The launch of the space shuttle Endeavour was postponed on Sunday due to stormy weather in the area, the US space agency said, adding that another attempt would be made Monday.
"Looks like the team is ready but the weather is not. At this time we are no-go," NASA's launch director Pete Nickolenko said. Another attempt was scheduled for 6:51 pm Monday (2251 GMT).
The delay was the fourth to plague the mission so far, with first two postponements due to potentially hazardous fuel leaks, and the last two due to weather.
The final decision was made about 10 minutes before the launch time, after weather specialists in Florida and Texas agreed that storms in the area would make it too risky for the shuttle to attempt a return landing if needed.
The takeoff had been scheduled for 7:13 pm (2313 GMT) and NASA television showed the shuttle's seven-person crew climbing aboard and making final preparations for the mission until the delay was announced.