The charity “Inspiration4” mission set off in a Dragon capsule, designed and built by Elon Musk’s SpaceX company.
The mission is being headed by billionaire Jared Issacman, who is head of Shift4 Payments, a credit card-processing company in Pennsylvania.
The 38-year old and pilot is paying for the flight while raising money for St Jude Children’s Research Hospital in Memphis, and will serve as the spacecraft commander.
He has not revealed how much he has coughed up for the flight, but it is known that he is donating $100 million (£73 million) to St Jude as part of the mission.
Here is everything you need to know about it.
How will the mission work?
The SpaceX Dragon capsule launched in the early hours of Thursday (16 September) morning, aiming for an altitude of 335 miles.
That is 75 miles higher than the International Space Station, and on a level with the Hubble Space Telescope.
The capsule is fitted with a domed window where the usual mechanism for docking with the ISS would normally be, as it is not needed for this trip.
The window will give the crew panoramic views of the Earth below, as they tend to experiments and research during their three-day mission above our planet.
Who are the four ‘amateur’ astronauts?
The crewmates joining Issacman are Sian Proctor, a community college teacher in Arizona, Chris Sembroski, a former Air Force missileman from Washington, and Hayley Arceneaux, 29, who works at the cancer research hospital the space flight is fundraising for.
Proctor, 51, was born in Guam, where her late father worked at Nasa’s tracking station for the Apollo moonshots.
She beat 200 businesses for an out-of-this-world experience after an independent panel of judges chose her space art website, Space2inspire.
Sembroski, 41, was not picked in the random draw to find a crewmate, but his friend was instead.
His friend declined to fly for personal reasons and offered the spot to Sembroski, who worked as a Space Camp counsellor in college and volunteered for space advocacy groups.
How can I watch the launch?
The mission’s launch was live streamed by Netflix through their YouTube channel, as part of a 90-minute live special which saw some big name celebrity guests.
Beginning at 12am UK time on Thursday 16 September, the live special was hosted by Queer Eye’s Karamo Brown and award-winning journalist Soledad O’Brien.
The show also included former NASA astronauts Leland Melvin, Cady Coleman and Ron Garan, and actors who appear in Netflix series including Lost in Space, Shadow and Bone and Another Life.
In terms of the time of the actual launch, Inspiration4 lifted off at 1.02am from NASA's Kennedy Space Center in Florida.
How does the documentary work?
Countdown: Inspiration4 Mission To Space is Netflix’s first documentary “to cover an event in near real-time”, the streaming giant said in a tweet.
It will show the four civilians completing their three-day trip orbiting the Earth, it added, with five episodes showing the lead up to the launch and the mission itself.
The series is being created by the makers of basketball documentary, The Last Dance, and launched on Netflix in September.
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