ALOS-4 launch and early orbit operation result

The Advanced Land Observing Satellite-4 (ALOS-4) is a satellite to observe the Earth's surface using its onboard phased array type L-band synthetic aperture radar (PALSAR-3). The L-band radar technology has continuously been developed in Japan. With further improved observation performance compared to the predecessor PALSAR-2 aboard the ALOS-2, JAXA and its prime contractor, Mitsubishi Electric Corporation, developed ALOS-4 aiming at achieving both high resolution and a broader observation swath. ALOS-4 will increase the observation frequency to once every two weeks so that disaster prevention agencies can find abnormal changes such as unusual volcanic activity, land subsidence, or landslides at an early stage to warn people nearby. In addition, the observation swath will be drastically increased from 50km to 200km while keeping the high resolution. Therefore, we can observe a broader area at the same time when a large-scale disaster that damages wide areas occurs, such as a huge earthquake or multiple eruptions at the same time. ALOS-4 was launched by the 3rd H3 launch vehicle at JAXA’s Tanagashima Space Center, Japan. This paper describes the ALOS-4’s initial operation results and its performance.