SpaceX is due to launch its pioneering Inspiration4 space mission.
The private mission, which was purchased by billionaire Shift4 Payments founder Jared Isaacman, will see him blast off to space with physician assistant Hayley Arceneaux, science communicator Sian Proctor and engineer Chris Sembroski.
Elon Musk 's SpaceX company will send the four civilians soaring above Earth, where they will float for three days before falling back down and splashing into the ocean.
They will make "the world’s first all-civilian human spaceflight to orbit" on the space company's Crew Dragon capsule, which will be mounted on top of a Falcon 9 rocket.
This is a huge step for space tourism, which SpaceX hopes will allow the super-rich to charter journeys to space.
When is the SpaceX launch time?
The Inspiration4 launch was due to take place today, Wednesday September 15.
However, the launch window has now been pushed back to 1.02am UK time on Thursday, September 16.
SpaceX tweeted: "Static fire test of Falcon 9 complete – targeting Wednesday, September 15 for launch of Dragon’s first all-civilian human spaceflight. The 5-hour launch window opens at 8:02 p.m. EDT."
The space company has said this will "allow additional time for final preparations, vehicle checkouts and data reviews”.
However, keep in mind that there is a five-hour launch window, which means the rocket could take off at any time between 1.02am and 6.02am.
How to watch SpaceX launch live
If you manage to stay away tonight, you can watch the launch live on SpaceX's YouTube channel.
The coverage will start at 8.45pm UK time tonight.
What is the purpose of the mission?
The Inspiration4 mission objective is part of Jared's fund-raising goal to "give hope to all kids with cancer and other life-threatening diseases".
Isaacman is funding the entire mission himself with an aim to "raise $200 million for kids with cancer and other life-threatening diseases in honour of this mission".
You can head to St Jude's Research Hospital to learn more.
The Research hospital specialises in treating childhood cancer by auctioning off various items.
You can also watch Countdown: Inspiration4 Mission to Space on Netflix to find out more.
Who is Jared Isaacman?
Jared Isaacman is the founder and chief executive of e-commerce firm Shift4 Payments.
He started the internet company, which offers financial solutions to other firms, in 1999 from his parents house when he was 16.
The 38-year-old tech mogul is now a billionaire, end his business employs 1,200 people.
It has not been disclosed exactly how much Isaacman was charged by SpaceX – but it's believed to be a very substantial sum.
He has extensive experience flying jets, and can pilot both commercial and military planes.
Isaacman is also the founder of Draken International – the world's largest private airforce.
