The "Hypersonic Technology" funding programme of the Federal Ministry of Research and Technology (BMFT) is intended to make a German contribution to the technological preparation of the "next generation" of space transport systems. The "lead concept" for the German hypersonic technology programme is the SÄNGER spacecraft. The SÄNGER concept is a two-stage, horizontally launching and landing reusable space transport system which is to be capable of launching from Europe into space and returning to Europe from there.

Subject and objective of the project

The first phase of the hypersonic technology programme was originally scheduled for completion at the end of 1992. However, since the level of technology required for the transition to the next phase apparently cannot be achieved by the end of 1992, the BMFT intends to extend Phase I by probably three years.

In May 1990, the Committee for Research, Technology and Technology Assessment decided to have TAB conduct a technology assessment of the SÄNGER space transportation system. This was completed in June 1992 and the final report was published in October 1992.

The aim of the project was to improve the information basis of the parliament for the future consultation and decision-making processes on the hypersonic technology programme and the lead concept SÄNGER.

Results

In a first phase of the project, the following central statements were elaborated with the help of external experts.

• From today's point of view, a system SÄNGER requires at least 20 years of development until operational introduction. The prerequisite is that the initial steps currently initiated with the German hypersonic research programme and the concept studies for a technology demonstrator for the SÄNGER sub-stage are consistently pursued with high priority and that the necessary resource allocations are planned for the long term in the near future.
• Overall, the technological difficulties at SÄNGER are not considered to be insurmountably high; however, the large number of new technologies required, which must be implemented together in a complex system, makes the construction of a demonstrator appear necessary as a first step.
• The initially propagated connection with the development of hypersonic transporters (HST) is not likely to be a cost-reducing factor in the development of a space transport system, since the prospects for such a project (HST) are to be regarded as extremely low for operational reasons and because of the expected environmental impact, and the technical requirements are very different, apart from similarities in the technological bases.
• SÄNGER's engines will make more noise than Concorde's due to their design. Thus, the use of SÄNGER is likely to be possible only from airports located in practically unpopulated areas. Since SÄNGER usually has to take off from southern bases in a more or less southern direction for mission reasons alone, possible deployment locations should be found e.g. on the Iberian Atlantic coast. As far as other environmental impacts are concerned, in particular the effects on the ozone layer, these are currently being investigated in a study specifically concerned with the environmental effects of SÄNGER, which has been commissioned by the BMFT.
• The development costs for SÄNGER are currently estimated at around 23 billion accounting units (AU), which is more than twice as high as the costs currently stated for the development of Ariane 5 and HERMES (10.5 billion AU).
• Excluding amortization of development costs,launch costs for SÄNGER at 12 launches per year are AU 23 million per launch compared to AU 277 million for one of two HERMES launches per year. Specific transportation costs for the SÄNGER/HORUS-C unmanned version are $3,000 to $4,000/kg payload versus about $11,ooo/kg using Ariane 44L.
• If the development costs are included in the costs to be amortized, this results in extremely long amortization periods before significantly lower transportation costs are realized in the case of the present project proposal SÄNGER. The transport demand that can be estimated from current programs is assumed. Initial estimates show that the conservatively derived demand figures of about 12 to 14 SÄNGER launches per year in the area of ESA activities - the ESA long-term plan, however, only extends to 2000 - are probably too small to be able to realize the advantages that are possible in principle with SÄNGER.
• A noticeable reduction in costs could occur through an expansion of the user base and a broader distribution of development costs. At the same time, this would be a step in the direction of stronger international cooperation, which, however, may be in conflict with the demand for European autonomy. If Germany were to aim for system leadership in the development of SÄNGER, it can be assumed that it would have to bear at least 40 % of the development costs in order to achieve both project leadership and strong technological participation.

In a second phase, the results available so far were reviewed and further developed and placed in a broader space policy context. The final report first provides an overview of the space transportation systems available today and an analysis of their main deficits. From this deficit analysis, requirements for future space transportation systems are derived. Finally, the most important concepts for next-generation space transportation systems currently under discussion - including the SÄNGER concept - are presented.

Afterwards, the conception, procedure and organization of the German hypersonic technology program and the goals pursued with this program or a future space transport system of the type SÄNGER are described. These goals are almost predominantly optimization goals - space transportation should become more economical, safer, more environmentally friendly in the future, for example - which presuppose the need for space transportation and space transportation systems.

Subsequently - after the controversial discussion about the social benefit of space travel - space policy utilization scenarios are described and discussed, especially with regard to possible future market segments for a space transportation system of the SÄNGER type contained therein.

Subsequently, the objectives pursued with the hypersonic technology programme or a future SÄNGER system are analysed in detail, including reduction of costs, increase of safety and reliability, improvement of environmental compatibility, implementation of space transport from European airfields, improvement of the technological basis for future aerospace projects as well as for other fields of high technology (spin-off), technological preparation of the next generation of space transport systems.

Finally, the need for political decision-making with regard to the hypersonic technology programme and the guiding concept SÄNGER is summarised. Finally, political options for action are discussed.