Slim hopes dashed, NASA managers this morning ordered the shuttle Endeavour's crew to forego any landing attempts today and to remain in orbit until at least Friday because of low clouds, high winds and rain this afternoon at the Kennedy Space Center.

The decision was radioed up to the crew at 10:55 a.m.

"We are going to call off any deorbit attempts for today," said astronaut Duane Carey in mission control.

Commander James Wetherbee and his crewmates then began backing out of their deorbit preparations and rigging the shuttle for yet another day in space.

Despite a marginal forecast, entry flight director Wayne Hale says Endeavour's frustrated crew will be asked to make two full-up landing attempts Friday, if necessary. If the weather causes yet another 24-hour delay, Hale said he plans to bring the astronauts down one way or the other, in Florida or California, on Saturday.

Endeavour has enough on-board supplies to remain in orbit until Sunday in a worst-case scenario. But there's only enough propellant to support five actual deorbit attempts between now and then. Hale said that means two possible landing attempts Friday, two more Saturday and then an emergency reserve for Sunday if all else fails.

"The standard rule that we have in this business is that we will try until we only have one more day to land in Florida," he said. "When we only have one more day's worth of consumables, then what we'll do is call up Edwards and on that day, if you can't get into Florida, we would go ahead and proceed to California. The day that we would do that would be Saturday. We have no reason to quit early, there's no real pressing need to land Friday, so we would try Kennedy only for tomorrow.

"Right now, the propulsion system officer tells us ... we're still looking at the possibility of two attempts tomorrow, two attempts Saturday and then one emergency reserve Sunday morning," he said. "That's kind of our strategy."

The latest forecast for Friday calls for the chance of showers within 30 miles and the chance of a broken deck of clouds developing at 3,000 feet will diminish as the day wears on, making the crew's second landing opportunity a bit more favorable than the first.

"We're going to try to get to Florida tomorrow. The weather forecast is not too bad," Hale said. "It's not perfect, we're still going to be looking at clouds and showers. But if it turns out to be good enough, we'll land tomorrow in Florida."

Here are the numbers for both deorbit opportunities:

ORBIT...EVENT......................EST..........

199.....Deorbit burn ignition......12:51:17 p.m.
199.....Deorbit burn complete......12:54:14 p.m.
200.....Landing....................01:57:13 p.m.

200.....Deorbit burn ignition......02:27:17 p.m.
200.....Deorbit burn complete......02:30:15 p.m.
201.....Landing....................03:32:48 p.m.

Endeavour is bringing the international space station's fifth full-time crew home after six months in orbit. Assuming a landing Friday, Expedition 5 commander Valery Korzun, Sergei Treschev and science officer Peggy Whitson will have spent 184 days off the planet.

The delay getting home is no doubt frustrating, but Hale said the astronauts remain in good spirits.

"I've had several crew members tell me it's a little like going to a ball game," he said. "Having an extra inning or two is great fun, having more than an extra inning or two gets to be a little tiring. These guys worked really hard when they were docked at the international space station, they were glad to have a little bit of time off, I'm sure they enjoyed their first day off."

Even with the additional delay, "their spirits are excellent, they're troupers and they're going to hang in there whatever we decide to do," Hale said. "They understand we're doing it to give them the best possible conditions for a safe landing."