Measuring the Changing Earth with Landsat

The Landsat series is a joint NASA and U.S. Geological Survey satellite program designed and operated to observe these changes from space. Specifically, these satellites are intended to study land use and how it changes over time.

There have been nine Landsat satellites launched since 1972.

Landsat 9, which launched in September of 2021, is the latest satellite to reach orbit. Landsat 7 and 8 are still active. 

Landsat 9 hosts two instruments, similar to those aboard Landsat 8:

The first instrument captures observations of the planet in different kinds of wavelengths. It “sees” visible light — recording the colors blue, green and red.

It can also record wavelengths that we can’t see — near infrared and shortwave-infrared.

Earth’s surface emits heat. This instrument measures that heat — called thermal infrared radiation. This data can help us calculate soil moisture.

It can also track the rate of evapotranspiration — the movement of water from the soil, through plants and into the atmosphere. Data about evapotranspiration can tell us a lot about the health of plants.

This image is a good example of how Landsat’s instruments work. The bottom images show the landscapes depicted in the top but with thermal data. Blue-white colors indicate cooler surface temperatures while the orange-red indicate warmer surface temperatures.