*Takeshi Motohka1, Yukihiro Kankaku1, Satoko H. Miura1, Shinichi Suzuki1
(1.Japan Aerospace Exploration Agency)
Keywords:Remote Sensing, Synthetic Aperture Radar (SAR), Satellite
The Advanced Land Observing Satellite (ALOS-4) is an Earth observation satellite being developed by JAXA to enhance the L-band Synthetic Aperture Radar (SAR) observations by ALOS-2 that has operated since 2014. The mission objectives of ALOS-4 are: (1) to enable early detection of anomalies as well as post-disaster assessment by improving the crustal and ground deformation monitoring; (2) to provide rapid disaster monitoring by taking advantage of SAR's all-weather and night observation capabilities; (3) to continue ALOS-2's observations of forests, snow and ice, and oceans, and to expand new applications such as infrastructure displacement monitoring; and (4) to monitor oceans by simultaneous observation of SAR and AIS (Automatic Identification System). To achieve these objectives, ALOS-4 will be equipped with PALSAR-3 (Phased Array type L-band Synthetic Aperture Radar 3), which adopts novel digital beamforming technology, and will expand the observation swath by 4 times while maintaining high resolution of 3 m. This will allow us to significantly increase the frequency of observations over all of Japan, which will lead to more observation opportunities and improved accuracy of time series analysis. In addition to the high-resolution observation mode, the observation swath of ScanSAR mode will be expanded to 700 km, enabling us to observe events with wider spatial scales at once.
In this presentation, the development status and operation plan of ALOS-4 will be introduced. PALSAR-3 has completed the manufacturing and testing of the protoflight model (i.e., a model for on-orbit operation), and the expected performance was confirmed successfully. Testing of the entire satellite system is now in progress. The development of the ground system is also progressing, and the user interface “AUIG-4” for ALOS-2 and ALOS-4 observation requests and data provision, data product specifications for PALSAR-3, calibration and validation processes, and higher-order products such as global terrain-corrected orthorectified images are being prepared. As for the operation, we plan to start regular observation and public data provision after the initial check-out and initial calibration and validation for about six months after the launch of ALOS-4. The baseline of the Basic Observation Scenario (BOS) has been made and is available on the website (https://www.eorc.jaxa.jp/ALOS/en/alos-4/a4_observation_e.htm). We plan to conduct several operational simulations and optimize the BOS based on the results and feedback from users.