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Potential evolution of an international moon base programme
Acta Astronautica Vol. 26, No. 12, pp. 889-897, 1992 Printed in Great Britain. All rights reserved
0094-5765/92 $5.00+ 0.00 Copyright © 1992Pergamon Press Ltd
POTENTIAL EVOLUTION OF AN I N T E R N A T I O N A L M O O N BASE P R O G R A M M E r P. J. CONCHIE,C. M. HEMPSELL and R. C. PARKINSON British Aerospace (Space Systems) Ltd, Argyle Way, Stevenage SGI 2AS, England (Received 6 March 1991; received for pubfication 28 July 1992) Abstract--The Moon is a major target in expanding human activity in Space. President Bush has called for a Space Exploration Initiative. European participation may depend on achieving an affordable programme and identifying distinct elements for non-U.S, participation. Affordability requires that all participants can influence the "cost to user" of Base operations. If lunar activity is to evolve towards resource exploitation, there will need to be a progressive reduction in operating costs. European interest would prefer participation that allowed longer-term independent interests. The paper addresses how non-U.S, agencies could contribute valuable elements to an International Moon Base while meeting three criteria: - - Keep a core infrastructure under U.S. control. -Avoid a total reliance by the partner on U.S. services. - - Allow the partner to evolve towards an eventual, semi-autonomous or autonomous capability. The paper illustrates possible implications of meeting these constraints through "mini infrastructures" combining several elements to form a working architecture. It is concluded that any European participation in an International Moon Base Programme should contain both Space transport and surface elements.
I. INTRODUCTION The Moon is a major target of interest in the expanding human exploration and exploitation of the Solar System. The Moon represents the first extraterrestrial resource available to humankind. It is 18 years since the Moon was last visited, and N A S A plans its return in 2004. For comparison, 12 years after Columbus' landfall, Breton fishermen were working the cod banks of Newfoundland. Within 30 years, Cortez was engaged in the conquest of Mexico[I]. President Bush has announced the U.S. intention of returning to the Moon as part of his Moon/Mars Initiative, and also of inviting international participation "as equal partners". Affordability is likely to be a key issue in an International Lunar Programme. The challenge is greater than for low Earth orbit operations, and if we cannot find ways of reducing costs, the price will steadily preclude even the richer nations from further Space ventures. In addition, if there is a long-term interest in exploitation of lunar resources, an International Lunar Programme should direct progress towards the steady reduction in the cost of transport to, and operations on, the Moon. This paper addresses the question of how non-U.S. agencies (specifically Europe) could contribute to an International Lunar Programme while meeting four criteria:
tPaper IAF-90-641 presented at the 41st Congress of the International Astronautical Federation, Dresden, Germany, 8-12 October 1990. 889
- - to keep core infrastructure elements under U.S. control - - avoid the necessity of the partner having a high level of reliance on U.S. services, and to be able to control the implementation of his own Space Policy - - allow the partner to affect the affordability in a favourable manner to ensure continued participation - - a l l o w the partner to evolve towards an eventual, semi-autonomous or autonomous capability. The paper derives from an internal British Aerospace study on Long Term Space Architectures (LTA), which has been concerned with identifying affordable and integrated Space Infrastructure possibilities beyond the year 2000. A companion paper[2] describes the factors associated with a European Autonomous Space Station, and these results will be drawn upon in the current paper. 2. POLITICAL ISSUES With the invitation to join an international Space Exploration Initiative (SEI) comes a sense, within Europe, that "we have been here before". In 1984, President Reagan invited O E C D member states to participate in building Space Station Freedom. The precedent is not necessarily auspicious. Both the U.S. Freedom and European Columbus programmes are now more expensive, are later, and form a less
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integrated programme than when first envisaged (see [3] for the historical intent). An international SEI looks more expensive, further off, and more difficult for Europe to participate in (see[4] for some of the issues involved). Politically the objectives of the U.S.A. and its partners are likely to be different. U.S. intentions include establishing "Space Leadership" and appear to see Mars as a prime objective with the Moon as a secondary goal. European objectives would seek to protect European interests and could be directed towards the potential for Space resources and capabilities to solve terrestrial problems. Here the Moon would be a more significant goal than Mars. The establishment of a permanent Lunar Base involves acceptance that a major long-term objective of Manned Space Flight is the exploitation of extraterrestrial resources for the benefit of mankind. In this it differs from an objective to place a scientific expedition on Mars. In addition to scientific return, a Lunar Base Programme should encourage the exploitation of lunar resources not only to reduce immediate costs but also to develop towards the long range economic exploitation of lunar resources. International collaboration is thought of as a means to share costs on a programme too big for one nation alone. Because of inevitable compromise, such multi-national projects actually tend to increase the cost of the task. With SEI, the scale of the task means that ways of reducing costs will need to be sought. After all, the biggest incentive for collaboration by a second party is that it can afford to take part at a substantial level. With SEI there is a need to collaborate on making Space cheaper and agreeing to work together. Historically, the Intelsat organization was set up not to offset costs but to generate a wide international community in which satellite communications could be successful. Conchie's suggestion[5] that Intelsat could serve as a model for an international SEI programme deserves attention. Spread widely, such an organization would permit lunar operations in the context of the 1979 U.N. Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, declaring such resources as the "common heritage of mankind". By providing services to an agreed total system, individual contributors get better value by holding costs down. It seems that the major interests of a minority participant in an International Lunar Programme would be as follows: - - to have control over an element with clearly defined interfaces which can be developed as a unit largely unaffected by changes elsewhere in the system, that the element or elements chosen should provide technological stimulus and political rewards for the participants, -
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that a multi-year commitment or treaty exists between the participants, securing the continuing value of the elements being worked on, that eventual use of the system should be affordable at the level of activity required by each participant, unencumbered by restrictions which would inhibit commercial exploitation in competition with the majority participant.
In addition it is generally recognized that if the majority participant has a true majority share (50% of the programme) it will wish to maintain control of a "core" system allowing it to fulfil its major objectives in the event of failures by one or more of the minority participants. With Europe as a participant, the interests of Europe within an international programme are mirrored by similar interests of individual nations within the European programme. Fortunately there are likely to be sufficient elements within an International Lunar Programme to satisfy a wide range of participants. Co-operation in an international programme need not preclude replication of elements by different participants, and even an element of competition. Transportation is a key function. Within the Space Station programme the availability of Ariane 5 may provide useful logistic support in addition to the Space Shuttle, and ensures unrestricted European access to its facilities. Extending European transport capabilities to the Moon (not necessarily manned capabilities) would introduce healthy competition into the logistic supply line, and would provide resilience in the event of a system failure of one of the vehicles involved. Supply of cargo to the Moon is likely to be a controlling factor in the growth of lunar activity (see Section 5).
3. MISSION OBJECTIVES
The mission objectives of an International Lunar Base may be summarized as follows: - - to continue the geological exploration of the Moon - - to serve as a base for astronomical (and Earth) observation initiate activities leading towards the exploitation of lunar resources - - to investigate human performance under lunar conditions. -
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The first two of these objectives are abstract science, the second pair relate to eventual goals of colonizing the Moon for economic or other gains. Only the objective of exploration demands moving very far from a fixed site, and even that objective might be better served by "reaching out" from a beachhead where resources can be built up than establishing a number of isolated sites (see Section 4). The advantage of the Moon as a site for astronomical observations comes from its ability to provide a
International Moon Base large, stable platform with long, uninterrupted viewing periods. First indications are that contamination from Lunar Base operations will be local, and that a few tens of kilometers separation would give telescopes lower contamination levels than found in low orbit about Earth. Among instruments which have been proposed are[6]: 1 m optical variable star monitor gamma-ray burst and X-ray variability monitors radio telescope interferometer 16 m optical/ix, segmented mirror observatory lunar optical-u.v, synthesis array (LOUISA) gravity wave observatory primary neutrino detection.
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All these instruments require deployment, LOUISA, for example, demands 42 mirrors to be deployed over a 10 km diameter. Lunar industrial processes of interest range from the simple use of lunar regolith for shielding base modules to complex fabrication of structural materials. Some early processs which might have short-term pay-offs include: fibre production, weaving and panel production - - liquid oxygen production from local rocks recovery of metals by magnetic separation on-site manufacture of silicon for solar generations vacuum reduction of silicates[7] - - recovery of solar-wind implanted He3 and H2 - - location of usable, meteoric Ni-Fe lodes. -
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There has been a tendency to design lunar industrial plants as self-contained, prefabricated units. However, it is apparent that many would benefit from astronaut deployment on the lunar surface--particularly those using solar energy as prime power. Indeed, it would be possible to use a solar-concentrator array of mirrors for a number of lunar industry test plants in the early stages of a base. 4. TRANSPORT OPTIONS
Extending European transport capabilities to the Moon involves the introduction of one or more new vehicles to the planned transport infrastructure. Ariane 5 could place 6 tonnes into a lunar transfer orbit, and from there a cryogen-fuelled launch vehicle could land payloads of about i.5 tonnes on the lunar surface. Heavy lift variants of Ariane 5 could increase this by a factor of two [8]. More economical transportation would come from the development of a reusable Winged Launch Vehicle for transport to low Earth orbit, the use of a Space Station as a transport node, and development of a re-usable Orbital Transfer Vehicle (OTV), as described in [2]. An OTV with a propellant mass of 7 tonnes could inject 6 tonnes into lunar transfer orbit, but two OTVs
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operating as a staged vehicle could deliver 7.7 tonnes into lunar orbit, or about 2.8 tonnes onto the lunar surface with an expendable lander. Are such modest payloads large enough to be useful? A system required to return human beings to Earth (either directly or via lunar orbit rendezvous) would require a mass of 8-11 tonnes on the Moon. However, it we assumed that the primary function of a European system was cargo delivery, and that European astronauts would "buy passage" on a U.S. manned transport system, more modest cargo deliveries are quite possible. The surface infrastructure estimates in Section 5 indicate that 2.8 tonne payloads would be adequate for many purposes, including the support of a semi-independent base. From this arose the concept of an evolvable lander. The basis vehicle is shown in Fig. 1. The lander consists of two "pannier" propulsion units surrounding a central payload volume. The main engines are a 10 kN hydrogen/oxygen engine tested experimentally by IHI Japan in 198719]. By placing the cargo between the propulsion units it is possible to offload cargo on the Moon by dropping it down between the landing legs. Initially such a vehicle would be expendable. However, it would only require a few reuses ( < 5) to improve its operating costs significantly. If the lander were modified to return to lunar orbit empty, but then to accept a payload and new propellant (as a propellant capsule) through rendezvous with an incoming OTV, the propellant mass transported from Earth would increase from about 2.6 tonnes to 4.3 tonnes. The cargo delivered to the Moon's surface would drop by <200 kg except for the first flight (when it would be only 1.3 tonnes) and the final flight, when 3.5 tonnes could be carried. A further evolution would be to refuel the vehicle on the surface using lunar-generated liquid oxygen. For this evolution the propellant tanks would need to be enlarged, but the vehicle could now ferry 5.7 tonnes to the lunar surface. Figure 2 illustrates how the cost per tonne delivered to the lunar surface might evolve. Not only is the specific transport cost reduced and the mass per landing increased as we move to the right, but for a launch rate of 10 flights per year the total transport cost falls by about I BAU/year. Table 1 lists some approximate costs for development and facilities required to achieve these evolutionary steps, and it can be seen that the pay-off time for each step is quite short. Figure 3 shows how costs for a re-usable LLV vary with re-use and launch cost. As can be seen, the principal driver in transport cost remains Earth-toorbit launch costs, and LLV reuse needs to be very small to justify the additional complexity. A reusable LLV might also usefully support extended exploration of the Moon's surface from a central base. The slow speeds available to surface transport means that for journeys of 1000 km or
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100 Cost on Lunar 80 Surface (MAUtt) 60
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Fig. 2. Cost of delivery to lunar surface.
more, surface to surface "ballistic hops" are more economical than either surface transport or direct landings from Earth. The transport system described above is quite modest. Proposals for U.S. transport systems have used considerably larger vehicles[10,11], and it is Table 1. Approximate development and facility costs for lunar transport improvements Expendable LLV development 650 MAU OTV system development and facilities 1600 MAU Reusable LLV delta-costs 200 MAU Lunar LO x plant (600 kg/day) 1900 MAU
necessary to enquire whether there might be economic advantages in larger vehicles. Comparative cost exercises were made on equivalent assumption systems, and it was found that the cost per tonne was identical within 15% for differently sized systems. Larger systems are principally required if the logistic load requirement is larger. U.S. transport proposals also provided an initial estimate of the cost of transporting an astronaut to the Moon. Providing transport for one astronaut, with fully recoverable transport system, is the approximate equivalent of landing i.5 tonnes of cargo on the moon.
International Moon Base 80
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Fig. 3. Effect of LLV re-use and LEO launch cost on cost of .'livery to lunar surface. 5. SURFACE OPERATIONS Surface operations on the M o o n can be divided into: a permanent, fixed site base construction and operations - - mobile surface vehicles - - construction and operation of experiments and industrial plants. --
It seems inevitable that an initial permanent base will be constructed by landing a number of modules and joining them together. The larger the modules are the more mass-efficient do they become, and the less astronaut activity is required to bring the base into operation. However, assembling a Lunar Base is very different from assembly of a Space Station. Modules will have to be unloaded from the LLVs, dragged to the base site, joined together, and then (for extended stay operations) buried in perhaps 2 metres of regolith to provide radiation and thermal shielding. Base construction operations inevitably demand support equipment and vehicles.
As part of the study, an investigation was made of a minimal Lunar Base constructed from modules capable of being transported by the LLV described above. The concept is shown in Fig. 4, and might accommodate 2-6 astronauts. The module requirements are listed in Table 2. It is possible to construct a base in ~..~s way, but the system requires 8 landings for the basic system, and 15 landings for a 6 man assembly. Such small modules might be realistic for small, secondary bases, but would probably not be adequate for larger bases (although they might serve as the core for a base using inflatable extensions). The duplication of small modules does, however, keep development costs down, and such modules might be affordable by Europe. Logistics support to a Lunar Base is not insignificant. With open-cycle life support an annual logistic load for a 6 astronaut Base is in excess of 16 tonnes (7 flights of our LLV). A significant fraction is in supplies for the EVA suits, since the crew may be expected to spend large amounts of their time outside. Even suit maintenance becomes a problem with 6 month stay times. Use of water recovery in the ECLSS, and rechargeable EVA suits reduces the Table 2. Modules required for a small Lunar Base Two Crew Base
Habitability modules (2 off) Tower EVA module Power and communications module Lab "nodule (no payload) Garage Vehicles (CSV and EHV)
5.2 t 2.4 t 2.5 t 2.6 t 1.9 t 1.5 t 2.9 t
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10.4 t 4.8 t 2.5 t 2.6 t 3.8 t 3.0 t 2.9 t
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Fig. 4. Small modular Lunar Base.
Habitability modules (4 off') Towers (2 off`) EVA module Power and communications module Lab modules (2 off) Garage/shelter Vehicles (CSV and EHV)
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Fig. 7. Available work capability of small Lunar Base.
Fig. 5. Small Lunar Base logistics load. logistics load (Fig. 5) to 9.6 tonnes per year (4 LLV flights). Base maintenance and logistics support activities have been estimated to take 15-20% of the astronaut time. Even the process of assembling such a Base requires vehicular support. Three mobile surface vehicles were identified: - - A Construction Services Vehicle (CSV) capable of handling lunar regolith, and lifting, winching and dragging heavy equipment. --An Equipment Handling Vehicle (EHV) capable of towing, and with external manipulators for handing equipment and limited digging. --A Long Range Rover (LRR) capable of supporting extended survey expeditions. The LRR could be a caravan type vehicle towed by the EHV.
Concepts for the three vehicles are shown in Fig. 6. There is obvious commonality in terms of chassis, suspension, power etc., and it is reasonable to suppose that the vehicles would be developed as a set. The vehicles would also require a shelter for overnight, unpowered periods and support equipment for recharging and maintenance. Both the permanent Base and the Surface Vehicles are intended to support astronaut activity on the surface of the Moon. Some estimate was made on the availability of astronaut time after housekeeping and maintenance has been allowed for. A preliminary estimate is shown in Fig. 7 which indicates that for a 6-man base about half the total effort is available-some 5500 man-hours per year. It can be assumed that much of this would be EVA surface activity. Since many of the astronomy and industrial packages being considered require deployment and
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Fig. 6. Lunar surface vehicles.
International Moon Base construction activity, an attempt was made to compare available astronaut time to selected construction tasks. The simplest of these was the construction of the Base itself. At the other extreme might be tasks like building a lunar liquid oxygen plant (deploying 346 mirror units and up to 50 other elements) and a small electromagnetic accelerator capable of launching 100 kg units back into lunar orbit (7640 units over 5.6 km). Estimates for lunar activity workrates are very uncertain, but some estimates are given in Table 3. The results indicate that, with one LLV flight per month, with the current size of LLV, the build-up of activity on the lunar surface is more likely to be constrained by transport limitations than by astronaut availability. One answer to this might be to build a larger LLV, and match the incoming cargo rate with the available astronaut effort. However, the studies in Section 4 indicated that the cost of transport to the Moon was relatively insensitive to LLV size. In theory we could launch more often. What limits the rate of cargo delivery to the Moon is how much we are prepared to pay for transport. 6. A F F O R D A B I L I T Y
Affordability is a function of three factors: - - cost - - perceived value of the result - - availability of funding. Of these only cost is subject to engineering analysis. We may calculate costs to the approximate degree afforded by engineering definition. An early cost assessment may lead to identification of major cost centres, and hence to some understanding of the cost/value trade-off in defining requirements. Within this study costs were derived from a sub-system parameter analysis with wrap-around factors at system level (see[12] and [13]). Some allowance has been made for replicated sub-systems, and the actual cost will depend on the degree to which the task is seen as building useful infrastructure elements for minimum costs, and the degree to which technology gain is seen as a valuable goal in its own right. The system being proposed contains transport elements and surface elements. The transport element cost includes systems such as the OTV which reduce the operational support cost (recurring transport costs). As a basis for comparison, the total cost of developing and operating the system at 8 launches per year over 10 years has been compared in Fig. 8 for Table 3. Typical construction and deployment activities Assemble initial base Advanced base expansion Erect segment telescope Deploy L O U I S A Basalt fabrication plant Lunar LO x plant assembly Lunar accel assembly
2 m-too 2 m-mo 0.5 m - m o 2m-mo 2 m-too 8.8 m - m o 36m-mo
8 LLV flights 7 LLV flights I LLV flights 4-12 LLV flights I LLV flights 6-9 LLV flights 19 LLV flights
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Fig. 8. Comparative costs of investing in transport development. a system using a heavy lift Ariane 5, an expendable LLV and no further transportation development, with an evolving transport system as described in Section 4. The difference in cost amounts to 4.7 BAU, and the evolving transport system includes a 1.9 BAU investment in a Lunar Liquid Oxygen Plant. The evolving transport concept assumes the development of low cost WLV Earth-to-orbit transport, but this will have general application to launch services and Space operations (see[2]). Figure 8 indicates that the principal source of costs lies in continuing operational support. This is further broken down in Fig. 9. The procurement of base modules, surface vehicles and transport systems comes to 5.4 BAU (excluding the Lunar Liquid Oxygen Plant), which is only about 50% greater than currently planned for the European Columbus programme. Transport operations over 10 years (including crew delivery by U.S. systems) averages 950 MAU/year. In fact, since the system capability envolves over the 10 year period the cost drops from about 1370 MAU/year to 830 MAU/year while the payload delivered climbs from about 20 tonne/year to 46 tonne/year. If Europe did not develop its own transport capability, but bought it from the U.S., the total cost would not change very much, but money would have to be spent outside Europe for cargo delivery. We now turn to the question of perceived value. The direct scientific benefits from a Moon Base have been identified as being in the area of -
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geological exploration of the Moon astronomy human biology.
The astronomical benefit has been stated as being in the same band as one of the "Great Observatory" instruments like the Hubble Space Telescope. The cost of such instruments is high ( ~ 1.5 BAU) but Europe would probably not invest in such a project more than once every 5-8 years. This is equivalent to about 250 MAU/year. The benefits of geological
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Cost (BAU)
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Fig. 9. Breakdown of procurement and operations costs. survey and human biology together would probably not be seen as greater than this. To be of value, European investment in a Moon Base must include appreciation of indirect benefits, including: technology gain - - a c q u i s i t i o n of an infrastructure capable of exploiting extraterrestrial resources. -
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If we include these benefits, then it becomes desirable that Europe is left with the elements of a European "mini-infrastructure" which includes both surface and transportation elements. Some of these elements can be exploited directly. The OTV, for example, is a suitable vehicle for launch to geosynchronous orbit and elsewhere[2]. Depending on what other activities Europe is called upon to support, it appears that participation in the SEI, even along the modest lines outlined here, will involve new money for Space. The sums involved do not have to be excessive in comparison with other ESA infrastructure programmes. It has been suggested in the U.S. that funds from the "peace dividend" might be applied to SEI. It is not clear how large, and from what source, this "dividend" would be in practice. Reductions in troop manning levels would tend to be swallowed elsewhere. If there is a reduction in the military demand on the aerospace industrial sector, however, then investment in advanced Space activities of this sort might well be seen as worthwhile to maintain the advanced R&D capabilities. There must, however, be sounded a warning on this point. Perception of an International Lunar Base as a technology driver will undoubtedly push total costs upwards, even if the eventual operational costs are kept low as a desirable mission objective.
7. CONCLUSIONS The establishment of permanent bases on the Moon is a natural progression beyond the Space Station. Access to the Moon not only has a value in scientific and technology returns, but it is also a vital component to future Space industries. This study has indicated that it would be possible for Europe to participate in an International Moon Base programme at a significant level and moderate costs if the correct balance of collaboration and individual element choice is made. However, such a programme would require new money to be made available for Space activity, and would therefore have to be seen as bringing new benefits to the participants. Such benefits can be foreseen, both in providing a civilian technology driver, and providing long-term access to the potential resource benefits of Space [14]. Collaborative programmes will be necessary to carry through SEI in scope and timescale. The U.S. will require a significant international dimension if it is to survive through 4-6 administration changes. Europe needs collaborative participation to reap equivalent benefits, and will therefore have to assess its own programmes carefully for their balance of "autonomy" and collaboration. Imaginative programmes of this sort require equally imaginative international organization, with an acceptance of the reduction in sovereignty involved. Professionals in all communities need to be united both in their perception of the value and of the cost-effectiveness of the programme. And ultimately what will determine the success of the enterprise is whether it is capable of inspiring the taxpayer and being seen to contribute to his long-term increase in prosperity.
International Moon Base REFERENCES
1. A. Cooke, America. BBC, London (1973). 2. R. C. Parkinson, Cost impacts of supporting a future European space station. IAA-90-602, 41st IAF Congress, Dresden (1990). 3. R. F. Freitag, Space station planning. AAS 85-111, Europe~United States Space Activities Vol. 61 Science and Technology Series. American Astronautical Society, San Diego (1985). 4. R. J. Hannigan, The Bush initiative, a view from Europe. Space Policy February, 3 (1990). 5. P. J. Conchie, The space exploration initiative---why we are doing it? The Space Summit: An International Conference on Manned Space Exploration, Huntsville, Ala. (1990); Space News 1, No. 23, 9 (1990). 6. J. O. Burns et al., Observations on the moon. Scient. Am. 262, No. 3, 18 (1990). 7. D. R. Sparks, Vacuum reduction of extraterrestrial silicates. J. Spacecraft 25, 187 (1988). 8. J. C. Bouillot, French studies on advanced space trans-
9. 10. ll. 12. 13.
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portation systems. Proceedings of the 2rid European Aerospace Conference. Bonn, p. 129, ESA SP-263 0989). T. Mori, K. Higashino, K. Miyoshi and K. Suzuki, Development of a small LOX/LH 2 rocket engine. IAF87-284, 38th IAF Congress, Brighton (1987). Advanced space transportation system support contract--summary final report. Eagle Engineering Inc., 88-210, NASA CR 172104 (1988). A. Cohen, Report of the 90-day study on human exploration of the Moon and Mars. NASA Report (1989). Lunar base scenario cost estimates. Lunar Base Systems Study Task 6.1. Eagle Engineering Inc., 88-21 l, NASA CR 172103 (1988). R. C. Parkinson, A total system approach towards the design of future cost effective launch systems. IAA Symposium on Space Systems Cost Estimation, San Diego, Calif. (1990). C. M. Hempsell, An expanded space infrastructure. JBIS 42, Nov. (1989).
0094-5765/92 $5.00+ 0.00 Copyright © 1992Pergamon Press Ltd
POTENTIAL EVOLUTION OF AN I N T E R N A T I O N A L M O O N BASE P R O G R A M M E r P. J. CONCHIE,C. M. HEMPSELL and R. C. PARKINSON British Aerospace (Space Systems) Ltd, Argyle Way, Stevenage SGI 2AS, England (Received 6 March 1991; received for pubfication 28 July 1992) Abstract--The Moon is a major target in expanding human activity in Space. President Bush has called for a Space Exploration Initiative. European participation may depend on achieving an affordable programme and identifying distinct elements for non-U.S, participation. Affordability requires that all participants can influence the "cost to user" of Base operations. If lunar activity is to evolve towards resource exploitation, there will need to be a progressive reduction in operating costs. European interest would prefer participation that allowed longer-term independent interests. The paper addresses how non-U.S, agencies could contribute valuable elements to an International Moon Base while meeting three criteria: - - Keep a core infrastructure under U.S. control. -Avoid a total reliance by the partner on U.S. services. - - Allow the partner to evolve towards an eventual, semi-autonomous or autonomous capability. The paper illustrates possible implications of meeting these constraints through "mini infrastructures" combining several elements to form a working architecture. It is concluded that any European participation in an International Moon Base Programme should contain both Space transport and surface elements.
I. INTRODUCTION The Moon is a major target of interest in the expanding human exploration and exploitation of the Solar System. The Moon represents the first extraterrestrial resource available to humankind. It is 18 years since the Moon was last visited, and N A S A plans its return in 2004. For comparison, 12 years after Columbus' landfall, Breton fishermen were working the cod banks of Newfoundland. Within 30 years, Cortez was engaged in the conquest of Mexico[I]. President Bush has announced the U.S. intention of returning to the Moon as part of his Moon/Mars Initiative, and also of inviting international participation "as equal partners". Affordability is likely to be a key issue in an International Lunar Programme. The challenge is greater than for low Earth orbit operations, and if we cannot find ways of reducing costs, the price will steadily preclude even the richer nations from further Space ventures. In addition, if there is a long-term interest in exploitation of lunar resources, an International Lunar Programme should direct progress towards the steady reduction in the cost of transport to, and operations on, the Moon. This paper addresses the question of how non-U.S. agencies (specifically Europe) could contribute to an International Lunar Programme while meeting four criteria:
tPaper IAF-90-641 presented at the 41st Congress of the International Astronautical Federation, Dresden, Germany, 8-12 October 1990. 889
- - to keep core infrastructure elements under U.S. control - - avoid the necessity of the partner having a high level of reliance on U.S. services, and to be able to control the implementation of his own Space Policy - - allow the partner to affect the affordability in a favourable manner to ensure continued participation - - a l l o w the partner to evolve towards an eventual, semi-autonomous or autonomous capability. The paper derives from an internal British Aerospace study on Long Term Space Architectures (LTA), which has been concerned with identifying affordable and integrated Space Infrastructure possibilities beyond the year 2000. A companion paper[2] describes the factors associated with a European Autonomous Space Station, and these results will be drawn upon in the current paper. 2. POLITICAL ISSUES With the invitation to join an international Space Exploration Initiative (SEI) comes a sense, within Europe, that "we have been here before". In 1984, President Reagan invited O E C D member states to participate in building Space Station Freedom. The precedent is not necessarily auspicious. Both the U.S. Freedom and European Columbus programmes are now more expensive, are later, and form a less
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integrated programme than when first envisaged (see [3] for the historical intent). An international SEI looks more expensive, further off, and more difficult for Europe to participate in (see[4] for some of the issues involved). Politically the objectives of the U.S.A. and its partners are likely to be different. U.S. intentions include establishing "Space Leadership" and appear to see Mars as a prime objective with the Moon as a secondary goal. European objectives would seek to protect European interests and could be directed towards the potential for Space resources and capabilities to solve terrestrial problems. Here the Moon would be a more significant goal than Mars. The establishment of a permanent Lunar Base involves acceptance that a major long-term objective of Manned Space Flight is the exploitation of extraterrestrial resources for the benefit of mankind. In this it differs from an objective to place a scientific expedition on Mars. In addition to scientific return, a Lunar Base Programme should encourage the exploitation of lunar resources not only to reduce immediate costs but also to develop towards the long range economic exploitation of lunar resources. International collaboration is thought of as a means to share costs on a programme too big for one nation alone. Because of inevitable compromise, such multi-national projects actually tend to increase the cost of the task. With SEI, the scale of the task means that ways of reducing costs will need to be sought. After all, the biggest incentive for collaboration by a second party is that it can afford to take part at a substantial level. With SEI there is a need to collaborate on making Space cheaper and agreeing to work together. Historically, the Intelsat organization was set up not to offset costs but to generate a wide international community in which satellite communications could be successful. Conchie's suggestion[5] that Intelsat could serve as a model for an international SEI programme deserves attention. Spread widely, such an organization would permit lunar operations in the context of the 1979 U.N. Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, declaring such resources as the "common heritage of mankind". By providing services to an agreed total system, individual contributors get better value by holding costs down. It seems that the major interests of a minority participant in an International Lunar Programme would be as follows: - - to have control over an element with clearly defined interfaces which can be developed as a unit largely unaffected by changes elsewhere in the system, that the element or elements chosen should provide technological stimulus and political rewards for the participants, -
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that a multi-year commitment or treaty exists between the participants, securing the continuing value of the elements being worked on, that eventual use of the system should be affordable at the level of activity required by each participant, unencumbered by restrictions which would inhibit commercial exploitation in competition with the majority participant.
In addition it is generally recognized that if the majority participant has a true majority share (50% of the programme) it will wish to maintain control of a "core" system allowing it to fulfil its major objectives in the event of failures by one or more of the minority participants. With Europe as a participant, the interests of Europe within an international programme are mirrored by similar interests of individual nations within the European programme. Fortunately there are likely to be sufficient elements within an International Lunar Programme to satisfy a wide range of participants. Co-operation in an international programme need not preclude replication of elements by different participants, and even an element of competition. Transportation is a key function. Within the Space Station programme the availability of Ariane 5 may provide useful logistic support in addition to the Space Shuttle, and ensures unrestricted European access to its facilities. Extending European transport capabilities to the Moon (not necessarily manned capabilities) would introduce healthy competition into the logistic supply line, and would provide resilience in the event of a system failure of one of the vehicles involved. Supply of cargo to the Moon is likely to be a controlling factor in the growth of lunar activity (see Section 5).
3. MISSION OBJECTIVES
The mission objectives of an International Lunar Base may be summarized as follows: - - to continue the geological exploration of the Moon - - to serve as a base for astronomical (and Earth) observation initiate activities leading towards the exploitation of lunar resources - - to investigate human performance under lunar conditions. -
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The first two of these objectives are abstract science, the second pair relate to eventual goals of colonizing the Moon for economic or other gains. Only the objective of exploration demands moving very far from a fixed site, and even that objective might be better served by "reaching out" from a beachhead where resources can be built up than establishing a number of isolated sites (see Section 4). The advantage of the Moon as a site for astronomical observations comes from its ability to provide a
International Moon Base large, stable platform with long, uninterrupted viewing periods. First indications are that contamination from Lunar Base operations will be local, and that a few tens of kilometers separation would give telescopes lower contamination levels than found in low orbit about Earth. Among instruments which have been proposed are[6]: 1 m optical variable star monitor gamma-ray burst and X-ray variability monitors radio telescope interferometer 16 m optical/ix, segmented mirror observatory lunar optical-u.v, synthesis array (LOUISA) gravity wave observatory primary neutrino detection.
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All these instruments require deployment, LOUISA, for example, demands 42 mirrors to be deployed over a 10 km diameter. Lunar industrial processes of interest range from the simple use of lunar regolith for shielding base modules to complex fabrication of structural materials. Some early processs which might have short-term pay-offs include: fibre production, weaving and panel production - - liquid oxygen production from local rocks recovery of metals by magnetic separation on-site manufacture of silicon for solar generations vacuum reduction of silicates[7] - - recovery of solar-wind implanted He3 and H2 - - location of usable, meteoric Ni-Fe lodes. -
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There has been a tendency to design lunar industrial plants as self-contained, prefabricated units. However, it is apparent that many would benefit from astronaut deployment on the lunar surface--particularly those using solar energy as prime power. Indeed, it would be possible to use a solar-concentrator array of mirrors for a number of lunar industry test plants in the early stages of a base. 4. TRANSPORT OPTIONS
Extending European transport capabilities to the Moon involves the introduction of one or more new vehicles to the planned transport infrastructure. Ariane 5 could place 6 tonnes into a lunar transfer orbit, and from there a cryogen-fuelled launch vehicle could land payloads of about i.5 tonnes on the lunar surface. Heavy lift variants of Ariane 5 could increase this by a factor of two [8]. More economical transportation would come from the development of a reusable Winged Launch Vehicle for transport to low Earth orbit, the use of a Space Station as a transport node, and development of a re-usable Orbital Transfer Vehicle (OTV), as described in [2]. An OTV with a propellant mass of 7 tonnes could inject 6 tonnes into lunar transfer orbit, but two OTVs
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operating as a staged vehicle could deliver 7.7 tonnes into lunar orbit, or about 2.8 tonnes onto the lunar surface with an expendable lander. Are such modest payloads large enough to be useful? A system required to return human beings to Earth (either directly or via lunar orbit rendezvous) would require a mass of 8-11 tonnes on the Moon. However, it we assumed that the primary function of a European system was cargo delivery, and that European astronauts would "buy passage" on a U.S. manned transport system, more modest cargo deliveries are quite possible. The surface infrastructure estimates in Section 5 indicate that 2.8 tonne payloads would be adequate for many purposes, including the support of a semi-independent base. From this arose the concept of an evolvable lander. The basis vehicle is shown in Fig. 1. The lander consists of two "pannier" propulsion units surrounding a central payload volume. The main engines are a 10 kN hydrogen/oxygen engine tested experimentally by IHI Japan in 198719]. By placing the cargo between the propulsion units it is possible to offload cargo on the Moon by dropping it down between the landing legs. Initially such a vehicle would be expendable. However, it would only require a few reuses ( < 5) to improve its operating costs significantly. If the lander were modified to return to lunar orbit empty, but then to accept a payload and new propellant (as a propellant capsule) through rendezvous with an incoming OTV, the propellant mass transported from Earth would increase from about 2.6 tonnes to 4.3 tonnes. The cargo delivered to the Moon's surface would drop by <200 kg except for the first flight (when it would be only 1.3 tonnes) and the final flight, when 3.5 tonnes could be carried. A further evolution would be to refuel the vehicle on the surface using lunar-generated liquid oxygen. For this evolution the propellant tanks would need to be enlarged, but the vehicle could now ferry 5.7 tonnes to the lunar surface. Figure 2 illustrates how the cost per tonne delivered to the lunar surface might evolve. Not only is the specific transport cost reduced and the mass per landing increased as we move to the right, but for a launch rate of 10 flights per year the total transport cost falls by about I BAU/year. Table 1 lists some approximate costs for development and facilities required to achieve these evolutionary steps, and it can be seen that the pay-off time for each step is quite short. Figure 3 shows how costs for a re-usable LLV vary with re-use and launch cost. As can be seen, the principal driver in transport cost remains Earth-toorbit launch costs, and LLV reuse needs to be very small to justify the additional complexity. A reusable LLV might also usefully support extended exploration of the Moon's surface from a central base. The slow speeds available to surface transport means that for journeys of 1000 km or
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100 Cost on Lunar 80 Surface (MAUtt) 60
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Ariane 54 OTV + +ExpLLV ExpLLV
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Fig. 2. Cost of delivery to lunar surface.
more, surface to surface "ballistic hops" are more economical than either surface transport or direct landings from Earth. The transport system described above is quite modest. Proposals for U.S. transport systems have used considerably larger vehicles[10,11], and it is Table 1. Approximate development and facility costs for lunar transport improvements Expendable LLV development 650 MAU OTV system development and facilities 1600 MAU Reusable LLV delta-costs 200 MAU Lunar LO x plant (600 kg/day) 1900 MAU
necessary to enquire whether there might be economic advantages in larger vehicles. Comparative cost exercises were made on equivalent assumption systems, and it was found that the cost per tonne was identical within 15% for differently sized systems. Larger systems are principally required if the logistic load requirement is larger. U.S. transport proposals also provided an initial estimate of the cost of transporting an astronaut to the Moon. Providing transport for one astronaut, with fully recoverable transport system, is the approximate equivalent of landing i.5 tonnes of cargo on the moon.
International Moon Base 80
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Fig. 3. Effect of LLV re-use and LEO launch cost on cost of .'livery to lunar surface. 5. SURFACE OPERATIONS Surface operations on the M o o n can be divided into: a permanent, fixed site base construction and operations - - mobile surface vehicles - - construction and operation of experiments and industrial plants. --
It seems inevitable that an initial permanent base will be constructed by landing a number of modules and joining them together. The larger the modules are the more mass-efficient do they become, and the less astronaut activity is required to bring the base into operation. However, assembling a Lunar Base is very different from assembly of a Space Station. Modules will have to be unloaded from the LLVs, dragged to the base site, joined together, and then (for extended stay operations) buried in perhaps 2 metres of regolith to provide radiation and thermal shielding. Base construction operations inevitably demand support equipment and vehicles.
As part of the study, an investigation was made of a minimal Lunar Base constructed from modules capable of being transported by the LLV described above. The concept is shown in Fig. 4, and might accommodate 2-6 astronauts. The module requirements are listed in Table 2. It is possible to construct a base in ~..~s way, but the system requires 8 landings for the basic system, and 15 landings for a 6 man assembly. Such small modules might be realistic for small, secondary bases, but would probably not be adequate for larger bases (although they might serve as the core for a base using inflatable extensions). The duplication of small modules does, however, keep development costs down, and such modules might be affordable by Europe. Logistics support to a Lunar Base is not insignificant. With open-cycle life support an annual logistic load for a 6 astronaut Base is in excess of 16 tonnes (7 flights of our LLV). A significant fraction is in supplies for the EVA suits, since the crew may be expected to spend large amounts of their time outside. Even suit maintenance becomes a problem with 6 month stay times. Use of water recovery in the ECLSS, and rechargeable EVA suits reduces the Table 2. Modules required for a small Lunar Base Two Crew Base
Habitability modules (2 off) Tower EVA module Power and communications module Lab "nodule (no payload) Garage Vehicles (CSV and EHV)
5.2 t 2.4 t 2.5 t 2.6 t 1.9 t 1.5 t 2.9 t
= 19.0 t
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Fig. 4. Small modular Lunar Base.
Habitability modules (4 off') Towers (2 off`) EVA module Power and communications module Lab modules (2 off) Garage/shelter Vehicles (CSV and EHV)
P. J. Cor4cmE et al.
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Fig. 7. Available work capability of small Lunar Base.
Fig. 5. Small Lunar Base logistics load. logistics load (Fig. 5) to 9.6 tonnes per year (4 LLV flights). Base maintenance and logistics support activities have been estimated to take 15-20% of the astronaut time. Even the process of assembling such a Base requires vehicular support. Three mobile surface vehicles were identified: - - A Construction Services Vehicle (CSV) capable of handling lunar regolith, and lifting, winching and dragging heavy equipment. --An Equipment Handling Vehicle (EHV) capable of towing, and with external manipulators for handing equipment and limited digging. --A Long Range Rover (LRR) capable of supporting extended survey expeditions. The LRR could be a caravan type vehicle towed by the EHV.
Concepts for the three vehicles are shown in Fig. 6. There is obvious commonality in terms of chassis, suspension, power etc., and it is reasonable to suppose that the vehicles would be developed as a set. The vehicles would also require a shelter for overnight, unpowered periods and support equipment for recharging and maintenance. Both the permanent Base and the Surface Vehicles are intended to support astronaut activity on the surface of the Moon. Some estimate was made on the availability of astronaut time after housekeeping and maintenance has been allowed for. A preliminary estimate is shown in Fig. 7 which indicates that for a 6-man base about half the total effort is available-some 5500 man-hours per year. It can be assumed that much of this would be EVA surface activity. Since many of the astronomy and industrial packages being considered require deployment and
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International Moon Base construction activity, an attempt was made to compare available astronaut time to selected construction tasks. The simplest of these was the construction of the Base itself. At the other extreme might be tasks like building a lunar liquid oxygen plant (deploying 346 mirror units and up to 50 other elements) and a small electromagnetic accelerator capable of launching 100 kg units back into lunar orbit (7640 units over 5.6 km). Estimates for lunar activity workrates are very uncertain, but some estimates are given in Table 3. The results indicate that, with one LLV flight per month, with the current size of LLV, the build-up of activity on the lunar surface is more likely to be constrained by transport limitations than by astronaut availability. One answer to this might be to build a larger LLV, and match the incoming cargo rate with the available astronaut effort. However, the studies in Section 4 indicated that the cost of transport to the Moon was relatively insensitive to LLV size. In theory we could launch more often. What limits the rate of cargo delivery to the Moon is how much we are prepared to pay for transport. 6. A F F O R D A B I L I T Y
Affordability is a function of three factors: - - cost - - perceived value of the result - - availability of funding. Of these only cost is subject to engineering analysis. We may calculate costs to the approximate degree afforded by engineering definition. An early cost assessment may lead to identification of major cost centres, and hence to some understanding of the cost/value trade-off in defining requirements. Within this study costs were derived from a sub-system parameter analysis with wrap-around factors at system level (see[12] and [13]). Some allowance has been made for replicated sub-systems, and the actual cost will depend on the degree to which the task is seen as building useful infrastructure elements for minimum costs, and the degree to which technology gain is seen as a valuable goal in its own right. The system being proposed contains transport elements and surface elements. The transport element cost includes systems such as the OTV which reduce the operational support cost (recurring transport costs). As a basis for comparison, the total cost of developing and operating the system at 8 launches per year over 10 years has been compared in Fig. 8 for Table 3. Typical construction and deployment activities Assemble initial base Advanced base expansion Erect segment telescope Deploy L O U I S A Basalt fabrication plant Lunar LO x plant assembly Lunar accel assembly
2 m-too 2 m-mo 0.5 m - m o 2m-mo 2 m-too 8.8 m - m o 36m-mo
8 LLV flights 7 LLV flights I LLV flights 4-12 LLV flights I LLV flights 6-9 LLV flights 19 LLV flights
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Fig. 8. Comparative costs of investing in transport development. a system using a heavy lift Ariane 5, an expendable LLV and no further transportation development, with an evolving transport system as described in Section 4. The difference in cost amounts to 4.7 BAU, and the evolving transport system includes a 1.9 BAU investment in a Lunar Liquid Oxygen Plant. The evolving transport concept assumes the development of low cost WLV Earth-to-orbit transport, but this will have general application to launch services and Space operations (see[2]). Figure 8 indicates that the principal source of costs lies in continuing operational support. This is further broken down in Fig. 9. The procurement of base modules, surface vehicles and transport systems comes to 5.4 BAU (excluding the Lunar Liquid Oxygen Plant), which is only about 50% greater than currently planned for the European Columbus programme. Transport operations over 10 years (including crew delivery by U.S. systems) averages 950 MAU/year. In fact, since the system capability envolves over the 10 year period the cost drops from about 1370 MAU/year to 830 MAU/year while the payload delivered climbs from about 20 tonne/year to 46 tonne/year. If Europe did not develop its own transport capability, but bought it from the U.S., the total cost would not change very much, but money would have to be spent outside Europe for cargo delivery. We now turn to the question of perceived value. The direct scientific benefits from a Moon Base have been identified as being in the area of -
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geological exploration of the Moon astronomy human biology.
The astronomical benefit has been stated as being in the same band as one of the "Great Observatory" instruments like the Hubble Space Telescope. The cost of such instruments is high ( ~ 1.5 BAU) but Europe would probably not invest in such a project more than once every 5-8 years. This is equivalent to about 250 MAU/year. The benefits of geological
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Cost (BAU)
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m
Surface Vehicles
Base Modules
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Fig. 9. Breakdown of procurement and operations costs. survey and human biology together would probably not be seen as greater than this. To be of value, European investment in a Moon Base must include appreciation of indirect benefits, including: technology gain - - a c q u i s i t i o n of an infrastructure capable of exploiting extraterrestrial resources. -
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If we include these benefits, then it becomes desirable that Europe is left with the elements of a European "mini-infrastructure" which includes both surface and transportation elements. Some of these elements can be exploited directly. The OTV, for example, is a suitable vehicle for launch to geosynchronous orbit and elsewhere[2]. Depending on what other activities Europe is called upon to support, it appears that participation in the SEI, even along the modest lines outlined here, will involve new money for Space. The sums involved do not have to be excessive in comparison with other ESA infrastructure programmes. It has been suggested in the U.S. that funds from the "peace dividend" might be applied to SEI. It is not clear how large, and from what source, this "dividend" would be in practice. Reductions in troop manning levels would tend to be swallowed elsewhere. If there is a reduction in the military demand on the aerospace industrial sector, however, then investment in advanced Space activities of this sort might well be seen as worthwhile to maintain the advanced R&D capabilities. There must, however, be sounded a warning on this point. Perception of an International Lunar Base as a technology driver will undoubtedly push total costs upwards, even if the eventual operational costs are kept low as a desirable mission objective.
7. CONCLUSIONS The establishment of permanent bases on the Moon is a natural progression beyond the Space Station. Access to the Moon not only has a value in scientific and technology returns, but it is also a vital component to future Space industries. This study has indicated that it would be possible for Europe to participate in an International Moon Base programme at a significant level and moderate costs if the correct balance of collaboration and individual element choice is made. However, such a programme would require new money to be made available for Space activity, and would therefore have to be seen as bringing new benefits to the participants. Such benefits can be foreseen, both in providing a civilian technology driver, and providing long-term access to the potential resource benefits of Space [14]. Collaborative programmes will be necessary to carry through SEI in scope and timescale. The U.S. will require a significant international dimension if it is to survive through 4-6 administration changes. Europe needs collaborative participation to reap equivalent benefits, and will therefore have to assess its own programmes carefully for their balance of "autonomy" and collaboration. Imaginative programmes of this sort require equally imaginative international organization, with an acceptance of the reduction in sovereignty involved. Professionals in all communities need to be united both in their perception of the value and of the cost-effectiveness of the programme. And ultimately what will determine the success of the enterprise is whether it is capable of inspiring the taxpayer and being seen to contribute to his long-term increase in prosperity.
International Moon Base REFERENCES
1. A. Cooke, America. BBC, London (1973). 2. R. C. Parkinson, Cost impacts of supporting a future European space station. IAA-90-602, 41st IAF Congress, Dresden (1990). 3. R. F. Freitag, Space station planning. AAS 85-111, Europe~United States Space Activities Vol. 61 Science and Technology Series. American Astronautical Society, San Diego (1985). 4. R. J. Hannigan, The Bush initiative, a view from Europe. Space Policy February, 3 (1990). 5. P. J. Conchie, The space exploration initiative---why we are doing it? The Space Summit: An International Conference on Manned Space Exploration, Huntsville, Ala. (1990); Space News 1, No. 23, 9 (1990). 6. J. O. Burns et al., Observations on the moon. Scient. Am. 262, No. 3, 18 (1990). 7. D. R. Sparks, Vacuum reduction of extraterrestrial silicates. J. Spacecraft 25, 187 (1988). 8. J. C. Bouillot, French studies on advanced space trans-
9. 10. ll. 12. 13.
14.
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portation systems. Proceedings of the 2rid European Aerospace Conference. Bonn, p. 129, ESA SP-263 0989). T. Mori, K. Higashino, K. Miyoshi and K. Suzuki, Development of a small LOX/LH 2 rocket engine. IAF87-284, 38th IAF Congress, Brighton (1987). Advanced space transportation system support contract--summary final report. Eagle Engineering Inc., 88-210, NASA CR 172104 (1988). A. Cohen, Report of the 90-day study on human exploration of the Moon and Mars. NASA Report (1989). Lunar base scenario cost estimates. Lunar Base Systems Study Task 6.1. Eagle Engineering Inc., 88-21 l, NASA CR 172103 (1988). R. C. Parkinson, A total system approach towards the design of future cost effective launch systems. IAA Symposium on Space Systems Cost Estimation, San Diego, Calif. (1990). C. M. Hempsell, An expanded space infrastructure. JBIS 42, Nov. (1989).