HOUSTON - NASA has pushed back the planned launch of the final flight to overhaul the Hubble Space Telescope by up to five weeks due to external fuel tank delays, mission managers said Thursday.
Space shuttle program manager John Shannon said that the additional time required to include post-Columbia safety improvements in two shuttle fuel tanks supporting the Hubble servicing mission have delayed the spaceflight to no earlier than late September. A seven-astronaut crew was slated to launch toward Hubble aboard NASA's shuttle Atlantis on Aug. 28.
"We really cannot make that date with the external tank processing," Shannon told reporters in a briefing here at NASA's Johnson Space Center. "I really think it's a small price to pay, to tell you the truth, four to five weeks for all the improvements that we're getting on this tank."
Atlantis' next fuel tank, and a second reserved for a rescue shuttle, are NASA's first built from scratch that include modifications to limit the loss of foam insulation that could damage an orbiter during liftoff. Foam debris gouged a hole in the shuttle Columbia's left wing during its 2003 launch that led to the loss of the orbiter and its seven-astronaut crew as they reentered the Earth's atmosphere.
Since then, NASA has modified existing shuttle fuel tanks and required in-space inspections of orbiter heat shields to ensure they are in good health.
The agency required two of the new external tanks for the Hubble servicing flight because Atlantis astronauts will be unable to take refuge aboard the International Space Station (ISS) if their spacecraft suffers severe damage since the two destinations are in different orbits. Instead, a second shuttle — Endeavour — will be prepared to serve as a rescue ship.
The Hubble mission's delay also means NASA will have to push back a subsequent flight to haul new equipment to the International Space Station (ISS) and likely fly only five of the six shuttle flights originally slated for 2008, Shannon said. The ripple effect is not expected to impact NASA's plans to complete space station construction and retire the shuttle fleet by 2010, he added.
NASA's shuttle Discovery, meanwhile, remains on track for a planned May 31 launch to deliver Japan's massive Kibo laboratory to the space station, Shannon said.
Soyuz landing investigation
While shuttle officials prepare for Discovery's launch, NASA station managers and their Russian counterparts have canceled a short Soyuz flight outside the ISS as investigators hunt for the source of a malfunction that sent an earlier spacecraft off-course during its April landing.
The Russian-built Soyuz TMA-11 spacecraft landed on the central Asian steppes of Kazakhstan on April 19, but reentered the Earth's atmosphere at a steeper angle than normal and subjected its crew to higher gravitational loads. The Soyuz returned NASA astronaut Peggy Whitson, Russian cosmonaut Yuri Malenchenko and South Korean spaceflyer So-yeon Yi — who has since been hospitalized due to back and neck pain — to Earth after their station flights.
The spacecraft appears to have suffered a glitch during the separation of its crew capsule and propulsion module. A similar reentry malfunction afflicted a returning Soyuz spacecraft last October, prompting Russian engineers to take a new look at both malfunctions.
"We really need to let this commission finish their work to decide what the cause of the anomaly was before we understand whether the crew was subjected to any additional risk," said Mike Suffredini, NASA's space station program manager.
Space station commander Sergei Volkov and two crewmates were slated to move their own Soyuz TMA-12 spacecraft two a new docking port next week. But NASA and Russian mission managers opted to cancel the orbital trip on the off-chance that Volkov and his crew were unable to redock with the station, and forced to return to Earth while the investigation was still under way.
"We just wanted to not expose ourselves to that small risk," said Suffredini, adding that the Soyuz is still clear to return Volkov and his crew to Earth in the event of a major emergency.
Russian engineers expect to complete their investigation by the end of the month.
"We're going to have to give them some time to work through the data," Suffredini said.