As expected, storm buildups near the Kennedy Space Center forced entry flight director John Shannon to call off today's attempt to bring the shuttle Endeavour back to Earth. Instead, the shuttle crew will remain in orbit for a second additional day, extending the U.S. endurance record set by the returning Expedition 4 space station crew from 195 days to 196.

With a good forecast for Edwards Air Force Base in California's Mojave Desert - and with improving conditions expected in Florida - Shannon plans to bring Endeavour's crew back to Earth Wednesday, on one coast or the other. While Florida is the clear preference, the astronauts will be diverted to Edwards if conditions don't permit a return to Kennedy. The shuttle has enough on-board supplies to remain in orbit until Thursday in a worst-case scenario.

For shuttle commander Kenneth Cockrell, back-to-back landing delays are becoming the rule, not the exception. During shuttle mission STS-80 in December 1996, Cockrell landed Columbia at Kennedy on the crew's third try after two straight days of weather waveoffs. And mission STS-98 ended at Edwards Air Force Base, Calif., in February 2001 after two days of bad weather in Florida.

"Well Taco, I can say this, at least you're consistent," astronaut William Oefelein called from mission control. "As with STS-80 and 98, we're going to wave off today's second-day landing attempts and try for tomorrow. I think the silver lining is that at least we'll have a tie breaker for Edwards or KSC as to where you land most. The reason we're waving off is for some low broken (cloud) decks and for some attached thunderstorm concerns. When you're ready, we'll meet you in the deorbit prep backout."

"Well, we're disappointed," replied Cockrell. "I was hoping to not repeat the STS-80 and 98 episodes."

For three of Endeavour's crewmates - returning space station commander Yuri Onufrienko, Daniel Bursch and Carl Walz - today's delay marked an unwelcome extension to a marathon mission. They were launched to the station Dec. 5. On June 11, they set a new U.S. endurance record, beating the old mark of 188 days set by Shannon Lucid aboard the Mir space station in 1996. A landing Wednesday would close out a record 196-day voyage. With family and friends waiting in Florida, they're hoping for a return to the Kennedy Space Center.

Here are all the landing times for Wednesday at both Kennedy and Edwards (all in Eastern; RW=runway):

ORBIT...DEORBIT BURN...LANDING........SITE..RW
   
215.....09:43:49 a.m...10:52:32 a.m...KSC...15
216.....11:19:17 a.m...12:27:00 p.m...KSC...15
217.....12:50:27 p.m...01:58:10 p.m...EDW...22
218.....02:26:45 p.m...03:33:21 p.m...EDW...22
219.....04:05:31 p.m...05:10:41 p.m...EDW...22

The most recent forecast by the Spaceflight Meteorology Group at the Johnson Space Center in Houston calls for generally favorable conditions in Florida Wednesday, although the official forecast still calls for a chance of showers within 30 nautical miles. Scattered clouds are expected at 3,000 feet, a broken deck at 25,000 feet and winds out of 140 degrees at 10 knots with gusts to 16 knots. Crosswinds are not a factor.

At Edwards, SMG is forecasting clear skies with winds out of 230 degrees at 12 knots with peaks to 18 knots. But the winds will pick up as the afternoon wears on. Conditions at White Sands Space Harbor in New Mexico, NASA's last-resort landing site, are expected to be ideal.

NASA wants to get Endeavour back to Florida if at all possible to avoid a lengthy delay for its next mission in October.

Landings in California cost about $1 million and add a week or more to a shuttle's turnaround time. The issue is complicated in this case because of a Russian mission in late October to deliver a fresh Soyuz lifeboat to the outpost. Endeavour must be off the ground on its next mission by Oct. 11 or the flight will be delayed into November. Launch currently is targeted for Oct. 6.