National Aeronautics and Space Administration (NASA) said it would make a new attempt to launch the shuttle at 0717 IST Sunday (8:47 pm US Time Saturday ) on a complicated International Space Station (ISS) mission.
The seven astronauts - two women including Sunita Williams of Indian origin and five men including Sweden's first astronaut - were strapped into their seats ready for lift-off, but low-lying clouds forced a last-minute postponement of the 0805 IST Friday (9:35 PM US Time Thursday) blast-off.
"We had to scrub the launch tonight because the cloud ceiling exceeded our requirements," said NASA spokesman Bruce Buckingham.
The weather forecast for a Saturday (US Time) launch, however, was discouraging with only a 30% chance of favourable conditions.
The Discovery mission was to be the first night launch since the shuttle Endeavour flight of November 23, 2002. The three missions following the shuttle Columbia disaster of February 2003 took place during daylight as a safety precaution.
The shuttle's external fuel tank were filled with two million litres (5,00,000 gallons) of liquid hydrogen and oxygen when the launch was scuttled after a tense half-hour off-again-on-again weather conditions.
Discovery's mission will be the third and final shuttle launch of the year, and the fourth since the Columbia disaster, which killed all seven astronauts aboard and grounded the shuttle programme for more than two years.
NASA has planned 14 shuttle missions - including this one - through 2010 to finish building the International Space Station, which is considered a key element of US ambitions to send humans back to the moon and then to Mars.
NASA has described the space station construction mission as the most complex to date with three space walks to rewire the station and install a new 11-million-dollar truss segment.
NASA Test Director Jeff Spaulding described it as "one of the most complicated missions ever performed." The space agency has set a window for rescheduling the lift-off that lasts until December 26, but after December 17 it would have to reprogramme the shuttle's computer to adjust to the date change at the end of the year.
After December 26, the Discovery mission would have to wait until mid-January for another chance at lift-off.
The three shuttle launches following the Columbia tragedy - in August 2005 and in July and September 2006 - were scheduled during daylight so that ground and shuttle cameras could photograph the spacecraft's exterior tank in case pieces of thermal insulation or ice broke off during lift-off.
A piece of insulating foam damaged Columbia's heat-shield shortly after launch leading to the shuttle disintegrating upon re-entry to Earth's atmosphere.
The September launch of the space shuttle Atlantis marked the resumption of ISS construction, after the previous two missions focused on improving safety.