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Evolution of Earth Science: From a Single Satellite to an Entire Fleet

This side-by-side comparison highlights the growth of Earth observation, moving from a single pioneering instrument to a robust global monitoring network. On the left, a detailed diagram shows the Explorer 1 satellite, the first U.S. spacecraft to carry a scientific instrument—a cosmic ray detector—into orbit. On the right, a complex graphic displays NASA’s modern Earth science fleet, featuring over two dozen active satellite missions like Aqua, Terra, and Landsat 8 that collaborate to track the planet's atmosphere, oceans, and land surfaces in real-time.
Explorer 1 was the first satellite to carry science instruments. Currently, more than two dozen satellite missions are working to keep tabs on Earth science for NASA.
NASA

Explorer 1 was the first U.S. satellite. But it wasn’t launched with the sole purpose of seeing if our nation could do it: It was used to gather scientific information that we would otherwise have had no way of gathering. The primary science instrument on Explorer 1 was a cosmic ray detector that measured the radiation environment in Earth orbit. Explorer 1 began the era of studying Earth from space.

Today, NASA satellites continually orbit the globe as they collect information about Earth’s ocean, atmosphere and land surfaces. Satellites can even monitor the activity of life forms, such as phytoplankton, from remote vantage points.

Read articles about satellites and orbits written at elementary and middle-school levels.

Read about the major scientific discovery of Explorer 1.

Solve a math problem about the Van Allen Belts.

Download posters of current NASA Earth science satellite missions.

See Earth from a satellite's perspective with this free application.