In 2009, Landsat 5 completed 25 years of collecting data – 22 years beyond its design life. thumbnail: http://svs.gsfc.nasa.gov/vis/a010000/a010400/a010401/Landsat5_turns_25_ipodLG_gal.png

Above the Earth, Below the Surface: Landsat’s Role in Monitoring Water Quality
Safeguarding freshwater resources is crucial, and while scientists use a variety of ground-based techniques to gauge water quality, the Landsat program has provided water quality data from orbit for decades.