posted 06-15-2005 03:50 PM               

With new safety modifications, the Space Shuttle Discovery is back at Launch Pad 39B at NASA's Kennedy Space Center, Fla. Carried by a giant Crawler Transporter, Discovery arrived at the pad at 12:17 p.m. EDT today in preparation for its historic Return to Flight mission (STS-114) planned for July.

"We've addressed some additional concerns about ice formation on the external fuel tank," said NASA's Deputy Associate Administrator for International Space Station and Space Shuttle Programs Michael Kostelnik. "This is an even safer vehicle for Commander Eileen Collins and her crew, and the new modifications will ensure this important mission to the International Space Station is successful."

Discovery's journey took a little longer than expected. It left the Vehicle Assembly Building about 2:00 a.m. EDT for its four-mile journey. The Crawler Transporter, which has a top speed of about one mph, traveled even slower than normal today. It stopped frequently, so engineers could address overheating bearings. But when Discovery finally rolled up to the pad around lunchtime, it was a satisfying sight for those who have been working more than two years to get the Shuttle back to space.

"Seeing Discovery back on the launch pad is a visible testament to the dedication of everyone involved in making sure STS-114 is the safest mission it can be," said Space Shuttle Program Manager Bill Parsons. "We still have some work to do, but today is indicative that the hardware is getting ready for a launch in July."

With Discovery at the pad, workers will begin final preparations for launch. They will close out, test, and install the payload, NASA's Italian-built Multi-Purpose Logistics Module, Raffaello.

They will also load the hypergolic propellants for flight. The process includes adding the propellants, monomethyl hydrazine and nitrogen tetroxide, into the Orbiter Maneuvering System and the Forward Reaction Control System.

Discovery was de-mated from its previous External Tank (ET-120) and attached to a new External Tank (ET-121) on June 7. A new heater was added to ET-121 on the feedline bellows. The heater is designed to minimize potential ice and frost buildup on the bellows, a part of the pipeline that carries liquid oxygen to the Shuttle's main engines. ET-121 was originally scheduled to fly with Atlantis on the second Return to Flight mission (STS-121).

The new tank was fitted with temperature sensors and accelerometers to gather information about the tank's performance and measure vibration during flight.

"Returning Discovery to the launch pad is the last major processing milestone prior to launch," said NASA Launch Director Mike Leinbach. "The launch team is completing the final procedures and documentation, and we are looking forward to beginning the launch countdown three days prior to liftoff."

NASA plans to launch Discovery during a window from July 13 to 31. A launch date will be set during the Flight Readiness Review scheduled for June 29 and 30.