Discovery is making its last ever crawl to the NASA launch pad at Cape Canaveral in Florida.
The shuttle is getting ready for its 39th and final mission into space on November 1.
The shuttle fleet is being retired after nearly 30 years of service.
NASA invited hundreds of shuttle workers and their families to watch today’s events.
After Discovery’s last mission to the International Space Station, it will be Endeavour’s turn to make its final curtain call in February.