William E. Thornton was a man who did some really cool stuff in space! He was born a long time ago in 1929, and he grew up to be a scientist who studied things like physics and engineering. When he was older, he got to work for NASA, which is a big organization that sends people and machines into space.
One of the coolest things William Thornton did was he went to space himself! He was called an astronaut, which means he got to go up into space and float around in a spaceship. While he was up there, he did a lot of experiments to help scientists learn more about space and how it works.
One of the things William Thornton is most famous for is inventing something called the "Space Shuttle Remote Manipulator System." That's a really big name for something that people use to grab onto and move things in space. It's like a giant robot arm that can reach out and help astronauts do things that they can't do with their own arms. People still use something like this today whenever they go up to space!
William Thornton was really smart, and he did a lot of amazing things for all of us back here on Earth. Even though he's not with us anymore, we can remember him for his important contributions to space and science.