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STS-127: The programs

In advance of shuttle Endeavour's STS-127 mission to the station, managers from both programs discuss the flight.

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STS-127: The mission

A detailed step-by-step preview of Endeavour's STS-125 mission to install an external exposure platform on the station's Kibo science facility.

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STS-127: The EVAs

The lead spacewalk officer provides indepth explanations of the EVAs on Endeavour's assembly mission to the station.

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STS-127: The crew

The seven astronauts launching on Endeavour meet the press in the traditional pre-flight news conference.

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No leaks found during Endeavour fueling test
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 1, 2009


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Sensors near a repaired hydrogen vent line attached to shuttle Endeavour's external tank detected only the slightest traces of free hydrogen during a critical fueling test today, officials said, clearing the way for another launch attempt July 11.

 
Credit: NASA-KSC
 
The 7-inch vent line and the ground umbilical carrier plate used to connect it to a port on the side of the external tank will remain in their current configuration and engineers are confident the system will be leak free when Endeavour is fueled for launch on a space station assembly mission.

"We're in really good shape," said Mike Moses, the shuttle program launch integration manager at the Kennedy Space Center. "We're going to try on the 11th. ... We got it lined up just right and it doesn't leak."

The vent line is used to carry excess hydrogen gas away from the shuttle when the tank is filled with super-cold propellant. A valve used to route hydrogen to the vent line is closed a few minutes before launch when the tank is pressurized for flight.

Endeavour was grounded June 13 and 17 when sensors near the umbilical attachment plate detected hydrogen concentrations of more than 60,000 parts per million, or 6 percent. The allowable concentration near the shuttle is 4 percent.

After the second launch scrub, engineers collected detailed measurements and concluded the problem was caused by an alignment issue between the hydrogen vent port on the tank and the vent line interface. To ensure a tight fit, engineers replaced a rigid Teflon seal with a more flexible design, modified the umbilical plate mounting pins and installed washer-like shims to counteract the alignment issue.

During the June launch attempts, the leaks occurred after the hydrogen section of the external tank was nearly full and fueling operations were transitioning from "fast fill" to "topping." In both cases, the leaks exceeded 60,000 parts per million.

During today's test, sensors detected a barely measurable 12 parts per million, a level so low it's not considered a sign of leakage.

"In this case, there were absolutely no leak indications and when we did transition all the way through the replenish operations, there were absolutely no leak indications whatsoever noted," said Launch Director Pete Nickolenko. The 12 parts per million reading was right at the limits of detectability, he said, and "we're calling that system tight, we show that as no leaks."

Moses said the same techniques used to ensure a near-perfect alignment of the vent line hardware will be used on all subsequent flights to prevent any repeat of the leaks that grounded Endeavour last month.

Assuming no other problems develop, NASA now plans to restart Endeavour's countdown at 10 p.m. next Wednesday, setting up a launch attempt at 7:39:33 p.m. Saturday, July 11. On board will be commander Mark Polansky, pilot Douglas Hurley, Canadian flight engineer Julie Payette, David Wolf, Christopher Cassidy, Thomas Marshburn and space station flight engineer Timothy Kopra.

Assuming an on-time liftoff, Polansky plans to guide the shuttle to a docking with the International Space Station at 3:25 p.m. on July 13. Five spacewalks are planned between July 14 and July 23, starting in the early afternoon to late morning U.S. time, to install a Japanese experiment platform, to replace aging solar array batteries and to store spare parts.

Kopra will remain behind aboard the space station when Endeavour undocks July 25, becoming part of the Expedition 20 crew. He will replace Japanese astronaut Koichi Wakata, who was launched to the station in March and who will return to Earth aboard Endeavour. Landing at the Kennedy Space Center is targeted for 12:15 p.m. on July 27.

As it now stands, NASA will only have four days to get the shuttle off the ground or the flight will slip to July 27 because of a critical Russian Progress space station resupply mission scheduled for launch July 24.

The Progress can "loiter" in orbit for five days, but it must dock by July 29. And that means Endeavour must take off by July 14 to complete its mission in time to undock by July 27, making way for the Progress.

Because of Endeavour's problems getting off the ground, the next flight in the station assembly sequence, mission STS-128, has slipped from the first week of August to around Aug. 18. NASA plans to close out the year by launching the shuttle Atlantis Nov. 12, although that flight may slip into December when all is said and done.

Engineers recently ran into an unusual problem with Atlantis when an astronaut work light attachment knob was lost during the shuttle's recent Hubble Space Telescope servicing mission. The hardware ended up lodged between a cockpit window pane and a flight deck instrument console. When the shuttle returned to Earth, the pressurized crew module contracted slightly and the knob was pinned against the glass.

The knob eventually was extracted by pressurizing the crew module and using dry ice to cool the metal enough to cause a slight amount of shrinkage. But the inner pressure pane in window No. 5 must now be inspected to make sure it did not suffer any structural damage.

Engineers are hopeful the window can be flown as is because replacing the inner pressure pane would take four to six months. Access is extremely tight and cockpit instrumentation would have to be disconnected, reconnected and retested after a window swap out.

With the shuttle program scheduled for retirement at the end of next year, a six-month schedule hit for one orbiter would require major replanning. But Moses said today NASA cannot complete the space station with just two shuttles, Endeavour and Discovery, and if Atlantis needs a window replacement, it will get one.

But engineers are hopeful it won't come to that.

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Additional coverage for subscribers:
VIDEO: NO LEAKS FOUND DURING SPECIAL TEST PLAY
VIDEO: EXPLANATION OF THE HYDROGEN LEAK AND THE REPAIR PLAY

VIDEO: POST-SCRUB NEWS BRIEFING PLAY
VIDEO: FIRING ROOM UPDATE WITH LAUNCH DIRECTOR PLAY
VIDEO: SCRUB NO. 2 DECLARED DUE TO HYDROGEN LEAK PLAY

VIDEO: SUNDAY'S UPDATE FROM MISSION MANAGEMENT TEAM PLAY
VIDEO: LEAK POSTPONES SHUTTLE ENDEAVOUR LAUNCH PLAY

VIDEO: TIME-LAPSE OF SUN SETTING OVER PAD 39A PLAY
VIDEO: ANOTHER TIME-LAPSE OF GANTRY RETRACTION PLAY
VIDEO: TIME-LAPSE OF LAUNCH PAD TOWER ROLLBACK PLAY

VIDEO: PRE-LAUNCH INTERVIEW WITH MARK POLANSKY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH DOUG HURLEY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH CHRIS CASSIDY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH JULIE PAYETTE PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH TOM MARSHBURN PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH DAVE WOLF PLAY

VIDEO: THE STS-127 MISSION PREVIEW MOVIE PLAY
VIDEO: THURSDAY'S PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: JAPANESE SCIENCE FACILITIES ABOARD STATION PLAY
VIDEO: COUNTDOWN BEGINS TICKING FOR SATURDAY'S LAUNCH PLAY
VIDEO: LAUNCH COUNTDOWN PREVIEW BRIEFING PLAY
VIDEO: CREW ARRIVES JUST BEFORE MIDNIGHT PLAY | HI-DEF
VIDEO: GET TO KNOW ENDEAVOUR'S ASTRONAUTS PLAY

VIDEO: ASTRONAUTS PRACTICE EVACUATION OF SHUTTLE PLAY | HI-DEF
VIDEO: CREW BOARDS SHUTTLE FOR PRACTICE COUNT PLAY | HI-DEF
VIDEO: ASTRONAUTS SUIT UP FOR DRESS REHEARSAL PLAY | HI-DEF
VIDEO: CREW INSPECTS CARGO IN THE PAYLOAD BAY PLAY | HI-DEF
VIDEO: TRAINING SESSIONS AT LAUNCH PAD AND BUNKER PLAY | HI-DEF
VIDEO: INFORMAL CREW NEWS CONFERENCE AT LAUNCH PAD PLAY
VIDEO: ASTRONAUTS ARRIVE FOR PRACTICE COUNTDOWN PLAY

VIDEO: FLIGHT READINESS REVIEW SETS LAUNCH DATE PLAY

VIDEO: PAD 39A GANTRY ENCLOSES SHUTTLE PLAY | HI-DEF
VIDEO: ROLLAROUND MOVES ENDEAVOUR TO PAD 39A PLAY | HI-DEF
VIDEO: ENDEAVOUR IS HAULED OFF LAUNCH PAD 39B PLAY | HI-DEF
VIDEO: TIME-LAPSE OF SHUTTLE'S LAUNCH PAD SWITCH PLAY

VIDEO: SHUTTLE AND STATION PROGRAM UPDATE PLAY
VIDEO: THE STS-127 MISSION OVERVIEW BRIEFING PLAY
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY

VIDEO: PAD 39B AND ITS LAST SPACE SHUTTLE PLAY | HI-DEF
VIDEO: ENDEAVOUR'S SUNRISE ARRIVAL AT PAD 39B PLAY | HI-DEF
VIDEO: MIDNIGHT ROLLOUT FROM ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: ENDEAVOUR HOISTED FOR ATTACHMENT TO TANK PLAY | HI-DEF
VIDEO: CRANE ROTATES ENDEAVOUR VERTICALLY PLAY | HI-DEF
VIDEO: ENDEAVOUR MOVES TO ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: ORION AND ARES ROCKET PROGRESS REPORT PLAY
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