ALOS Data Users Handbook

Section 3 Outline of ALOS Satellite System3.2 Overview of Mission Instruments3.2.1 Earth Observing MissionOverview of three mission instruments for Earth Observing Mission onboard ALOS are given below. As for theALOS satellite operations including the three sensors, please refer to Section 5.3.2.1.1 PRISMPRISM is a panchromatic radiometer operating in the visible near infrared region, and has three telescopes forforward, nadir and backward view. The forward and the backward telescopes are installed for stereo images so asto realize a base-to-height ratio of 1.0 against satellite flight direction. An observation concept of PRISM isshown in Figure 3.2-1.PRISM has an Earth rotation correction function to correct distortion of observation views by the threetelescopes due to the Earth’s rotation and obtains images by selecting automatically the best image extractionposition.Each telescope of PRISM has over 70km of field of view; observation width will be 35km in the normalobservation mode (Observation Mode 1) with the three telescopes. The FOV can be pointed electrically ±1.5degree (approx. 17.5km). The nadir telescope can output data with a 70km swath width. For this mode, 35kmswath width data of the backward telescope can be output simultaneously.3-4