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NASA: No 'show-stoppers' for launchSpace shuttle clears another hurdle for return to space in July
 The next launch window for Discovery is July 1-19. YOUR E-MAIL ALERTS(CNN) -- The space shuttle Discovery is all but ready for launch in July, NASA officials said Wednesday following a review of the hazards posed by falling foam during liftoff. "There are no show-stoppers. We've made significant improvements since last year in the elimination of many of the hazards from foam," shuttle program manager Wayne Hale told a news conference at Kennedy Space Center in Florida. "Today, in our review, we did come to the conclusion that we have an acceptable risk posture to go fly, from the debris standpoint. That is a major milestone." Discovery is on launch pad 39B at the space center on Cape Canaveral, undergoing final preparations for launch. Two more reviews are scheduled in June before the final OK for launch is given. The next launch window is July 1-19. Hale's comments followed a two-day meeting of 100 managers and engineers to assess how well they've done in eliminating the potential for debris to fly off the external tank during liftoff. Despite his optimistic comments, Hale acknowledged the foam debris problem is not solved. "You're going to hear me say this over and over again as we go down to flight -- there will continue to be foam come off the external tank," Hale said. "What we have done in a very systematic manner is eliminate the largest hazards," he said. The orange fuel tank is covered with insulating foam to keep ice from forming when supercold liquid hydrogen and oxygen propellant are pumped into it hours before launch. The foam goes on like shaving cream and becomes brittle when it dries. It was a 1.6-pound piece of foam that broke loose from Columbia during launch and cracked a hole in the wing, ultimately causing the disintegration of the craft on re-entry February 1, 2003. All all seven astronauts on board were killed. The shuttle fleet was grounded last summer after a 1-pound piece of foam broke loose from Discovery's external tank on the program's return-to-flight mission, just missing the orbiter. NASA engineers determined the piece of foam was part of a 40-pound wedge of insulation called the protuberance air load ramp. Designers initially put the PAL ramp on the tank to smooth the flow of air over pressurization lines and a cable tray that runs along the side. After the close call last summer, managers decided to remove the PAL ramp altogether, eliminating that potential debris source. Engineers are now scratching their heads over how to redesign another worrisome set of structures on the tank called the ice-frost ramps. These pieces of foam cover the brackets that hold in place the cable tray and pressurization lines formerly shielded by the PAL ramp. Small pieces of foam have come off the ice-frost ramps on previous flights. Wind tunnel tests conducted by NASA this spring confirmed that under worst-case scenario conditions even small pieces of foam flying off the ice-frost ramps could cause critical damage to the orbiter. Even so, NASA officials have put off any modifications to those structures until after the next launch. "If we had not had to address the PAL ramp, which was a much larger hazard, then we probably would be working on the ice-frost ramps," Hale said. "The removal of the PAL ramp is the largest aerodynamic change we've made to the shuttle stack since we started flying it. The principle is make one change at a time." NASA officials will hold another meeting in Florida next week to assess the safety of design modifications made to the tank in recent months. Assuming that review goes as planned, NASA will hold a final flight readiness review June 16-17, when managers will make a decision whether to clear Discovery for flight. "We're looking forward to a good flight on the opening of the window, July 1," Hale said. 
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