Yoshihisa Arikawa

ALOS-2 launch and early orbit operation result

The Advanced Land Observing Satellite-2 (ALOS-2) carries the state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 which succeed to the ALOS/PALSAR. ALOS-2 was launched on 24th May 2014, and is performing the initial functional verifications of onboard components and systems. This paper describes the initial operation results on orbit and evaluates the performance.

Autonomous precision orbit control of ALOS-2 for repeat-pass SAR interferometry

ALOS-2, the next-generation Japanese SAR satellite, is designed to perform autonomous precise orbit control of Earth-referenced repeating orbits for effective repeat-pass SAR interferometry. The orbit control accuracy requirement of ALOS-2 is 500m (95%) with respect to the reference Earth-fixed flight path. This accuracy is guaranteed for all latitudes by not only drag-makeup maneuvers but also frequent inclination maneuvers. The on-board software of ALOS-2 can handle operations of orbit determination, maneuver prediction and planning, and maneuver executions for both drag-makeup maneuvers and inclination maneuvers. This feature of autonomy is expected to be great help for efficient ground operations of ALOS-2.

ALOS-2 orbit control and determination

The Advanced Land Observing Satellite-2 (ALOS-2) carries the state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 which succeed to the ALOS/PALSAR. ALOS-2 was launched on 24th May 2014, and is performing the initial functional verifications of onboard components and systems. This paper describes the initial launch operation results, and the plan of the performance evaluation regarding to the orbit control and determination.

First result from ALOS-2 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.

ALOS-2 launch and initial checkout result

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.