How traffic in space and 'orbital mechanics' delayed SpaceX and NASA launch until Saturday

Viewers have asked why NASA and SpaceX waited three days before trying the Falcon 9 launch again

The eyes of the world will again be on Florida on Saturday as two intrepid astronauts attempt to embark on a mission to the International Space Station.

Space giants NASA and SpaceX were hoping for a successful lift off on Wednesday night, but their plans were scuppered at the last minute because of poor weather conditions.

The next Falcon 9 launch is scheduled for Saturday at 15:22 EDT (20:22 BST), the Mirror reports.

Many confused viewers have questioned why they had to wait three days - and it turns out it's all down to "orbital mechanics" and other complex calculations.

Hans Koenigsmann, SpaceX’s vice president of mission assurance at SpaceX explained that Saturday will be the next time the International Space Station is in the desired place, relative to the launch site in Florida.

He explained: “The two days in between — it's just a matter of phasing and how the orbital mechanics work out.

“And there are some other factors that play into that, too - traffic on the station, and so on and so forth."

NASA and SpaceX decided to cancel Wednesday’s launch with just 17 minutes to spare, despite the fact that conditions looked to be clearing up.

John Insprucker, SpaceX’s principal interrogation engineer, said: “We do the flight analysis assuming that the temperatures of the propellants are below a certain amount, so that we know how much performance is available to the rocket — how much margin we're going to have.

"Once you get into propellant loading at T-35 minutes, you have to go as soon as you get to zero.”