The core satellite is expected to be able to measure detailed precipitation activities, using both of the dual frequency precipitation radar and the microwave scanning radiometer. The data acquired by such measurement will permit of sophisticating the presumed algorithm of quantitative rain measurement in the microwave scanning radiometer. The sub-satellite will conduct the precipitation measurement of the microwave scanning radiometer and the measurement will become more reliable by utilizing the presumed algorithm.

The sub-satellite constellation will be launched by NASA and other space organizations in the world. The number of satellites will be around eight. lt is possible to get a global rainfall distribution in every 1 hour when the microwave scanning radiometers aboard these 8 polar orbit satellites collect and process the data. GPM plans real-time transmission of the global rainfall distribution data. This real-time data can be utilized not only for scientific research, but for social fields, including weather forecast, flood prediction, water resource management.