Takhasi Hamazaki 
  
  
2.2 AVNIR-2 
  
  
  
  
  
  
  
  
  
The AVNIR-2 is an improved version of AVNIR on the ADEOS. Bandl: 0.42-0.50um 
The AVNIR-2 provides 10m-resolution multi-spectral image over Wave Length Band2: 0.52-0.60um 
70km swath width. The AVNIR-2 and the PALSAR are used Band3: 0.61-0.69um 
mainly for regional observation, disaster monitoring, and Earth Band4: 0.76-0.89um 
resources survey. For the disaster monitoring mission, the IFOV 10m 
AVNIR-2 and the PALSAR has a cross track pointing capability Swath Width 70km 
and able to observe anywhere in the world within 48 hours. | Pointing Capability +44deg/-44deg 
World’s first simultaneous observation with optical sensor and S/N >200 aid 
SAR is also possible. This unique data set is expected to MTF Band1-3: >0.25 
contribute the improvement of classification capability. AVNIR-2 Band4 :>0.20 
characteristics is shown in Table.2. Table 2. AVNIR-2 Characteristics 
2.3 PALSAR 
The PALSAR is an improved version of SAR on board JERS-1. The NASDA and the Ministry of International Trade 
and Industry (MITI) are jointly developing the PALSAR. The PALSAR consists of 8.9m by 3.2m active phased array 
antenna with 80 transmitter and receiver modules and electric unit. Off nadir angle is variable between 10 to 51 
degree. PALSAR has four operations mode: high-resolution mode, ScanSAR mode, Full polarimetry mode, and direct 
transmission mode. The resolution of the PALSAR is 10m in the high-resolution mode and maximum swath width is 
350km in ScanSAR mode. PALSAR characteristics is shown in Table.3. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
High Resolution 
Mode Single Dual Polarization Direct ScanSAR Polarimery 
Polarization Downlink 
Frequency L band (1270MHz) 
Chirp Bandwidth 28MHz 14MHz 14MHz 14/28MHz 14MHz 
Polarization HHor VV HH/HV or VV/VH HH or VV HH or VV HH/HV+VV/VH 
Incidence Angle 8-60deg 8-60deg 8-60deg 18-43deg 8-30deg 
(typ 39deg) (typ 39deg) (typ 39deg) (typ 24deg) 
Range Resolution 7-44m 14-88m 14-88m 100m 24-89m 
10m@39deg 20m@39deg 20m@39deg (Multi-look) 30m@24deg 
Swath Width 40-70km 40-70km 40-70km 250-350km 20-65km 
Bit Length 5 bits 5 bits 3/5 bits 5 bits 3/5 bits 
Data Rate 240Mbps 240Mbps 120Mbps 120/240Mbps 240Mbps 
  
Table 3. PALSAR characteristics 
3 ALOS SATELLITE SYSTEM 
3.1 Overview 
The ALOS is one of the biggest class earth observation satellites in the world. The size of the ALOS is roughly 9m in 
length and 28m in width and mass is 4,000kg. Primary structure is divided into upper, middle, and lower part and 
consists of CFRP truss members. Thermal expansion is strictly controlled with negative expansion CFRP truss, metal 
fittings, and precise heater control in order to minimize the thermal distortion in the orbit. The ALOS on-orbit 
configuration is shown in Fig.4. 
3.2 Highly Stable Attitude Control System 
In order to minimize geometric distortion of the image, satellite attitude movement (angular velocity) is stabilized 
within 2x10" degree per 5sec (equivalent to 2.5m distortion within 70km square scene). The disturbance from major 
vibration sources, such as data relay communication antenna pointing mechanics, AVNIR-2 pointing mirror drive 
mechanics, and solar array drive mechanics PALSAR antenna, are carefully controlled using feed forward technique 
and onboard parameter tuning. Newly developed 64bit Micro Processor Unit  (MIPS-R4900 core on | Mega Gate 
Array) is adopted for attitude and orbit control system (AOCS). 
  
138 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B1. Amsterdam 2000. 
  
33 
Hig 
obj: 
regi 
sen: 
In o 
list 
adja 
AO 
sent 
sect 
star 
com 
Cor 
trac 
GP: 
witl 
34 
The 
is 
Trai 
Sim 
to 
(DP 
35 
Inte 
data 
sate 
disa 
con 
for 
stati 
of 1 
State 
allo: