The countdown is continuing for Wednesday launch of the shuttle Discovery at Cape Canaveral in Florida. Take is scheduled for 3.51 p.m (1951 GMT) and forecasters are predicting a 70 percent chance that weather conditions will be acceptable for take-off.It is NASA’s first human space flight since the space shuttle Columbia exploded over Texas two years ago, killing all seven astronauts on board. NASA managers have noted that some unresolved issues could delay tomorrow night’s launch. Questions remain unanswered about how the shuttle’s new fuel tank will perform or whether engineers will have access to data on how heat-resistant tiles have been affected in the past. Columbia was damaged by foam insulation that fell from its fuel tank during launch 16 days earlier. As the shuttle plunged through the atmosphere, superheated gases blasted into the ruptured wing and destroyed the ship.