Copyright © 1994 by Japanese Rocket Society. All rights reserved

The Space Tourism Study Program of the Japanese Rocket Society is studying passenger transport to orbit as a possible near-future space activity that could create a demand for more rockets on a larger scale and at much lower cost than the present launch industry (Ref. 1). To provide a general guideline for inter-disciplinary studies by the Business Opportunity, Transportation and Medical Standards Sub-Committees, an industrial perspective shown by Table 1 was developed to provide a framework for studying the first phase of space tourism, in which passengers take short flights to low Earth orbit (Ref. 2).

Based on this first guideline, the Transportation and Medical Standard Sub-Committees have conducted feasibility studies in their specialized fields. This paper considers the requirements needed to satisfy the expectations of space tourists in the first phase of space tourism, based on the experience of those people who have been to space in the past.

For the purposes of this paper, the main attractions of space flight to be provided to passengers are considered to be Earth sight-seeing, and experiencing weightlessness during flight, as recommended in (Ref. 3). The main factors which will determine the quality of these entertainments are orbital conditions and vehicle accommodation. The influence of these in the first phase of space tourism is discussed in the following.

Recently preliminary market research has shown that, for the approximately 70% of the population who say they would like to visit space, the most popular activity in space is Earth sight-seeing (4). Thus this activity should be given priority in the first phase of space tourism. The sights on Earth that passengers can see from a space vehicle are determined primarily by the orbital conditions which are expressed mathematically by the six parameters of satellite orbits. From the point of view of service-providers and customers, orbital conditions can be interpreted as the take-off site, the direction of the flight and the altitude reached (which, together with the positions of the apogee and perigee, determine the track along the ground), the departure time, the flight duration and the landing site.

The factors that influence the value of a flight from the point of view of Earth sight-seeing can be divided into factors external to the vehicle and factors internal to the vehicle. That is, even if vehicles are designed to be capable of making orbital flights that go over appropriate regions or countries, passenger accommodation factors such as window and seat arrangements and the vehicle orientation during the flight will also be important to enable guests to enjoy Earth sight-seeing fully. The main factors that will be important are considered in turn below.

For the first phase of space tourism, in which passengers will remain within the launch vehicle, the choice of orbital parameters is in fact freer than it will be in the second phase, when launch vehicles will deliver passengers to an orbiting accommodation-vehicle or vehicles. In that case the range of possible take-off and landing times and sites will be tightly constrained in order to permit rendez-vous with minimum use of propellants. These constraints will not apply to flights in which passengers remain in the launch vehicle. In this case the factors to be considered include the following.

Fully-reusable passenger-carrying space vehicles will be able to operate from much simpler sites than the launch sites of present-day expendable rockets. Ideally passenger flights should take off from many major airports, which are easily accessible and have air traffic control facilities. However at least initially just a few sites will probably be acceptable. Because most passengers will wish to see more than just the Earth's equatorial region, take-off sites near the equator will not have the advantage over high latitude sites that equatorial launch sites have today for launching satellites into geo-stationary orbit. Consequently many other places could be attractive take-off sites for passenger space flights, such as the 43 degree north latitude Tokachi District Space Flight Center project (5).

From commercial considerations, the number of take-off sites will be limited by the investment that will be needed in propellant-handling and other facilities. However, it could be a popular service if launch vehicles were used to make sub-orbital flights from a wider range of local sites to the main take-off "hub" sites for orbital flights. This could probably be done without requiring refuelling at the "spoke" sites, although it would also be possible to refuel the launch vehicle using a mobile propellant tanker.

The view of Earth from low orbit varies according to the orbital altitude. In the absence of viewing aids the scenery of Earth seen from 200 km is fairly similar to that seen from higher altitudes such as 400 km (3), but the field of view grows wider with altitude. Thus a range of different orbits, including eccentric orbits in which the altitude varies considerably, perhaps reaching 1000 km or more at apogee, might be interesting for customers. At present it is not known what sorts of view would be most popular. Market research using simulations of views from different altitudes and with different viewing equipment could probably be useful to learn people's preferences.

For the short flights considered for this first phase of space tourism, very low orbits (or perigees) of some 100 kilometers altitude may also be interesting. These are unstable in the sense that aerodynamic drag from the upper atmosphere leads to re-entry within a few days, but for a flight of a few hours they could offer particularly good viewing, though over a narrower field of view.

The inclination of the orbit will determine the maximum latitude of the Earth's surface that passengers will be able to see. Thus, although flights to equatorial orbits taking off from sites near the equator will have the lowest propellant costs to reach a given altitude, they will also provide the narrowest range of views of Earth - just a narrow strip round the equator. There are of course many interesting sites at higher latitudes; for example it seems likely that many passengers will wish to view their home-towns, and most people in advanced countries live at latitudes above 30 degrees. Consequently flights to relatively high-inclination orbits should be provided. In addition there will be demand for flights in polar orbits, which provide views of the Earth's north and south poles, as well as offering the possibility of seeing any point on Earth, depending on the orbital parameters.

The views of Earth available during a flight will be determined in detail by the space vehicle's ground track. Companies providing passenger space travel services should select orbital flight plans that provide a particularly attractive range of views, and publish pamphlets showing different characteristic sights. Flights will probably be named after the main sight-seeing targets, such as "Tropical Jungles", "Polar Flight", "Pollution Watch", "Big City Lights" and so on. There is clearly wide scope for imaginative planning. Travel companies should also take care to avoid monotonous flights such as orbits that pass over oceans most of the time. The variety of ground tracks and areas visible could also be increased by using elliptical orbits in which the vehicle altitude varies widely during the flight.

The views of Earth available will also vary according to the different seasons, which affect weather including storms, vegetation and so the colour of the landscape, natural phenomena such as snow cover and forest fires, and even human activities. Thus passengers may choose to fly at different times of the year according to their differing tastes. This possibility could become a significant attraction for repeat customers, who represent an important part of the demand in many businesses.

Since the weather, and particularly the degree of cloudiness which will greatly affect the view, varies according to the season, the demand for orbital flights will probably be seasonal. Thus companies may need to make considerable efforts to attract customers at off-peak times, such as by offering discounts, by improving the experience of weightlessness, or by emphasizing the viewing of space rather than Earth at times of poor weather at sites which are major attractions. It may also be necessary to re-schedule flights to see particular sights at short notice according to weather conditions, particularly at certain times of year. This would create some uncertainty for passengers, which would be inconvenient. But to the extent that such uncertainty is inevitable, such as for passengers wishing to view northern Europe in winter, it should be acceptable.

Viewing of irregular phenomena such as snow falls, floods, volcanoes, forest fires and aurora could be planned only at short notice. For passengers interested in such sights, a service enabling reservations and bookings to be made at short notice would be necessary, as in the case of standby seats for passenger air travel today. For the time-frame under consideration, an inter-active service using electronic-mail bulletin boards might be attractive.

Orbiting the Earth at low altitude, passengers will spend about one third of each orbit in darkness. Those who have been to space have said that the view at these times is as interesting as during "day-time". The range of interesting "dark-side" sights includes such natural phenomena as lightning, aurora, bush-fires and volcanoes as well as human-made sights such as highways, city lights, fishing fleets and oil-field gas-flares (6, 7). Take-off times and orbital paths should therefore also be selected so as to include passing over sites that are interesting when viewed in the dark. Sunset and sunrise, which occur every orbit, are also said to be beautiful sights.

While most passengers will probably wish to land at the site from which they took off, there will probably also be demand for flights landing at different sites. In this case the flight would have the bonus of providing "free" high-speed travel to the passenger's destination. The destination sites would usually be selected from the limited number of "hub" sites from which orbital flights were made. Such a service would overlap with the possibility of providing a world-wide sub-orbital passenger service. Though more expensive than passenger air travel today, this might become an important commercial service for reusable passenger launch vehicles, and would compete with supersonic air travel. Due to the ease of precise navigation in the era of GPS and other satellite navigation systems, sub-orbital charter flights might be arranged to and from many destinations.

During the first phase of space tourism passengers will remain within the launch vehicle through-out the flight which will last a few hours. Thus the accommodation arrangements within the vehicle will be very important in determining the conditions under which passengers can view the Earth.

The design of passenger windows, and particularly their size, position and depth relative to the vehicle's walls, will be very important for viewing outside the launch vehicle. Ideally passengers should each have their own window so that they can look outside continuously. Some passengers might be pleased to share a window another person, but probably only if it was sufficiently large and accessible for both to view at once. In this case some passengers might prefer to share with one or more friends, since this would enable them to discuss the view together. The astronauts who visited the US space station "Skylab" in the early 1970s suggested that windows should be surrounded by a wide area of free wall to enable people to view in any direction when in weightlessness. This would require a lot of space but would probably be popular. If free space was available above and below a window (even if not around 360 degrees), two people might share it in weightlessness viewing from opposite directions, rather than being side-by-side as on Earth. This might be an economical way to use windows.

If windows were not provided, but only electronic screens showing the view outside the spacecraft, it would be hard for a space tourism service to compete with the computer simulations of space flight that will become commercially available on Earth at much lower prices than actual space travel as "virtual reality" technology improves.

The quality of viewing outside will also depend on each passenger's position relative to the windows. It would be desirable if, once they reach orbit, passengers were free to float beside a window and look through it in any direction. This will require hand-grips and/or foot-grips at appropriate positions and angles beside windows to allow passengers to move and to anchor themselves easily in weightlessness.

During take-off and landing passengers will be in a more-or-less horizontal position, but they would like to be able to view outside the vehicle without moving their heads while the vehicle is accelerating, which is particularly disorienting. This might be achieved through the use of mirrors placed at the correct angle above their windows, which could be folded away during orbital flight.

For optimal sight-seeing, viewing aids such as binoculars would be helpful to allow passengers to see the Earth in more detail. Some passengers would like to take their own equipment, including cameras, which may have to be included in their mass allowance.

The recent innovation by some airlines of showing passengers the view from a camera in the aircraft's nose during take-off and landing would be particularly interesting for passengers in a launch vehicle. As in aircraft today, the view of take-off and landing, as well as other information, could be shown either on relatively large communal screens and/or on individual screens.

The view that each passenger has will be strongly influenced by the vehicle orientation relative to the Earth and to passengers' windows and seating arrangements. For a circular seat layout, as suggested in (8) and analysed in (9), each passenger's view will be a little different from their neighbours. It will be necessary to take this into account when preparing the vehicle flight-plan in order to provide all passengers with attractive views. This could be achieved, for example, by pointing the vehicle's nose towards the Earth and maintaining a slow rate of rotation of the vehicle around its axis of symmetry, so that each passenger has experience of being at the "front" and at the "rear" of the vehicle. Maintaining a slow rotation like this might also be popular during take-off and re-entry, if it was feasible.

In order to see well outside the vehicle, the lighting inside the viewing cabin should be relatively dim. As in aircraft, passengers should be able to adjust their personal lighting without irritating their neighbours. In addition, for viewing outside while in the shadow of the Earth it would be best if cabin lights were turned off to enable passengers' eyes to become fully dark-adapted.

Many passengers would enjoy hearing a detailed commentary about the view of Earth that they can see. A range of different styles of commentary are possible, including different types of background music, which will be more or less interesting to different groups of passengers according to nationality, age, travel experience, and so on. Members of particular groups with common interests such as biology, mountaineering, astronomy, history, religion and so on could be specifically catered for in this way.

If passengers are seated in a circular layout their views of Earth will be different, which could require different versions of the commentary to be prepared. This could be handled relatively easily using individual screens and/or head-phones.

For experiencing weightlessness the design of the space inside the vehicle will be of central importance. In particular, how large a volume is available, how many people will share it simultaneously, for how long each passenger may use the space, and what guidance they receive will determine how enjoyable the experience is. Factors which will have an important influence on the entertainment value include the following.

The larger the volume that could be available for passengers to experience weightlessness the better. Ideally, for an individual to practice moving freely in weightlessness a cubic volume at least some 2.5 meters across would seem desirable. However, if several people use the volume simultaneously, a larger volume would be necessary. In order for everyone to have the opportunity, it may be necessary for passengers to be allotted particular times for use of the space according to a schedule.

Unlike in aircraft, the space between each passenger's own couch and the cabin ceiling will also be available for floating in weightlessness. Since people will enter the cabin in Earth gravity, but will lie down for take-off and landing, the volume above the couch will be quite large - probably some 2 m by 2 m by 0.5 m. If the cabin ceiling was made higher than in aircraft this volume would be large enough for passengers to practice at least more restrained activities in their own space. This might be particularly popular with people who travel with family or friends, with whom they could share the combined space in turn or together. In this case, if a central space is also available, it should perhaps be used for more lively activities like gymnastics.

Some passengers may wish to experience weightlessness, rather than viewing outside the vehicle, throughout the time between take-off and landing, and vice-versa. Some people may prefer to spend more time in the central space, in which case other people may be able to use those peoples' "personal" space. All this should be planned before each flight as far as possible in order to avoid disappointment for passengers not having the experiences they expect.

Passengers wishing to concentrate on activities in weightlessness may be numerous enough to justify operating a dedicated vehicle. This might have fewer windows than the standard vehicle, and have passenger accommodation arrangements that leave a wide-open interior space in orbit. For example, it might be possible to use a seating structure that folds away leaving an open two-storey space some 5 metres tall over the full width of the vehicle. This would enable passengers to enjoy weightlessness fully.

Many passengers will enjoy the experience of weightlessness more if they could receive some guidance on how to move effectively, and about particularly entertaining "tricks". Some such instruction could take place before the flight, but it may also be desirable for one or more of the cabin crew, who should all be skillful in moving around in weightlessness, to provide guidance during the flight.

As well as the experience of floating and moving around in weightlessness, playing with small objects is also said to be entertaining. This would be possible in passengers' own seating area. Playing with water is particularly entertaining (7, 10), but might require a special enclosure to prevent escaped water from irritating other people and causing danger for the vehicle. For this too, some guidance either before or during the flight would probably be helpful.

In order to make the experience of weightlessness pleasant, well-designed hand-holds should be placed in convenient places to help people manoeuvre. In addition, to avoid possible injuries to each other, passengers should change their shoes for soft slippers or socks before the flight. Velcro tape might also be used on people's clothes and shoes to enable them to stabilise their position against the "floor" and "walls" of the cabin, which could be covered with an appropriate material.

Although Earth sight-seeing and weightlessness are considered to be the main objectives of space tourism for the present study, a number of other activities will also be popular, and should be catered for as far as this is possible within the strong constraints on the cost and mass that will be commercially acceptable.

Those who have visited space say that the stars are much brighter and more colourful when seen from space. Astronomy is a popular hobby on Earth, and market research shows that astronomical observation would be popular (4), so many passengers will probably wish to view astronomical sights as well as the Earth. This will be easiest during the periods of "night-time" when the vehicle is passing through the Earth's shadow. As for Earth viewing it will be necessary to darken the cabin, and an expert commentary would probably also be popular, as well as viewing equipment.

Many passengers will be keen to take videos and photographs as memories of their unique trip, both of the view out of the vehicle's windows, and of playing in weightlessness inside the vehicle. For passengers who wish to bring cameras with them, these will represent part of their mass allowance. Passengers will probably wish for advice confirming that their cameras will operate correctly in weightlessness. With the advent of electronic cameras and home fax machines, it might also be popular to provide telephone links for passengers to call or send pictures to friends on Earth.

It would probably also be a popular service for the travel company to make a video of each flight, including take-off, the view from the passenger cabin, passengers' activities during the flight, and return to Earth. This could be professionally edited and sold to passengers who wished for it. Since miniature video cameras are available, such videos might be taken automatically by a suite of pre-programmed video cameras mounted in the vehicle. Passengers might book in advance for extra video to be taken of them.

During the early stages of space tourism flights will last only a few hours, and so meals will not really be necessary. However, as described in (3), passengers will certainly enjoy taking a meal in zero gravity, and so food and drink should be provided. As during vacations, many passengers may also like to drink some alcoholic drinks.

Although we teach children to have good table manners and "not to play with their food", passengers may wish to do this in weightlessness. Passengers will probably also wish to take photographs of eating, in order to remember these entertaining aspects of weightlessness, as the American astronaut Joe Allen was photographed playing with his orange juice.

Another aspect that will be significant for many passengers is providing formal recognition of their visit to space, as described in (3). For example it is traditional in the USA to give an "astronaut badge" to anyone who reaches an altitude of 50 miles or more, in recognition that they have visited space. There are also a number of clubs around the world of which passengers could become members after they have visited space. It is likely that other such clubs will also be formed as the number of people who visit space grows.

At present the number of people who have visited space, or reached orbit, is known precisely. Thus, for some years to come it will be possible to provide passengers with recognition of being, for example, the 2049th member of the human race to visit space. Such historical significance might be attractive to many people. A business such as the Guiness Book of Records might collaborate in such an activity.

Many passengers will wish to buy "omiyage" for friends as mementoes of their space flight. Although carrying these on board the vehicle will be expensive, small light-weight items such as cards, cakes, handkerchiefs etc, may be popular even at prices which reflect their transport cost. Videos of the trip, as mentioned above, will also be popular. As at airports, many other goods would probably be popular even if available only on Earth.

There are a number of factors in addition to the above which will have a significant effect on passengers' enjoyment of space flight, and so on the commercial demand for orbital tourism services.

As emphasized by Professor Mitarai (11), trust in the safety of the passenger vehicle is a fundamental requirement to generate substantial commercial demand. Like aircraft, in order to obtain certification and insurance the vehicles will have to achieve a high level of reliability through flying repeatedly. In addition, safety procedures and equipment such as emergency oxygen-masks similar to those provided in aircraft will be necessary.

Public perception of safety is influenced by other factors than safety statistics alone. For example, in the early days of aviation in the USA the first trans-Atlantic flight led to the "Lindberg boom" in demand for passenger flight. The "Ford Reliability Tours" started by Henry Ford to improve both the reliability of aircraft and public perceptions of aircraft safety were also extremely valuable (12). Similar activities may well be valuable in increasing the public's confidence in space travel.

In addition to vehicle safety, other objective factors such as the establishment of effective aerospace traffic control, space debris reduction, and avoidance of such relatively dangerous regions as the South Atlantic Anomaly will be important.

It will be very important for passengers to feel well throughout their space flight. For this, problems such as "space sickness" and congestion in the head need to be resolved. Although about 50% of those who have visited space have suffered from temporary nausea, a number of anti-emetic drugs have recently been found to be highly effective in preventing this (13). As a result NASA has reportedly stopped further research on this subject. For holiday-making passengers possible side-effects of medication such as slight drowsiness, equivalent to the effect of drinking a little alcohol, seem sure to be acceptable. Since, as on board a ship, if one passenger vomits others feel less comfortable, it may be appropriate to establish a standard treatment for all orbital passengers such as a standard dose of Promethazine sometime before take-off.

The feeling of congestion in the head caused by redistribution of body fluids in weightlessness can be irritating for some people, and could be rather unpleasant for people suffering from a cold. It may therefore be necessary for passengers who catch a cold shortly before their flight to take some appropriate medication, or to re-schedule their flight. Some pre-flight preparation, such as physical training and/or medication, either at home or during a pre-flight residential period leading to partial reduction of body fluid before flying may help to make people comfortable in weightlessness.

A number of minor bodily discomforts on Earth can be more irritating in weightlessness. For example, many people experience occasional discomfort from having one nostril blocked, and unblock their nostril by tilting their head to one side. This remedy depends on gravity, and so is not available in weightlessness. Consequently it may be desirable to have medication such as nasal sprays available to overcome such discomfort. Stomach gases can also be uncomfortable in weightlessness, and so counter-acting medication would be useful.

As on aircraft it will not be necessary to treat serious injuries. However, there are a number of minor injuries that people may suffer, in part because of being in an unfamiliar weightless environment, which it will be useful for cabin staff to be able to treat. These include nose-bleeds, minor cuts and bruises, getting something in the eye, choking, and spraining or dislocating a finger. People wearing contact-lenses or spectacles who experience difficulties may also need help.

Providing full toilet facilities like those on aircraft would be expensive and heavy, but at least some minimal facilities will be necessary. As described in (2), using a wash-basin and/or toilet in weightlessness is different from using one on Earth and may well be of interest to passengers.

For flights lasting a few hours, as proposed for the first phase of space tourism, some preparation may be enjoyable, though passengers will have different preferences. Travel companies should produce a detailed booklet providing advice for customers, giving guidance on such matters as health and moving in weightlessness. Many people may wish for reassurance that space flight is not medically dangerous, and that they do not need to be unusually healthy in order to visit space - a common misunderstanding. There may also be considerable demand for a residential training period of a few days providing an entertaining preparation for space flight. There is likely also to be a lively market for books about space flight written by well-known writers and "tarento" who have travelled to orbit themselves.

As in commercial aircraft flights, many passengers will probably enjoy listening to music in orbit. This may be catered for as in aircraft both collectively through cabin loudspeakers, and individually through headphones.

Although less critical than the space vehicle's engineering design, the interior design of the passenger cabin will be very important for the public. Like many other aspects mentioned above, this also provides the vehicle production company with a good opportunity for publicity, due to the great interest that the media are sure to take in every aspect of space tourism, and particularly those aspects that can be shown in photographs and on video.

The people who visited the space station "Skylab" differed considerably in their reaction to living in weightlessness. Some enjoyed the strangeness of complex perspectives, and some found them confusing, and wanted a strong "local vertical" as in a one-gravity environment. It should be remembered, however, that the people who lived in "Skylab" were always very busy with work, and weightlessness was irritating to them because it slowed their work. For holiday-makers weightlessness will not be irritating in this way, but will mainly be entertaining, particularly since "space sickness" is no longer a problem. Thus there is scope for interesting experimentation in the interior design of a passenger vehicle, intended to give an exciting "feel" to the new world of weightlessness.

As in any closed environment, an air-conditioning system will be needed to keep the air fresh and pleasant-smelling. In addition since, since dust will not fall to the floor as in aircraft, it will be desirable to keep the amount of dust in the air very low in this way, in order not to irritate people's eyes. A functional idea learned from the US Space Station "Skylab" was that it is useful to have a noticeable air current moving through the vehicle, since things that get lost usually arrive at the filters over the air-intakes of the air-conditioning system (7). In a passenger vehicle some people are sure to lose things, so such a system could be useful. From a more basic point of view, it will be necessary to design the interior to have no sharp projections against which passengers floating around the vehicle in weightlessness could hurt themselves.

Electronics designers must also consider such details as providing screens showing the vehicle's current altitude, velocity, latitude and longitude in order to give passengers a feeling of the unique quality of space flight. This might be integrated with the other information functions mentioned above in a "passenger data system". In combination with other electronic systems such as a video network and telephone links to Earth, the passenger service electronic system would be an interesting project for electronics makers, separately from the vehicle avionics.

People who have been to space have also learned lessons about suitable clothing. These concern such matters as allowing for the small changes in body shape that occur in weightlessness, and having pockets that retain their contents effectively in weightlessness. Thus it will be useful for space tourism companies to offer passengers advice on this matter, and also to offer suitable clothing for sale. Clothing of course also has importance for people for non-functional reasons. If space tourism becomes a popular pastime, it seems likely that innovative clothes manufacturers will produce a range of fashionable clothes designed for use in the unique environment of weightlessness.

As in the case of aircraft, there will probably be a significant demand for charter flights, that is block-bookings of a launch vehicle by a group of people who wish to travel together. This is particularly likely if launch vehicles carry as few as 50 passengers, as assumed in the JRS study (14), in which case a range of different social groups might use such a service, such as astronomy clubs and travel clubs. It also seems likely that some religious groups would arrange for members to travel to space together to view the Earth and the Universe. Such markets could no doubt be stimulated by appropriate creative marketing.

Even for the first phase of space tourism, in which passengers will make orbital trips of a few hours, there are clearly many different aspects of the passengers' experience that must be considered and planned in detail in order to provide a satisfying service - which is the key to commercial success.

Simulation of space flight using a detailed mock-up of a passenger cabin could be useful for determining potential passengers' preferences concerning such aspects as seating and window layout, orbital paths, view of the Earth and vehicle orientation. Experiments in an aircraft performing parabolic flights could be useful for studying the accommodations needed for inexperienced passengers to enjoy weightlessness.

In addition to the functional aspects of passenger launch vehicle design, the interior design of such vehicles also provides exciting opportunities for industrial designers. Holding a competition for such designs might be a good way of stimulating new ideas while obtaining useful publicity.

The results of ongoing studies on the above subjects will be fed back to the Japanese Rocket Society Sub-Committees studying vehicle design and general flight plans, as well as to those studying the medical and business aspects of space tourism.

1. M Nagatomo, 1993, "On JRS Space Tourism Study Program", Journal of Space Technology and Science Vol.9 No.1, pp 3-7.
2. P Collins, 1993, "Towards Commercial Space Travel", Journal of Space Technology and Science Vol.9 No.1, pp 8-12.
3. T Akiyama, 1993, "The Pleasure of Spaceflight", Journal of Space Technology and Science Vol.9 No.1, pp 21-23.
4. P Collins, Y Iwasaki, H Kanayama and M Ohnuki, 1994, " Potential demand for passenger travel to orbit", Engineering Construction and Operations in Space IV, American Society of Civil Engineers, Vol 1, pp 578-86.
5. (anon), 1990, Hokkaido Aero-Space Industrial Base Project, Pamphlet of Hokkaido Aerospace Industrial Development Council.
6. T Tachibana and T Akiyama, 1992, " UCHU YO! (Space!)", Bungeishunjuu.
7. H Cooper, 1978, " A House in Space", Granada Publishing.
8. Kawasaki Heavy Industry, 1993, " Passenger seat arrangement for space vehicles", Journal of Space Technology and Science Vol.9 No.1, 1993, p 7.
9. T Nagase, 1994, " Study on plan for single stage rocket for general space travel", (in Japanese), Masters Thesis, Tokyo Univ.
10. T Akiyama, 1991, " Official photo record of Japanese astronaut", (in Japanese), Shogakukan.
11. G Mitarai, 1993, "Space tourism and space medicine", Journal of Space Technology and Science Vol.9 No.1, 1993, pp 13-15.
12. M Holden, 1992, The fabulous Ford trimotors, McGraw-Hill.
13. J Davis et al, 1993, " Comparison of treatment strategies for space motion sickness", Acta Astronautica, Vol 29, No 8, pp 587-91.
14. K Isozaki, H Taniuchi, K Yonemoto, H Kikukawa and T Maruyama, 1994, "Vehicle design for space tourism", Proceedings of 19th ISTS, Paper no. ISTS 94-g-22p.