1 Komukai-Toshiba, Saiwai-ku
Kawasaki City, Kanagawa Pref. 210
Date Visited: October 21, 1992
Report Author: C. Mahle
Mr. C. Ohara
Dr. S. Kuroki
Mr. T. Onodera
Mr. T. Sumi
Dr. Y. Kuriyama
Mr. S. Takayama
Mr. S. Kuniyasu
Mr. T. Oishi
Mr. T. Nakamura
Dr. Y. Yamaguchi
Mr. T. Todo
Toshiba is a large corporation established in 1876, with $35.5 billion in annual sales. Communications satellite activities are located in the Information and Communication Systems and Electronic Division Group with $18.8 billion annual sales (Toshiba Annual Report 1991). This group has nine business areas, among them Space-Related Products (since 1966) located at Toshiba Komukai Works in Kawasaki City (Toshiba, "A Guide to Komukai Works"). The main products of Toshiba Space are: Space Systems (spacecraft, etc.), Satellite Communication Systems (VSATs, Inmarsat ship and Standard C, GPS, mobile and portable earth stations), and four product lines not related to space. Toshiba Space has a staff of about 350 people with additional people helping during peak loads.
Starting with components such as sensors, Toshiba has steadily expanded its role in satellite manufacturing, building entire satellites since the late 1970s. Today Toshiba produces a wide range of space products, from components through the integration of large spacecraft such as the ETS-VI. Components include spacecraft antennas (deployable, unfurlable and robotically assembled), phased array antennas (for space radar applications), optical antennas, high power space TWTAs (from 10 to 300 W, at 8 to 38 GHz), spacecraft thermal control subsystems, batteries and power electronics subsystems, spacecraft structure subsystems, ion engines with associated electronics, and autonomous satellite control subsystems. In addition, Toshiba produces satellite data relay and tracking systems (including satellite orbit control) with associated ground support equipment.
Satellites constructed and/or integrated by Toshiba include BSE (launched in 1978), ETS-III (1982), BS-2a (1984), BS-2b (1986), and ETS-VI (a 2,000 kg class satellite ready for launch in 1994). Toshiba is contractor for the COMETS experimental satellite bus (launch expected in 1997). They are working on a number of space programs such as space robotics (assembly of large antennas in space), deployable and unfurlable antennas (up to 100 m diameter), and a J-1 launcher payload (OICETS, an optical ISL experiment with the ESA-ARTEMIS payload as correspondent).
Industry obtains development funding for space related technology developments from various government agencies. CRL, NASDA, ATR, ISAS, and MITI are all involved in funding developments of specific technologies, spacecraft components and major satellite programs such as ETS-VI. Industry sometimes spends its own R&D funds at the beginning of the process to demonstrate concept feasibility or develop a breadboard model. These results are then used to propose to the government that it fund a development program.
Toshiba's long range space related plans are focused on the concept of a future space communications network, consisting of GEO data relay satellites along with their ground segment, communicating with LEO satellites, manned and unmanned shuttles, space platforms and in the longer term, a Lunar base and Mars exploration. Such a network will require as one of the enabling technologies large spaceborne antennas (30 m to 100 m dia.) which may have to be assembled in space. Specific additional technologies mentioned included both RF and laser acquisition and tracking, spread spectrum technologies, satellite operations know-how and ground support systems.
These plans are an outgrowth of present activities. Toshiba is the systems integrator for the space network system, ground support system, satellite and orbit control for the ETS-VI satellite. These facilities will be located at Tsukuba Space Center. To test these facilities before the ETS-VI launch, NASDA plans to test the compatibility between the NASA TDRS satellite and an earth station which simulates a LEO satellite. After ETS-VI is launched, testing will proceed with a link through a NASA LEO spacecraft.
Toshiba is working on several space antenna projects including phased array radar antennas, shaped-beam parabolic reflector antennas, shaped-beam shaped- reflector antennas, deployable antenna reflectors with foldable segments or with solid petals, deployable mesh reflectors and reflectors that can be robotically assembled in space.
Toshiba is the prime contractor for the Tropical Rainfall Measurement Mission (TRMM), a joint NASA and NASDA mission to be launched in 1997 by the H-II rocket. They developed a 13.8 GHz, 128 element planar slotted waveguide array antenna for the TRMM radar. Peak gain is 47.7 dB with a plus/minus 17 degree scan angle and sidelobes better than 30 dB down. Phased array antennas are being considered for future precipitation radars and 23/26 GHz ISLs.
Reflector antenna technology developed recently generates a single shaped beam covering the Japanese Islands. One corrugated feed-horn illuminates shaped Gregorian reflectors. Measurements at 22 GHz shows excellent performance.
A 20 GHz segmented foldable 3.5 m diameter reflector antenna was developed for ETS-VI. The surface accuracy achieved was 0.17 mm rms at ambient temperature and 0.23 mm rms under worst-case thermal conditions. Mass of the honeycomb sandwich with CFRP facesheets was 43.6 kg including thermal wrap and spring-loaded reflector deployment mechanism. These are state of the art results.
A 22 GHz multibeam Cassegrain reflector antenna (2.3 m diameter) is under development for COMETS; six beams (with frequency reuse) cover the Japanese Islands.
For future missions, technologies for large reflectors (up to 100 m dia.) are under development. A videotape of the deployment of two antennas was shown, a 5 m diameter shaped solid petal Cassegrain reflector antenna and a 3 m diameter mesh antenna. The 5 m diameter deployable Cassegrain antenna, developed for NASDA, is intended for use at Ka-band (23 and 32 GHz) as well as S-band (2.1 to 2.3 GHz). 24 petals fold into a 1.6 m diameter structure for launch and are deployed by a single motor drive. This reflector has achieved a surface tolerance of only ±0.35 mm rms including thermal distortion.
Work is continuing on a robotically assembled Cassegrain reflector antenna to be tested on the space station. All essential mechanisms will be tested on ETS-VII. The 3 m diameter tetrus-type mesh reflector (developed for SCR) has a mass of 16 kg and was tested at C-band; a scaled up version with 30 m dia. would have a mass of less than 700 kg and work at UHF and S-band. The expected surface accuracy over the -150 to +100 degrees centigrade temperature range is plus/minus 5 mm with active control by actuators. SCR has sponsored a GEO platform study which would use such an antenna. The 30 m diameter antenna design and the 3 m diameter scale model have a folding scheme developed by Professor Miura.
Optical antenna work is directed towards OICETS, and the ISL between GEO and LEO. A multiyear program is in place to develop the hardware; so far an engineering model has been developed (the complete package masses 113.6 kg with a 30 cm mirror, and uses 151.3 W), to be followed by a flight model by 1996.
Toshiba has developed 100 W and 200 W TWTs at 12 GHz, and 10 W, 200 W, and 300 W TWTs at 22 GHz. (The 300 W 22 GHz tube was sponsored by SCR.) A 20 W TWT at 38 GHz is under development. A 20 W X-band TWT has also been developed and flown on JERS-1. Efficiencies quoted for the high power units are 50% and higher, with power conditioner efficiency of 90% and higher. The 12 GHz TWTs have had extensive life tests, but have not yet flown.
Toshiba has built NiCd flight batteries for several satellites (ETS-III, etc.) using cells from a variety of manufacturers. 35 Ah cells made by Sanyo are used in the most recent flight battery assembled for NASDA. Since 1985, Toshiba has pursued development of NiH2 batteries for NASDA culminating in a flight battery with 16 35Ah NiH(subscript 2) cells for ETS-VI and 4 x 31 35Ah NiH( subscript 2) cells for COMETS. Toshiba plans to use 70% depth-of-discharge in operation. This is the only flight battery with this technology built outside the United States.
Within the next five years, under a NASDA contract, Toshiba expects to develop a line of NiH(subscript 2) cells from 90 to 100 Ah as well as a common pressure vessel (CPV) battery with 2.5 to 12.5 V output voltage. In addition, at Toshiba R&D Center, there is work on nickel-metal-hydride (NiMH) batteries for space use and on lithium-ion secondary battery cells (expected energy density approximately 100 WH/kg).
Toshiba has developed all the necessary technologies to build complete spacecraft structures for large (1500 to 2000 kg dry mass) experimental and commercial communications satellite comparable to SS/Loral's INTELSAT VII and GE Astro's 7000 series. Solid engineering capabilities have been demonstrated in a number of well-known composite materials. Toshiba has developed several good mechanisms such as a solar array drive, and precision antenna pointing mechanisms (two orthogonal axes with 0.015 degree pointing accuracy). These will see first flight on ETS-VI. The software for the antenna positioning control electronics is developed in C or Fortran, then reduced to assembly code for the flight model.
Toshiba does solid work on thermal modeling, passive and active thermal control systems including embedded heat pipes (NH(subscript 3)). Under development are two-phase fluid loop thermal management systems for future high power satellites which need 5 KW heat rejection; an experimental model was described (Toshiba, "Space Achievers").
An ion engine was developed for ETS-VI. Toshiba developed the power control and performed the integration with the MELCO-designed xenon ion thrusters. An individual thruster has 23 mN thrust and a specific impulse of 2906 sec. Life expectancy should exceed 9000 h. The complete subsystem weighs 95 kg, requires 1570 W and can consume up to 41 kg propellant. Two thrusters are used simultaneously for north-south stationkeeping (four times per week for 2.7 h). This subsystem will also be used for COMETS.
An engineering model large xenon ion thruster (30 cm in diameter) with a thrust level of 150 mN and a specific impulse of 3500 sec has been developed for an orbital transfer vehicle application.
Momentum wheels are built by Mitsubishi Precision and integrated with electronics by Toshiba.
Excellent work was presented on autonomous satellite control. Toshiba has developed its own 16-bit MPU radiation-hard processor (CMOS, 10K gate array) for ETS-VI. The architecture of this system is excellent and well thought out. It includes a fault-tolerant multiprocessing operating system. This is probably one of the most advanced systems of its kind to be flown on a commercial satellite. The system on ETS-VI has four CPUs with voting and failure detection for operation of attitude control.
Toshiba developed ETS-III, which is considered a small satellite by today's standards. Currently, Toshiba is studying (Phase A) a J-I payload. Further missions may include a LIDAR experiment, a communications experiment, and/or technology demonstrations. These are currently proposed to NASDA.
Toshiba has invested heavily in semiconductor capabilities and facilities. However, due to the small scale (i.e., the relatively small quantities involved), space-qualified microwave semiconductor activities are limited. Toshiba does not produce space-qualified GaAs FET SSPAs; the space microwave semiconductors in production at Toshiba are HEMTS.
There is no work on high temperature superconductors for space applications; the work is directed only towards the energy field.
With the exception of payload electronics, Toshiba Space Programs Division has the capability to build complete large communication satellites with technologies that are state-of-the-art compared to other spacecraft builders. Toshiba is clearly committed to develop high quality space technology in large deployable antennas, optical communications, high power TWTAs, antenna pointing systems, batteries, ion thrusters, autonomous satellite control and operations, and ground systems.