ALOS-4

ALOS-4, also called Daichi 4 and short for Advanced Land Observing Satellite-4, is a Japanese radar Earth observation satellite operated by the Japan Aerospace Exploration Agency (JAXA) and built under prime contractor Mitsubishi Electric Corporation. It follows ALOS-2 and carries the PALSAR-3 phased array L-band synthetic aperture radar, which offers finer resolution and a wider observation swath than the PALSAR-2 radar on its predecessor. Because radar needs neither sunlight nor clear skies, the satellite can image the ground day and night and through cloud, which suits it to watching disaster-hit areas, forests and sea ice and to monitoring displacement of infrastructure. It also carries an Automatic Identification System receiver, SPAISE3, to track ships at sea. It has a design life of seven years, a mass of about 3000 kg and a sun-synchronous orbit near 610 km, and it was launched on an H-3-22S rocket from Tanegashima Space Center on 1 July 2024.