Spacecraft and Instruments
A Japanese H-IIA rocket
launched the GPM
Core Observatory into orbit
on Feb. 27, 2014.
The Core Spacecraft was developed and tested in-house at NASA Goddard Space Flight Center.
A scientific spacecraft carries numerous instruments designed to measure specific phenomena. Scientists must control, very precisely, where each instrument on the spacecraft is pointing, so that data is collected from the intended targets. Not only do the instruments have to be moved from target to target, they must be held steady on a target long enough, as the spacecraft moves through space, to collect the needed data.
GPM is pointing toward Earth to measure precipitation. It is vital to control the attitude (or physical orientation) of the Core Spacecraft accurately so that we can map exactly where the resulting data originates on Earth. The Core observatory is uniquely instrumented with a conically-scanning radiometer and a cross-track scanning radar:
The well calibrated GPM Microwave Imager (GMI) measurements and the well characterized scene obtained from the Dual-frequency Precipitation Radar (DPR) combine to provide an excellent reference against which to calibrate other microwave radiometers in the GPM constellation when overlapping measurements of same Earth scene are made. The DPR has the capability to make detailed three-dimensional measurements of cloud structure, rainfall, and rain rates. These detailed measurements are providing a further understanding of the microwave radiometric measurements made by the GMI.