"290 Days to Rollout," declares the placard posted under the US flag here, counting down to the shuttle's scheduled September 2004 launch, the first since the space shuttle Columbia broke apart in midair on February 1, killing all seven astronauts on board.

In the middle of the Orbital Processing Facility (OPF) where Atlantis is being overhauled, a six-story structure surrounds the shuttle like a screen, exposing only its undercarriage.

The 120 NASA specialists working on getting the shuttle back up and running are never all visible at any one time, concealed behind platforms, scaffolding, cables and protective tarps.

On every level, various technicians each focus on a small part of Atlantis, like surgeons working on a patient covered with a sheet revealing only the operation site.

Specialists are now inspecting and installing new reinforced panels that will protect the wings' leading edge, in the hope of avoiding a repeat of the Columbia tragedy.

"That's where the plasma flow got in, between panel 8 and 9" on Columbia's left wing's leading edge, said Scott Thurston, the orbital vehicle manager as he stood under Atlantis's left wing and pointed to an area where the aluminum inside the wing is visible.

The leading edge, located on the front of the wing, is exposed to extremely hot air flows. This plasma, topping 1,000 degrees, opened a channel between Columbia's heat-protective tiles, enabling the shuttle's aluminum structure to melt, Thurston said.

In charge of preparations for the shuttle before the Columbia disaster, Thurston played a central role in the investigation into the deadly accident.

The plasma penetrated the shuttle through a crack in the wing's protective skin, caused when the shuttle was struck with a piece of insulating foam that broke away from an external tank during liftoff, investigators said.

In addition to reinforcing the carbon-carbon material of the wings' leading edge, technicians are also replacing steel clips inside the panels with lighter, yet more durable, titanium fasteners, Thurston said.

Other specialists are working on the black tiles which form the heat shield that protects the shuttle's underbelly. Every damaged tile located in a place that is highly exposed during re-entry into Earth's atmosphere will be replaced. Tiles in less vulnerable areas will merely be repaired.

Thurston expressed confidence that the shuttle would be ready for its scheduled September 2004 launch. Referring to the 15 recommendations made by the Columbia Accident Investigation Board, he declared: "For my part, the criteria will be met, and beyond."

"We'll be ready for September," he said.

SPACE.WIRE