Project Manhigh was a very important project that was run by scientists a long time ago. You know how the sky above us looks like a big blue blanket during the day? Well, scientists wanted to learn more about what was up there in the big blue blanket, so they came up with a plan to send people really, really high up into the sky in big balloons.
These people were called astronauts, and they were very brave because they had to go way up, higher than the clouds or any buildings. They would go up in a big balloon that was filled with helium, which is a gas that makes things float.
Once they were up really high in the sky, the astronauts would do experiments and take pictures of everything they saw up there. They wore special suits that made sure they could breathe and move around comfortably in the cold and dry air up there.
All of this exploring and experimenting helped scientists understand more about the Earth and the sky above us. They learned a lot of new things about how the weather changes and how different things look from way up high.
So, Project Manhigh was like a big adventure where scientists sent really brave people in big balloons to learn more about what's up above us.