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Discovery rolls out

Discovery travels from the Vehicle Assembly Building to pad 39A in preparation for the STS-124 mission.

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STS-124: The programs

In advance of shuttle Discovery's STS-124 mission to the station, managers from both programs discuss the flight.

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STS-124: The mission

A detailed preview of Discovery's mission to deliver Japan's science laboratory Kibo to the station is provided in this briefing.

 Part 1 | Part 2

STS-124: Spacewalks

Three spacewalks are planned during Discovery's STS-124 assembly mission to the station.

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STS-124: The Crew

The Discovery astronauts, led by commander Mark Kelly, meet the press in the traditional pre-flight news conference.

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Discovery passes final review for May 31 launch
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: May 19, 2008

NASA managers today cleared the shuttle Discovery for launch May 31, at 5:02:09 p.m. EDT, on a long-awaited three-spacewalk mission to deliver and attach Japan's huge Kibo laboratory module to the international space station. The decision to proceed came after a lengthy discussion on the health of the station's Soyuz lifeboat after back-to-back re-entry problems that led to rough, off-course landings.

 
Credit: Chris Miller/Spaceflight Now
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Russian engineers are still assessing what went wrong during the descent of the Soyuz TMA-11 spacecraft April 19 when two of the three modules making up the vehicle failed to separate properly before atmospheric entry. The propulsion module ultimately broke free of the crew section, allowing Yuri Malenchenko, outgoing station commander Peggy Whitson and a South Korean space tourist to complete a steep but otherwise safe landing in Kazakhstan.

It was the second such entry mishap in a row and Russian engineers have launched a major investigation to determine what went wrong and whether the Soyuz TMA-12 spacecraft currently docked to the station is healthy. It is a critical issue because the three-seat Soyuz is the station crew's only way home in the absence of a space shuttle in the event of an emergency that might force an evacuation.

It is a critical issue for NASA as well because the agency plans to rotate U.S. crew members during Discovery's flight, ferrying Gregory Chamitoff to the station to join Expedition 17 commander Sergei Volkov and Oleg Kononenko and bringing Garrett Reisman back to Earth. Another shuttle is not scheduled to visit the space station until November. The Soyuz TMA-12 spacecraft will serve as the station's lifeboat until October when a fresh crew is launched aboard a fresh Soyuz. Current plans call for Volkov, Kononenko and U.S. space tourist Richard Garriott, who will ride the new Soyuz to orbit, to return to Earth aboard the TMA-12 spacecraft Oct. 23.

Going into today's executive-level flight readiness review to set a launch date for Discovery, NASA managers discussed a variety of options, including whether to delay the shuttle flight until Russian engineers get a better idea about the status of the Soyuz currently in orbit.

But the Russian investigation into what went wrong during the Soyuz TMA-11 descent is not expected to be complete until the end of June or later and a one week to two week delay for Discovery would not improve the station crew's safety margin.

Bill Gerstenmaier, NASA's chief of space operations, said the odds of a station failure that would force a Soyuz evacuation are low - on the order of 1-in-124 over six months - and that a safe landing would be likely even if similar entry problems occurred.

"If something comes out of the investigation that says the Soyuz is not acceptable as a return vehicle, then we would go take some appropriate action," Gerstenmaier said. "But we haven't seen anything along those lines. For emergency return, Soyuz is OK. ... But the Russians are working through it methodically, trying to identify if there's anything that would invalidate its use as an emergency return vehicle. As long as that doesn't occur, then we proceed with our normal plans. And I don't see anything between now and the 31st that's going to change any of that thinking."

Sources familiar with recent NASA discussions on the Soyuz issue said an assessment of the relative risks of various options played a key role. While the odds of a station problem that would force evacuation are thought to be around 1-in-124 over six months, the overall risk of a catastrophic shuttle failure over the course of Discovery's mission - including all phases of launch, orbital operations and re-entry - is on the order of 1-in-78, according to NASA's latest assessment. Given those relative odds, and the belief that the station is five times more likely to suffer a non-recoverable failure in the absence of a crew to repair it, NASA managers opted to press ahead with an on-schedule launch for Discovery.

"It's a fairly low probability that we'd need to use (the Soyuz) in an emergency case," Gerstenmaier said. "In fact, we analyzed that, we did a probabilistic risk assessment of what the chances were of having to use the Soyuz as a rescue vehicle. It's a low probability we're going to have to use it. But if we use it, we think there's a good probability it'll return the crew and do what it needs to do. So as a parachute or a backup system, it has the reliability that we think we need for a backup system. We have yet to prove it has the reliability that we would use for a nominal return situation."

Discovery is in good shape and on schedule for launch May 31. The only technical problem of any real concern since the shuttle was moved to pad 39A was the failure of a multiplexer-demultiplexer computer system that required a changeout. When the MDM, known as FA2, failed, it caused two of the shuttle's four flight computers to lose synchronization. In flight, that could force a crew to switch to a backup flight system computer, limiting their ability to cope with additional failures. But the MDM was successfully replaced and tested and no concerns about it were raised during today's flight readiness review.

"It's an extremely complicated mission," Gerstenmaier said. "Adding the Kibo module is a big deal for the Japanese. This really brings them up to speed. And adding the Kibo module is not easy. ... We need to be careful we don't assume success and take our eye off of what we're doing. We've got to stay focused. The Soyuz is fine, it will take care of itself, we've got time to work that. That needs to get resolved by the fall. The issue right now in front of is us we need to be 100 percent ready to go fly this flight, we've got to be 100 percent ready to get the Kibo attached. ... We need to work all that activity during the flight and that needs to be our focus."

Commander Mark Kelly, pilot Kenneth Ham, flight engineer Ronald Garan, Karen Nyberg, Michael Fossum, Japanese astronaut Akihiko Hoshide and Chamitoff plan to fly to the Kennedy Space Center on May 28 for the 3 p.m. start of their countdown to launch.

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Additional coverage for subscribers:
VIDEO: NEWS BRIEFING FOLLOWING FLIGHT READINESS REVIEW PLAY

VIDEO: INTERVIEW WITH COMMANDER MARK KELLY PLAY
VIDEO: INTERVIEW WITH PILOT KEN HAM PLAY
VIDEO: INTERVIEW WITH MS1 KAREN NYBERG PLAY
VIDEO: INTERVIEW WITH MS2 RON GARAN PLAY
VIDEO: INTERVIEW WITH MS3 MIKE FOSSUM PLAY
VIDEO: INTERVIEW WITH MS4 AKIHIKO HOSHIDE PLAY

VIDEO: ASTRONAUTS PRACTICE EVACUATION OF SHUTTLE PLAY
VIDEO: CREW BOARDS DISCOVERY FOR PRACTICE COUNTDOWN PLAY
VIDEO: TRAINING SESSIONS AT LAUNCH PAD AND BUNKER PLAY
VIDEO: CREW NEWS CONFERENCE AT LAUNCH PAD 39A PLAY
VIDEO: ASTRONAUTS ARRIVE FOR PRACTICE COUNTDOWN PLAY

VIDEO: TIME-LAPSE OF GANTRY ENCLOSING DISCOVERY PLAY
VIDEO: PAD'S ORBITER ACCESS ARM SWUNG INTO POSITION PLAY
VIDEO: TIME-LAPSE OF CRAWLER RETREATING AFTER ROLLOUT PLAY
VIDEO: SHUTTLE DISCOVERY ROLLED TO PAD 39A PLAY

VIDEO: SHUTTLE AND STATION PROGRAM BRIEFING PLAY
VIDEO: STS-124 MISSION OVERVIEW PART 1 | PART 2
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY

VIDEO: KIBO LABORATORY TRAVELS TO THE LAUNCH PAD PLAY
VIDEO: TRANSPORT CANISTER WITH KIBO ROTATED UPRIGHT PLAY
VIDEO: CRANE PLACES KIBO MODULE INTO TRANSPORT CANISTER PLAY

VIDEO: DISCOVERY HOISTED FOR ATTACHMENT TO FUEL TANK PLAY
VIDEO: THE SHUTTLE MOVES TO THE VEHICLE ASSEMBLY BUILDING PLAY
MORE: STS-124 VIDEO COVERAGE
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