There are some who believe that Japan is very good at developing and perfecting technologies that were developed in foreign laboratories. There is very little evidence from this panel's recent visits to both industrial and government laboratories in Japan to sustain such a view. In a broad range of technologies, Japan appears to lead the world. In areas such as lithium-ion high density batteries, very large deployable antenna reflectors, flexible deployable solar cell arrays, shaped or molded antenna reflectors for specialized antenna beam formation, optical communications systems, precise spacecraft pointing systems, and many other areas, Japanese laboratories appear to be at the cutting edge of state-of-the-art basic R&D.
Much the same can be said about advanced satellite communications applications. The Japanese DBS system, currently known as the BS-3 system, has more than five million subscribers and can also provide HDTV broadcasting. Although the HDTV service now essentially serves commercial rather than residential customers, the falling price of HDTV cameras, VCRs and receivers is likely to change that in the next few years. Progress in introducing ISDN services, rapid growth of mobile communications, and advances in interactive media suggest that Japanese applications for education, health, entertainment, business services, etc. are truly advanced. A visit to the Toshiba Science Museum was instructive. It showed a single corporation developing an extremely wide range of advanced applications that include HDTV, precision robotics, intelligent buildings, advanced intelligent sensors, interactive digital imaging, 3-D projection systems, advanced power and battery systems, etc.
Some of the more impressive advanced long-range concepts being examined in Japan at this time are outlined below.
Ironically, such concepts were first discussed in the U.S. over a decade ago, but today only the Japanese (especially SCR) are actually carrying out feasibility and initial design studies in this field. This technology appears to be some five to ten years away from practical implementation, depending upon the level of funding it receives in the next few years. Although developed for mobile satellite applications at L-band, this technology could easily also be applied to DBS and even FSSs in an orbital antenna farm configuration.
The advances in DBS and MSS that will come with the ETS-VI and COMETS experimental satellites will strongly aid Japan's applications satellite program for the rest of the 1990s. The restrictions in frequency bandwidth for mobile services has led to experiments with much higher bandwidths for future mobile services on COMETS. Developmental work of phased-array DBS antennas is moving ahead, including work on future interactive systems. Experiments with variable power on demand will be carried out with COMETS, using some 3,000 meteorological stations to detect heavy rain attenuation and to adjust power levels.
The ability to use satellites for a variety of broadband services is being explored by KDD, NTT, CRL, ATR, NEC and others. These projects include such applications as interactive CAD/CAM, scientific visualization, tele-education, tele-work networking, virtual reality, interactive imaging and design procedures, and large scale multi-site scientific experimentation. Most of this effort can be characterized as comparable to experimental work being conducted by NASA, ARPA, and others in the U.S. The only major area not currently being addressed seems to be HDR satellite services to facilitate supercomputer interconnect or service restoration.
There is some impressive work being carried out in Japan with regard to GEO large scale antenna platforms and also satellite cluster concepts. Work at ATR is even exploring the use of fiber optic physical cross links between and among a cluster of satellites in GEO. These concepts, which may define the future some ten to twenty years hence, are being investigated in innovative and highly advanced research projects. There was little evidence of additional satellite or propulsion studies examining other truly advanced concepts such as microwave stabilized satellites in LEO (i.e., spidersats), laser satellite systems operating from aerostats, or drone rocket stabilized platforms. There was also little evidence of synergistic thinking in terms of using LEO systems for communications, environmental and earth sensing tasks on a multi-function basis. In fact, LEO and MEO satellite systems currently receive only limited research support in Japan except for certain truly experimental packages.