NASA managers said Thursday that they were "go" for Saturday's scheduled launch of the shuttle Discovery on its second post-Columbia test mission, although Florida's stormy weather has made the preparations slightly more complicated.
The go-ahead was given after a launch readiness review that wrapped up Thursday afternoon, said John Shannon, chairman of the mission management team for Discovery's STS-121 flight to the international space station.
"There were no dissenting opinions that were reported," Shannon told reporters. He said the managers did not revisit a debate over the external fuel tank's ice/frost ramps, foam structures that engineers see as a potential source of hazardous debris, because that issue had been "closed out" during an earlier meeting known as the flight readiness review.
During the flight readiness review, NASA's chief safety official and chief engineer said they were "no-go" for the launch because of the ice/frost ramp issue, but they declined to appeal the management team's decision to go ahead anyway.
Shannon characterized Thursday's review as "a very positive meeting where we just worked through any open actions that were opened at the flight readiness review."
"All of those were closed out," he said.
He acknowledged the concerns that engineers have lodged about the ice/frost ramps, citing the argument that "from a strictly engineering standpoint we would not fly" until the ramp had been redesigned. But he said NASA Administrator Mike Griffin made the decision to go ahead with the mission after assessing the "real risk that it poses" and looking at the "whole picture" for future flights.
Shannon noted that imagery obtained during Discovery's launch would go toward "a better redesign" of the fuel-tank foam.
In the wake of Thursday's management meeting, weather loomed as the biggest unknown for the launch schedule. Forecasters have set the chances of favorable weather at only 40 percent for Saturday and extending into next week. Discovery's launch window extends from Saturday to July 19; after that, the next opportunity comes up in late August.
A lightning alert temporarily held up one of the key preparations for launch: the loading of potentially explosive propellants aboard the shuttle itself. However, the alert was lifted Thursday evening. NASA spokesmen said the delay would have no real impact on the countdown, due to the multiple built-in holds included in the schedule.
Launch managers touched on other points during Thursday's news conference:
- If Discovery's launch is significantly delayed, that could complicate preparations for the next mission in the queue, which is currently set for liftoff in late August or early September, said shuttle launch director Mike Leinbach. "Since the Columbia accident, we've only flown one time. We really haven't been in the turnaround environment that we were in prior to Columbia. ... It's a bit of a challenge, especially with newer folks in the program," he said.
- Shannon said he had spoken with Charles Camarda, who was reassigned from his post as director of engineering at NASA's Johnson Space Center after a management dispute. Camarda is now working with the NASA Engineering and Safety Center in Virginia, and Shannon said he could still play a role in the Discovery mission. "He assured me that he would attend the MMTs [mission management team meetings] and help out however he could," Shannon said.
- Leinbach drew a laugh from journalists during discussion of a plan to keep Kennedy Space Center's vultures away clear of the launch. The concern arose after last year's launch, when a vulture was struck by Discovery during the first seconds of the shuttle's ascent. NASA will set up a baited trap to catch as many of 60 vultures — and leave an option open to hold the countdown in its final minutes if birds are detected near the pad. But NASA has an obligation to protect the birds as well, Leinbach said. "We live on a national wildlife refuge here," he explained. "So we're not free to mess with the birds in a terminal fashion."