SpaceX has launched and exploded a 500-tonne rocket in mid-air as part of the last major safety test before sending astronauts to the International Space Station (ISS).
The In-Flight Abort Test saw the Falcon 9 rocket experience a planned "rapid, unscheduled disassembly" shortly after take-off.
The launch was originally planned for Saturday but was postponed until Sunday due to adverse weather conditions.
Sunday's launch was delayed three separate times but a six-hour launch window allowed it to eventually lift-off at 10.30am ET (3.30pm GMT).
More than 50 years after Nasa sent astronauts to the moon, SpaceX is about to use the same Florida launch site to send its own crew capsule skywards.
No astronauts will be on board the Crew Dragon spacecraft, however, as shortly after it takes off from Complex 39A at the Kennedy Space Center, the Falcon 9 rocket carrying it will explode.
That is if everything goes to plan for the "In-Flight Abort Test", designed to prove that SpaceX is able to keep astronauts safe in the event of catastrophic failure.
Lift-off is planned for 8am ET (1pm GMT), with the Falcon 9 set to get torn apart during its descent shortly after.
If successful, a major milestone towards SpaceX's ambition of taking astronauts into space will be achieved.
SpaceX had to stand down from an attempted launch on Saturday due to bad weather in the Atlantic, where a dedicated recovery team are in place to gather up debris from the explosion.
For today's launch, Nasa says there is a 60 per cent chance of favourable weather, with the primary concern being a thick cloud layer.
There's been a delay. New launch time scheduled for 9am ET (2pm GMT), Nasa Administrator Jim Bridenstine says.
The new launch schedule will therefore look something like this:
- 8.40am ET (1.40pm GMT) - Nasa live stream of launch begins
- 9am - Launch of In-Flight Abort Test
- 9.10-9.30am - Falcon 9 rocket explosion
- 10.30am - Post-test news conference
Another delay!
SpaceX says the launch had to be pushed back by an hour "to optimise for decreasing winds in the recovery area".
This is what the updated launch schedule looks like:
- 9.40am ET (2.40pm GMT) - Nasa live stream of launch begins
- 10am - Launch of In-Flight Abort Test
- 10.10-9.30am - Falcon 9 rocket explosion
- 11.30am - Post-test news conference
Both Nasa and SpaceX are live streaming today's launch, with both feeds going online around 15-20 minutes before the launch.
We'll have both links here as soon as they are live.
This is what the launch site looked like earlier this morning (note the launch time is now 10am ET)
The six-hour launch window means there is room for a couple of more delays if needed.
Hopefully not, but it all depends on the weather.
The fact today's launch was delayed slightly, rather than postponed entirely like yesterday's attempt, is promising.
With just over 90 minutes to go until the launch, we've got time to hear from SpaceX about what today's test hopes to achieve:
This test, which does not have Nasa astronauts onboard the spacecraft, is intended to demonstrate Crew Dragon's ability to reliably carry crew to safety in the unlikely event of an emergency on ascent.
If the In-Flight Abort Test is successful, the Crew Dragon capsule will separate from the Falcon 9 rocket shortly after lift-off at the moment of "peak mechanical stress".
While the rocket experiences a "rapid, unscheduled disassembly", the Crew Dragon spacecraft will deploy its parachutes and float safely to the ground.
SpaceX and Nasa can then begin planning for crewed missions to the ISS using Crew Dragon.
SpaceX CEO Elon Musk shared a video simulation of what these first crewed flights will look like. It's impressive.
No astronauts will be onboard the Crew Dragon today, however Nasa's Bob Behnken and Doug Hurley will be suited up to rehearse the experience.
Hurley (right) was two years old when Nasa first sent astronauts to the moon.
T minus 1 hour
Another delay!
That puts us another 30 minutes back.
Here's what the updated launch schedule looks like:
- 10.10am ET (3.10pm GMT) - Nasa live stream of launch begins
- 10.30am - Launch of In-Flight Abort Test
- 10.40-9.30am - Falcon 9 rocket explosion
- 12pm - Post-test news conference
While we wait, here's a picture of some spacesuits.
The one on the left is the one worn by Neil Armstrong when he landed on the moon in 1969.
The one on the right is what astronauts will be wearing when they travel aboard SpaceX's Crew Dragon spacecraft.
Around half an hour until the live stream begins. We'll share a link to watch it as soon as it's live.
This is what the launch site looked like around 20 minutes ago.
Nasa just shared a helpful animated graphic showing how the In-Flight Abort Test should take place.
Just over 20 minutes to go now until launch. Weather permitting.
Live streams of the launch are about to begin on NASA TV and SpaceX's website.
Please allow a moment for the liveblog to load.
