Dietrich E. Koelle

Orbital transfer systems for lunar missions

Abstract For future Lunar mission operations basically two types of transfer systems can be conceived (a) the conventional direct-injection expendable vehicle approach, and (b) the re-usable orbit-to-orbit (LEO-LLO-LEO round-trip system. The second solution has been studied in Europe in the SPACE TUG Phase A Study in 1971/72 for NASA as a fully reusable system and this is compared to a more recent NASA-MSFC transfer vehicle concept with expendable propellant tanks and aerobraking. The results of an analysis on mission opportunities for LEO-LLO transfers is presented. A European option is also shown for mode (a), using the ARIANE 5 for lunar missions with an optimized cryogenic transfer vehicle, derived from the H.10 Stage (ARIANE 4) plus a lunar vehicle derived from the MMII-CRAF propulsion module using the 27.5 kN engine from the ARIANE L.9 Stage which could land a 3.4 ton vehicle on the lunar surface. Finally a completely new option (c) is discussed: the use of a ballistic SSTO vehicle for lunar landing missions after refuelling in LEO. This seems to be a highly effective single transportation element approach compared to the seven elements SATURN V-APOLLO-LM system of the 60ies.

Economics of small fully reusable launch systems (SSTO vs. TSTO)

Abstract The paper presents a design and cost comparison of an SSTO vehicle concept with two TSTO vehicle options. It is shown that the ballistic SSTO concept feasibility is NOT a subject of technology but of proper vehicle SIZING. This also allows to design for sufficient performance margin. The cost analysis has been performed with the TRANSCOST- Model, also using the “Standardized Cost per Flight” definition for the CpF comparison. The results show that a present-technology SSTO for LEO missions is about 30 % less expensive than any TSTO vehicle, based on Life-Cycle-Cost analysis, in addition to the inherent operational/ reliability advantages of a single-stage vehicle. In case of a commercial development and operation it is estimated that an SSTO vehicle with 400 Mg propellant mass can be flown for some 9 Million

The transcost-model for launch vehicle cost estimation and its application to future systems analysis

per mission (94/95) with 14 Mg payload to LEO, 7 Mg to the Space Station Orbit, or 2 Mg to a 200 800 km polar orbit. This means specific transportation cost of 650

Cost reduction trends in space communications by larger satellites/platforms

/kg (300

Cost analysis for single-stage (SSTO) reusable ballistic launch vehicles

/lb), resp.3.2 MYr/Mg, to LEO which is 6 −10% of present expendable launch vehicles.

Launch cost analyses for reusable space transportation systems (Sänger II)

Abstract The first part of the paper describes the structure of the analytical cost estimation model (1982 edition) for launch vehicle development, fabrication and launch operations cost. Especially the new approach for a cost assessment of operations cost including refurbishment (in case of reusable vehicles), direct and indirect operations is presented for discussion and subsequent improvements by introduction of more reference values. The model uses the Man-Year (MY) as cost unit which is independent from inflation and currency exchange rate changes. The second part of the paper deals with its application to future systems analysis and cost comparison with the example of a potential future European launcher (Post-Ariane-4) with 15 tons LEO payload capability: ten different two-stage launch vehicle concepts (expendable, semi-reusable and fully reusable) with storable and cryogenic propellants are analysed with respect to development cost and cost per launch. The key problem for a future European launch vehicle is the optimum solution between the (limited) development effort and the desired minimum launch cost. More advanced (partially) reusable systems could provide an essential reduction in cost per launch, require, however, a higher development effort. In such a case an analytical cost model based on realistic reference data can provide important data for the vehicle concept selection process.

Launch vehicle evolution - from multistage expendables to single-stage reusables

Abstract The paper analyses first the satellite growth trend in the past and the specific characteristics of communication satellites, as there are specific mass per channel and payload share vs. spacecraft mass. With assistance of a cost model (derived from actual spacecraft cost) it is shown that larger satellites are more cost effective. The same applies to the launch cost, also showing a reduction in specific cost (per kg or per channel-year) for larger payloads. Finally different types of communication satellites/platforms are compared (two smaller satellites, one large satellite, modular docked assemblies) for the same total communication capacity of 72 000 dual telephone channels. It is shown that for each orbital communication capacity a certain optimum spacecraft size exists which leads to minimum space segment cost.

The impact of launch vehicle type and size on development cost

Abstract The ballistic SSTO Vehicle seems to be the prime candidate for a future reusable launch system for medium-size cargo due to its inherent technical and operational simplicity by limiting the number of stages to just one, and by using conventional rocket propulsion. Based on the MBB vehicle studies from 1969/70 and 1986 (BETA II) and taking into account requirements of the recent SDIO-Contract (“Delta Clipper”) a cost and cost driver analysis is presented using the TRANSCOST Model. First, the potential development cost for ballistic SSTO vehicles in the range of 200 to 1000 tons propellant mass are presented and the main influencal parameters - including the so-called “non-technical” factors - are discussed. The results are compared with actual total development cost of other launch systems. Then the potential ground and flight operations cost are discussed, based on the proposed “Standardized Launch Cost Definition (SLC, Level I, Level II Cost). In this case especially the impact of annual launch frequency on the cost per launch is shown, and the expected specific transportation cost compared with the present values of expendable launchers. A substantial cost reduction is to be expected, even under non-optimistic assumptions.

Cost efficiency as design and selection criterion for future launch vehicles

Abstract With the revival of studies for more economic fully reusable launch vehicles on both sides of the Atlantic, cost estimation analyses become of major importance. This is due to the fact that the essential cost reduction expected by fully reusable launch systems need to be substantiated for the justification of the development effort. The TRANSCOST model developed in the 1970–1983 period for launch vehicle cost analyses dealt mainly with expendable launch vehicles. This paper shows updated material and CERs for launch cost including fabrication and operations cost for future reusable and winged systems, such as Sanger II with the ETHV hypersonic manned winged upper stage.

Future low-cost space transportation system analysis

Abstract The paper provides a survey about the technical development trends and alternatives in the launch vehicle area. The traditional solution is the multistage expendable launch vehicle. The American STS with the reusable winged Shuttle is the first step towards a reusable system. While the launch cost of an expendable system comprises about 70% hardware cost, the STS (Shuttle) has reduced the hardware cost per flight to some 50%. A fully reusable vehicle would come down to less than 30%. The technical development trends as engine performance, stage mass ratio, vehicle payload ratio, etc. are discussed and the requirements for fully reusable two-stage and single-stage vehicles shown. For each launch vehicle concept examples are presented which have been conceived in the past 20 years. It is shown how the trend to fully reusable systems will allow to reduce the launch cost. As final and most cost-effective solution the single-stage winged vehicle will probably evolve for manned space transportation and small payloads, while for heavy cargo transportation the unmanned single-stage ballistic vehicle seems to be the most advantageous concept.