Water on Earth goes around the planet in a lot of ways, but our knowledge of how they travel varies with the path taken. And I guess few people will argue that the most mysterious way, one that is scarcely understood, is going under our feet. With no way to dig deep into soil and measure the amount of water contained everywhere and anytime, the effect of water changes inside Earth are still not well understood.
To fill in the gaps in this part of the water cycle, NASA's Jet Propulsion Laboratory is flying a spacecraft that tackles just this problem by detecting signals from the water underground. SMAP uses a large L-band radar that actively scans for the density variations under vegetation and a radiometer that detects the thermal signals from the soil itself. Combining the more accurate radiometer and the more precise radar measurements, there will be advancements in the understanding of the effect of soil flooding/freezing on the climate and local ecosystem developments, as well as forecasting on possible flooding and drought conditions around the world.
With so many possible uses of the data, it is no wonder that this ends up as one of NASA's highly recommended Earth observation missions for development in the past few years!
[ame="http://www.youtube.com/watch?v=AuO0pH-1JYg"]NASA | SMAP Radiometer versus Radio Frequency Interference[/ame]
