Today is the day when Navy SEAL Christopher Cassidy and six other astronauts were supposed to launch the space shuttle Endeavor on a 16-day round-trip to the International Space Station. The six other people in space mission STS-127 are flight commander Mark Polansky, pilot Douglas Hurley, and mission specialists Julie Payette, David Wolf, Thomas Henry Marshburn and Timothy Kopra.

NASA flight engineer Timothy Kopra, an Army pilot, will stay behind aboard the International Space Station when Endeavour departs. He will replace JAXA Astronaut Koichi Wakata who will take the trip back home to Earth.

Their mission is to deliver two new modules and attach them to the Japanese Kibo laboratory complex. Chris Cassidy, assigned as mission specialist on the flight, will participate in 5 space walks, the first two of which he will be inside a vehicle coordinating with the other astronauts while they attach the remaining parts to the facility. Wolf and Kopra will do the mission’s first spacewalk, Wolf and Marshburn on the second, Wolf and Cassidy on the third and Cassidy and Marshburn on the fourth and fifth. Polansky, Hurley and Payette will handle shuttle operations.

The launch was scheduled at 7:17 am today, but was postponed due to a gaseous hydrogen leak observed during tanking. Endeavour has been re-scheduled to launch no earlier than June 17, 2009.

With this mission, Chris Cassidy would become the 500th individual to reach orbit and the 2nd Navy SEAL to do so; William Shepherd was the first Navy SEAL in space. If the launch and everything else set after it went as scheduled, Endeavour would have docked with the space station on Monday around 3:55 am and would have been back at the Kennedy Space Center at 12:18 am on June 29. Of course, that would change now that the launch was moved to a later date.