This paper describes the current status of Advanced Land Observing Satellite-4 (ALOS-4) which will carry L-band SAR system, namely Phased Array-type L-band Synthetic Aperture Radar-3 (PALSAR-3) and SPace based Automatic Identification System for ships Experiment (SPAISE3). In particular, its mission and characteristics of both instruments; PALSAR-3 and SPAISE3 are shown.
The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite- 2 (ALOS-2, "DAICHI-2") is the latest L-band spaceborne synthetic aperture radar (SAR). PALSAR-2 observes the world mainly with 10 m resolution / 70 km swath Stripmap mode and 25 m resolution / 350 km swath ScanSAR mode. The 3-m resolution Stripmap mode is mainly used upon Japan. 350 km ScanSAR observation could detect large scale deformation e.g., the Mw 7.8 Gorkha, Nepal earthquake and its aftershocks in 2015. ALOS-2 ScanSAR is the first one that supports ScanSAR-ScanSAR interferometry in L-band spaceborne SAR. However, because of the parameter setting error for the orbit estimation, ALOS-2 PALSAR-2 ScanSAR could achieve little number of interferometric pair until the software modification on February 8, 2015. That is, the burst overlap timing required for the interferometric analysis was insufficient and it depends on the observation date. In this paper, we report the investigation results of this case and discuss the current status of the ALOS-2 ScanSAR InSAR. Some archives achieved before February 8, 2015 can be used for interferometric analysis with after Feb. 8. However, most of them have no interferometric pair. We also report that the archives acquired after February 8, have enough burst overlapping.
Advanced Land Observing Satellite-2 (ALOS-2, "DAICHI-2") performed various emergency observation with its Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) in Asia in 2015. Especially for corresponding to the emergency request from Sentinel Asia related to the Mw 7.8 Gorkha Nepal Earthquake 2015, PALSAR-2 successfully detected not only the crustal deformation but also the avalanches and local displacements. In this presentation, we describe these performances, analysis and the other emergency observations.
The Advanced Land Observing Satellite-2 (ALOS-2) was launched from Tanegashima Space Center by H-IIA rocket successfully on 24th May 2014. ALOS-2 carries the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) as the state-of-the-art L-band SAR system which succeeds to PALSAR onboard ALOS. PALSAR-2 uses almost whole bandwidth allocated for L-band active sensor of Earth Exploration Satellites Service specified by the Radio Regulation in order to realize the high resolution observation, and also, it transmits more than 6 kW power for lower Noise Equivalent Sigma Zero using 180 TRMs driven by Gallium Nitride (GaN) amplifier which is the first use in space. Furthermore, because ALOS-2 carries the SAR system only, PALSAR-2 antenna can be mounted under the satellite body. It enables to observe right-/left-looking observation by satellite maneuvering. And the high accuracy orbit control to maintain the satellite within 500 m radius tube against the reference orbit enables high coherence for the InSAR processing. Using these new technologies, ALOS-2 has been operating to fulfill the mission requirements such as disaster monitoring and so on. This document introduces the initial result of ALOS-2 from the first year operation.
The Advanced Land Observing Satellite-2 (ALOS-2) carries the phased array type Synthetic Aperture Rader (SAR) with the L-band frequency named PALSAR-2. ALOS-2 provides necessary data for disaster management, land and infrastructures management, resource management and so on. For disaster management by satellite based SAR, high resolution and wide swath width observation are needed. The Pulse Repetition Frequency (PRF) must be higher to improve azimuth resolution with less ambiguity caused by aliasing, but lower PRF is necessary to realize wider swath width. From this reason, high resolution and wide swath width are conflicting requirements for SAR. We have realized the requirements by adopting the multi-beam technology. PALSAR-2 has one transmitter and two receivers (dual beam system). This makes possible to reduce PRF and PALSAR-2 enables to receive the back scatterings, which are received in twice in the single beam receiver, at the same time. Therefore PALSAR-2 can realize high resolution and wide swath width capabilities by mean of the dual beam system. Improving resolution and swath width leads to increasing the data volume. Large amount of data need longer time to send the data to ground stations. From this reason the high speed data transmitting system with multi-mode X-band modulator has been developed. The modulator works with 800Mbps in 16QAM mode. This paper presents the initial on-orbit checkout result of ALOS-2.
The Advanced Land Observing Satellite-2 (ALOS-2) carries the state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 which succeeds to the ALOS / PALSAR. PALSAR-2 has an enhanced performance in both high resolution and wide swath compared to PALSAR. It will allow comprehensive monitoring of disasters. Wider bandwidth and shorter revisit time will give better conference for interferometry SAR (INSAR) data analysis such as crustal deformation and deforestation. ALOS-2 was launched on 24th May 2014, and has been completed the initial functional verifications of onboard components and systems. This paper describes the initial operation and checkout results including the comparison with the previous SAR satellite image and the disaster monitoring. Some key features of orbit control and determination to improve the coherency of the repeat-pass INSAR observation are evaluated.
The Advanced Land Observing Satellite-2 (ALOS-2) carries the state-of-the-art L-band Synthetic Aperture Radar (SAR)
called PALSAR-2 which succeeds to the ALOS / PALSAR. PALSAR-2 will have enhanced performance in both high
resolution and wide swath compared to PALSAR. It will allow comprehensive monitoring of disasters. Wider bandwidth
and shorter revisit time will give better conference for INSAR data analysis such as crustal deformation and
The Proto Flight Test (PFT) of ALOS-2 has been conducted since June 2012. In parallel, the PFT of PALSAR-2 has
been conducted since March 2012. As of August 2013, ALOS-2 system has completed the interface test with ground
system and is preparing for the Vibration test, Acoustic test and Electromagnetic Compatibility test. After completing
these tests, ALOS-2 will be transported to JAXA Tanegashima Space Center for launch.
The initial commissioning phase of ALOS-2 is planned for six months which are comprised of LEOP (Launch and Early
Orbit Phase) and initial Cal/Val phase. During the LEOP, all components will be checked with direct downlink via Xband
and with data relay communication via JAXA’s DRTS (Data Relay Test Satellite). During the initial Cal/Val phase,
the PALSAR-2 data will be verified and calibrated by using Corner Reflectors and Geometric Calibrator at ground. The
data acquisition during the commissioning phase will be consistent with the systematic acquisition strategy prepared for
the routine operation.
This paper describes the current status and operation plan of ALOS-2.
The Advanced Land Observing Satellite-2 (ALOS-2) will succeed to the radar mission of the ALOS “Daichi” which had
contributed to cartography, regional observation, disaster monitoring, and earth resources surveys for more than 5 years until its termination of operation in May 2011. The state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 onboard ALOS-2 will have enhanced performance in both high resolution (1m * 3m at finest in the Spotlight mode) and wide swath (up to 490km in the ScanSAR wide mode), compared to ALOS/PALSAR. Wider bandwidth and shorter revisit time will give better conference for INSAR data analysis such as crustal deformation and deforestation. The SAR antenna consists of 5 panels with total 1,080 radiation elements which are driven by 180 Transmit-Receive-Modules in order to steer and form a beam in both range and azimuth direction. In order to reduce range ambiguities,PALSAR-2 is capable to transmit up or down chirp signal alternatively and has phase modulation with zero or pi as well. The Proto Flight Model of ALOS-2 including PALSAR-2 is under integration and testing at JAXA’s Tsukuba Space Center. From experiences of the ALOS operation, a systematic observation strategy to achieve consistent data acquisitions in time and space was crucial. Since more observation modes of PALSAR-2 than those of PALSAR may trigger more conflicts among user requests, a basic observation scenario must be prepared to fulfill the mission requirements. This paper describes the current development status of ALOS-2 and a draft acquisition strategy for PALSAR-2.
The Japan Aerospace Exploration Agency (JAXA) is planning a satellite system including Advanced Land Observing Satellites 2 and 3 (ALOS-2 and ALOS-3) for the ALOS follow-on program. ALOS-3 will carry the optical sensor named “PRISM-2” and extend the capabilities of earlier ALOS missions. PRISM-2 will be able to collect high-resolution (0.8m) and wide-swath (50 km) imagery with high geo-location accuracy, as well as provide precise digital surface models (DSMs) using stereo pair images acquired by two telescopes. These capabilities are ideal for obtaining large-scale geographical information such as elevation and land cover-maps for use in many research areas and practical applications, including disaster management support.
JAXA has conducted a phase A study of the ALOS-3 spacecraft and PRISM-2, and is now working on prototype models of key components of PRISM-2’s telescope, focal plane, and data compressor.
This paper introduces a conceptual design for PRISM-2 and the ALOS-3 system.
ALOS-2 and ALOS-3 will succeed to radar and optical mission of Advanced Land Observing Satellite “Daichi” which
had contributed to cartography, regional observation, disaster monitoring, and resources surveys for more than 5 years
until its termination of operation in May 2011.
ALOS-2 carries the state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 which succeeds to the
ALOS/PALSAR with enhanced performance in both high resolution (1m * 3m at finest in the Spotlight mode) and wide
swath (up to 490km in the ScanSAR wide mode). Wider bandwidth and shorter revisit time will give better conference
for INSAR data analysis such as crustal deformation and deforestation. The Proto Flight Model of ALOS-2 including
PALSAR-2 is under integration and testing at JAXA’s Tsukuba Space Center.
ALOS-3 carries the optical sensor called PRISM-2 which succeeds to the ALOS/PRISM mission with enhanced
performance in high resolution (0.8 m), wide swath (50 km) and high geo-location accuracy. PRISM-2 will acquire
stereo pair images with two telescopes for stereo mapping and precise Digital Surface Models. It is also considered to
carry Hyper-spectral Imager Suite (HISUI), which is developed by the Ministry of Economy, Trade and Industry (METI)
of Japan. JAXA has conducted the phase-A study on ALOS-3 spacecraft and mission instruments, with prototype testing
of key components.
This paper describes an overview of ALOS-2 and ALOS-3.
The Advanced Land Observing Satellite-2 (ALOS-2) carries the state-of-the-art L-band Synthetic Aperture Radar (SAR)
called PALSAR-2. PALSAR-2 has a Spotlight mode (1 to 3 m), a Stripmap mode (3 to 10 m) and a ScanSAR mode,
whilst PALSAR onboard ALOS had 10 m spatial resolution at best.
The new technologies, such as maximum bandwidth allocation for L-band SAR, the spotlight mode with Active Phased
Array Antenna, high power efficiency device of GaN and chirp modulation technique, have been verified by testing its
Engineering Model (EM). The critical design of ALOS-2 including PALSAR-2 was completed in June 2011.
This paper describes current development status of ALOS-2 and brief results of EM.
The Japan Aerospace Exploration Agency (JAXA) is planning a satellite system for the Advanced Land Observing
Satellite (ALOS) "Daichi" follow-on program. ALOS-3 will succeed the ALOS missions with enhanced capabilities.
ALOS-3 will carry optical sensors and be capable of collecting images with high-resolution (0.8 m) and wide-swath (50
km). ALOS-3 will also acquire stereoscopic imageries by two telescopes. These are ideally capable for collecting the
large-scale geographical information that is used in many practical applications, including disaster management support.
JAXA has been conducting the conceptual design for the ALOS-3 and its mission instruments. This paper introduces
outline of the spacecraft and the instruments.
The Advanced Land Observing Satellite-2 (ALOS-2) is a follow-on mission from ALOS "Daichi". The state-of-the-art
L-band Synthetic Aperture Radar (SAR) aboard ALOS-2 will, in response to society's needs, have enhanced
performance compared to ALOS/PALSAR. ALOS-2 will have a spotlight mode (1 and 3 m) and a high-resolution mode
(3 to 10 m), while PALSAR has 10m resolution. The Preliminary Design was completed in March, 2010. Phase C/D has
been started and the Engineering Models are currently under development. This paper describes the current development
status of ALOS-2.
The Advanced Land Observing Satellite (ALOS) "Daichi," launched in January 2006, has been operating successfully
on orbit for four and a half years. In that time it has delivered a very large number of high-resolution images and has
contributed to making basic maps, updating maps, gathering information on natural resources, and disaster management
support in a variety of fields. The Japan Aerospace Exploration Agency (JAXA) has been planning a satellite system for
the ALOS follow-on program. The ALOS follow-on program consists of two satellites: one is a radar satellite called
ALOS-2, the other is an optical satellite called ALOS-3.
ALOS-3 carries an optical imager with more enhanced capabilities than those of the Panchromatic Remote-sensing
Instrument for Stereo Mapping (PRISM) aboard ALOS. ALOS-3 will produce a precise basic map with its systematic
observation to be used in the Geographical Information System (GIS). ALOS-3 will also promptly provide precise postdisaster
images to detect damaged areas through emergency observations when disasters occur.
JAXA has been defining system requirements for the spacecraft and the mission instrument of ALOS-3, as well as
conducting the conceptual design.
This paper introduces the latest design, the mission concept, and the current status of ALOS-3.
The post-ALOS program has been defined in the basic plan for Japan's space policy which was established by the
Strategic Headquarters for Space Policy on June 2nd, 2009. It emphasizes the continuity of the ALOS mission not only
disaster monitoring but also land infrastructure management, earth environment and resource monitoring and so on.
JAXA had completed the System Definition Review of the ALOS-2 satellite and ground system in February, 2009 and
started phase B design of the new L-band SAR, satellite and ground system with the target launch in 2013.This paper
introduces the mission and major specification of ALOS-2 satellite and L-band SAR.
The Advanced Land Observing Satellite (ALOS) "Daichi" launched in January 2006 has been operated successfully on
orbit for more than 3 years, delivering a huge number of high-resolution images and contributing to a variety of fields
that include disaster management support and regional environment monitoring. Consequently, the Japan Aerospace
Exploration Agency (JAXA) is planning the ALOS follow-on program. The ALOS follow-on program consists of two
satellites: one is a radar satellite called ALOS-2, the other is an optical satellite called ALOS-3. ALOS-3 will produce
pan-sharpened images as a base map of the Geographical Information System (GIS) in systematic observation. ALOS-3
will also promptly provide precise images for determining the damage of a disaster-stricken area in an emergency
observation because one of the most important missions of ALOS-3 is disaster monitoring. Some observation capabilities
are required to be upgraded from ALOS. ALOS has a panchromatic band with 2.5 m resolution. To provide precise
observation data, ALOS-3 has been improved to have a high resolution better than 1 m and 50 km or wider swath. JAXA
has been conducting the conceptual design and defining the system requirements for the spacecraft and the mission
instrument for ALOS-3.
In January 2006, JAXA launched the Advanced Land Observing Satellite (ALOS) "Daichi" by H-IIA #8. Since then,
"Daichi" has been operated to support the missions including disaster monitoring, which is one of the important
missions, and JAXA has been conducting demonstration experiments for more effective use of remote sensing satellites
for disaster mitigation with Japanese government agencies and institutes. Also, requirements to the satellites system for
disaster monitoring were summarized, which are prompt observation within 3 hours after a disaster stricken,high
resolution and wide coverage by optical sensors and synthetic aperture radars. Rapid monitoring of damaged area
becomes more important to keep safety and relief of the people involved in catastrophic disasters. L-band radar wave can
penetrate leaves and grasses and measure the ground movement directly, however, anothoer shorter waves (X or C-band radar) has
difficulty in penetrating leaves and grasses.For that reason, L-band SAR is most appropriate. This paper introduces a concept
and design of satellite system with L-band SAR and optical sensors for the next generation disaster monitoring.