Discovery launch delayed until Independence Day

[BGonaSTICK]

For a second straight day, the shuttle Discovery was grounded because of cloud cover over the Kennedy Space Center today, delaying a long-awaited mission to service and resupply the international space station. Launch was rescheduled for around 2:38 p.m. on the July Fourth holiday.

Commander Steve Lindsey and his six crewmates had hoped to blast off at 3:26 p.m. to kick off only the second post-Columbia shuttle mission, but the weather wouldn't cooperate and launch director Mike Leinbach called off the countdown around 1:15 p.m., well ahead of the opening of Discovery's launch window.

"OK, Steve, we've talked to launch weather and landing weather and the ops manager and we've concluded we are not going to have a chance to launch today," Leinbach told the crew. "And so in order to preserve as much time for the scrub-turnaround as possible to get the PRSD (fuel cell system) topped off on board the ship and to give you guys the maximum opportunity on orbit to extend a day and get your third EVA, we've decided to terminate the count today, stand down for 48 hours, do a single commodity hydrogen reactant top off, targeting the next launch attempt for Tuesday afternoon."
"Yeah, we copy, and looking out the window it doesn't look good today and we think that's a great plan," Lindsey radioed from Discovery's flight deck.

By standing down early today and foregoing a possible launch try Monday, engineers will have time to refill on-board hydrogen tanks to power the shuttle's electricity producing fuel cells. After launch tries Tuesday and Wednesday, however, the team will need 48 hours to reload fuel cell oxygen.

The forecast for Tuesday calls for a 60 percent chance of acceptable weather, but the outlook gets worse as the week wears on. Fuel cell reactants determine how long a shuttle can stay in orbit. Had Discovery gotten off Saturday, Sunday or Monday, Discovery would have had enough electrical power generation capability to permit a one-day mission extension for a spacewalk to test wing leading edge repair techniques.

By topping off the hydrogen supply, Lindsey and company should be able to get the mission extension if they get off Tuesday or Wednesday.

As it was, today was a second straight disappointment for the astronauts, who have been training for this flight for nearly two years. But the day began with forecasters predicting a 70 percent chance of bad weather and as it turned out, their pessimism was justified.

The launch window Tuesday opens around 2:33 p.m. and closes 10 minutes later. The preferred in-plane launch time is 2:38 p.m. The launch window and preferred in-plane launch time likely will change by a few seconds based on updated tracking of the international space station.