[James]

So what's the plan?


Falcon 9 rocket on Pad 39A, Kennedy Space Center


Some time after 13:00 EDT (17:00 GMT / 18:00 BST) we expect to see the astronauts walk out and get into cars for transportation to the launch pad.

The timing for today's launch has to be precise. The Falcon 9 rocket must leave the ground at 16:33 EDT (20:33 GMT / 21:33 BST), or the astronauts won't be able to catch the International Space Station (ISS) which passes overhead at 27,000km/h (17,000mph).

The rocket carrying Bob Behnken and Doug Hurley takes more than eight minutes to get to orbit. Once the Crew Dragon has separated, it makes the rest of the journey to the ISS using its own thrusters.

But one section of the rocket will touch down softly on a ship using engine power so that it can be re-used on a future flight. This is a SpaceX speciality that sets its Falcon apart from all other orbital rockets in use today.

Watch the Crew Dragon fly over the UK

Skywatchers in the UK should be able to see the International Space Station and the Crew Dragon capsule pass over the United Kingdom later.

The space station will pass over first, at around the time of launch. Then, the Crew Dragon, carrying Doug Hurley and Bob Behnken, will fly past around 25 minutes after lift-off (roughly 21:58 BST).

It's a unique and historic opportunity to see them both before the rendezvous with the ISS some 24 hours later.

Social embed from twitter

Jonathan Amos
@BBCAmos
A little more detail on the visibility of #CrewDragon this evening in the UK, assuming the launch goes ahead. ISS comes over first (at the time of launch), followed by the capsule about 25 mins later. ISS will be closer to the horizon. Info from www.heavens-above.com

From https://www.bbc.co.uk/news/live/scie...nment-52790778