Richard Gray
BBC Future

Image source, Getty Images

The privately funded spacewalk by Jared Isaacman and Sarah Gillis will be a new milestone in the history of spaceflight.

They will join an exclusive club – only around 260 other people have ventured outside a spacecraft with nothing but a spacesuit between them and the vastness of the Universe.

It takes a cool head, a fair amount of bravery and an acceptance that things can – and do – go wrong.

You can see some of the most beautiful, and frightening moments, in the history of spacewalks in this story.

We can now bring you SpaceX's live coverage of their mission - press play below to watch.

Shortly before the walk, the stream will also have analysis from the BBC's own team of experts.

Image source, SpaceX

We've been getting some incredible images from the Polaris Dawn mission as it orbits the Earth - and a glimpse of life inside the spacecraft...

Image source, SpaceX

Image source, Getty Images

Jared Isaacman, 41, has bankrolled the Polaris Dawn mission and is also the mission commander.

In 1999 he founded the payment processing company Shift4 Payments, which according to Forbes handles payments for a third of America's restaurants and hotels.

Forbes also says he has a net worth of $1.9bn.

He began taking flying lessons in 2004 and five years later set a world record for circumnavigating the world in a light jet.

Isaacman also founded Draken International, which owns the world's largest private fleet of military aircraft.

The cost of this week's mission has not been revealed - but he reportedly spent $200m on a previous SpaceX civilian mission in 2021.

Isaacman is due to walk into space in around an hour's time - stay here for updates and analysis.

Georgina Rannard
Science reporter

This spacewalk is a risky and daring move. SpaceX and the four crew on the Dragon craft are trying something no-one has done in decades - a spacewalk without an air lock.

The US Federal Aviation Administration has oversight of the Dragon rocket and craft, but once it is in space, it is not regulated.

The only tests they have to pass are ones set by SpaceX themselves. The crew on board have signed consent forms. Nasa has confirmed that it has no involvement with the Polaris Dawn mission.

The Dragon capsule has been to space dozens of times before, but the spacesuits are untested and it remains to be seen how the craft will perform when depressurised and exposed to the space vacuum outside.

But of course government space exploration does not have a perfect safety record.

In 2003, the Space Shuttle Columbia broke apart while re-entering Earth's atmosphere, killing all seven astronauts on board.

And in 1986 the entire crew of Space Shuttle Challenger died when the machine broke apart 73 seconds into its flight.

SpaceX has been giving regular updates on the Polaris Dawn Mission, since it set off on Tuesday:

• The crew travelled 1,400km above Earth, external, the furthest humans have travelled into space since the last US Apollo mission in 1972
• They completed six orbits of Earth, external at that height
• Then, the craft performed a series of descent burns for today's spacewalk, reaching an orbit of approximately 700km, external

Image source, SpaceX

Welcome to our live coverage of what promises to be a historic day in the history of space exploration.

On Tuesday, SpaceX's Polaris Dawn mission blasted off from the Kennedy Space Center in Cape Canaveral, Florida.

Four people are on board: Billionaire businessman Jared Isaacman, retired US Air Force Lt Colonel Scott Poteet, and mission specialists (and SpaceX employees) Sarah Gillis and Anna Menon.

Today, we're expecting Isaacman and Gillis to carry out the first ever spacewalk by civilians - that is, people who aren't full-time professional astronauts.

You can watch the action live from space later this morning by clicking Watch live at the top of the page - and there will be text updates, pictures, and clips throughout.