|What's missing, Scoobypedia?|
The Astronaut Ghost was the disguise of Simon Simonson, a scientist.
A Pup Named Scooby-Doo
He wanted revenge because his experiment didn't get to go into space, but Velma Dinkley's did. So he dressed up as the ghost to disrupt the mission by 'haunting' the space center. (Dawn of the Spooky Shuttle Scare)