NASA faced the prospect of more stormy weather Monday as it tried for the fifth time to launch shuttle Endeavour to the international space station. NASA began loading about 1.9 million litres of liquid oxygen and hydrogen into the huge orange external tank in a process that will take about three hours. Thunderstorms prevented Endeavour and seven astronauts from blasting off Sunday evening. Forecasters said there was a 60 percent chance the weather would force yet another delay Monday evening for the space station construction mission.