Weather delays shuttle launch

Showers and thunderstorms have been rumbling across parts of the Southeast for the past few days and will continue to do so on Saturday. Cape Canaveral, Fla., site of the Kennedy Space Center, is one place the unsettled weather will rumble over into the evening hours. That could force NASA to delay the launch of the space shuttle Endeavour.

After being delayed twice due to a leak in the fuel tank, Endeavour is finally set to launch into space on Saturday at 7:39 p.m. EDT. In order to proceed with a launch, any thunderstorm or lightning must be at least 11.5 miles away from Cape Canaveral, The Minneapolis Star Tribune reports.

Two previous launch attempts on June 13 and 17 were scrubbed during fueling when a hydrogen vent line attached to the side of the tank began leaking as the hydrogen section of the tank neared its full load. Engineers ultimately determined the vent port housing was built into the tank slightly out of alignment, causing a quick-disconnect fitting to pull away slightly under cryogenic conditions.

After the second delay, engineers replaced a rigid one-piece Teflon seal with a more flexible two-piece seal and used shim-like washers on the vent line attachment plate to make it less susceptible to temperature-induced movement.

To make sure the repairs would work, Endeavour's tank was re-loaded with oxygen and hydrogen July 1. Sensors detected no measurable leakage and engineers are confident the system will work as required Saturday, CNET News reports.

The primary task for Endeavour’s crew of seven astronauts, led by two-time shuttle flier Mark Polansky, is to complete construction of Japan’s $1 billion Kibo science laboratory.

They’ll add a nearly 8,400-pound “front porch” that will house up to a dozen experiments exposed to the harsh environment of space.

It’s the final piece of a lab on which assembly began last year and will have spanned three shuttle missions, The News-Press reports.