By Takashi Hatakeyama
The Japanese government is considering participation in the U.S. “satellite constellation” system by manufacturing and launching some of the satellites. The satellite constellation system will deploy many high-performance satellites in low orbits to accurately track the movement of missiles. It is difficult to intercept new Chinese, Russian, and North Korean missiles with conventional missile defense systems. The government will start deliberations from fiscal 2021 on modes of cooperating with the U.S. scheme to counter such new missiles.
The government will move forward with the development of highly sensitive infrared sensors that can detect and pursue missiles over a wide area, with a view to loading the sensors onto the satellites.
Missile interception systems adopted from the U.S., such as Aegis vessels, are based on the premise that they will be used against ballistic missiles following a parabolic trajectory. China and Russia have developed hypersonic glide missiles with irregular trajectories. North Korea also has new missiles that follow irregular trajectories at low altitudes. All of these weapon systems may neutralize conventional interception systems.
With over 1,000 small satellites, the U.S. satellite constellation system aims to monitor not only missiles, but also enemy movements on the ground and air and space debris. Missile interception capabilities need to be enhanced to actually intercept missiles.
In the Basic Plan on Space Policy approved by the Cabinet in June 2020, the Japanese government included a statement on “taking necessary measures” to consider collaborating with the U.S. satellite constellation project. The fiscal 2021 budget plan approved by the Cabinet in December 2020 earmarks 170 million yen for research on the optimal altitude for the satellite constellation to detect and pursue hypersonic glide weapons. An additional 1.2 billion yen was appropriated for the development of small, lightweight infrared sensors, an area in which Japan excels.
The total cost of the satellite constellation system is said to be more than one trillion yen. It would be difficult for Japan alone to develop such a system. A government source says that one possible plan would be for “Japan to launch several dozen satellites and request the U.S. share information.” Aspects of the scheme remain unknown, such as its cost-effectiveness and how to ensure technological accuracy. Japan will search for ways to cooperate aside from “[satellite] launches,” such as technical support. Japan and the U.S. already share information obtained through radars on vessels of the U.S. Navy and Maritime Self-Defense Force. The two countries also share satellite imagery.
The U.S. plans to launch 20 satellites by 2022, and 250 satellites by 2025. The U.S. plans to have over 1,000 satellites to detect and pursue missiles, reconnoiter and monitor ground movements, and survey space debris. Compared with conventional high-performance early-warning satellites, which weigh over one ton and orbit the earth at an altitude of 360,000 kilometers, the satellites planned for the constellation system will be low-cost, weigh just several hundred kilograms, and orbit at altitudes from 300 to 1,000 kilometers.
China and Russia are developing “killer satellites,” which can attack satellites of other countries. Having a great number of small satellites will ensure some survive even if others are destroyed. One of the aims of the satellite constellation system is to increase its “survivability” in a contingency.
The expansion of the arms race into space by the U.S., China and Russia has intensified in recent years. As of February 2020, the numbers of “military use” satellites owned by each country are as follows: U.S., 128; China, 109; Russia, 106; India, 21. Japan has only 14. Japan’s cooperation in the U.S. scheme stems from the sense of crisis over
its lagging far behind in missile interception capabilities.