CLARREO (Climate Absolute Radiance and Refractivity Observatory) is a high-priority NASA decadal survey mission, originally selected as such by the National Research Council in 2007. The CLARREO mission is intended to provide a metrology laboratory in orbit to accurately quantify and attribute Earth's climate change (see List of climate research satellites). The mission is also designed to transfer its high accuracy to other spaceborne sensors. It would serve as a reference calibration standard in orbit, making climate trends apparent in their data sets within a 30-year time frame. These measurements may go on to enable testing, validation, and improvement of climate model prediction.