On this date in 1972, Landsat 1 (then known as the Earth Resources Technology Satellite) was launched from Vandenberg Air Force Base. Landsat 1 was in operation until 1978. In the past three and a half decades, Landsat 1 has been succeeded by Landsats 2, 3, 4, 5, and 7… making today the 35th year of continuous Landsat satellite operations.

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.