Aquarius is one of the most sensitive microwave radiometers ever built, and the first NASA sensor to track ocean salinity from space.
"It can detect as little as 0.2 parts salt to 1,000 parts water -- about the same as a dash of salt in a gallon of water. A human couldn't taste such a low concentration of salt, yet Aquarius manages to detect it while orbiting 408 miles above the Earth."
来源:http://science.nasa.gov/science-news/science-at-nasa/2011/07jun_aquarius/