CAPE CANAVERAL, Fla. (AP) _ After 2 1/2 months of repairs to its external fuel tank, space shuttle Atlantis on Tuesday began a slow journey back to the launch pad in anticipation of lifting off in early June on a construction mission to the international space station.
The 3.4-mile trip from the Vehicle Assembly Building aboard the massive crawler-transporter started just after 5 a.m. EDT and was expected to last seven hours.
It was the second trip to the launch pad that Atlantis has made this year. The shuttle was at the launch pad in late February when a freak hail storm shot golf ball-sized hail at the shuttle, making thousands of dings to insulation foam on the external fuel tank.
NASA managers postponed a mid-March launch and ordered the shuttle returned to the Vehicle Assembly Building for repairs. It was only the 17th time in the 26-year-old shuttle program that one of the vehicles had to be moved back to the Vehicle Assembly Building from the launch pad.
The launch _ the first of the year _ is now planned for no earlier than June 8, although a final decision will be made at the end of the month.
The technicians sprayed on new insulation foam in some areas, hand-poured foam on other areas and sanded down other foam so it blended in with surrounding areas. One technician even designed and built in a week a special tool that could be used to apply new foam.
``It's a real success story _ almost bordering on an Apollo 13 type story to develop that in such a short time,'' John Chapman, NASA's manager of the external tank project, said last week, referring to the engineering ingenuity that delivered the moon-bound crew safely back to Earth in 1970 after an oxygen tank ruptured on the spacecraft.
Foam debris coming off the external fuel tank is of special concern to NASA since the seven astronauts aboard Columbia perished when a piece of foam from the tank struck a wing during launch, allowing fiery gases to penetrate the space shuttle while returning to Earth.
Astronaut Clayton Anderson has been added to the previously-six-man Atlantis crew so he can replace U.S. astronaut Sunita Williams on the international space station.
NASA managers hope Atlantis' launch puts the space agency back on a regular schedule of shuttle missions after a five-month hiatus. The last space shuttle flight was in December, and three more missions are scheduled for this year after Atlantis.
The space agency has 14 more missions to finish building the space station and repair the Hubble Space Telescope before the shuttle fleet is grounded in 2010. The next-generation spacecraft, Orion, isn't scheduled to fly astronauts until 2015.
Last week, leaders of almost two dozen aerospace companies sent a letter to members of Congress urging them to support funding NASA an additional $1.4 billion above the administration's 2008 budget request of $17.3 billion to narrow the gap when the United States won't have manned spaceflights.
``Future U.S. leadership in space is at stake,'' the letter said.