ALOS 3 (Daichi 3)

ALOS 3 [JAXA]

JAXA's ALOS 3 (Advanced Land Observation Satellite 3) was an optical Earth observation satellite to be used for cartography, regional observation, disaster monitoring, and resource surveying. It is the follow up to the optical component of ALOS.

Achieving improved optical observations of wide-swath with high-resolution as successor of optical mission of Daichi. The Advanced Optical Satellite is a successor of the optical mission of the Advanced Land Observation Satellite ALOS (Daichi). The new satellite will achieve improved ground resolution (0.8 m) while observing a wide -swath (70 km) by a larger sensor with higher performance compared to Daichi, and continuously observe not only Japan but also global land areas to construct a system that can swiftly and timely acquire, process and distribute image data. Based on the accumulated data captured in pre- and post-disaster times, the satellite aims to become one of the imperative devices for disaster prevention and preparation activities of countries and municipal governments.

Observation data acquired by the satellite is also expected to be useful in various fields such as contributing to the maintenance and updates of precise geospatial information in Japan as well as developing countries, and research and applications on coastal and land environmental monitoring by its observation capabilities.

The optical sensor onboard the Advanced Optical Satellite will improve its ground resolution by approx. three times from that of Daichi (2.5 to 0.8 m at nadir) while maintaining a wide-swath of 70 km at nadir. Such a high-resolution sensor with a wide-swath is a unique characteristic of the sensor, which is achieved using maximize our accumulated knowledge and manufacturing technology for a large optical system and a high resolution detector.

The Advanced Optical Satellite can normally perform observation covering a wide area of 70 km in width and 4000 km in along-track direction as the strip-map observation mode. In addition, the satellite has also capable following observation functions.

• Acquire stereo-pair image at a certain ground point from two different directions.
• Covering a wide-area of 200 km (in along-track direction) × 100 km (in cross-track direction) in an orbit path by satellite’s single orbital passage.
• Changing observation direction from satellite nadir. The satellite can observe any given point in Japan within 24 hours after receiving the request by the pointing capability up to 60° in all direction against the satellite nadir.

The mission instrument ALOS-3 is a wide-swath and high-resolution optical imager. It works both in panchromatic mode (black and white) with a ground resolution of 0.8 m and a swath width of: 70 km at nadir, as well as in multi-band (color) mode with a ground resolution of 3.2 m and a swath width of 70 km at nadir. Following bands are available: Band 1 0.40~0.45 µm (Coastal), Band 2 0.45~0.50 µm (Blue), Band 3 0.52~0.60 µm (Green), Band 4 0.61~0.69 µm (Red), Band 5 0.69~0.74 µm (Red Edge) and Band 6 0.76~0.89 µm (Near-Infrared).

ALOS 3 was launched on 3 March 2023 on the maiden H-3-22S rocket, but failed to reach orbit when the launch vehicles second stage engine failed to ignite.