Posted: Wed, Jun 6, 2007, 8:41 AM ET (1241 GMT)

The countdown for Friday night's launch of the shuttle Atlantis started Tuesday night, with no technical problems reported and a favorable weather forecast. The countdown for the STS-117 launch started at 9 pm EDT Tuesday (0100 GMT Wednesday) for a launch scheduled for 7:38 pm EDT (2338 GMT) Friday. Preparations for the launch were proceeding smoothly, with no major issues reported. Forecasts call for a 70 percent chance of acceptable weather for the launch, with similar weather forecast for Saturday and Sunday as well. The seven-man crew will fly to the ISS to install a new truss section and solar panel, as well as replace current ISS astronaut Sunita Williams with Clay Anderson.