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With Hurricane Lili bearing down on the Louisiana-Texas coastline, NASA managers today decided to delay the planned launching of the shuttle Atlantis Wednesday to give workers at the Johnson Space Center near Houston time to prepare for severe weather - and possibly evacuate.

The 111th shuttle launch, which had been scheduled between 2 p.m. and 6 p.m. EDT (1800-2200 GMT) Wednesday, will be delayed at least 24 hours and possibly longer depending on Lili's eventual path, shuttle program managers decided late this afternoon.

Flight controllers radioed the international space station's crew shortly before 5 p.m. EDT (2100 GMT) and said it was "more than likely" the Johnson Space Center would have to be evacuated.

If that scenario actually plays out, the crew was told, the station's solar arrays would be locked in place, reducing the available power to the station, to eliminate any chance of problems that might crop out while flight controllers were not actively monitoring critical systems.

The reduced power, in turn, likely would force the crew to turn off lights in the outpost and air circulation systems in the Quest airlock module. Flight controllers said the crew would be able to communicate with NASA engineers at a Russian flight control center near Moscow.

In the event JSC is, in fact, evaculated, UHF communications systems in California and Virginia would be activated to improve contact with the ground. The astronauts would have to manually control the station's stabilizing gyroscopes and possibly oversee a rocket firing by an attached Progress supply ship to boost the lab's altitude.

"The intention, however, is to generally still operate the vehicle from the backup mission control center in Moscow during the possible evaculation period," an astronaut radioed the crew from Houston. "But we wanted to make sure you had the right data to perform some of these procedures if necessary."

"Understand," replied flight engineer Peggy Whitson.

"OK. If 9A (Atlantis) slips more than a couple of days we may need to perform a Progress reboost, including attitude handovers between U.S. and Russian segments, and we may ask you to play a role in that in the event we're evacuated. Of course, stand by for deltas to all of this as the weather situation dictates."

Given Lili's current track toward the Gulf Coast, the decision to delay Atlantis' launching was not a surprise.

"We're going to be conservative and we would not entertain launching until we were sure that hurricane does not present a threat to our mission control center in Houston," shuttle program manager Ronald Dittemore said Monday.

The weather in Florida remains generally favorable, with a 60 percent chance of acceptable conditions during the shuttle's launch window Wednesday. The odds improve to 70 percent "go" both Thursday and Friday.

But NASA's shuttle mission control center is located at the Johnson Space Center and program managers do not want to proceed with launch preparations if mission control might have to be evacuated at some point because of Lili.

In addition, shuttle managers want to give JSC workers currently in Florida a chance to get home to their families if necessary.

"It is likely that if the storm continues on its path that's projected by the weather experts that we'll send all the folks home, back to Houston, so they can take care of their immediate needs in the local area and make sure their families are safe," Dittemore said Monday.

"And when that issue has passed, we'll look up again and determine when we're going to begin launch operations."

Launch could be delayed longer than one or even two days under some scenarios covering the possible evacuation and shutdown of the Johnson Space Center.

If critical systems are shut down prior to a general evacuation, it could take three to four days to power back up and reconfigure for launch. Under that scenario, launch could slip to the weekend or even early next week.

But predicting the path of a hurricane is as much art as science and it's not yet clear what impact Lili will eventually have. At this point, all that can be said is launch is being delayed at least 24 hours. Another meeting to assess the progress of the storm is planned for 7:45 a.m. EDT (1145 GMT) Wednesday.