CubeSats are tiny, standardized satellites that come in units called “1U” - cubes that are 10 centimeters on each side, about the size of a small Rubik’s cube box. Bigger versions get built by snapping together more units (2U, 3U, 6U, and so on). The standard was invented in 1999 by professors at Stanford and California Polytechnic State University.
Before CubeSats, building a satellite cost hundreds of millions of dollars and only big space agencies could afford one. CubeSats use off-the-shelf parts like phone cameras and tiny computers, so universities can build one for tens of thousands of dollars. Many high schools have now launched their own CubeSats too.
CubeSats hitch rides on bigger rocket launches, packed into special dispensers and pushed out into orbit one by one. Some rockets have dropped off over 100 CubeSats in a single launch. From space they track wildfires, photograph hurricanes, run weather experiments, and even test out new technologies for bigger missions to come.
