ALOS-4, "DAICHI-4" is a successor of the ALOS-2, "DAICHI-2" Taking over the SAR observation missions of ALOS and ALOS-2, it will contribute to early detection of anomalies caused by crustal and ground deformation, understanding of disaster situations in wide areas, and advancement of forest resource management.

ALOS-4 Main Specifications

Life Designed life : 7 years
Launch Date July 1, 2024
Launch
Vehicle		 H3
Launch Site Tanegashima Space Center, Japan
Attitude
(at Equator)		 628km
Lap Time About 100 min
Revisit Time 14 days
Spacecraft Mass Approx. 3t
Orbit Size
(on orbit)		 10.0m×20.0m×6.4m (D×W×H)
Mission Data
Transmission		 Direct Transmission and Optical Inter-orbit Communications
PALSAR-3
(Frequency)		 L band(1.2GHz)

ALOS-4 is equipped with an Automatic ship Identification System(AIS), Space-based Automatic Identification System Experiment 3 (SPAISE3).

Equipped sensors of ALOS-4

ALOS-4 is equipped with the earth observation sensor called Phased Array [type] L-Band Synthetic Aperture Radar 3 (PALSAR-3) that enables land observation rain or shine and day or night.

mission

Primary Mission of ALOS-4

Rapid disaster
situation assessment
through all-weather
observation

  • 01

    Prompt assessment of damage in the event of torrential rain

  • 02

    All-weather observation contributes to a quick understanding of the disaster situation

National land
resilience through
high-precision
monitoring of
crustal and
ground deformation

  • 01

    Continuous monitoring of volcanic activity

  • 02

    Monitoring crustal movements nationwide

  • 03

    Monitoring infrastructure displacement

Maritime domain
awareness

  • 01

    The world's most advanced satellite AIS (Automatic Identification System) "SPAISE3"

  • 02

    Monitoring sea ice to support safe navigation of ships

Contributing to
global issues

  • 01

    Forest monitoring using L-band SAR

  • 02

    Grasping rice planting area and growth status

Progress and continuation from ALOS-2 to ALOS-4

01Increased observation width and frequency
ALOS-4 will be the first satellite-mounted SAR to use Digital Beamforming (DBF) technology, which will expand the observation width fourfold (to 200 km) while maintaining the high spatial resolution of ALOS-2 (3 m), greatly increasing the frequency of observations of crustal and surface movements even during peacetime. 01
02Spatial resolution
ALOS-4 continues ALOS-2's observational capabilities with a resolution of 3m. High-resolution observations make it possible to capture the state and changes of the Earth's surface in greater detail. 01
03Digital Beam Forming (DBF)
Digital Beam Forming (DBF) is a method in which analog signals received from the ground by antennas are first converted to digital signals, then processed at high speed to adjust the phase and combine the signals. This technology makes it possible to form beams in multiple directions simultaneously, enabling wider observation ranges than ALOS-2. 01
04Expanding the transmission beam width
In order to enable wide-area observation, it is necessary to expand the transmission beam width and to have a large transmission power and antenna gain that makes this possible. In ALOS-4, the transmission power was increased by expanding the antenna size by 1.2 times compared to ALOS-2. Normally, antenna size and beam width are inversely proportional, but by introducing Phase Spoling technology, which changes the phase setting in the direction of radio wave irradiation and enables the formation of a wide beam pattern, it is possible to expand the beam width without restricting the antenna size. 01