Space Technological Cooperation and Application in the Asia-Pacific Region

By Chen Shupeng, Li Huiguo

With the multipolarization of international economy and regional realignment, the Asia-Pacific economy is thriving and prospering day by day. The demands for resources exploration and development and environmental monitoring and protection using space technology are increasing. Especially, since the United Nations Environmental and Development Congress held in Rio de Janeiro of Brazil, many countries have made their action programs correspondingly based on the Agenda 21.

In accordance with the two themes on Development and Environment of global concern, many countries and international organizations in the Asia-Pacific region have been taking some new policies, and are participating in and appealing for the international cooperations in space technology. Whether or not having the abilities of space technology, these countries have expressed the common aspiration for making full use of space application potentiality and strengthening space application to improve regional sustainable development of society and economy.

Technological Cooperation and Information Sharing

In China there are more than 460 institutions and organizations with about 10000 engineers and technicians directly engaged in or participating in the application research, tests and production of remote sensing satellites. And more than 100 remote-sensing image processing systems as well as over 10 provincial, autonomous regional and municipal remote-sensing centers have been established. According to incomplete statistics more than 200 million US dollars has been invested in this field since the 1970s.

China's satellite remote sensing data resource mainly came from Landsat-MSS data in the 1970s; Since 1986 when China's remote sensing receiving ground stations we re-established, it has mainly depended on the Landsat-TM data, meanwhile it also has introduced some satellite data from the SPOT, JERS-1, ERS-1, Space shuttle, and the former Soviet Union's satellites and NOAA meteorological satellite data. Since the early 1970s, China has launched 35 indigenous satellites of different types. The remote sensing data obtained are mainly from recoverable satellites and also from 7 area-survey scientific experimental satellites, 2 land territory-survey satellites, 1 scientific experimental satellite with the resolution of 5 meters, 3 photography positioning satellites and 2 polar satellites (FY-1). By October, 1994, China planned to have launched 5 satellites including 2 recoverable scientific-experimental satellites, FY-2 meteorological satellite, DFH-3 communications satellite, SJ-4 scientific experimental satellite. With its high performance of acquisition ability, the recoverable satellites carry the scientific experimental and technological detecting data obtained from the space back to the ground.FY-2 satellite is the first geostationary meteorological satellite developed by China; SJ-4 can be engaged in atmospheric physical sounding with its new processing capabilities, by adopting the geosynchronous orbit and three-axis stability, DFH-3 is characterized by large capacity, long-life-span and high-precision, and can serve the communications and broadcasting. It is predicated that China will launch about 30 foreign satellites of various types through 2000.

China's remote sensing satellite ground stations have been put into operation for many years, which have provided more than 3000 Landsat-TM pictures for domestic and foreign users.

It might be difficult to commercialize the satellite systems. The satellite remote sensing information, however, has been gradually gaining market in recent years. Even US EOSAT still depends on the support from the Department of Commerce. French Spot Image Co. has recovered only 80% of its ground investment. In the Asia-Pacific region remote sensing satellite receiving stations are more densely distributed than other parts of the world. The region has more than 10 Landsat's ground receiving stations compared with 5 in the North America, 2 in the South America and 1 in Australia. Overlapping coverage rate is high, and rent and maintenance cost are rather high. So it is necessary for the countries in this region to cooperate, win the preferential treatment those countries that own the remote sensing satellites and to discuss and solve the market price competitive problem.

Sharing of International Meteorological Satellite Information

The meteorological satellite has been widely used in the various aspects of global environment monitoring besides the meteorological field. Now meteorological satellite information is not only available to the countries which have not owned meteorological satellites for the time being but also becomes major information resources of the global natural change research and a major approach to natural disaster monitoring due to its feature of quickly covering the globe in a short period.

For example, the countries in the Asia-Pacific region have achieved successful experiences in monitoring the generation and development of typhoon, and its position, estimating its intensity and life time of the rainstorm weather system ( a few hours), and monitoring the existence of atmospheric aerosols and trace gases, ice-snow coverage, flood range, vegetation index and crop-growth, etc.. The Chinese Government paid more attention to and praised the satellite monitoring of the forest fire in northeast China occurred in 1987 and the calculation of the wheat output with satellite sensed data in north China since 1988. In particular, the digital data with high resolution have provided much effective information for monitoring the atmosphere and geophysical field as well as preventing and mitigating natural disasters. China also obtained many successful experiences in analyzing indications of earthquake, monitoring red tide and the pollution of water and atmosphere.

China has designed and developed its own meteorological satellite data receiving and image management, and widely received and used meteorological satellite data of other countries. Being involved in the international cooperative activities of World Meteorological Organization, China also energetically develops its own meteorological satellites. In 1988 and 1990, it launched 2 polar-orbiting satellites and obtained high-quality cloud pictures. As the advent of economic and trade society, it is a necessary trend of scientific and technological development that the basic information and data are shared by the countries in the Asia-Pacific region.

Establishment of Satellite Communications Network

At present, more than 120 civilian communications satellites in the world have been launched, operating in the 版36,000km牧 synchronous orbit. They are used by over 150 countries, and undertake 2/3 of traffic of international communications and find their applications through 5000 lines in various domestic communications fields of the world's countries. China has opened about 3500 lines and linked itself with more than 47 countries over 5 continents through international communications satellites over the Indian and the Pacific Ocean. The whole world is linked together through this satellite communications. In addition to 8 large A-level ground stations, the International Satellite Surveying and Controlling Station owned by International Satellite Organization for the Pacific and Indian region and TDMA datum station are set up in Beijing.

China's communications satellites' space resources have been increased considerably. Since the 1980s China has launched 6 indigenous satellites, including transponders from the AsiaSat-1, CHINA-5 (purchased American satellite in orbit), from the Intelsat and APstar, the total number of its transponders is more than 40.

In the application of communications satellites, China has worked out a series of plans for pilot projects. Now it has about 40,000 TV-receiving stations, 100,000 family TV receiving sets and 10 sets of programs through the satellite are being transmitted, covering about 80% of its population and providing effective services for the remote and minority nationalities regions. The educational TV station now offers 2 regular programs and broadcasts 30 hours per day. Through over 500 relay stations and more than 5000 receiving stations, more than 1.2 million middle and primary school teachers take the teacher training courses, 6 million people receive professional training and 20 million farmers receive rural practical programs, which plays an important role in improving teachers' quality, developing the cultural education in remote areas and promoting the regional economy.

Application of the VSAT system is developing rapidly. The People's Bank of China has established a network with 200 branches. Its application potential in the railway and shipping systems is also great. It is expected to increase their efficiency by 30-40%. In order to meet the needs of the urgent communications and TV live broadcast, China has about 10 mobile satellite ground stations of 2.4-meter Ku-band and 7.2-meter C-band, which are used in networking the BBPs in cities.

Burma, Thailand and Pakistan are establishing satellite communications ground stations networks. The Symposium on International Satellite Communications Application in 1988 and the Symposium on Countering Disasters by Means of Space Technology in 1991, both organized by UN and held in Beijing, China, and the Symposium of International Space Application held in Austria in 1993, all made valuable technical exchange on satellite TV educational systems and small satellite communications systems. China is willing to provide necessary technological support for this purpose.

Popularization and Application of GPS

The Global Positioning System (GPS), the second generation satellite navigation system originally developed by the US military at the cost of more than 3 billion dollars for 15 years, was finally completed in June, 1993 in advance. It is composed of 21 satellites and 3 spare satellites to cover the whole world. The system can observe at least 4 satellites in 24 hours. The United States declared publicly that upon the completion of the whole system, it would implement the policies of SA (selected availability) and AS (Anti-spoofing) and purposely reduce the broadcasting ephemeris precision of GPS to lower than 100 meters and limit the use of P code (or Y code) outside the US and its allies. The distance measuring/precision of P code is about 0.3m while the precision of C/A is 10 times that of P code.

The Asia-Pacific region is a place where plates converge, earthquakes occur frequently and the earth crust movement is active. So it is necessary to make cooperation to establish the GPS network composed of 6~7 tracking stations and the corresponding data processing centers. Through comprehensive processing and calculating, GPS precision ephemeris and false distance corrections of 1~2m precision can be worked out and provided to the users in the Asia-Pacific region, which may improve relative positioning accuracy and data processing efficiency, overcome the difficulties brought about by the US through changing at any odd time the satellite working conditions, benefit the surveying and mapping of mountainous and desert areas and reduce field works. Generally, when distance less than 500 km, its precision may reach 5m which can basically meet the need of aviation, navigation, railway, highway transportation services and the rescue work.

The Development of Seasats and Small Satellite Fleet

In 1973, the US Skylab was for the first time equipped with the first set of microwave scatterometer which has the functions of both height finder and microwave radiometer. In 1978 the US launched the Seasat-A, which was equipped with the radar altimeter (ALT), Seasat-A scatterometer (SASS), Scanning Multichannel Microwave Radiometer (SMMR) and Synthetic Aperture Radar (SAR). The satellite could quantitatively provide all weather and all time global ocean information about sea-surface wind conditions, wave height, wave spectrum, interwave, sea surface temperature, moisture content in atmosphere, sea ice and marine geoid. The surveying precision met practical requirement, marking that the ocean monitoring has entered space era. The former Soviet Union has also launched a number of ocean satellites. Japan launched two satellites in 1987 and 1990 respectively to collect the data of continental shelf and shallow sea areas so as to serve the development of marine biological resources and marine environmental protection. In the coming years, a series of ocean satellites will be put into operation in the world, and most of them will be related to international cooperative programs on global oceanographic research such as Tropical Ocean Global Atmosphere Program ( TOGA), the World Ocean Circulation Experiment (WOCE) and the Global Ocean Influx. With small earth observation satellites, on the one hand, a complex task can be broken down into a few simple parts which could be undertaken by several small satellites to reduce cost, and on the other hand, the period of the repeated observation could be shortened by using multi-satellite system. For instance, the small meteorological satellite put forward by the US Spectrum is equipped only with an advanced very high resolution radiometer (AVHRR), which can produce 3-D cloud image and other land and sea parameters. The mass of the satellite is only 159kg. The sea color multi-spectrum observation satellite projected by French Matra only weighs 200~300kg.

For the high-altitude physical and astronomical observation, the US has launched the Explorer for more than 50 times and China launched Shijian-4 to observe the charged particles and plasmas at the height of 版200牧~版36,000km牧, weighing only 400kg; all belonging to the small satellite series.

Finding natural disasters and monitoring environmental changes do not require very high ground resolution (30m) nor a long period of observation. Professor Chen Fangyun and others suggested using 7 small satellites to meet these requirements. The investment would be low but the efficiency may be high. The weight of such a satellite would be 200~250kg. In recent years, it is proposed to use small satellites in low orbit to cover the earth for mobile communications. For example, the Motorola's Iridium system is planned to include 66 satellites with altitude of 780km and corresponding ground systems. Its communications system adopts the time division multiple access (TDMA) technique. The Globalstar system introduced by Loral/Qualcom is to be composed of 48 satellites with an altitude of 1400km and its communications system adopts time domain multiplexing/frequency division/code division multiple access (TDD/FD/CDMA) techniques. China put forward a mobile communications system composed of Medium Earth Orbit (MEO) satellites called Global Mobile Satellite Information System (GMSIS). Angles of elevation of these satellites will be high for mobile users, obstruction caused by ground obstacles be low, and the satellites used to cover the planet be less.

The small satellite is both the cooperator and the competitor of the large satellite. A new generation of small satellites are developing rapidly and more suitable to be batch produced, to meet various users突 requirements and provide a new opportunity for the developing countries to participate in space application. Multiple small satellites could be launched on one rocket or be launched with other satellites.

The Exploration and Experiment of Space Environment

Japan and China began to conduct space microgravity research successively. Mongolia and Vietnam have participated in microgravity experiments on the former Soviet Union's Intercosmos. Since 1987, China has conducted 30 piggyback experiments on materials and 200 ones on biology with its recoverable satellites, developed high altitude balloon, carrying microgravity falling module technology, and constructed 20m falling tube and 7m quartz falling tube equipment. The property of semiconductor material, the gallium arsenide grown in space is obviously superior. As the integrated circuit chip, the material greatly increases the calculation speed and improves anti-radiation ability. However, the defect of uneven high impedance and low impedance needs to be solved. Moreover, China has also carried out extensive experiments on multiple alloy processing and protein crystal growth in space, and the space piggyback of microorganism and seeds, which will greatly contribute to researches on the genetic variation caused by space environment, such as the experimental growing of rice, tomato, green pepper back from space, the future's protein engineering, drug manufacturing, biochip manufacturing and new breeds cultivation.

Companies from Germany and France participated in the piggyback experiments on China's satellites and obtained ideal results. China will provide greater convenience for the countries in the Asia-Pacific region.

The Chinese Academy of Sciences established a low latitude sounding-rocket launch site in Hainan Province and developed two kinds of rockets. The ZN-1(Vega-1) weighs 62kg, its payload is 4.8kg and maximum flight altitude is 70km. The ZN-3(Vega-3) weighs 282kg, its payload is 25kg and maximum flight altitude is 147km. They have been successfully launched for 22 times.

Since 1977, the Chinese Academy of Sciences has made more than 170 high altitude balloon flights. The highest flight altitude is over 40km, the volume of the balloon ranges from 10000 to 40,000 m狀ㄢ and the payload is over 500kg. The cross ocean flight was made in cooperation with Japan, and a long-distance flight (> 5000km) was made in cooperation with Russia to conduct the atmospheric chemical observation and natural disaster monitoring in the troposphere and stratosphere over the middle and high altitude countries and regions covered the westerly belt. Moreover, it has also done good job in monitoring the loess dust in the air and the diffusion of volcanic ashes.

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