Nasa sent 1 of 2 twins into space to see what difference there would be in space. After a year they brought back the twin and did a side by side comparison. They noticed how some of there physical features changed. They noticed that the one that was sent into space had weaker bones, his cheeks puffed out, and he grew an inch or two taller.
Ham! Ham is the first chimp to go to space 50 years ago and return home safely. The U.S. decided to send a chimp into space because of the similarities to humans. He was trained by hearing and seeing specific lights and sounds to see how he would react.