This is a new concept for scatterometry, using the reflection of GPS signals from the ocean surface to study severe storms and cyclones. CYGNSS is a constellation of eight micro-satellites that will make accurate measurements of ocean surface winds in order to better understand the life-cycle of tropical cyclones, typhoons and hurricanes. Why eight? Because the satellites do not have to carry a transmitter, but instead rely on the GPS satellites to provide the transmitted energy. This means that the individual satellites weigh about 170 kg, and that eight of them can be accommodated in one launch. This is a great idea, scheduled for launch in 2016, and I’ll write more about it in the coming weeks.
Here is a reference for CYGNSS: http://earthobservatory.nasa.gov/blogs/fromthefield/category/cygnss/?src=eoa-features