The crew of space shuttle Discovery began the Terminal Countdown Testing on Wednesday at NASA's Kennedy Space Center in preparation for a July launch, NASA TV reported.
"It's great to be here," said Discovery Commander Steve Lindsey, "We're all pretty optimistic that early July looks good".
The seven crew member arrived at Florida on Tuesday, a day later than scheduled, because of the Tropical Storm Alberto.
Their activities on the first day involve safety training -- where the astronauts familiarize themselves with launch pad escape routes, fire suppression procedures and an emergency egress walkdown.
The astronauts and ground crews will go through a full launch dress rehearsal during the tests, which will last till Friday. NASA managers then will begin a final preflight review that is expected to last until Saturday. Finally NASA is expected to set a firm launch date for the launch of Discovery.
Space shuttle Discovery's launch is targeted for July 1 in a launch window that extends to July 19. The mission, coded STS-121, will visit the International Space Station and continue evaluating new shuttle safety improvements. At least two spacewalks are planned during the 12-day mission, which also includes repair work to the station.
The crew member includes Commander Steve Lindsey, pilot Mark Kelly, flight engineer Lisa Nowak, spacewalkers Piers Sellers and Michael Fossum, astronaut Stephanie Wilson and the European Space Agency's Thomas Reiter of Germany.