Posted: Tue, Feb 5, 2008, 4:57 AM ET (0957 GMT)

NASA started the countdown late Monday for the launch of the space shuttle Atlantis on a long-delayed mission to the ISS, although weather could further delay the launch. Countdown clocks started at 5 pm EST (2200 GMT) Monday for the launch of mission STS-122, scheduled for Thursday at 2:45 pm EST (1945 GMT). While officials are not reporting any technical issues that could delay the launch, weather is a concern, with a 60% chance of clouds, rain, and lightning that could delay the launch. STS-122 was scheduled to launch in December, but two launch attempts were scrubbed by erroneous readings from fuel sensors in the shuttle's external tank; the problem was eventually traced to faulty connectors that were replaced. Atlantis is carrying the European lab module Columbus, the next major component to be added to the space station.