COSMIC is made up of a constellation of six microsatellites, the first to use radio occultation.

Illustration courtesy Orbital Sciences Corporation

Ever wonder why your Global Positioning System (GPS) device sometimes places you in the middle of a building, when you're pretty sure you're still on the street or sidewalk? Frustrating, yes, but the problem is not with the accuracy of the GPS network itself (the GPS satellites' locations are known quite precisely). The problem comes from distortions in the GPS signal caused by the atmosphere around you. Temperature, pressure and humidity in the air -- and even electrical variations in the upper atmosphere -- all have a cumulative effect on the GPS signal by the time it reaches your location.

Turning vice into virtue, COSMIC is a groundbreaking joint project by the United States and Taiwan that listens to the distortion in the GPS signal and calculates information that can be used to improve weather forecasting, predict climate change and monitor the Earth's changing magnetism.

Using a concept developed in the 1960s for the Mariner IV mission to Mars, and based on the success of a preliminary proof-of-concept experiment (Global Positioning System/Meteorology, or GPS/MET) in the late 1990s, the University Corporation for Atmospheric Research (UCAR) in Boulder, Colo., and Taiwan's National Space Organization (NSPO) reached an agreement in 2001 to develop a more robust experimental program. While its official title is the Formosa Satellite Mission #3/Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC), it is generally referred to in the United States simply as COSMIC. The NSPO is providing 80 percent of the $100 million funding for the project, with UCAR and other American agencies providing the rest [source: Henson].

Perhaps more interesting than COSMIC's name is what it's proposing to do. Its five-year mission is to show that it doesn't take a lot of resources to provide the kind of fundamental science needed to redefine meteorology and begin building the archive of accurate climatological data needed to improve existing climate models. This in turn will teach us a great deal about climate change.

Ultimately, the observations made by COSMIC could allow us to predict hurricanes, droughts, other major natural disasters and even thunderstorms much more accurately.

Next, let's take a look at the different components that make up COSMIC.