Discovery Launch Unlikely Tonight

NASA's first night-time shuttle launch in four years appears to be in jeopardy due to weather concerns. There is only a 40% chance of decent weather at the launch site this evening. Tomorrow night, the forecast is even worse, with only a 30% chance of acceptable weather, and then the forecast goes back to 40% for Saturday night.

Additionally, the weather forecasts for the emergency landing sites in Spain and France are pretty poor. Even if the weather is pristine in Florida, NASA won't launch the shuttle unless there is clear weather at at least one of the emergency landing sites.

My guess would be Saturday for Discovery's launch, but that's just a guess.

The purpose of this launch is to ferry supplies to the International Space Station, add another truss segment, and re-wire some of the station's power grid.