Japan is an earthquake-prone and volcanic country where two-thirds of the land area is covered by forestry. The L-band Synthetic Aperture Radar (SAR), which was aboard the past two satellites, namely FUYO-1 (JERS-1) between 1992 and 1998 and DAICHI (ALOS) between 2006 and 2011, is a sensor using a radio wave (microwave), and it enables observations of land surface conditions even during the night and under bad weather. The special feature of the L-band radio wave (whose wave length is about 24 cm) is an ability to gather information from the land surface by penetrating vegetation such as forests (too a certain extent), thus it can acquire changes on the land more precisely compared to other band’s SAR when some diastrophism takes place due to an earthquake or a volcanic activity.
DAICHI-2 (ALOS-2) is equipped with a global-leading L-band SAR (PALSAR-2) to conduct a health check mainly of the earth’s land areas in details. The observation performance has been improved to more promptly conduct accurate observations of the surface while maintaining a wide observation band. Hence, it will acquire more useful data that is directly related to our safe life as it can observe not only diastrophisms but also floods or landslides caused by a natural disaster, such as a storm or a gale, accurately in a timely manner. Its predecessor, DAICHI, responded to many requests for disaster monitoring from overseas, and, as a result, Japan was able to receive a lot of image data from foreign satellites in return in addition to those taken by the DAICHI when we were hit by the Great East Japan Earthquake. This data was very helpful to understand the situation of the unprecedented huge natural disaster in Japan. We would like to maintain this international cooperation framework with the DAICHI-2.
Besides natural disaster observations, the DAICHI-2 will regularly observe tropical rain forestry, which is difficult to observe optically due to thick clouds covering it frequently, as well as snow and ice conditions in the polar areas. By combining observation data acquired over more than 11 years, we will keep observing the time elapse to capture changes of forestry, which is a greenhouse gas sink, as well as the transformation of snow and ice due to the greenhouse gas effect. By doing so, we will contribute to environmental issues on a global scale.
With the L-band SAR, which is one of Japan’s specialties that has been inherited for a long time, the DAICHI-2 is a “national project” that contributes to safety and security in cooperation with domestic and overseas pertinent agencies. As an engineer, I am proud of participating in such an important project while I feel a heavy responsibility throughout the development of the satellite. I will do my utmost to achieve this project’s mission goal by launching and operating it smoothly in order to meet the expectations of its users and, eventually, of the people who are the ultimate beneficiaries.
(May, 2014 Updated.)