Uncooperative weather prevented NASA from launching the Ares I-X demonstration vehicle from Pad 39B at Kennedy Space Center. The decision, made at 11.21am eastern time, came after almost 3.5 hours of countdown attempts - the launch having come within 2 minutes and 38 seconds of lift off at one point before weather again intervened. The agency says it will review forecasts for the next 24 to 48 hours before announcing a new launch target date.