NASA has scrubbed the launch of space
shuttle Discovery amidst persistent
weather problems, keeping the seven-member crew
grounded. The
shuttle was scheduled for a 9:35 p.m. ET launch time on Thursday. Another attempt has been scheduled for 8:47 p.m. Saturday, although there is only a 30 per cent chance of good
weather. Each launch scrub comes at a high price, with Thursday's delay costing NASA roughly US$500,000. The biggest issue Thursday was a bank of low clouds sticking around because of a cold front coming through Florida. This is just a timing factor, weather officer Tech. Sgt. Matt Timmerman said. It's more unfortunate than unusual. NASA rules prohibit launching in low clouds because engineers need clear skies to observe the shuttle during ascent. In case of emergency, the shuttle commander needs to be able to see clearly enough to guide the shuttle on a difficult back-flip maneuver to land safely at Kennedy Space Center. On top of all this, all three overseas emergency landing sites in Spain and France are forecast to have bad weather. NASA has through Dec. 17 to launch. The space agency doesn't want Discovery in orbit when the New Year starts because of concerns about a computer change-of-date problem. But if Discovery is still grounded by Dec. 18, NASA said it could decide to keep trying anyway through the day after Christmas. NASA has already had to wrestle with two technical concerns before resolving them Wednesday. The first was a split-second power surge that occurred early Tuesday when power was about to be switched from the shuttle's launch platform to Discovery itself. Tests found no problems with the shuttle, main engines, boosters and external fuel tank. The second involved booster-seal glue that helps connect segments of the solid rocket boosters. A recent test by the manufacturer raised questions about whether the glue was as strong as it should be. After evaluating data, NASA managers concluded that the adhesive passed all the acceptable criteria and was good to fly. Along with spacewalking astronauts rewiring the space station, Discovery will deliver a 2-tonne addition and replace one of the space station's three crew members. This is the first planned night launch in four years. Former aerospace engineer Tim Cole explained that daytime launches are preferable for obvious reasons, but limited launch windows available for this particular mission (the are only four available in the next five days) means the agency must attempt a night launch. They have to launch into an orbit that will allow the shuttle to get to the International Space Station, and you don't have unlimited opportunities, Cole told CTV News net from Ottawa. NASA required daylight liftoffs for the three flights after the 2003 Columbia accident to make sure the agency could get good photos of the external fuel tank. Foam breaking off the tank at liftoff caused the damage that killed Columbia's seven astronauts.