Propulsion Systems

In Europe there are two major contractors for monopropellant and bipropellant spacecraft propulsion systems, MBB and Matra-Marconi. MBB produces all propulsion components for most European programs from tanks to piping and thrusters (some U.S. components such as valves are used). However, MBB does not always produce the electronics. The MBB bipropellant thruster technology is flying successfully on Inmarsat 2, EUTELSAT II and TELECOM II. There were well publicized problems with an MBB thruster on GALILEO, which has led to an extensive improvement program. There are a number of qualified U.S. bipropellant suppliers and to date U.S. manufacturers have continued to use U.S. propulsion technology.

MBB has developed one of the two European ion thrusters (the other has been developed by RAE in the U.K.). The MBB thruster has been qualified in ground testing and was to fly on a shuttle platform EURECA in mid-1992. 2,400 hours of operation are planned, and recovery of the platform in 1993 will allow detailed analysis of operation and wear-out mechanisms, etc. ESA has also funded the ARTEMIS program which will use both thrusters for north-south station keeping in a mid-1990s flight. Hughes has developed a xenon thruster under NASA and INTELSAT sponsorship but there is no flight program on the horizon. In fact, the last NASA ion thruster flight may have been on ATS-6 about 20 years ago.

Figure 2.32. Outline of H-I Launch Vehicle -- The H-I is a three-stage launch vehicle capable of launching a larger geostationary satellite weighing about 550 kg. Development of H-I was initiated in 1981 based on the technology accumulated through the development of N-I and N-II rockets. NASDA has so far launched 7 satellites using H-I (EGS in 1986, ETS-V in 1987, CS-3a and 3b in 1988, GMS-4 in 1989, and MOS-1b and BS-3a in 1990), and plans to launch two more satellites called BS-3b and ERS-1, respectively, in 1991 and 1992.

Table 2.8 Major Characteristics of the H-I (Nominal Value) -- A

Figure 2.33. The H-I

Table 2.9
Stages of the H-I

Figure 2.34. H-I Launching Performance Capability

Figure 2.35. Flight Sequence of the H-I

Figure 2.36. Development and Operation Schedule of the H-I

Table 2.10 Launch Record and Plan of the H-I

Figure 2.37. Outline of H-II Launch Vehicle -- The H-II is designed to serve as NASDA's main space transportation system in the 1990s to meet the demand for larger satellite launches at a lower cost and still maintain a high degree of reliability. It will be capable of sending a single two ton class payload or multiple payloads totaling two tons into geostationary orbit. The H-II is a two-stage rocket equipped with two large solid rocket boosters (SRBs) on the first stage for thrust augmentation.

Table 2.11
Principal Specifications of the H-II

Figure 2.38. The H-II

Table 2.12
Stages of the H-II

Table 2.13
Payload Capability of the H-II

Figure 2.39. Characteristics of the H-II

Table 2.14
Characteristics of the H-II

Table 2.15
Characteristics of Major Subsystems of the H-II

Table 2.16
Development Schedule of the H-II

Figure 2.40. Flight Sequence of the H-II

Figure 2.41. Outline of the J-I Launch Vehicle -- The J-I is a three-stage launch vehicle capable of launching an approximately 1-ton class satellite into low earth orbit. The development of J-I is carried out in co-operation with ISAS (Institute of Space and Astronautical Science). The first stage of J-I is derived from H-II SRB and the upper stages and nose fairing are from M-3S-IIs.

Table 2.17
Major Characteristics of the J-I (Nominal Value)

Figure 2.42. The J-I

Table 2.18
Stages of the J-I

Figure 2.43. Characteristics of the J-I

Figure 2.44. Flight Sequence of the J-I Launch Vehicle

Figure 2.45. Development Schedule of the J-I

Figure 2.46. Ideas for an Advanced J-I

MBB's participation in the EURECA and ARTEMIS programs are highlighted in Figures 2.47, 2.48, 2.49, 2.50 and 2.51. The EURECA spacecraft was successfully deployed from the shuttle in August of 1992. MBB could develop a competitive edge if the flight demonstration meets its objectives. The ARTEMIS chart shows that both the MBB and RAE thrusters are scheduled to be flown. Table 2.19 presents applications for ion thrusters. More detailed information on the MBB unit is included in technical papers (Protto, Silvi and Greco; Silvi; Perrotta et al.).

In Japan, an ion engine development program generated a 2 mN thruster using mercury as propellant, successfully flight tested on ETS-III in 1981. Since then a 23 mN thrust ion engine has been developed. For the ETS-VI satellite, a cluster of four such ion engines will provide north-south station keeping for 10 years design life.

Toshiba developed the power supply and thruster control electronics (Figures 2.52 and2.53) (Handout, 21 Oct. 1992, Toshiba Corp., Space Programs Division) and performed the integration with the MELCO-designed thrusters. Life tests are under way on several thrusters, three have already achieved operation for excess of 6,500 h. Thruster life expectancy exceeds 9,000 hours. An individual thruster (Figures 2.54 and 2.55) has 23 mN thrust and a specific impulse of 2,906 s (more details are listed in Table 2.20 (Handout, 21 Oct. 1992, Toshiba Corp., Space Programs Division). The complete subsystem for ETS- VI has a mass of 95 kg, draws 1,570 W and consumes up to 41 kg propellant. In operation, two thrusters are used simultaneously for north-south station keeping (four times per week for 2.7 hours). This subsystem will also be used for COMETS.

An engineering model large xenon thruster (30 cm dia.) with a thrust level of 150 mN and a specific impulse of 3,500 s has been developed by Toshiba for an orbital transfer vehicle application (Figure 2.56and Table 2.21) (Handout, 21 Oct. 1992, Toshiba Corp., Space Programs Division).

Bipropellant thruster technology for orbit insertion and stationkeeping has also been developed and will be employed on ETS-VI (Figure 2.57).

The U.S. commercial satellite community will not use ion propulsion technology until it has been proven, so it is likely that one of the European or Japanese suppliers will eventually be the winner. There is some activity on Arcjets in Europe although the U.S. probably has a potential commercial lead with the use of the Rocket Research Thruster which was developed by NASA and will fly on TELSTAR 4 in 1993.

Figure 2.47. Electric Propulsion Activities in Europe (Courtesy MBB)

Figure 2.48. RF-Ion Thruster Operating Principle (Courtesy MBB)

Figure 2.49. Eureca Mission Sequence (Courtesy MBB)

Figure 2.50. Block Diagram RITA on EURECA (Courtesy MBB)

Figure 2.51. Ion Propulsion on ARTEMIS (Courtesy MBB)

Table 2.19
Applications of Ion Propulsion

Published: July 1993; WTEC Hyper-Librarian