HUNDREDS OF THOUSANDS of people have flocked to  Florida in the hope of witnessing the historic last-ever launch in the US space shuttle program.

The shuttle Atlantis is scheduled to set off on its final mission today at 11.26am (4.26pm Irish time) from the state’s so-called ‘Space Coast’. But there are widespread fears it could be delayed, as heavy rain bucketed down in the area yesterday with several lightning strikes near the launch pad. Shuttle weather officer Kathy Winters warned there was a 70 per cent chance it would be postponed, saying “Weather is not looking good for launch,” AFP reports.

However, Nasa officials gave the order for the shuttle’s tanks to be fuelled today in the hope that the weather would break. “Mike Moses, the mission management team chair, said some people might call it silly to try and play in the rain this morning, but he said we’re going to absolutely try for tanking,” said ‘countdown commentator’ Allard Beutel, according to CBS News.

As many as 750,000 people are expected to crowd close to Kennedy Space Centre hoping to see the launch, according to the BBC. It’s feared this could cause problems for Nasa staffers getting to and from work if the take-off is delayed.

Until at least 2015, when commercial space flight is expected to come on-stream, US astronauts can only reach the International Space Station on a Russian Soyuz spacecraft – at a price of more than €30million a ticket. Colonel Karol Bobko, the commander of Atlantis’ first mission in 1985, told the Daily Telegraph: “I’m sad about it. We just don’t have the resources to meet our ambitions.”

Watch: Time-lapse video of Atlantis’ six-hour journey to the launch pad