Nasa SpaceX launch - as it happened: Historic liftoff cancelled moments before takeoff over weather

Here you can see the chevrons along the floor, which indicate where people at the top of the elevator should flee if there is an emergency. If that happened, they'd get into buckets which work like zip lines and carry them safely back down to the ground.

You can also see the Pad Team, who are all wearing sleek black outfits with identifying numbers on their back. It all looks very futuristic!

Up at the top, there's also a phone, which allows astronauts to make any last phone calls before they set off.

Here you can see a little more of those outfits being worn by the Pad Crew. They're even more futuristic than the spacesuits themselves, arguably. (Though they look sort of dystopian, while the astronauts are dressed a little more like the Jetsons dream of space.)

The astronauts have "ingressed" – they're in their capsule, and are getting strapped in. There's still plenty left to be done, which for now will include checks such as communications tests, and they're not setting off for more than two and a half hours.

This might be the first time that SpaceX has sent a human into space. But the company is currently noting that they've actually been sending living things – mice – into space for years. So that work to create technology that could sustain life on its journey through space actually began before you might have thought.

The astronauts are speaking to mission control. And notably we're not getting the famous mention of "Houston" when mission controllers speak with the spacecraft – because it's not Nasa who are running all of this.

Instead, the astronauts speak to "SpaceX" who identify the craft as "Dragon". "SpaceX, we have a problem" doesn't exactly have the same ring to it – though of course we hope they don't actually have to say anything like that.

There's not very much going on for the next half an hour or so. The hatch on the capsule will be shut in 35 minutes, when more preparations will begin. For now, final checks and work is continuing, as the astronauts get settled into their seats.

Elon Musk is speaking live, alongside Nasa administrator Jim Bridenstine. (They're inside because the weather is bad.)

"This is a dream come true," he says. "I think for me and for everyone at SpaceX. This is not something I ever thought would actually happen. When starting SpaceX in 2002, I really did not think this day would occur. I expected a 90% chance we'd fail to get to low earth orbit with a small rocket.

"[If you'd have told me about today] I would have said man what are you smoking?

"To say it's a dream come true – I didn't even dream it would come true."

Musk – looking emotional – reveals the words he said to the families as they said goodbye to the astronauts.

"We've done everything we can to make sure your dads come back OK," he says.

The hatch has been closed! That happened earlier than expected.

Now the Pad Team are up to something. Not quite sure what it is! Commentators suggesting it's a leak check to ensure that everything is sealed as it should be.