Mission Background

The main objective of the ALOS mission was to provide the user community with data of sufficient resolution to be able to generate 1:25,000 scale maps.

ALOS - known in Japan as DAICHI was developed by JAXA (Japan Aerospace Exploration Agency, Tokyo; formerly NASDA) to contribute to the fields of mapping, precise regional land coverage observation, disaster monitoring, and resource surveying. It could collect enough data by itself for mapping on a scale of 25,000 to 1 without relying on points of reference on the ground.

Its contributions to the monitoring of environmental destruction and natural disasters made it a valued part of the ESA Third Party Mission constellation. It was launched by an H-IIA launch vehicle from the Tanegashima Space Centre (TNSC) on 24 January 2006.

ALOS Mission Parameters
Orbit Height 692 km
Orbit Type Sun-synchronous Sub-Recurrent
Orbit inclination 98.16°
Local equator crossing time 13:45 (±15 minute)
Orbit Period 98.8 minutes
Repeat Cycle 46 days Sub Cycle: 2 days
Position determination accuracy Within 1 m (offline)

Satellite Design

ALOS had three sensors: the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), which comprised three sets of optical systems to measure precise land elevation; the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), which observed what covers land surfaces; and the Phased Array type L-band Synthetic Aperture Radar (PALSAR), which enabled day-and-night and all-weather land observation.

ALOS Technical Specifications
Mass 4000 kg
Dimensions 8.9 m x 27.4 m x 6.2 m
Design lifetime 5 years

Mission Operations

ALOS was launched into a geocentric, Sun-synchronous orbit inclined at 98 degrees and with a period of 98.5 minutes and a repeat cycle of 46 days.

The main ground station was located at the JAXA Earth Observation Centre. ESA built and operated the European/African ground segment for ALOS, known as the ALOS Data European Node (ADEN). In exchange, ESA receives full data rights over the ADEN zone (Europe, Africa, Middle East) for distribution to all users residing in the zone. Unless already held in the ESA archive, project data outside of the ADEN zone is no longer available via the TPM scheme.

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