SpaceX launch set to go ahead despite '50-50 chance' of crippling storms

Tonight’s historic SpaceX launch is set to go ahead despite more thunderstorms on the forecast.

The planned liftoff of the Falcon 9 rocket will be the first time a private company has sent NASA astronauts into space – provided it goes ahead.

Elon Musk’s company came within 17 minutes of launching on Wednesday, before the threat of lightning forced a delay.

Weather forecasters have set the odds of acceptable conditions at 50-50 for this evening’s feat, but NASA says it’s pressing ahead anyway.

SpaceX and NASA managers have been monitoring the weather not just at Kennedy Space Center, but all the way up the Eastern Seaboard and across the North Atlantic to Ireland.

Waves and wind need to be within limits in case the SpaceX Dragon crew capsule, carrying astronauts Doug Hurley and Bob Behnken, has to make an emergency splashdown on the way to orbit.

Their destination is the International Space Station, a 19-hour flight away.

"The problem, of course, in Florida in May is there will be thunderstorms. So that's true today as it probably will be every day in May and probably early June here," NASA Administrator Jim Bridenstine said as the countdown clocks hit the 5-hour mark.

"We look like we've got about a 50-50 shot here and we're going for it."

Wednesday's countdown was halted at just under 17 minutes because of the threat of lightning.

"Falcon/Dragon are designed to withstand multiple lightning strikes, but we don't think it would be wise to take this risk," SpaceX's chief executive and founder Elon Musk tweeted at the time.

Mr Bridenstine said both astronauts have assured him they're now "ready to go."

"I would be lying to you if I told you I wasn't nervous," the NASA Administrator said.

"We want to do everything we can to minimise the risk, minimise the uncertainty so that Bob and Doug will be safe."

All being well, the launch will take place at 8.22pm UK time (3:22pm local time ).

If successful, it will be the first launch from the US with NASA astronauts for nearly a decade.