The very limited scope of commercial space activities to date has been due primarily to the very high cost of launch. The rate of growth of commercial space activities in future will depend critically on how fast and how far launch costs fall. In normal commercial situations, costs fall progressively over an extended period. However, the evolution of the space industry to date has been very different from the evolution of other new industries, due to the strategic role played by launch vehicle technology during the "Cold War". In particular, all launch vehicles were developed by government agencies, and most had military requirements as a major design driver. Non-military European and Japanese launch vehicles were also developed by government agencies, with the aim of catching up with US technology.

As a result of this situation, the costs of launch in the Western nations have not fallen significantly over the past twenty-five years. (Soviet launch costs fell during this period through the production of many hundreds of units of a standard launch vehicle, but the scope for launch cost reduction using expendable vehicles is strictly limited.)

However, as could be expected, technological advances that have occurred in many fields during this period have made major launch cost reductions possible. Until recently, these possibilities were ignored by government agencies developing and operating expendable, or partly expendable, vehicles. However, since 1990 the US Strategic Defence Initiative Office has been funding the development off a fully-reusable, single-stage to orbit ( SSTO) launch vehicle (2, 3). Following commercial design approaches originating in the 1960s (4), and developed progressively during the l980s (5), this program has the stated target of reducing launch costs to just a few percent of their current level by the late 1990s with the "DCY" launch vehicle (6).

An important, but not widely recognised effect of reducing launch costs is that the production costs of space hardware will also fall more or less proportionately. This is for several reasons, but primarily because space will become accessible, and so spacecraft will be able to be maintained and repaired in orbit. As a result the cost of much space hardware will reach approximately the level of hardware built for other extreme but accessible environments, such as underwater, which are typically 1% of space industry costs (7).

Thus there is now the prospect that the costs of space activities will fall to a few percent of current levels within a few years (8). This is such an unusual, even unprecedented, situation that it is perhaps worth devoting a few paragraphs to outline some of the implications of launch costs of the order of 20,000¥/kg ($70/lb). At such prices many new space activities will become commercially attractive that are uneconomic today.

If the SSTO project achieves a reduction in launch costs of even 90%, commercial launch services will become available at a price of some 20 man¥/kg ($700/lb) for launch to LEO. This will make all expendable launch vehicles, existing or planned, commercially uncompetitive. This effect will be even more complete when the target of a 99% cost reduction is achieved.

Thus the development of fully-reusable, low-cost launch vehicles will cause a radical restructuring in the launch industry, in favour of those industrial groupings that develop low-cost reusable vehicles best designed to serve the markets that develop for low-cost launch services.

There are currently plans for the construction of a US/intergovernmental space station, "Freedom," at a total cost of sdme 5 cho¥ ($40,000 million). However, using this facility would not be easy for commercial organizations, both because they would need large government subsidies if the cost was to be acceptable, and because the legal regime on board is unattractive for commercial operators, as discussed elsewhere in this volume.

However, at launch costs of some 2 man¥/kg ($70/lb) the cost of constructing and launching a permanent orbiting laboratory would be of the order of 100 oku¥ ($80 million). Companies with annual R&D budgets of the order of 1000 oku¥ ($800 million) or more might find such a cost acceptable for a private micro-gravity research laboratory. Thus it is likely that consortia of companies would build and operate private labolatories in space when launch costs reach those proposed for the current SSTO program.

In recent years there has been growing interest in the possibility of providing travel services to low Earth orbit for fare-paying passengers. Consideration of the subject has reached as far as the development of preliminary designs for orbital hotels by a leading construction company (9). In order to be a commercially attractive proposition, however, such a project requires launch costs to fall to a few percent of current levels, as discussed in (9), and the authors tentatively proposed a date of 2020 for its realization.

However, with the apparent prospect that the required level of launch costs might be reached as early as the late 1990s, such a project as Shimizu Kensetsu's space hotel may be realistically achievable as early as the turn of the century. Of even more interest is that with launch costs of the order of 2 man¥/kg ($70/lb), the cost of building and launching a hotel of some 200 tons could be as little as 100 oku¥. An investment of this order of magnitude could be financed even by a single large company, and certainly by a consortium of private companies and by competing consortia.

Studics on the possibility of supplying large quantities of electric power to Earth from solar arrays in orbit concluded that it was technically feasible, and probably environmentally beneficial, but could be commercially competitive only at much lower launch costs. At some 2 man¥/kg ($70/lb), provided that the preliminary experiments that will be necessary give satisfactory results, SPS development would become a commercially attractive investment proposition. Thus, with the apparent prospect of this launch cost level being achieved later in the present decade, an SPS demonstration project such as "SPS 2000" (10, 11) becomes an attractive project today.

A number of major construction companies have recently started to study the Moon as a site for engineering activities in the future (12, 13). At present cost levels these projects would be too expensive to be commercially feasible, and so could be funded only by governments, if they had political reasons for doing so. However, at launch costs of 2 man¥/kg ($70/lb), a lunar base could be established for a sum of the order of 1000 oku¥ ($800 million). By comparison with the annual turnover of several cho¥ (several tens of $billions) of large companies today, we can see that even such a project would be possible for a consortium of private companies.

A visit by a team of engineers and scientists to an Earth-approaching asteroid would require perhaps 500 tons of equipment to be delivered to low Earth orbit. When cargo and passenger launch services are routinely available at some 2 man¥/kg ($70/lb), such an expedition could cost as little as some 200 oku¥ ($150m). This is of the same scale as the privately-funded "Biosphere 2" closed eco-system project currently in progress in the USA, and could also be funded privately, as were various famous expeditions of Earth exploration in the past.

Thus, although it is not possible to predict in detail how commercial space activities will develop in the future, it is clear that the prospect of the radical reduction in launch costs planned for the current SSTO project in the coming years greatly expands the range of projects that could become feasible.

The growth of such a range of commercial space activities would create demand in orbit for a range of other activities, including industrial research, manufacuring, media activities, passenger accommodation, construction, inter- and intra-orbital transport, warehousing, and servicing of the orbital vehicles and structures used in these activities. Those responsible for all such activities will have a common interest in the timely development of appropriate commercial space law in a number of areas.

A reduction in launch costs also has another important implication for the development of space law. In general the attractiveness of different possible legal agreements depends on the ratio of the benefits arising from the proposed laws to the costs of implementing them. As the costs of space activities fall, the costs of implementing certain legal agreements will fall, as discussed below. Some of the benefits will also fall, since the replacement value of orbital assets will be lower. But in addition, effective space law will also save human lives and prevent injuries, of which the value is not dependent on launch costs. Consequently, as the costs of space activities fall, the benefit-to-cost ratio of well-designed space law measures will shift decisively in favour of the benefits.

The need for space law arises because near-Earth space is a limited and valuable resource. Thus for example, the carrying out of certain activities in low Earch orbit ( LEO) can make certain other activities impossible, or more difficult and hence more expensive. Hitherto Earth-orbital traffic has been low, and the limitations have not caused major problems in LEO, as they have in geo-stationary Earth orbit ( GEO), of which the use is already closely regulated by international agreement. However when launch costs fall far enough to make large scale near-Earth space activities commercially attractive, the need for commercial space law will increase.

Indeed in one respect this situation is already changing, as artificial orbital debris begins to threaten other spacecraft. In the next section we consider the possible development of commercial space law in reation to space debris in the light of lower launch costs. In the subsequent sections, in order to consider the implications of possible future commercial space activities for space law in more detail, we consider the implications of two of the projects mentioned above, which will have requirements in common with other commercial activities in space, but which also each pose particular problems for the development of space law. They also both have the potential to become major space activities, involving orbital assets worth many thousands of oku¥ ($billions), and many thousands of vehicle movements each year in near-Earth space. They therefore pose the greatest challenges for the development of commercial space law that will allow the efficient and equitable use of near-Earth space.

There is a large and rapidly growing literature on the problem of space debris and its legal aspects - see (14, 15) for recent reviews. As the quantity of orbital debris has increased, the danger of a "runaway", whereby successive orbital collisions between pieces of debris creating progressively more debris, has increased. This has the potential to create a cloud of debris around the Earth, which would greatly inhibit space activities. Consequently early action to prevent such a "runaway" would be very cost-effective if appropriate collective action can be agreed by space users.

Various steps, both technical and legal, can be taken towards the resolution of this problem: 1) the subject can be studied; 2) the production of more debris can be prevented by altering the design or operation of new spacecraft; 3) existing debris can be removed in a variety of ways; and 4) owners of spacecraft can be made legally liable for damage caused by debris from their spacecraft.

The first two of these steps are currently under way, and the third and fourth are the subject of initial studies. Interestingly, proposals for the latter started as early as 1971 (16, 17) when the prospects for launch cost reduction seemed good, and such ideas were therefore timely. Twenty years later, launch costs have not fallen, but major cost reductions in space activities are now once again a near-term possibility. The subject is therefore worthy of serious re-examination, as well as involving many interesting legal issues.

1. From a legal point of view, little needs to be said about the study of the problem of space debris. It is clearly highly desirable to characterize the problcm as accurately as possible. Wide international cooperation in this endeavour also helps to create a good background for subsequently achieving more difficult agreements on remedies.

2. The extent of legal agreement on reducing debris production is of course constrained by the costs that are imposed on space users. Matsumori et al have produced a very useful preliminary analysis of the costs of debris prevention, including such activities as changes in design of spacecraft to reduce the release of fragments (18). It is however worth noting once again that, like other costs of space activities, the costs that Matsumori et al discuss would fall in line with reductions in launch costs. Consequently legal agreements requiring spacecraft designers to employ such methods would become easier, and less costly for commercial activities.

3. An interesting technical possibility is the removal of existing orbital debris. A variety of approaches have been proposed, involving primarily two types of spacecraft, craft that rendez-vous with large debris pieces and collect them for reuse or controlled deorbiting (19, 20), and craft that decelerate small debris pieces using lasers or other directed energy devices (21). Such spacecraft would be complex, potentially dangerous, and very expensive at present-day costs. At the cost levels possible later this century with vehicles such as the DCY, such missions should be feasible. Being a public good, the cost of such a system should ideally be borne by those who benefit from it. A range of different legal arrangements whereby this might be brought about are possible.

4. Under current space law, launching states are responsible for damage caused to other spacecraft only where fault is proven on the part of the launching state or of persons for whom it is responsible. One approach to resolving the space debris problem would be to make owners and operators of spacecraft strictly liable for damage caused by their spacecraft and by any debris which it creates. While such an objective is rational, and is analagous to the legal situation concerning air, land and sea travel, its implementation would require the resolution of a number of definitional problems.

A major problem arises from the fact that the orbits of spacecraft orbiting passively do not remain fixed with respect to the Earth, to each other, or to any system of co-ordinates. They evolve through time due to various perturbations. Thus, it is difficult to design general rules for establishing responsibility for collisions between spacecraft, as discussed in (23).

In addition, the introduction of liability for damage would require the introduction of real-time radar tracking of all orbital debris in order to be able to identify the legal person responsible for each piece. This would require one or more orbiting radar stations of considerable complexity, which would be prohibitively expensive at today's launch costs. However at costs of a few percent of today's it could be a tolerable investment on the part of space users in exchange for the benefits that it would bring.

Another legal development which has the potential to reduce debris is the introduction of a law of salvage, as discussed for example in (24, 25). A law of salvage analogous to marine salvage would have the advantage of employing a remedy that has already been well-known and well understood in the law of the sea for centuries. However, for obvious reasons the introduction of space salvage law would be likely to be effective only in removing larger and more valuable pieces of debris.

Consequently, although individual users of space can take steps to reduce the risk of damage to their assets caused by space debris, the definitive resolution of the problem caused by economically worthless orbital debris is a natural case for collective action involving the promulgation of appropriate space law. In this it is a typical "public good" in the economic sense that all users of space assets would benefit from a reduction in space debris, and hence purely private actions will tend to be inadequate.

It has been suggested that, with the reduction of launch costs to the level proposed for the SDIO's SSTO Program, the commercial demand for passenger traffic to Earth orbit could increase rapidly to as much as one million passengers per year (26). This would involve some one hundred commercial flights per day to as many orbital "hotels". Operators of commercial passenger travel services in space, including both launch vehicles and orbital accommodation, will have an interest in the development of space law that facilitates the development of their business.

Without making detailed assumptions about these activities it is nevertheless possible to identify certain legal problems that will require resolution by considering their commercial objectives. In order to operate profitably, their offerings to customers must be attractive and cost-effective. Their facilities and services must therefore be safe, economical and insurable. Below we consider serveral space law requirements that could result from such a scenario.

Operators of space passenger services will clearly have an interest in eliminating any danger from orbital debris in the most cost-effective manner, for several reasons. First, their passengers' lives will need to be safeguarded. Second, the cross-sectional area of orbital hotels will be large relative to existing spacecraft and so the danger of collisions will be proportionately higher. Third, being commercial companies, they will have to use whatever approaches minimize their costs. Thus, as these commercaial activities increase, the interest in debris control will increase.

As the quantity of traffic in LEO increases, the danger of collisions between operating spacecraft will also increase. It has been proposed that the introduction of orbital traffic rules may become desirable at a certain level of activity in low Earth orbit (16, 17, 23, 27). One possible approach to this would be to define particular low Earth orbits, and to allocate slots in them as is done today with positions in GEO. The determination of the optimum orbits for these purposes, and the most appropriate legal rights for registered users, will be a complex matter, involving trade-offs between many different factors, technical, commercial and legal. In particular it will be considerably more complex than the case of GEO, as discussed in (23, 27).

This procedure could provide for an efficient use of certain portions of LEO, but would impose some costs on users of LEO, both in preventing them using orbits that they might wish to, and in imposing station-keeping costs on some users of the orbits. These are analogous to the costs of adopting traffic rules in the air and on the sea. Furthermore, any such costs to space users of implementing such space law agreements will of course be much less when launch costs fall far below today's costs. Agreements that impose such costs in order to obtain wider benefits would thereby become more likely to be acceptable internationally.

An important consideration in connection with this subject is the danger of certain orbital uses being pre-empted by the prior use of orbits in an unregulated manner. Some orbits are much more valuable than others; for example, certain families of "rendezvous compatible" and "site-synchronous" orbits are particularly convenient for frequent travel between particular orbital positions and launch sites. It would be economically wasteful if some of the more important of these became unavailable through failure to make timely plans.

Although current space law includes the Convention on international liability for damage caused by spacecraft, there will be a need for elaboration of the existing legal situation relating to such damage in a number of respects. First, as pointed out in (1), there is currently no obligatory procedure for the settlement of disputes. Hitherto there have been so few cases that this has not been important, but as commercial activity in space increases, this will clearly be a source of difficulties. Second, according to the Liability Convention, liability for damage to spacecraft in space exists only where fault is proven. This will also require elaboration, and as discussed above, eventual extension to include damage caused by debris. Third, the liability of the government of the launching state (or state of registration) for damage caused by spacecraft is not obviously a good arrangement for spacecraft intended to operate in space for long periods of time. To change this would require making changes to existing space law, and the development of international private law. Despite the complexity of achieving this, it may nevertheless by the correct direction for the further evolution of space law.

Commercial insurance will play an important role in the development of commercial space activities, and in the evolution of commercial space law. At least three major categories of insurance will be required for the development of space passenger travel. In order for such insurance to be commercially viable for both the insurance companies and for their customers, the providers and users of space services, considerable amounts of information will be required concerning the proposed space activities, and new legal measures and technical procedures will be needed. In general the process of commercial insurance becomes more efficient the more statistical data that is available. Although a scenario involving tens of flights per day, and hundreds of thousands of passengers per year is still much smaller than other existing travel industries, it is at least of the order of magnitude required for risks to be reliably calculated.

In view of the current liability of the governments of launching states for damage caused by spacecraft, adequate third-party insurance will be a minimum requirement made by the appropriate launching state of commercial spacecraft owners and operators, as proposed for example in Japann (28). Owners and operators will therefore have to obtain such commercial insurance cover, and provide the launching state with other information needed to reassure the state that the proposed activities pose no threat.

In addition companies will wish to insure their spacecraft, both launch vehicles and orbiting accommodation, against accidental damage, fire, and other normal risks insured by terrestrial companies. The scale of cover required will of course be much less when launch costs are lower than today, making the commercial insurance market capable of playing a much greater role than it has to date.

Customers will also wish to ensure themselves during their stays in commercial spacecraft, as people commonly do today while travelling. Again, as the cumulative number of commercial passenger space flights increases, insurance will quickly become an efficient means of reducing risks to customers.

The legal regime aboard the US space shuttle, Spacelab and the planned US/intergovernmental space station have been the subject of considerable discussion. The involvement of governments of several different nations in a single facility, and the need for all to accept the common arrangements, have led to great complexity, as discussed in this volume.

The case of commercially owned and operated craft in orbit will be similar in one respcct, but very different in others. Commercial craft, whether transport vehicles or orbital accommodation, will be similar in needing to abide by existing space law. However, they will be very different in being owned and operated by private organisations, whether national or international - not by governments. They will also be different in being motivated primarily by the need to be attractive to potential customers. Thus the legal regime aboard a commercial craft in space will be determined by the owners and operators, who will have considerable freedom, subject to the constraint of existing law.

It seems likely that in some cases the owners and operators will choose to adopt an existing legal regime, such as that of the state of nationality or the launching state. However, it is also likely that in some cases new departures will be made, and a novel legal regime will be formulated. Such experimentation is surely to be welcomed, and from a legal point of view is potentially of great interest, involving both the fundamental philosophy of law (29), as well as practical problems of the interpretation of the interfaces between such a regime and existing law. The need to be attractive to potential customers will create incentives for such new legal regimes to be simple, equitable and liberal, while the long-standing precedent of maritime law and the important powers of the captain of a vessel also seem likely to play a role in such innovation.

A matter of great importance in connection with legal regimes is (unfortunately) the question of taxation. The customers of commercial space travel companies will be terrestrial residents, and so the companies will be subject to taxation on Earth. However, as the industry grows it will lead to the establishment of a range of businesses in orbit supplying services in space to the travel companies as customers. At this stage the question of taxation will become more complex. Realistically, the question of legal independence from Earth will not become a serious issue until people are living permanently in space. However, it is conceivable that at an intermediate stage a system of local government in Earth orbit might be developed to which companies operating in orbit would pay taxes as a contribution to the costs of maintaining a safe and efficient Earth-orbital space traffic system. Needless to say, such a development would raise many interesting new legal issues.

As a potentially major commercial project that would become attractive at the launch costs predicted for the SSTO project, the development of satellite solar power stations ( SPS) would have implications for space law in a number of different areas. These were discussed by a number of authors in the early stages of SPS studies -- see for example (30, 31, 32) - though less work has been done recently due to the perception that launch costs are too high for the SPS to be commercially feasible. In the following, some technical aspects of major legal issues are briefly reviewed and then nearer-term implications are considered. The topics already considered in relation to passenger accommodation will all be important for the SPS project, but the development of SPSs would also raise a number of other legal issues.

HTOL

As in the case of passenger accommodation services, owners and operators of satellite solar power stations will have a great interest in the control of space debris, for several reasons. First, the project will also involve many people in orbit, who will need be protected against debris. Second, SPSs will have very large surface areas, and so will be subject to debris impacts many orders of magnitude more frequently than other orbital craft. Most activity, and particularly the construction of large structural elements, is likely to take place in orbits some distance above the zones currently most contaminated by space debris, but the problem will still be very significant.

Third, since the development of commercial SPS units will involve large-scale construction operations in various Earth orbits, major efforts will be necessary to avoid debris production. The introduction of legal responsibility for damage caused by space debris would require tyhe owners of such operations to take a range of actions in this direction.

The SPS project will mainly utilise low equatorial orbit (LQO), GEO, and at least one intermediate orbit also in the equatorial plane for construction actuties. Agreement between several different companies or operators to utilise a single orbit or orbital zone for each activity could greatly economise the use of Earth orbital space, as well as reducing the risks of collisions, as discussed in (23).

The issues raised above about the need for some elaboration of space law relating to damage caused to spacecraft in space also apply to the SPS project. In addition there are a number of other issues within this category concerning the definition of "damage". For example, the large-scale use of ion engines for transfer of large cargo payloads between orbits may have deleterious impacts on other spacecraft using the same regions of near-Earth space. However, any such impacts would be made by atoms and molecules, far smaller than the smallest pieces of debris, and hence would generally be impossible to trace to the craft responsible.

Operational SPSs will also transmit many gigawatts of microwave energy through space towards the Earth. Although the intensity of the beams near the Earth will be low (of a few hundred watts per square meter), it will be much more intense nearer the transmitting antenna. Within a few thousand kilometres of the transmitting antenna surface it is likely that the power intensity will be sufficient to damage or disturb the operation of satellites passing directly through the beam. As an indication of the need for the elaboration of space law in this area, it has been argued that damage caused by transmission of microwaves is not covered by existing space law (30).

Passage of LEO spacecraft and aircraft through an SPS beam, while not directly damaging to people, could cause electromagnetic interference to these vehicles, but could also be avoided through simple design changes. In addition, passage of a large spacecraft through the beam would reduce the power delivered to the receiving antenna on Earth. Precautions will therefore be needed to prevent these occurrences. Such steps all represent costs of SPS development.

The SPS project will involve commercial assets of very high value, and the risks to be insured will be of similar size to those for insurance of such costly and potentially dangerous assets as offshore oil-rigs and commercial airliners today. However, once there is a reasonable record of accumulated experience there would seem to be no reason why the commercial insurance industry should not be able to cover the risks involved. Exceptional measures such as those in the nuclear power industry today, whereby governments assume the extreme risks which exceed the capacity of commercial insurance markets, would not seem likely to be necessary. The maximum realistic risks from an SPS accident are the crash of a heavy launch vehicle, or a collision in orbit between two large spacecraft. These are clearly far less than the devastation caused by a single nuclear accident such as that at Chernobyl, which is understandably not insurable commercially.

There is no reason in principle why, when launch costs are low enough for SPS development to be commercially attractive, it could not be carried out and funded by electric utilities, like the development of other large electric power generation systems. Thus the owners of orbiting SPS bases might also be private organizations, and would have freedom to create novel legal regimes. For practical reasons the need to be commercially attractive will act as a pressure encouraging the evolution of the most efficient legal regime, as happened in the early days of international trade in Europe (29).

As an even large project than the passenger space travel scenario, SPS development will lead to the establishment of an even wider range of commercial activities in space, including eventually the use of lunar and other non-terrestrial resources. Such fundamental questions as whether the launching state should remain responsible for such activities, and which bodies if any should have the right to impose taxation, will therefore become even more important.

This subject arises due to the likely need for power station operators to be able to use their plant for some thirty years in order to be able to earn a commercial return. The meaning of the word "appropriation" is of course open to different interpretations, but together with the likely need for "exclusion zones" of some sort around SPS facilities, this issue will be important for the SPS project and for space law. However, achieving a satisfactory operational definition of these concepts is a matter of some complexity, as discussed in (27).

Because of the obvious value of sunlight to operators of commercial satellite solar power stations, it may be helpful to introduce the concept of rights to sunlight in space law in order to prevent encroachment on other companies' sites. This too would be relatively complex to define operationally. The principle of "first come first served" would seem to have some degree of natural justice in this case. However, under such a rule a solar power satellite of perhaps 100 square kilometres in area would pre-empt a very large volume of space if interpreted strictly. Thus some flexibility would seem to be required; for example, shading by a satellite a few square meters in area would be irrelevant, while shading by another SPS would be unacceptable.

It is currently believed that any deleterious environmental impact of SPS on the Earth will be very small, and will be greatly outweighed by the system's benefits when compared with alternative sources of electric power for Earth. Nevertheless the possibility of significant terrestrial environmental impacts will inevitably involve the project with terrestrial environmental law, while the size of the rectennas will inevitably make them subject to detailed environmental impact studies. Environmental law is currently in a period of rapid evolution, both nationally and internationally, and it is likely that future standards for many forms of pollution will be stricter than present day standards. Such developments would seem likely to make the SPS even more attractive relative to other large energy sources.

The above discussion relates primarily to the stage of full commercial operation of large-scale satellite power stations. In the years before these are developed, a series of smaller satellites will be developed, such as the "SPS 2000" project (10, 11). These will be generally similar to existing satellites, except for being substantially larger, and transmitting much higher power levels. It has been pointed out elsewhere (33) that under existing law SPSs fall within the definition of telecommunications satellites, and so will be subject to regulations of the ITU and related bodies.

SPS 2000 and subsequent models will be experimental vehicles. While it would be possible to design such spacecraft to operate within existing ITU regulations, it may be that a wider range of useful experiments could be performed if these were infringed in certain ways. For example, in order to obtain the maximum information about possible radio-frequency interference from the SPS system, and how to avoid this, it could be useful to operate experimental systems in various ways that generate microwave noise outside currently allowed limits. Such experiments will be geographically limited. It would therefore seem possible that, provided that they took place over a relatively limited time-period and did not cause costs to other users of the electro-magnetic spectrum, the necessary waivers could be agreed, in view of the fact that the project is of potentially international benefit. In particular, host governments of SPS 2000 ground stations would have an interest in making them as valuable as possible as SPS development facilities.

If the SPS 2000 project is successful in improving the case that SPSs could be an economic and environmentally attractive source of electric power for Earth, successor experiments are likely to involve larger satellites with greater power outputs in higher orbits, for which similar or more extensive waivers might be valuable. However, although these projects may benefit from changes in the law relating to the use of the electro-magnetic spectrum, they do not seem likely to require changes in the law concerning utilisation of orbital space, in particular GEO.

The contrary seems likely to be the case operational SPS units. These are likely to be designed to meet ITU regulations about electro-magnetic spectrum utilisation (though it is possible that it would be considered more cost-effective to alter these regulations in certain ways in order to accommodate the SPS system better). However, the SPS space segment would involve so many units of such a large scale in GEO and other orbits, and the intense microwave regions extending from SPS transmitting antennas would be so important, that formalised changes in the use of GEO and other zones of near-Earth space seem likely to be desirable.

The objective of SPS 2000 and related projects is to develop a major new energy source for the Earth. If as a result of continuing work, including the operation of such satellites, the SPS project appears feasible and attractive, it may be considered beneficial to alter ITU rules in appropriate ways. Such agreement would of course only be likely provided that the development of SPS was seen as being of genuine international benefit.

On the basis of the recent US decision to develop a low-cost reusable SSTO launch vehicle, there appears to be a good chance that in the later years of this decade the cost of launch to Earth orbit will fall substantially (3). As a consequence the cost of space hardware will fall proportionately, and the range of activities undertaken by humans in space will widen considerably. In particular, the activities of private commercial organizations in space will increase substantially as the costs involved become sufficiently low to enable them to earn attractive profits.

These activities will require the development of appropriate commercial space law in a number of areas considered above. As the scale and scope of such commercial activities grow, the range of legal problems that will require resolution will grow to include fundamental issues. This task provides an opportunity for the world community to create an innovative legal regime that is encouraging to private individuals' and organisations' activities in space. This will require the minimum amount of regulation possible, the simplest procedures, and the least restrictive interfaces with existing space law and with existing legal regimes. A useful guide for determining minimum requirements of space law can be found by considering the needs of commercial insurance companies, which are likely to play an important role in the evolution of the commercial space activities discussed above.

The two major projects discussed above, which require only a reduction in launch costs of the scale proposed for the SSTO project to become commercially attractive, both depend on terrestrial customers, and will therefore be linked with terrestrial law. However, at least some of the secondary service activities that will develop in space along with these projects are likely to depend exclusively on these projects as customers. They will therefore have minimal contact with terrestrial law. This situation will raise interesting questions about what legal regimes might apply to such companies. The development of such exclusively space-based activities will increase interest in the development of true "Astrolaw", to be created according to the needs of individuals and organizations operating in space without primary reference to terrestrial laws.

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