KENNEDY SPACE CENTER, FL (CBS) - NASA is gearing up to resume shuttle flights this spring with a three-spacewalk mission to repair the international space station's stabilization system, to deliver critical supplies and equipment and to prove the design defects that contributed to the Columbia disaster have been corrected.

America's space shuttle fleet could return to flight as early as May. Photo: NASA

Implementing an overlapping suite of approaches, NASA managers believe the chances of Columbia-like damage to Discovery during launch are minimal. But if damage does, in fact, occur, they are equally confident they will be able to detect it, determine if it is entry critical and, if it is, carry out at least rudimentary spacewalk repairs.

Those repair procedures are still evolving and may not be fully tested and certified by the time Discovery's May/June launch window rolls around. But NASA managers say certified repair procedures are not required for flight because of the elimination of major debris, improved damage detection and the crew's worst-case ability to use the space station as a "safe haven" until another shuttle, already prepped for flight, could be launched on a rescue mission.

"I believe in our flight rationale, which says we are fixing the vehicle," said LeRoy Cain, the ascent-entry flight director for Columbia's final mission and now, for return to flight. "We are eliminating critical debris from being liberated from the tank and the boosters, the launch pad, every source that we can think of, we think we're eliminating critical debris. That's number one for me.

"I really feel like the chances of us having something come off of the stack and create a problem for us in our flight are exceedingly low."

Even so, engineers are working around to clock to perfect techniques for repairing damage to the ship's heat-shield tiles and the reinforced carbon carbon panels making up the wing leading edges and the shuttle's nose cap.

"The objectives of what's intended in the Columbia Accident Investigation Board report is to have the capacity to repair damage to the thermal protection system," said NASA Administrator Sean O'Keefe. "The only way you're going to be able to determine whether or not you can do any level of repair is after the first two flights.

"So the answer to that probing question in this semantical debate will be settled as a reality of what's possible after the first two flights. One test is worth worlds of opinions on this kind of thing and it settles all kinds of arguments."

Astronauts Stephen Robinson and Soichi Noguchi will provide at least some of the answers by testing tile repair materials and procedures in orbit. They may also test rudimentary techniques for repairing RCC panels, although that is problematic. While repair procedures may not be certified, tests in the space environment are considered critical to validating whatever techniques might ultimately be adopted.

"When we started this, we knew it would be extremely difficult to do a repair technique both on tile and on RCC," said shuttle program manager William Parsons. "The CAIB (Columbia Accident Investigation Board) said to do the best that we could to come up with some technique to repair RCC and repair tile. We have done that. We have continued to put the best and brightest this agency has to offer on this, we've used every resource this agency and this nation have to work on this, we've made a lot of progress.

"We think there are some issues that we still need to resolve, but we still have some time to go resolve that. And then we're going to go fly a test mission. We're going to have a detailed test objective in the payload bay of the orbiter, we're going to go out there and we're going to test some of the techniques, we're going to bring them back and (test them).

"We can do a lot of things on the ground, but we have to take them on orbit, put them in work on orbit, bring them back and then see if they work as well as we think they'll work. In a state of emergency, we would have a technique that we would be ready to perform. But right at this moment, we're still working through some of the technical details on how to do good tile repair and RCC repair."

Discovery currently is targeted for launch on the 114th shuttle mission around 4:11 p.m. on May 14. That date is little more than a target, however, and launch easily could slip a few weeks depending on the progress of work to close out open issues.

But engineers believe Discovery has a good chance of getting off the ground before its launch period closes June 3. The next available window, which depends on the space station's orbit, the shuttle's ability to reach it and a post-Columbia requirement to launch in daylight for photo documentation, opens July 13 and runs through Aug. 1.

STS-114/International Space Station: Upcoming Events
Editor's note:
For the purposes of ground processing, NASA is tracking May 12 for Discovery's launch even though lighting constraints are not met until May 14.

December
12/22/04: Progress 15 supply ship undocks from international space station
12/23/04: Progress 16 supply ship launches from Kazakhstan (5:19 p.m. EST)
12/25/04: Progress 16 docks with station (7:05 p.m. EST)
12/31/04: STS-114: External tank departs Michoud, La.

January
01/06/05: STS-114: External tank arrives at Kennedy Space Center
01/26/05: ISS Expedition 10 crew: Spacewalk No. 1
01/20/05: STS-114: OBSS thermal protection system survey boom installation in shuttle cargo bay

February
02/09/05: STS-114: External tank mated to solid-fuel boosters
02/11/05: STS-114: Crew equipment and interface checks
02/27/05: Progress 16 supply ship undocks from space station
02/28/05: Progress 17 supply ship launches

March
03/02/05: Progress 17 supply ship docks with space station
03/02/05: STS-114: 48-hour full-up mission simulation at Johnson Space Center
03/07/05: STS-114: Shuttle rollover to Vehicle Assembly Building
03/16/05: STS-114: Shuttle stack moved to launch pad 39B
03/25/05: ISS Expedition 10 crew: Spacewalk No. 2
03/30/05: STS-114: External tank is loaded with fuel for a test

April
04/15/05: ISS Expedition 11/ESA crew launches aboard a Soyuz
04/17/05: ISS Expedition 11/ESA crew docks with space station
04/25/05: ISS Expedition 10/ESA crew lands
04/26/05: STS-114: Flight readiness review
04/29/05: STS-114: Terminal countdown demonstration test

May
05/08/05: STS-114: Crew flies to Kennedy Space Center
05/09/05: STS-114: Countdown begins
05/12/05: STS-114: Launch

At the controls on Discovery's flight deck will be veteran commander Eileen Collins, pilot James Kelly and flight engineer Robinson. Seated to Robinson's right will be Japanese native son Noguchi.

Strapped in below on the shuttle's middeck will be Mir-veteran Andrew Thomas, Wendy Lawrence and Charles Camarda. All but Camarda and Noguchi are shuttle veterans.

The shuttle's primary cargo includes a refurbished control moment gyroscope to replace one that failed earlier aboard the space station; a tool kit and spare parts module that will be mounted on the station's airlock to enable future assembly work; and a pressurized logistics module loaded with space station equipment and supplies.

In an interview by the author for the book "Comm Check: The Final Flight of Shuttle Columbia," Collins was asked if she had any second thoughts about commanding mission STS-114.

"Absolutely not," she said. "In fact, I am more committed to flying this mission than I ever would have been. ... I am excited, I am going to be extremely confident because look at all this work that is being done, not just done because of (Columbia), but other things that we think are risky. I am so confident, I am so excited, I want to get our country back flying in space again, so I am not one blink of an eye worried about safety."

And her crewmates?

"I have talked to everybody on my crew several times, 'Hey, I want to make sure that all of you are comfortable, that you feel safe, if you don't want to fly this mission you don't have to. No requirement.' They are all feeling the same way I am. They are onboard, they can't wait to get back and fly."

Robinson, a private pilot who owns three airplanes, lives on an airstrip and doesn't own a television, said spaceflight is inherently risky and that the Columbia disaster "does not reset that calculation."

"We feel that there is a risk and it is worth it," he said in an interview for "Comm Check." "I feel that it is an important enough thing to do, that the risk - and we have a very realistic view of risk, especially now - the risk is worth it. It doesn't change my mind at all. It is that important. I am totally dedicated to do it."

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