What is ALOS ?

 Advanced Land Observing Satellite "DAICHI"

ALOS stands for Advanced Land Observing Satellite, which was launched by Japan Aerospace Exploration Agency in January 2006. Its Japanese name is "DAICHI".

The dimension of DAICHI is 3.5m wide x 4.5m long x 6.5m high, with its Solar Battery Paddle is 22m x 3m wide, gross weight is approximately 4 tons, which is one of the largest among Land Observing Satellites.

■ ALOS major specifications

Operational Period January 24, 2006 (Launched) – May 12, 2011
Available Data Period May 16, 2006 – April 22, 2011
Launching Vehicle H - IIA
Launch Site Tanegashima Space Center, Japan
Spacecraft Mass Approx. 4 tons
Generated Power (Solar paddle) Approx. 7kw (at End Of Life)
Designed EOL 3-5 years
Orbit Sun Synchronous, Sub recurrent
Repeat Cycle: 46 days
Sub-Cycle : 2 days
Altitude : 691.65km (Above the equator)
Inclination : 98.16 deg.
Attitude Determination Accuracy 2.0 x 10-4 deg. (off-line, with GCP)
Position Determination Accuracy 1m (off-line)
Data Rate 240Mbps (Via Data Relay Test Satellite)
120Mbps (Direct Transmission)
On-board Data Recorder Solid-state Data Recorder (90Gbytes)
 

■ General Concepts of "Three Sensors"

ALOS has three remote-sensing instruments, PRISM is a panchromatic radiometer with high resolution in order to obtain terrain data including elevation. AVNIR-2 is a visible and near-infrared radiometer for observing land and coastal zones and provides for better spatial resolution. PALSAR is a phased array type L-band Synthetic Aperture Radar, an active microwave sensor for cloud free and day and night land observation.

Sensor Spatial Resolution /Swath Width Characteristics Utilization
PRISM
Spatial Resolution : 2.5m
Swath Width : 35km(Triplet mode)
70km(Nadir Only)
It has three independent optical systems for viewing nadir, forward and backward producing a stereoscopic image along the satellite's track. Cartography, making DSM for mapping, urban planning, agriculture, forest monitoring, coastal monitorig, monitoring illegal dumping, flood monitoring etc.
AVNIR-2
Spatial Resolution : 10m
Swath Width : 70km
The Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) is a visible and near infrared radiometer for observing land and coastal zones. It provides better spatial land-coverage maps, wide range of urban planning, agriculture(vegetation research), forest monitoring, coastal monitoring, pollution monitoring on ports and harbors, plants monitoring, flood monitoring etc.
PALSAR
Spatial Resolution : 10m(fine resolution mode)
100m(Scan Sar mode)

Observation Swath : 70km(fine mode)
250-350km(Scan SAR)
The Phased Array Type L-band Synthetic Aperture Radar (PALSAR) is an active microwave sensor using L-band frequency, which can observe with fine resolution in a conventional mode as well as wider swath with a SAR images. It enables to make DEM, extract topography data by interferometry, estimate biomass, forest monitoring, agriculture, monitoring oil spill, moisture of soil, shipping inspection etc.

■ Major Mission Of ALOS

Major Mission of ALOS includes cartography, regional observation, disaster monitoring and resource surveying. As examples of an exploration study, JAXA sets 12 categories as "major categories of research". They are, "Land Use and Land Cover Research", "Disaster Prevention and Disaster Monitoring", "Land and Mineral Resources", "Biological Resources", "Oceanography", "Agriculture" and so forth, and to promote the study that encourage to use Satellite data.

■Cartography

ALOS can manage mapping as well as updating of maps of Japan and around other countries mainly in the Asia-Pacific region. Using ALOS PRISM enables to obtain many kinds of data, which range from artificial components such as roads and constructions, target area of rivers and to water regions, and to topographical DEM data. With ALOS data, more detailed mapping is achieved as PRISM can also present information on vegetation and soil by adding optical sensor and synthetic aperture radar to DEM data.

■Regional Observation
ALOS practices essential regional observation to maintain "Sustainable Development" on a worldwide scale. Providing information on environment and resources by extracting data taken by the Satellite, ALOS supports preservation and maintenance of environment and resources, and encourages sustainable development and utilization on a regional level.

■Disaster Monitoring
ALOS can conduct disaster monitoring over Japan and around the world. Collaborating with existing Satellites and disaster monitoring systems, ALOS collects and provides data regarding major disaster such as volcano eruption, flood, and earthquake.

■Resource surveying
ALOS can survey natural resources with PALSAR.

■Others
ALOS contributes to technology development that is needed for future earth observation.

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