HOUSTON - While NASA hopes to solve its external tank foam woes in time to launch another space shuttle in the near future, discussions are underway on how to get the most out of the Discovery's current presence at the International Space Station (ISS) should mission managers opt to extend its flight by one day.

By not running a booster fan typically used to circulate air between the shuttle and station, and implementing other conservation techniques, flight controllers have built up 21 hours in available time the shuttle can remain on orbit if needed, said Phil Engelauf, mission operations representative for Discovery's STS-114 spaceflight, during a mission status briefing here at NASA's Johnson Space Center (JSC).

The measures have allowed Discovery's crew to save on the valuable cryogenic reactants used to power the shuttle's fuel cells, and will hope full reach the full-day mark soon, he added.

"We're optimistic that we'll get enough cryo margin to insert that day," Engelauf said, adding that should mission managers decide to go with the one-day flight extension, it would most likely occur between Aug. 3-4.

Discovery's successful launch and, so far, nearly flawless spaceflight has been somewhat overshadowed by a foam debris problem that resurfaced with its external tank. During its July 26 launch, the tank unexpectedly shed chunks of foam insulation much too large to meet NASA's standards. A similar foam shedding event critically wounded the space shuttle Columbia during launch in 2003, punching through the heat shield on the orbiters left wing. Hot atmospheric gases entered the damaged area as Columbia returned to Earth on Feb. 1, 2003, destroying the vehicle and killing its astronaut crew.

Shuttle program managers said this week they do not plan to launch another shuttle until they understand and fix the new foam issue. The Atlantis orbiter was slated to launch the STS-121 mission during a flight window stretching between Sept. 9-24. That shuttle's Aug. 3 rollout to the launch pad, and other processing operations, have not been changed as of today, said John Shannon, NASA's manager of flight operations and integration for the shuttle program, during the briefing.

The potential of another long gap in shuttle flights to the ISS - Discovery's STS-114 flight is the first in two and a half years - has led to some discussion of how to utilize Discovery's resources and crew if mission managers decide to do so, shuttle officials said.

The addition of even a single, unscheduled day in Discovery's timeline could be a boon for the ISS crew, they added.

With seven extra hands on board, ISS Expedition 11 commander Sergei Krikalev and flight engineer John Phillips could catch up on maintenance tasks that may have fallen by the wayside as the astronauts prepared for Discovery's arrival, Engelauf said, adding that any unique tools, spare laptop computers or other material that could be useful to the station now or in the future could be transferred to the ISS.

"The crew of Discovery and on the current space station assignment are looking at what, if anything, we can do while Discovery is there to pre-position the station for a longer gap between flights should there be one," NASA administrator Michael Griffin told reporters via teleconference, stressing that it is much too soon to assume NASA's next shuttle flight is beyond 2005.

Earlier today, a NASA spokesman said the Discovery astronauts are checking if they can pack up any additional water - produced by reactions in the orbiter's fuel cells - to leave with the ISS crew.

By being smart and working hard to address the unexpected foam shedding issues seen during Discovery's Tuesday launch, NASA could loft the Atlantis orbiter in one of two flight windows this year, Griffin said.

"If we can do those things and are successful, then we'll catch one of those flight opportunities, and if not the date will move," Griffin said. "We don't start out by assuming we can't succeed."

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