3:30 PM - 3:45 PM
[STT40-07] Overview of ALOS-4 initial calibration and validation results and current operational status
★Invited Papers
Keywords:ALOS-4, SAR
Japan Aerospace Exploration Agency (JAXA) launched the Advanced Land Observing Satellite-4 (ALOS-4) by the third H3 Launch Vehicle at 03:06:42 (UTC) on July 1st, 2024, from the Tanegashima Space Center. The Phased Array type L-band Synthetic Aperture Radar-3 (PALSAR-3) onboard ALOS-4 utilizes state-of-the-art technologies such as DBF (Digital Beam Forming) to significantly enhance observation frequency and expand observation swath compared to ALOS-2 PALSAR-2. Additionally, ALOS-4 flies the same orbit as ALOS-2, enabling combined analyses, such as interferometric SAR, with both satellites data. It facilitates high-frequency, long-term time series analysis and will be contributed to a wide range of fields. After the launch of ALOS-4, the initial check-out phase was conducted for approximately three months to verify the functionality of satellite systems including the equipment such as PALSAR-3. As of February 2025, the initial calibration and validation (cal/val) phase of PALSAR-3 is ongoing for starting of observations based on the Basic Observation Scenario (BOS) and provision of PALSAR-3 standard products to users. In this presentation, an overview of the operational results after the launch including the initial cal/val phase, and the current observation plan of ALOS-4 PALSAR-3 will be presented.
After separation from the launch vehicle, the solar array paddles and mission antennas including PALSAR-3 were deployed successfully, and the initial check-out phase had started. During this phase, the first light images of PALSAR-3 were taken from July 15 to 17, 2024 and confirmed to acquire an observation width of 200 km with 3 m resolution successfully. Thereafter, the initial cal/val phase started in October 2024. During this phase, various cal/val items, such as geometry, antenna patterns, radiometric accuracy, polarization, and image quality are evaluated. In particular, PALSAR-3 observation modes and beams used in BOS have a high priority in the evaluation. This is because PALSAR-3 has many modes and beams, and it is difficult to evaluate all of them in a limited time.
After completing the initial cal/val operation, the observations will be conducted for prepare pre-disaster basemap images and time-series observations based on the BOS. Another observation modes of PALSAR-3 are defined for time series observations in domestic and abroad. In addition, thematic observations based on user requirements will be also conducted. The BOS will be continuously reviewed and improved by corresponding the results from the simultaneous operation with ALOS-2 and user feedback. The latest BOS is available at the following website: https://www.eorc.jaxa.jp/ALOS/en/alos-4/a4_observation_e.htm
After separation from the launch vehicle, the solar array paddles and mission antennas including PALSAR-3 were deployed successfully, and the initial check-out phase had started. During this phase, the first light images of PALSAR-3 were taken from July 15 to 17, 2024 and confirmed to acquire an observation width of 200 km with 3 m resolution successfully. Thereafter, the initial cal/val phase started in October 2024. During this phase, various cal/val items, such as geometry, antenna patterns, radiometric accuracy, polarization, and image quality are evaluated. In particular, PALSAR-3 observation modes and beams used in BOS have a high priority in the evaluation. This is because PALSAR-3 has many modes and beams, and it is difficult to evaluate all of them in a limited time.
After completing the initial cal/val operation, the observations will be conducted for prepare pre-disaster basemap images and time-series observations based on the BOS. Another observation modes of PALSAR-3 are defined for time series observations in domestic and abroad. In addition, thematic observations based on user requirements will be also conducted. The BOS will be continuously reviewed and improved by corresponding the results from the simultaneous operation with ALOS-2 and user feedback. The latest BOS is available at the following website: https://www.eorc.jaxa.jp/ALOS/en/alos-4/a4_observation_e.htm