NASA’s decision to postpone the space shuttle’s return to flight from May 22 until mid-July will not delay preparations for a possible shuttle mission to service the Hubble Space Telescope, NASA Administrator Mike Griffin said April 29.

Griffin said he informed key members of Congress Thursday evening that he would direct engineers at Goddard Spaceflight Center to start preparing for a space shuttle servicing mission to Hubble on the assumption that one ultimately will go forward.

A final decision on a shuttle mission to service Hubble will not be made until after a safe and successful return to flight, he added. However, with that launch now delayed nearly two more months, Griffin said the Goddard team has to get started now to preserve the option of saving Hubble before the popular telescope is scheduled to go dark around 2008.

“We are going to ‘bet on the come’ a little bit that we can do the servicing mission and get folks at Goddard started on doing what they would have to do to make that happen,” Griffin said, employing a gambling term familiar to craps players. “[But] we’re not going to allow Hubble preparations to interfere with return to flight.”

Also factoring into Griffin’s decision to put the Goddard Hubble servicing team back to work, he said, was direction from Congress, included in last year’s budget bill, to spend $291 million this year getting a servicing mission ready to go.

Griffin said the decision to delay Discovery’s launch was reached the night of April 28. The postponement was agreed to to give people in the shuttle program more time to conduct additional analysis and to make a number of fixes, including installing another heater on Discovery’s external fuel tank to prevent ice buildup that could break off in flight and damage the orbiter.

Unresolved debris issues, malfunctioning external tank sensors and soiled thermal protection blankets also contributed to the delay, which will push back preparations to deliver a large cargo pod to the international space station (ISS).

It was “no one thing, but the sum of all these things together that necessitated that we move [the launch] out six to seven weeks,” Griffin said.

Space shuttle officials are now targeting no earlier than the July 13 launch date for Discovery, after it became clear that lifting off during the current window – which runs from May 22 to June 3 – would be unattainable. The new launch window closes July 31.

“We’re going to return to flight, we’re not going to rush to flight,” Griffin said. “We’re going to do it right.”

The space shuttle is sitting atop launch pad 39B at NASA’s Kennedy Space Center in Florida as part of the agency’s first return-to-flight mission STS-114. A countdown test with the crew and orbiter stack is scheduled for next week at Kennedy Space Center .

The STS-114 flight is slated to test a host of new tools and techniques designed to increase shuttle flight safety, a direct response to the loss of the Columbia orbiter and its seven-astronaut crew. Columbia broke up during re-entry on Feb. 1, 2003, which investigators later determined was a result of wing damage caused by external tank debris shed two weeks earlier at the mission’s launch.

“Every time we’ve established a launch date, it’s been on the best data available,” said William Readdy, NASA’s spaceflight program chief, during the press conference. “Since we first established a launch date in June 2003, we’ve adjusted it a half- do zen times based on new data.”

It was new data on the potential danger of ice debris striking the shuttle that pushed shuttle managers to set the new launch date. The ice, which tests have shown can break off in chunks of up to five inches long, forms on regions of a 17-inch wide liquid oxygen feed line running down the external tank.

Tank engineers had previously installed a drip lip to the area of most concern – a bellows unit that expands and contracts — which reduced the risk of ice by about 70 percent, NASA officials said.

“A very small piece of ice can cause problems,” said NASA shuttle program manager William Parsons in a separate briefing today from Johnson Space Center in Houston. “Ice does not cause the same damage foam…we understand foam much better because we’ve done a lot of testing.”

The damage to Columbia’s wing leading edge was caused by a briefcase-sized chunk of insulation that separated from the external tank during liftoff. Tank engineers have since redesigned portions of the tank to reduce the amount of foam shedding.

“The testing on the ice lagged behind the testing on foam, but was clearly put in place,” said Wayne Hale, deputy shuttle program manager at Johnson Space Center , during the briefing. “But we had plans on how to deal with it [and will] now that we know that we have to do something about it.”

Shuttle engineers could install a removable heater to the bellows area to prevent ice build-up. The heating unit already is expected to ride on the third external tank to fly, and will likely be installed on another tank already inside NASA’s 52-story Vehicle Assembly Building to iron out assembly processes before a unit is attached to Discovery’s fuel tank.

But Hale said that heater assembly kits will not arrive at Kennedy Space Center until May 5, and there still remains some testing to determine if they will ultimately fly aboard Discovery.

Earlier this month, shuttle mission managers and launch workers performed a critical test of Discovery’s revamped external tank, fueling it with 500,000 gallons of liquid oxygen and hydrogen, which the orbiter burns to reach space.

During that test, problems were detected in two of the tank’s four fuel sensors, used to measure liquid hydrogen propellant levels, for reasons engineers still do not fully understand. Four functioning fuel sensors are required in order to launch the shuttle, Readdy said.

Discovery’s two-month launch delay also will affect space station operations, where the two Expedition 11 crew members were anticipating the shuttle’s May arrival to bring a wealth of food, supplies and new science equipment.

NASA’s space shuttle fleet has been grounded since the Columbia accident , leaving space station crews dependent on Russian Soyuz spacecraft to reach the ISS and the automated Progress vehicles for cargo deliveries. Discovery will deliver a large cargo container to the ISS, as well as large station components that currently cannot be launched aboard any other spacecraft.

William Gerstenmaier, NASA’s ISS program manager, said more water — currently the key consumable aboard the station — would be added to a Progress vehicle set to launch in June.

“Each one of our international partners was disappointed that we’re not going to launch the shuttle in that first window, but I think they understood clearly why we’re doing it,” Gerstenmaier said.

Brian Berger is editor in chief of and the SpaceNews magazine. He joined in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...