Japan and Early Warning Satellite Systems

With the spread of more capable ballistic missiles in Asia, Japan has recently undertaken increasingly serious studies of early warning and ballistic missile national defense systems. Like its reevaluation of photographic reconnaissance spacecraft, early warning satellites would not violate Japan's prohibition on offensive military space systems. Alternatively, Japan may join with the US in a tactical ballistic missile defense system which would rely on American detection spacecraft in LEO and /or GEO.

An early warning capability that can detect ballistic missiles immediately after launch is significant from the viewpoint of further improving the reliability of the BMD system, since it supplements the role played by Japan’s FPS-5 radars and other sensors’ information.

However, a satellite system with early warning capability will be required to unfailingly detect the act of launching as well as the launch position, launch time, and launch direction immediately after the launching of a ballistic missile, and to report about it in an extremely short time. From the technical side, it is essential to minimize false detections by developing sensors immune to the effects of atmosphere and clouds that are best suited for the missiles’ infrared radiation properties, and by preparing a database on the effect on infrared waves by the infrared properties of each missile, and meteorological phenomena of clouds and the atmosphere. It must be taken into account that building such a system including database development and sensor optimization require years of strenuous efforts.

According to the US Missile Defense Agency, there is a program aimed at using advanced infrared sensors, etc., to enable them to not only detect missile launches but also identify and track ballistic missile in space, and promptly relay the information about the target to the terrestrial surveillance sensors and interception systems. The precision of interception is expected to be further improved if such technology is put to practical use.

Early warning information is required not only for the BMD system but also for other ministries from the perspective of civil protection and gathering information. Furthermore, satellites with such capability are useful in monitoring disasters such as wildfires, volcanic activities, and aircraft accidents, space situational awareness such as rocket launches, and other information gathering, due to the advantage of highly sensitive infrared sensors. The US employs early warning satellites in these areas as well. Since satellites with such a capability can be used for multiple purposes including BMD, their employment must be considered on a broad basis and R&D advanced under the interactive, concerted efforts of the government as a whole.

The Ministry of Defense and the SDF will employ defense-related technologies hitherto accumulated to consider further R&D of high-sensitive infrared sensor which plays a crucial role in the early warning capability in advance.

FY 2013 Initiatives based on the results of investigations on the missile launch by North Korea included research on mounting infrared sensor onto satellites. Conduct research on specifications of sensor system and ground facilities necessary for demonstrating two-color infrared image sensor in outer space. It also included research on the method of infrared sensor demonstration (¥ 6 million) and conduct study and research necessary to reduce cost of launch,etc. in preparation for consideration of demonstration of aforementioned infrared sensor in outer space.

The government will mount a sensor (detection device) on the ALOS-3 satellite to be launched in 2020 to launch an experimental research to possess the function of an early warning satellite to detect ballistic missile launch such as North Korea. The image sensor that uses tiny semiconductor particles is the world's first technology that can detect infrared rays in two wavelength bands. It will repeat and verify experiments for 6 years as to whether it can detect the infrared rays at the time of missile launch from space.

On board the satellite is a "two-wavelength infrared sensor" developed by the Ministry of Defense. Infrared sensors are excellent at detecting high temperature heat sources such as missiles and aircraft exhaust gas at any time of day and night, and dual wavelength infrared sensors use detection and identification ability by using two wavelength bands of mid infrared and far infrared It is a feature to improve it. By combining the images of two wavelengths, it is possible to clearly capture gas from combustion, and to clearly distinguish the shape of the exhaust gas.

The sensor will be mounted on the Advanced Optical Satellite (ALOS-3) launched by the Japan Aerospace Exploration Agency (JAXA) next year on the H2A rocket. ALOS-3 is an earth observation satellite that continuously observes the global land area, and orbits at an altitude of 669 kilometers. The Ministry of Defense is expected to verify the missile detection function of the sensor in the SDF's missile launch test and training that will be conducted at the right time to the orbit.