Advanced Land Observing Satellite-4: Mission Concepts and Technical Overview: Pioneering a new era of L-band SAR

JAXA’s Advanced Land Observing Satellite-4 (ALOS-4) is the successor to the ALOS-2 satellite. On July 1, 2024, ALOS-4 was successfully launched, and on July 15, it acquired the first observation images by PALSAR-3. The new satellite carries a Phased Array-type L-band Synthetic Aperture Radar-3 (PALSAR-3) and SPace based Automatic Identification System for ships Experiment 3 (SPAISE3). The objectives of ALOS-4 are enhancing the ALOS-2 mission and exploring new applications of L-band SAR. PALSAR-3 has a wider swath width and frequent time-series data acquisition capability, and SPAISE3 improves the ship detection rate in crowded sea areas. The tests of the satellite and ground systems have been completed, and the functions and performance have been confirmed as designed. The PALSAR-3 CAL/VAL and observation plans have also been formulated for consistent data acquisition from ALOS-2. ALOS-4 will monitor land deformation and subsidence, natural disasters, environmental and ecosystem concerns, and maritime applications for social benefit.