Space Briefing Book:


Written by: Space Foundation Editorial Team

Satellites are foundational components of modern society, permitting communications, global positioning, Earth and solar system study, and a range of other activities. Satellite applications include:

Earth Science

Remote sensing satellites are used to study the Earth, including things like weather events, ecological trends and ocean temperatures.

Solar System Study

Satellites are used to study the many celestial bodies in the solar system. To date, artificial satellites have orbited many significant planets and moons in our solar system, as well as numerous smaller objects like dwarf planets, asteroids and comets.


Similar to Earth science uses, reconnaissance or intelligence satellites employ a suite of sensors and communications tools, deployed and used by government agencies for defense or intelligence purposes, including early missile detection and emergency broadcasts.


Most of the satellites in orbit are used for relaying communications around the Earth’s curve.

Position, Navigation and Timing (PNT)

Navigation satellites deliver geospatial positioning, identifying a single point on the ground by its latitude, longitude and altitude.

Orbiting Carbon Observatory (OCO-2)

A rendering of NASA’s Orbiting Carbon Observatory (OCO-2). Credit: NASA/JPL-Caltech

Satellite Weight Categories

Satellites can be grouped by weight into six basic categories.

Large: 2,200+ lbs (1,000+ kg)

Medium: 1,100-2,200 lbs (500-1,000 kg)

Small: 220-1,100 lbs (100-500 kg)

Microsatellite: 22-220 lbs (10-100 kg)

Nanosatellite: 2.2-22 lbs (1-10 kg)

Picosatellite: .22-2.2 lbs (0.1-1 kg)

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