of the salvageable hardware. Since almost all of the demonstration satellite is salvageable (except perhaps the ion thrusters and associated systems used to transport it from LEO to GEO), one can take the salvage value to be essentially 80 percent of the on-orbit cost of the demonstration satellite. The reason that the salvage value of the demonstration satellite is not 100 percent of its cost is because of the time value of money (discounting) and the time delay between investment in the demonstration satellite and start of construction of the full-scale satellite. The second principal salvage use of the demonstration satellite, use as a power source for a laser space transportation system, is a viable salvage use whether the demonstration program is a success or not. The salvage value for this use derives mainly from cost savings in the cost of transporting chemical propellants from earth to LEO for use in LEO to GEO transportation of personnel and logistics. The considerably higher specific impulse of a laser rocket permits about a 70 percent reduction in the mass of propellant that must be transported to
TABLE 1.2 SPS SATELLITE ANO RECTENNA SALVAGE VALUE
LEO compared to chemical rockets. The availability of a multi-100 MW power supply enables laser rocket transfer times from LEO to GEO to be quite comparable to chemical rocket transfer times. The value of a laser space transportation system is clearly dependent upon the amount of LEO to GEO and other geocentric space traffic. If the SPS program does not proceed beyond the demonstration phase, the bulk of the geocentric traffic will be in support of geosynchronous platforms, providing the salvage value shown in Table 1.2. If the SPS program continues into an operational phase, however, the value of a laser space transportation system is substantially greater. Particularly with a continuing SPS program, the laser space transportation system appears so attractive that it is likely that it will be developed and used independent of what is done with the demonstration satellite. Many potential salvage uses of substantial value exist for full-scale SPS satellites. Their value, however, is very uncertain due to the fact that these uses occur 50 to 80 years in the future. The uses which appear to be most attractive include laser transportation systems, both space-to-space and for aircraft on oceanic routes, as a power supply to recover Amor and Apollo asteroids and, although not quantitatively evaluated, as a power supply for a high-energy, high-vacuum physics laboratory in space. It is conceivable that these uses, plus other less exciting salvage uses such as power for a space manufacturing base or space habitat, could provide sufficient demand for salvage use of an entire fleet of 60 5GW SPS satellites. The SPS rectennae will most likely all be salvaged. The salvage will include recovery of steel and aluminum which have a combined value of about $290 million (at current prices) less removal cost plus recovery of the land. Taking the removal cost to be 25 percent of value (and adding discounting) the net salvage value of
these materials would be about $67 million. It is likely, however, that the cost of removing the concrete for recovery of the land would be approximately equal to the net value of the steel and aluminum. Thus the principal salvage value of the rectennae is likely to be the present value of the land referenced to the initial * operation date of the system. This is approximately $33 million at a land value of about $1,000 per acre. A more valuable salvage use of the rectennae would be their reuse with new SPS satellites. In this case, especially if existing concrete footings and other components are reusable, the salvage value of the rectennae could approach 30 percent of their new cost. Since the rectennae cost represents about 26 percent of the total SPS cost of about $13.9 billion, this value could approach $1.1 billion. If only land and the rectenna support structures are salvageable, the salvage value is about $620 million. This lower number allows substantial evolution to occur in the rectenna technology. Finally, those items which are not salvaged must be disposed of. The disposal options considered and their respective costs are given in Table 1.3. Five disposal options are considered. Disposal to or Ly the stable (equilateral) libration points in the earth-moon system would provide a location where the satellites might be recovered at some point in the distant future and salvaged for some, presently unknown, use. No stationkeeping or control of the satellites would be necessary once they are in this orbit. The second disposal option presented is to boost the satellite to an orbit above GEO. Twice GEO is presented arbitrarily. The AV required is obviously a function of how high the satellite is boosted and the value provided is nominal. This orbit could utlimately require some stationkeeping * Corresponds to WBS item 1.4.1.1.1 in the Rockwell International cost estimate.
TABLE 1.3 DISPOSAL OPTIONS AMD COSTS activity; however, this activity might be very minimal (once every 1000 years, for example, depending on requirements). The third and fourth options dispose of the satellite forever by removing it from geocentric space. These could be desirable options if it becomes important to assure that no future concern need be given to the satellite. The final disposal option, earth reentry, is probably the least desirable from not only the aspect of cost--it requires the highest velocity increment--but from environmental and risk concerns as well. This disposal mode is unlikely to be implemented. 1.4 Conclusions and Recommendations The conclusions and recommendations with respect to the demonstration satellite are as follows. The preferred salvage use is to use the demonstration satellite as a power source for a laser space transportation system. This will require installation of a laser power transmitter on the satellite. Accordingly it is recommended that the demonstration satellite be equipped with both a microwave
power transmitter and a laser power transmitter and be used to demonstrate both SPS configurations. Upon completion of the demonstration, the microwave power transmission system could be salvaged for use on a full-scale SPS satellite if the microwave SPS option is found desirable. The demonstration vehicle, however, would remain in GEO and, using the laser power transmission system, power laser rockets for LEO to GEO transportation. The value of the recommended salvage use is strongly dependent on the continuation of the SPS program, but even in the absence of a continuing SPS program, it appears sufficient to justify the development of a laser space transportation system exclusive of the SPS demonstration project. For planning purposes it is reasonable to assume that this salvage use will offset about 80 percent of the on-orbit cost of the demonstration satellite hardware. The conclusions and recommendations with respect to the full-scale satellites are as follows. Several potential salvage uses exist for full-scale SPS satellites, each with a salvage value ranging up to about $3 billion. Preferred salvage uses appear to be use as a power supply for a laser space transportation system, use as a power supply for powering aircraft on oceanic routes, use as a power supply to recover Amor and Apollo asteroids and use as a power supply for a high-energy, high-vacuum physics laboratory in space. The average salvage value of an SPS satellite appears to be in the range of 5 to 10 percent of the satellite capital cost or about $500 million to $1 billion. Some specific uses, however, may provide significantly higher salvage values, but they are likely to be limited to only a few satellites. A basic theme which seems to dominate the salvage value results is that the uses which utilize the entire satellite intact have a higher value than those which require segmenting the satellite. The more the satellite is cut up, the less it appears to be worth as salvage.
In any event, if it becomes necessary to dispose of SPS satellites, a number of disposal options appear feasible. The cost of disposal is on the order of $100 million. This amount has a present value referenced to the initial operation date of the satellite of about $30 million or only about 0.3 percent of the capital investment cost of the satellite. It is clear from the above analysis that an assumption of zero net salvage and disposal cost for the SPS satellites is conservative. A less conservative assumption, for purposes of comparing SPS to alternative systems, would be to take a net salvage value between 5 and 10 percent of satellite capital investment cost. 1.3 Backup Documentation The remaining sections of this report provide backup documentation to the results shown above. Both in review of the backup documentation and interpretation of the above results, the reader should keep in mind that the analyses and results presented here are based upon long-range projections of space and other activities and thus contain considerable uncertainty.
2. A POST-2000 MISSION MODEL Oscar Morgenstern once said, "Predicting things is very difficult, especially the future." Yet, if one is to establish the salvage value of SPS demonstration and full-scale satellites, one must describe the environment within which these satellites are salvaged. At the very least, this means identifying a space mission model for the time period during which the salvage operation will take place. Basically this time period may be divided into two parts: the years 2000 to 2030 during which time the principal object of salvage is the SPS demonstration satellite; and the period 2030 to 2060, and possibly beyond, when full-scale SPS satellites would become available for salvage. To begin with, one should recognize that these time frames, at least in terms of specific economic projections, are quite far in the future. The earlier time frame begins 20 years from now and spans a period of 30 years, ending half a century from today. The second period, beginning in the year 2030, is a period of projection that is one-half a century and more in the future. On the scale of life of five-year and ten-year plans, and of long-range planning that does not go beyond the end of the 20th century, it is, for all practical purposes, impossible to develop a mission model containing specific space missions. Rather, over the period 2000 to 2030, projections of space activities are highly uncertain, although there is some hope to identify and establish general trends. These trends can be identified on the basis of existing technologies and technology projections for the relatively near term. For example, an operational space transportation system based on the Space Shuttle and advanced Shuttle derivatives is likely to lead to reduced costs for space activities and, subsequently, to an increasing level of commercial business in space.
Furthermore, there is some hope for identifying the major directions which this “industrialization of space" will take. Beyond the year 2030, however, one’s ability to project even general trends diminishes greatly. A fifty-year period is sufficient for major new and totally unforeseen technologies to develop and become commercialized. Without specific knowledge of these technologies (and that knowledge cannot be had today), projections of post-2030 space activities are entirely speculative. It is with the above qualifications that the following projections of future space activities are made. The first steps in making a long-range projection of space activities is to determine where the impetus for such activities will arise. At the present time funding for space activities derives almost entirely from national governments; principally the U.S. and U.S.S.R. U.S. Federal Government expenditures on space, * spanning both DOD and NASA, encompass about $6 billion for FY 1980. Looking at free world activities and taking this $6 billion to be a measure of free world government sponsorship of space activities and assuming, furthermore, that at the very most this government sponsorship is unlikely to accelerate at a real rate of growth greater than 3 percent per year, one sees a potential level of government- sponsored activitiy in space by the year 2060 of only some ten times larger, or $60 billion per year (1980 $), than the present amount. A space program sponsored only by NASA and DOD (assuming that they exist in the year 2060) at the level of $60 billion per year could possibly support some salvage activities on SPS satellites, but they would be severely limited. It is highly unlikely, however, that one would be faced with the problem of salvaging SPS satellites in a space program that is principally funded by NASA and DOD, and to a lesser extent by other governments. The simple fact is that one The Budget of the United States Government, Fiscal Year 1980.
would not be concerned about salvage of SPS satellites unless an SPS program is indeed implemented. Furthermore the presence of an SPS program infers, in itself, the successful development of a number of space-based technologies that should lead to widely expanding use of space by the private sector. The transition from federal funding to private sector funding for space activities is already evident with communications and information satellite programs, and the acceleration of these trends due to improved space transportation technologies is clearly forthcoming. The successful implementation of an SPS program assures that highly advanced technologies in low cost space transportation including both earth to LEO and LEO to GEO will have been successfully developed. In addition, technologies for the construction and deployment of large-scale space structures, long duration manned facilities and low cost solar cells are assured. These technologies will be available by about the year 2000, or at the time of implementation of the SPS system, and will thus contribute to the economic development of space in the intervening period (2000 to 2030). At the present time the private sector is making significant strides forward in space-based activities with a focus on communications and data gathering. Present communications activities in the private sector include not only COMSAT (a quasi-private sector organization) but a number of U.S. corporations such as Western Electric, RCA, IBM and so on. These activities should begin to mature around the year 2000 with the implementation of large communications platforms in geosynchronous orbit. Both these and lower altitude platforms will also probably be implemented by the private sector for data collection. The data collection systems will include both natural resources and environment monitoring such as the LANDSAT and SEASAT satellites have done to date. It is conceivable that the communications industry alone could grow to a level of expenditure of between
$15 billion and $100 billion per year by the year 2060, and that data collection activities would be on the order of $10 billion to $100 billion per year by that time. Space-based communications expenditures are likely to grow in order to handle personal communications, business data transfer and video communications including teleconferencing. The advantages of teleconferencing in business applications are fast becoming apparent and this mode of communication is likely to supplant a significant fraction of business travel. It is an interesting aside to note that advanced communications activities such as this are highly energy conservative. By the year 2060 it is conceivable that between 30 and 60 large communications platforms will be in place, many in geosynchronous equatorial orbit, but some in other orbits to serve more extreme latitudes. The present desire for geostationary satellites is clearly shown in Figure 2.1. By the year 1990 some 150 satellites will have served various functions, mostly communications, in that orbit. FIGURE 2.1 GEOSTATIONARY SATELLITES—TO DATE AND PLANNED
As data collection in space becomes an economic reality, it is rapidly found that satellites can produce prodigious quantities of data. A single advanced earth resources satellite, for example, might produce as much as 10 bits of data per second. Clearly, no human will ever examine all of the available data. Thus it is reasonable to expect a substantial amount of space-based data processing in order to reduce these data to an informational level upon which decisions can be based. Space-based data processing in large (by current standards) computers, co-located with the data collection sensors in space, thus enabling the communications link with earth to carry minimal amounts of processed data, is likely. An intriguing and totally unpredictable area of space activity is space-based manufacturing. Space, of course, offers a unique environment including high vacuum and zero gravity which should be of considerable benefit to particular manufacturing processes. The unfortunate fact at this time is that since this environment has heretofore not been available to the private sector, the technology for using it has not been developed. As a result, to date, NASA and others have studied a variety of products that might potentially be manufactured in space and found that indeed there may be benefits in doing so. Unfortunately there is a considerable time lag between today and the date at which commercial spacebased manufacturing facilities will be available to the private sector. Thus the principal conclusion to which one might arrive is that there are many potential products that could be beneficially manufacturered in space, but none of them are the products that have been examined to date, nor are they products that one would choose to manufacture in space based upon what is known today. Accordingly the annual expenditures on space-based manufacturing is highly uncertain at this time. Conceivably they could be as low as a fraction of a percent or as high as possibly 10 percent of the gross national product, say a range of $10 billion to $500 billion per year.
The third major category of private sector activity in space is energy. If SPS is implemented, these expenditures will be quite high. For example, the operation and maintenance expense on a fleet of 60 SPS satellites will be on the order of $30 billion per year. Capital construction of new SPS satellites could add another $20 billion to $50 billion or more to this amount. Worldwide implementation of SPS on a large scale plus construction of space-based energy systems for lunar exploration, asteriod retrieval and space habitation could increase this amount to as much as $250 billion per year. In addition to the above four categories of space-based activities, there are a number of other activities that are likely to occur in space. These include physics and astronomy, solar system exploration, basic and applied research, space tourism, space-based navigation systems and so on. These miscellaneous activities are likely to involve expenditures in the range of $5 billion to $50 billion per year by the year 2060. Summing these figures as shown in Figure 2.2, the private sector potential activities in space range from a low of about $65 billion per year in the year 2060 to a high of about $1 trillion per year. FIGURE 2.2 POTENTIAL SPACE ACTIVITY LEVELS, 1980-2060
The major observation which one draws from Figure 2.2 is that dramatic growth in space-based activities, if such growth indeed occurs between now and the year 2060, will derive mainly from private sector ventures undertaken because they are economic. The challenge to NASA is to focus space programs between now and the year 2000 in such a way as to promote the economic utilization of space. Given the proper opportunities, it is conceivable that as much as 20 percent of the gross national product in the year 2060, or say $1 trillion per year, will be derived from space-based activities. On the other hand, without proper encouragement and technology development from NASA and other government agencies, this amount could be very much smaller and the government could still dominate annual expenditures on space activities as late as the year 2060. 2.1 The Period 2000 to 2030 In the context of the above discussion, it is possible to make useful observations on space-based activities during the period 2000 to 2030. A principal activity in space during this period will quite clearly be space-based communications, data collection and data processing. It is also evident that the current trend of placing an ever increasing number of relatively small satellites in geosynchronous orbit cannot continue. Communications and data needs will be satisfied in the future by the use of large geosynchronous platforms rather than by a number of smaller satellites. Accordingly the following general trends are identified for the post-2000 time period: 1. Space will be populated with fewer larger spacecraft. This will be accomplished by transition to large mutli-purpose platforms. 2. Bandwidth limitations will be overcome by using higher power levels and spot beams. 3. Multi-purpose platforms will not be co-located with SPS due to conflicting requirements such as the potential need for turning SPS satellites out of the sun during maintenance periods.
4. Mutli-purpose platforms will occupy many important orbits, not only GEO. 5. On-orbit servicing capability will be maintained for all multi-purpose platforms. Because of their high value, downtime on these platforms will be extremely expensive. The balance between man and robotics for providing on-orbit servicing capability is very uncertain at this time. 6. Many activities in space will be internationally sponsored, and it is likely that large geosynchronous platforms will be considered multinational territory. 7. Many of the activities performed in space in the post-2000 period will be performed there because it is economic to do so independent of government funding. These activities will thus represent a significant transformation of space-based activities from the government to the private sector. 8. A fully reusable space transportation system and multi-purpose platforms will dramatically lower the cost of the space activities and thus promote increasing private sector investments in space. 9. System complexity will shift from the ground segment where it is presently to the space segment, enabling ground-based users to participate in the use of space-based communications and data collection with relatively low investment. However this does not infer that the majority of expenditures on a particular system will be on the space segment. To the contrary, the lowering of costs for ground-based users is likely to increase the number of ground-based users dramatically, thus maintaining the preponderance of expenditures on the ground segment. For example, if the worldwide market for personal communicators at $100 per communicator is 100 million units, a total expenditure on the ground segment of some $10 billion will ensue. This might be compared to an expenditure on the space segment in support of these communicators of, say, $5 billion. Of particular interest in the post-2000 time period are geosynchronous platforms. It has already been observed that geosynchronous orbit will be dominated by large platforms during this period. The seeds of this transformation have already been sown, and it is expected that during the late 80s and early 90s a number of U.S. domestic and Intelsat platforms in the 25 kilowatt class will be placed in geosynchronous orbit. During the period of the mid-90s to about the year 2010, the placement of some five to ten larger platforms in the 100 to 500 kW class is likely. Beyond the year 2010 one can look for the replacement of the earlier
platforms by a new class of platforms in the 1 to 5 MW class, growing to a total of some 15 to 30 platforms by the year 2030. The larger platforms are likely to be manned either by robots or by two-man crews rotated periodically. The purpose of man will be to effect immediate service, repair and maintenance as necessary to keep the platform properly functioning. The cost of the advanced platforms will be in the range of $2 billion to $10 billion each, and they will have a structure and power supply life approaching 50 years with other systems being updated on about a ten-year cycle. The advanced geosynchronous platforms will be supported by a manned geosynchronous facility which is also likely to be a space-based manufacturing facility to manufacture and rebuild components and subsystems for the geosynchronous and other space platforms. As a result it is likely that 50 to 500 persons will be stationed in geosynchronous orbit in support of the geosynchronous platforms. Spacecraft power and lifetime trends to date, as shown in Figure 2.3, clearly reflect these trends. Twenty-five kW platforms are presently in the planning ♦ stage and studies on 100 to 500 kW platforms for the late 1990s time period have ** already been performed. The continuing improvements in lifetime and growth in power levels shown in Figure 2.3 are fully compatible with SPS-based technologies. It is interesting to consider the traffic necessary to support the geosynchronous platforms that are likely to be put in place in the 2000 to 2030 period. Payloads Requirements/Accommodations Assessment Study for Science and Applications Space Platforms, Second Quarterly Review, TRW, June 10, 1980. Third Quarter Briefing: Conceptual Design Study--Science and Applications Space Platform (SASP), McDonnell Douglas Astronautics Company, June 11, 1980. ♦* Space Industrialization—Background, Needs and Opportunities, Rockwell International, Report No. SD-78-AP-0055, April 14, 1978.
FIGURE 2.3 HISTORICAL AND PROJECTED GROWTH OF SPACECRAFT POWER AND LIFETIME These traffic requirements are shown in Table 2.1. This table reflects the fact that there are two fundamentally different classes of payloads which need to be transported to geosynchronous orbit. The first class involves durable goods such as the materials for construction of new platforms. It is probably economic to transport these materials between LEO and GEO using a low-thrust electric cargo orbit transfer vehicle (COTV). The implications in this decision indicate that the cost of capital for the durable goods during the period of transportation is more than offset by the cost savings afforded by the electric COTV. Nondurable goods, however, such as man and his logistics, require more rapid forms of transportation. The present option for the personnel orbit transfer vehicle (POTV) involves the use
TABLE 2.1 TRAFFIC TO SUPPORT GEO PLATFORMS (KG/YR) of chemical propellants (oxygen and hydrogen) to enable LEO to GEO trips to be made on the order of one-half day. It is evident from Table 2.1 that rather large quantities of chemical propellants are necessary to support a POTV system. It is thus apparent that alternatives to the use of a chemical POTV could be quite advantageous. 2.2 The Post-2030 Time Period Very little more can be said about space activities in the post-2030 time period than has been noted already above. It is likely that this period will see the widespread use of space by man including space habitation and utilization of extraterrestrial resources. It is also likely that many scientific endeavors will move into space: astrophysics, astronomy, high-energy physics and biological research
are examples. It is this context in which salvage value of SPS satellites was considered.
3. SPS DEMONSTRATION SATELLITE SALVAGE ALTERNATIVES * According to the Rockwell International SPS development program plan, the completion of the SPS Technology Advancement phase by 1990 will provide the technical confidence to proceed with a pilot plant demonstration phase. The primary objective of this development phase would be the demonstration of all SPS technologies to those utility firms and consortiums that would ultimately capitalize and operate the production or full scale operational system. The pilot-plant or demonstration satellite will be constructed in low earth orbit using a heavy lift launch vehicle (HLLV) for mass transportation and construction support systems. The demonstration satellite will be transferred to geosynchronous orbit by an on-board electric propulsion system. The demonstration satellite will operate in the same mode as the full-scale SPS satellite by directing a microwave power beam at a total power level of a few hundred MW to a standard modular segment of the proposed operational ground rectenna. The demonstration/operational period may range from six months to a few years, during which time the SPS elements of the full-scale solar power satellite will be operated in the operational environment. Operational data will provide the quantitative basis for analyses which will support full SPS commercial capability. The initial step will be to establish a base in low-earth orbit that is capable of constructing the demonstration satellite. The demonstrator satellite, shown near completion in Figure 3.1, is sized to the projected electric orbit transfer vehicle (EOTV) power level of 335 MW at the array. Allowing for radiation degradation * Satellite Power Systems (SPS) Concept Definition Study, Final Report, Vol. 1, Rockwell International, Contract NAS8-32475, March 1979.
FIGURE 3.1 SPS DEMONSTRATION SATELLITE IN FINAL PHASES OF CONSTRUCTION (SOURCE: ROCKWELL INTERNATIONAL) and power distribution losses, power to the microwave antenna will be approximately 285 MW. Microwave transmission losses further reduce this value to about 230 MW at the rectenna, resulting in recovery of 8 MW of power for a sparsely populated 7-km-diameter demonstration rectenna or 2 MW of power for a 1.75-km demonstration rectenna. The demonstration satellite is a single unit or bay of the operational SPS which consists of 30 such bays as shown in Figure 3.2. A list of the basic items which comprise the demonstration satellite and their related DDT&E and first unit costs are summarized in Table 3.1. The mass properties of the full-scale and demonstration satellites are summarized in Table 3.2. Because of the large investment in the demonstration satellite and the associated transportation costs and the on-orbit capability that will exist, there is
FIGURE 3.2 FULL-SCALE OPERATIONAL SPS SATELLITE CONFIGURATION (SOURCE: ROCKWELL INTERNATIONAL) a natural concern as to the alternative uses of the demonstration satellite upon completion of the demonstration program, and the economic value associated with these uses. The following sections discuss alternative uses, and the value derived therefrom, to which the demonstration satellite may be put upon completion of the demonstration program. Four alternative uses have been considered, namely: 1. Use of the demonstration satellite as the first building-block of the first full- scale SPS satellite. The economic value, or salvage value, of the demonstration satellite derives primarily from the costs which would be foregone in the construction of the full-scale satellite through the incorporation of the demonstration satellite into the full-scale satellite. 2. Use of the demonstration satellite as a source of power for non-SPS space activities. This use requires the systematic disassembly of the demonstration satellite and transferral and use of the disassembled power subsystems as power supplies in other space missions. Here the salvage value of the demonstration satellite derives primarily from the costs (both hardware and associated transportation) foregone by the other space missions through their use of the demonstration satellite power subsystems.
TABLE 3.1 DEMONSTRATION SATELLITE COST STRUCTURE*
TABLE 3.2 MASS PROPERTIES OF FULL-SCALE AND DEMONSTRATION SPS SATELLITES (106 KG)
3. Use of the demonstration satellite as a power supply for a laser orbit-to-orbit transportation system. A laser orbit-to-orbit transportation system would derive value through transportation cost savings primarily on the cost of transporting otherwise-needed propellants to LEO. 4. Use of the demonstration satellite as a source of space-based materials. The salvage value of this use derives from transportation costs and material costs which may be foregone by using the basic materials existing in the demonstration satellite. 3.1 Growth to Full-Scale Satellite It is currently envisioned that the demonstration satellite will consist of an energy conversion segment, an interface segment and a power transmission segment. The energy conversion segment will consist of primary and secondary structure, concentrators, solar blankets, switchgear and converters, conductors and insulation, attitude control and information management subystems. The interface segment includes the primary and secondary structure, mechanisms, conductors/in- sulation and slipring brushes. The power transmission segment will be representative of the full-scale satellite antenna to the extent of using identical components. It will include structures, transmitter subarrays, power distribution and conditioning, batteries, insulation and phase control elements. Current plans call for growth of the demonstration satellite into the first full-scale SPS satellite. By growing the demonstration satellite into the first full- scale satellite, certain costs may be foregone (that is, a cost item that would have to be incurred if the demonstration satellite were not available for use, would not be incurred since the demonstration satellite is available for use) whereas others may be incurred. The present value of the net of these costs referenced to the initial operation date of the demonstration satellite, is the salvage value that may be derived from this use of the demonstration satellite. It is assumed throughout the following that the demonstration satellite is in orbit and all associated DDT&E and first unit costs are sunk.
The salvage value of the demonstration satellite when used as an initial element in a full-scale satellite is summarized in Figure 3.3 and discussed below. The salvage value, SV, is SV = PV1 + PV2- PV3- PV4 where PV1 is the present value of the full-scale satellite costs that may be foregone. PV1 accounts for the hardware costs for providing a capability equivalent to the demonstration satellite capability and the transportation costs associated with transporting this equivalent capability. The demonstration satellite capability must be adjusted for degradation effects which are a function of time (the time interval to the deployment of the first full-scale satellite) and both hardware and transportation costs must be adjusted for learning effects (assumed to be a function of time) that may also take place during this interim period. PV2 is the present value of consumer surplus benefits that will result if the marginal FIGURE 3.3 SALVAGE VALUE—GROWTH TO FULL-SCALE SATELLITE
RkJQdWJsaXNoZXIy MTU5NjU0Mg==