Sven Abitzsch (Dipl.-Ing.)

At present, the next generation of crewed lauch vehicles is under consideration. The trend is toward clear, cheaper access to space by using reusable launch vehicle ( RLV) design with airliner-type operation capability. Although such a design requires a very high development cost investment, it is the only one which promises a substantial reduction of cost per launch (1). With it the economical success of RLVs could be bolstered. Therefore, proposers of RLV design hope to convince private investors to help finance development cost. That would greatly increase momentum towards commercialization of the space transportation market.

But a RLV design can only accomplish its low-cost target, if it can reach high launch-per-year rates. For the moment and in the medium term no adequate market is in sight to support such high launch rates. The situation for crewed missions is even worse.

The prospects for the implementation of RLV technology and with it for commercial space services, could best described as the "chicken and the egg" problem:

• high launch costs will lead to low transportation demand
• low demand results in small markets with low turnover - that won´t convince any aerospace industry to invest in expensive new launcher developments, nor any private investment
• so, access-to-space costs still remain high and markets small

Since space tourism came into view again in the '80s, the utilization of its market potential for development and operation of next-generation launchers has been brought into focus. So the following idea emerged: would it be feasible to establish a positive interaction between the obvious demand for space tours and the need for vast markets to achieve RLV´s operation cost targets?

The philosophy behind this approach is persuasive at first sight. The demand for space tours establishes a market, urgently needed to justify the high development investments for RLV-technology. On the other hand, RLVs will enable cheaper access to space. This would lead to an increase of commercial business within aerospace industry with its widely discussed positive implications. Moreover, cheap access to space would boost the space tourism market itself. As a result, a sustainable crewed space transportation market would have been born. Moreover, this would be the solution of the "chicken and the egg" problem.

This leads to the following hypothesis: The next generation of low-cost launch vehicles require space tourism and vice versa. A perfect symbiosis could be established!

One vital question still remains, will the cost of space tours as offered by launch vehicles in the future fit into the demand price figures? That is, will a sufficient number of people exist who are willing to pay high-price tickets, which are most likely throughout initial phase of space tourism, until the price will come down to more affordable levels for the majority? If so, then a sustainable space tour market could be set up. Otherwise, this "price gap" must be bridged or the general public will have to accept that a self sustained market will never show up.

To become clear about the prospects of space tourism the most important task is to get more detailed demand data. So, it was high time for space tourism market research.

The first demand figures concerning space tourism have been published in the mid '80s by Society Expeditions and AMEX CO.(2). At certain points they generated data of how many persons would like to visit space (Amex) and a demand price curve (Soc.Exp.). Because of their selective database comparability between these figures was always very limited. Nevertheless, for more than seven years these data were the only ones estimating space tour demand.

Since 1993 space tourism market research has been performed more systematically. In that year the first market research on demand for space tourism was carried out in Japan by P. Collins at the National Aerospace Laboratories and Tokyo University (3). In view of the encouraging results, two similar studies followed until yet. They have been carried out in Germany, 1994 (4) and in the USA, 1995 (5). Because all of these studies employed unified questionnaires and were conducted during a short period of time, it is possible to compare their results directly.

Following, market survey results, most relevant for the evaluation of global space tourism demand, will be presented in comparison.

Although not representative, all collected market survey data has been adjusted wherever necessary. For example, mismatches between the structure of the survey participants and the overall population statistics have been compensated by weighting the collected data. So that the figures shown below are as quite representative as possible.

Figure 1 shows the basic level of interest in travelling to space, broken down by age and country. As an overall average, the most enthusiastic space tourists are Japanese with approx. 70% . It seems to be that Germans are not very interested in space tourism, with 43% this is the lowest percentage. Maybe a reason for that lies in the more prosaic german life-style. All in all, these levels are most promising concerning the prospects of space tourism.

Figure 2 shows the activities the respondents would prefer during a space trip. It is notable that all market surveys came to the same result, the simplest thing to do in space is also the most prefered one - looking at earth. The other activities, space walk excluded, could be realized without great expense as well.

These figure delivers important information about the space tour vehicle design. So, it won't be neccessary to include expensive high-tech attractions which will consume additional payload capacity. Sufficient opportunities for each space tourist to look at earth will be more essential. That is, an adequate number of windows and an attractive flight profile (e.g. highly inclined orbit) to see as much as possible of the earth would be highly recommended.

Despite of cultural differences between asian, european and american people, the similarity of the three survey results is striking. This will be favourable for space tourism's operation, because no specific offer have to be taken into account concerning the origin of passengers.

Figure 3 shows the lenght of a space trip as preferred by the respondents. Obviously a substantial majority would prefer to go to space for several days, one week or more. No greater variety between the market surveys exist as well. So it is reasonable to conclude that, as long as no orbital hotel exists enabling people to stay a few days in space, the demand for space tourism will not reach its full potential. This could become one of the most serious problems for the initial phase of space tourism's operation. As far as can imagined, the first years of space tourism service will be dominated by short trips into low earth orbit (6, 7).

Finally, what is of most interest for initiation of space tourism is the number of people who are willing to pay, and how much, for a space trip. So in figure 4 the amount people would pay for a space trip is displayed. The amounts are shown as a multiple of an average income per capita in each country. To become independent of both, exchange rate and inflation rate distortions, the socalled purchasing power parities (PPP) in international dollars ($int.) have been implemented as common monetary database. Based on a globally standardised market basket, real purchasing power of an income could be compared directly among several countries. Beyond that, global enterprises like space tourism will require such comparison.

For transformation into absolute amounts, following PPP-values have to be considered: Germany, 16580 $int.; Japan, 20200 $int.; USA 25850 $int. (year of comparison:1994)

The amount the respondends interested in space tourism would pay for a space trip are represented as cumulated data, considering that a person who would pay an one year's income, would pay a six months' income all the more. Due to that fact, the nearly 100% values for one months' pay could be explained.

Acccording to several studies on space tourism's market development, the initial phase will require higher prices (6, 7). This could reach to values up to four times of the average space tour service price. So, considering figure 4, it is very promising that a significant portion of potential space tourists would pay a three to five years' income for a space trip. For japan this represents an amount of $int.60600 to $int.101000. But, it has to be studied in more detail, if customers would pay this amount for an initial offer of say "one day in space". This leads to the general question of market segmentation and price elasticity. Further market research would be essential in this field.

Figure 5 shows a breakdown of reasons given by those who did not wish to travel to space by country. For some 5-10% the idea of space tourism is just not realistic and roughly 1/3 cited safety concerns. Presumed a space tourism system will become operational and will proof its safety, then these two groups probably will change their mind. This will lead to additional potential for the space tourism demand and the overall average of people interested in visiting space could grow by 10% (!).

To sum up it can be said that the several surveys show no great variation in substantial data, with exception of the overall interest in visiting space. Moreover it appears from these results that the desire to travel to space is consistent in all cultures. This is very encouraging for the prospects of space tourism in general because it will support the idea of conducting space tourism as a global enterprise, so sufficient demand could be assured especially for the early very expensive phase of space tourism.

To assess the prospects of space tourism global demand data would be obligatory. One way to get these data would be to carry out further national market surveys and combining them to a global one. This procedure will generate highly reliable results but will also take some time and lots of ressources to be completed. Before this will be done, a faster and cheaper approach has to be implemented. For the porpose of a preliminary assessment of the global demand for space tourism an alternative procedure is presented in figure 6.

The most important steps can be summarized as follows:

• Each region in the world promising an appropriate demand for space tourism has been taken under consideration. So a "relevant world of space tourism" has been defined. In general this world consists of the OECD, the fast developing countries in asia (APEC) and latin america, high GNP per capita countries (several OPEC-countries) and east european countries
• Then, in view of cultural and economical differences, these countries have been grouped into three homogenous "lead-regions" - Asia, Europe and America/Australia.
• The space tourism market surveys as far as yet conducted have been used as reference database, each representing one of these lead-regions.
• Each country of these lead-regions has been compared with the assigned reference country under aspects of income, population, economy and appropriate growth trends. Of special interest was the income per capita proportion which has been utilized to calculate a correction factor.
• This factor has been used to determine the market potential of each country, assuming that the income per capita correlates directly with demand.
• By joining these figures of all countries, a projection of the global market potential for space tourism could be generated.

In Figure 7 the estimated global market potential is shown in comparison with the results of the market surveys carried out in Japan, Germany and the USA/Canada. The market potential is shown as passengers per year vs. ticket price. The maximum potential lies at 20 million. passengers per year. But this requires a ticket price of $1000 or less which won't be achievable from today's view. So, this maximum potential is just of illustrative porpose.

It is notable that a ticket price of $50,000, the price Society Expeditions offered its "project space voyage" for the year 1992, could produce approximately one million space tourists per year (!) worldwide. This is much more than the 10,000 space tourists Society Expeditions had expected in 1985.

Another vital finding for space tourism is that a price of more than say $100,000 would not lead to a sustainable market. The demand will fall back to very low numbers of passengers. It has to be stated that data for prices above $100,000 is insufficient and therefore demand figures could be well in the range of sampling errors.

All in all, sufficient demand leading to a self sustaining space tour market could be expected for ticket prices of $50,000 or less. This price target should be taken into account as the primary factor for vehicle design resp. vehicle selection.

Figure 8 and 9 are showing the potential of a space tourism business in view of annual turnover. Presumed each tourist would take a space trip for the price accordingly to the market surveys, following annual turnover is to be expected.

These figures are amazingly impressive. They show a maximum market volume of approximately $60 billions per year(!) and that with ticket prices of $50,000 as well. Considering this, space tourism bears a market potential that could revolutionize the whole aerospace industry referring commercialization trends.

Referring to the findings of space tourism market research the most important requirements a space tourism system have to meet, can be summarized as follows:

• The space tourism system has to come up to expectations of space tour participants, namely to the most preferred ones: looking at earth and experience of weightlessness. The vehicle design should therefore provide a sufficient number of windows and sufficient interior space to fly around.
• High inclined orbits are favourable, covering a greater proportion of earth's surface.
• Due to medical restrictions the acceleration level should be kept lower than 3 G.
• Although most survey participants prefer longer space trips, it would be recommended to limit the space tour to several hours in accordance to avoid space sickness. There is no general time limit until space sickness will occur, but it has been shown that in the first hours of space flight the space sickness rate is at low levels (8).
• By reducing flight time, some space tourists may think to get insufficient service for their money. To compensate for this feeling a kind of luxurious space camp should be implemented before each space flight. In providing technical information, health monitoring and professional space training, a space camp will intensify the feeling of becoming a "real astronaut". A great psychological momentum in gaining customer's content.
• In general, appropriate procedures are required to proof health conditions of space tourists. Because of the fact that some tourists will be dismissed from space flight due to medical reasons, it would be recommended to accomplish health inspections very wise, best in connection with a space camp.
• Most important, it would be essential to meet the demand price figures. Considering the market surveys, a sufficient demand will be established at ticket prices of $50,000 or less .

A space tourism vehicle which obviously will meet these requirements is shown in figure 10. This design has been developed 1994 by Kawasaki and Fuji Heavy Industries, Japan.

Fig. 10: 50-passenger SSTO space tourism vehicle, Japan (9)

Referring to reference (9) this vehicle will meet all the specific requirements of space tourism. It is notable that today all vehicle proposed for space tourism will be ballistic single stage to orbit ( SSTO) concepts. One reason for that is the overall conviction that ballistic SSTO vehicles are thought to be feasible within near-term technology (9). So, for this study the SSTO concept has been adopted to proof its economical feasibility for the porpose of space tourism. The economical feasibility of vertical take off and landing ( VTOVL) vehicles (eg. SÄNGER), has been studied earlier in (7).

To estimate the space transportation system cost figures, the widespread TRANSCOST (10) model of D E Koelle has been utilized. Figure 11 shows the demand price curves in combination with the space tourism transportation cost vs. passengers per year. So the feasibility of space tourism can be examined. In addition to the japanese SSTO the Phoenix E of Hudson (11), proposed with Society Expeditions offer, and the German Sanger (12) vehicle designs are presented. The price figures do not comprise development and financing cost. These cost have to be brought up by private investors and refinanced through revenues.

It could be seen that a sustainable space tourism market will emerge when demand price lies above supply cost. This first will occur at ticket prices of about $200,000 with a volume of 1000 passengers per year. If ticket price will come down to $100,000 a number of 10,000 to 100,000 passengers per year will establish. It is notable that in this price regime, the US market alone will count up to 30,000 space tourists. The maximum market potential considering these figures will emerge at ticket prices of approx. $35,000 with 2,000,000 space tourists per year. That would produce an annual turnover of $70 billions(!). Beyond that, the demand price could not be achieved through the proposed space tourism vehicles.

The prospects of space tourism are very promising. In accordance with figure 11, space tourism has the enormous potential the proposers ever had expected. Space tourism will become the primary market for RLVs and the largest market for crewed space programs at all, assuming the transportation cost figures could be achieved. But with regard to the recent market surveys, the scope for price variations have become a broader one. A sustainable and promising market could be even achieved at higher than previously anticipated prices.

As stated earlier, the demand for space tourism presumable will not reach its full potential with just a basic offer of day trips to space. The majority of people interested in space tourism have a preference for a longer stay in orbit. So, it would be required to add obital accommodation through space hotels. A corresponding concept developed by SHIMIZU CORP. of Japan shows Figure 12. This additional offer will cost in a first approximation some $10,000 for a stay of a few days (13).

When the pure transportation cost to and from orbit will fall to a target price of say $50,000 then the additional cost of staying in a space hotel would sum up to an overall space trip price of about $60,000. These cost figures will open space tours to the group of customers preferring a longer stay in orbit, and this at reasonable price. In addition, this will launch a secondary market for the space transportation system due to hotel supply flights.

It seems reasonable to conclude that the space tourism business will develop in several phases. First, day trips in a space tour vehicle will be offered at high prices, this will found an exclusive market for higher income people and in addition, enables early and high proportions of revenues through skimming pricing. After approximately five years of operation, cost degression will grant substantial price cuts, so that a greater portion of people could take a space trip, this would be the executive phase. Some studies support this assumption of high cost degression during the first years (6, 7). After an additional period of 5 to 10 years, the "mass market" will show up with low leveled prices and the highest turnover. This would be the time of implementing space hotels to ensure both, spurring new demand from the exclusive market segment (eg. higher income people) and later on enhance the basis of customers as explained above. This phased approach will counteract any saturation trend.

In each phase, supporting activities to stimulate demand could be implemented. Most promising would be a kind of space tour lottery first announced in (7). This lottery would provide the means to people to whom space tour tickets are too expensive. Thus, these people could fly earlier than expected boosting demand and, therefore supporting price degression owing to the economy of scale.

The far end of space tourism from today's view, could be a trip to the moon. In connection with the development of an advanced lunar base, passenger flights to moon could be offered at relatively low cost. An in depth study of the IAA concerning lunar development estimates passenger roundtrip cost from earth to the moon to less than $3 million (14). This seems to be an exorbitant price, but with regard to the time horizon - 2050 and beyond - and assuming increase of wealth will continue at a reasonable level, it's quite possible that demand for moon trips will emerge.

A comparison of space tourism market research carried out recently in Japan, Germany and USA/Canada has been presented the first time showing the current state of demand for space tourism. These market studies reveal very promising figures concerning the overall assent to space tourism. So, the percentage of people interested in travelling to space reaches from 43% up to 70%.

After implementation of a procedure to assess global demand for space tourism out of these market data, it can be concluded that space tourism economically is of highest interest.

A space tour at a ticket price of $50,000 - as offered 1986 by Society Expeditions - could result in a space tour business with an annual turnover of approximately $60 billion, with a volume of one million passengers per year visiting space.

With regard to market segmentation and corresponding price strategies (eg. skimming pricing, introductory pricing), these figures could be widely varied. In order to convince private investors, an early positive cash flow could be secured.

Considering these turnover figures, the base for a commercial venture could be laid with the result of private investment entering aerospace industry. So, space tourism service will not require government funding and will therefore lead to the always pronounced goal of commercialization with its widely discussed positive effects for the overall space business.

Crucial is, however, the availability of a safe, reliable and low-cost launch vehicle. As far as yet foreseeable, a fully reusable ballistic SSTO vehicle would be most appropriate. Recent research in this field still showing promising results. The cost figures, anyhow, should be met when the RLV design will turn out as technically feasible.

In any case, space tourism more than any other commercial space venture has the potential to support low-cost-launcher operation and therefore justifies development of RLV technology.

Moreover, it can be even concluded that without space tourism none of the proposed low-cost-launchers will be guaranteed a sufficient market, so low-cost operation will be in question and the goal of cheap access to space could not be achieved.

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13. P Collins, 1993, "Towards Commercial Space Travel", Journal of Space Technology and Science Vol.9 No.1, Japanese Rocket Society
14. Lunar Development Subcommittee of the Committee on International Space Plans and Policies: The Case for an International Lunar Base, 1st Cosmic Study of the IAA, International Academy of Astronautics, Paris, 1990
15. S Matsumoto et. al., October 1989, "Feasibility of Space Tourism: Cost Study for Space Tour", 40th IAF Congress, Malaga, Spain, IAF-89-700