GPM Spacecraft and Instruments
The foundation of the GPM mission is the Core Observatory satellite provided by NASA and JAXA. Data collected from the Core satellite serves as a reference standard that will unify precipitation measurements from research and operational satellites launched by a consortium of GPM partners in the United States, Japan, France, India, and Europe. The GPM constellation of satellites can observe precipitation over the entire globe every 2-3 hours. The Core satellite will measure rain and snow using two science instruments: the GPM Microwave Imager (GMI) and the Dual-frequency Precipitation Radar (DPR). The GMI captures precipitation intensities and horizontal patterns, while the DPR provides insights into the three dimensional structure of precipitating particles. Together these two instruments provide a database of measurements against which other partner satellites’ microwave observations can be meaningfully compared and combined to make a global precipitation dataset.
The Core Observatory satellite flies at an altitude of 253 miles (407 kilometers) in a non-Sun-synchronous orbit that covers the Earth from 65°S to 65°N — from about the Antarctic Circle to the Arctic Circle. The GPM Core Observatory was developed and tested at NASA Goddard Space Flight Center. Once completed, it was then shipped to Japan, and a Japanese H-IIA rocket carried the GPM Core Observatory into orbit from Tanegashima Island, Japan, on February 27th, 2014.
A test technician completes the final electrical integration of the GMI.
Credit: Ball Aerospace
GPM Microwave Imager (GMI)
The GMI uses 13 different microwave channels to observe energy from the different types of precipitation through clouds for estimating everything from heavy to light rain and for detecting falling snow. As the satellite passes over Earth, the GMI constantly scans a region 550 miles (885 kilometers) across. The Ball Aerospace and Technology Corporation built the GMI under contract with NASA Goddard Space Flight Center.
Dual-Frequency Precipitation Radar (DPR)
The DPR provides three-dimensional information about precipitation particles derived from reflected energy by these particles at different heights within the cloud system. The two frequencies of the DPR also allow the radar to infer the sizes of precipitation particles and offer insights into a storm’s physical characteristics. The Ka-band frequency scans across a region of 78 miles (125 kilometers) and is nested within the wider scan of the Ku-band frequency of 158 miles (254 kilometers). The Japan Aerospace and Exploration Agency (JAXA) and Japan’s National Institute of Information and Communications Technology (NICT) built the DPR.