While NASA technicians need to replace a faulty electronics box on one of shuttle Discovery's solid rocket boosters, the agency is confident the work won't delay its plannned launch scheduled from July 1 to July 19.

A routine testing last week revealed the booster's power distribution system unexpectedly shifted from a prime to a backup circuit. NASA engineers think this was caused by a faulty integrated electronics unit that serves as the primary communications link between the booster and shuttle orbiter computers. The faulty unit is set to be replaced in the coming weeks as other prelaunch work continues as normal. "We're taking weekends off. That's how well the flow is going at the pad," said NASA.