SpaceX Polaris Dawn: Watch LIVE as a billionaire attempts the world's first private spacewalk

More than 435 miles (700km) above our heads, the crew of SpaceX's Polaris Dawn mission is making history as they embark on the world's first private spacewalk.

Starting from 10:58 BST (05:58 ET), billionaire Jared Isaacman became the first non-professional astronaut to step out into the vacuum of space.

During a two-hour float at nearly twice the height of the International Space Station, Isaacman and mission specialist Sarah Gillis will take turns exiting their spacecraft.

The risky mission will see Isaacman and Gillis face dangerous radiation and life-threatening pressure changes as they test SpaceX's new spacesuits.

MailOnline will be bringing you all the latest as it happens, so be sure to follow the livestream below to watch this groundbreaking mission.

SpaceX has confirmed that the four-hour window for the spacewalk will take place at 05:58 ET (10:58 BST).

'On Thursday, September 12 the Polaris Dawn crew will attempt the first-ever spacewalk – also known as an extravehicular activity (EVA) – from Dragon,' it explained. 

'The EVA is targeted to start at 5:58 a.m. ET. If needed, a backup opportunity is available on Friday, September 13.'

Onboard are the billionaire Jared Issacman, former airforce commander Scott 'Kidd' Poteet, and SpaceX employees Sarah Gillis and Anna Menon. 

Today's spacewalk has been pushed back from the original time of 07:23 BST (02:23 ET) although SpaceX did not state the reason for the delay. 

Since the spacecraft is communicating via ground-based networks, while watching the live stream you may notice the video occasionally drops out but this should be no reason for concern. 

At the bottom of the livestream you can see the internal pressure of the Dragon capsule, the EVA suit pressure, the current stage of the mission, the speed of the spacecraft, and the current altitude in kilometres.   

After half an hour, the pressure inside the Dragon has fallen below one psi - Jared Isaacman will now tug on the hatch to break the initial friction and allow it to open. 

Isaacman has now made made his way out of the forward hatch of Dragon Resilience in the first ever commercial spacewalk. 

As he exited the craft Isaacman said: 'Back at home we all have a lot of work to do, but from here Earth sure looks like a perfect world' 

Initial confirmations from mission control suggest that the spacewalk is progressing well and Isaacman is now out of the craft. 

Isaacman is now testing the mobility of the EVA suit as he stands on the Skywalker platform.  

The crew prepared the cabin for spacewalk by securing any loose items and donned their spacesuits. 

The spacewalk officially began when pure oxygen began to flow into the astronauts suits.  

Having sealed their helmets, gasses from the ship are now pressurizing the suits and allowing the astronauts to breathe as the capsule vents its remaining air.

All four members of the crew underwent suit checks, ensuring that the helmet's heads-up display functions and that there were no air leaks. 

This is the first time that the SpaceX EVA suits have been used outside of laboratory conditions so the crew will be extremely careful to ensure that they are working well. 

With leak checks complete, the crew then waited for the cabin pressure to fall towards a level which matches the vacuum outside. 

As the pressure fell, the spacecraft has made its way into the 'EVA orientation' with the trunk section pointing towards the sun to shield the astronauts.  

Mission commander Isaacman will then carefully pull himself out of the capsule and into open space.

This Dragon spacecraft is the first to be fitted with a 'Skywalker' hatch which will help the astronauts pull themselves through the opening. 

 He will test the suit's mobility with 12 minutes of pe-prepared movements before making his way back into the spacecraft and getting into his seat.

Mission specialist Sarah Gillis will then exit the spacecraft and perform the same series of manoeuvres before returning to her seat.

Unlike the EVA suits used by NASA's astronauts, the SpaceX suits only get their life support through an umbilical connecting to the ship rather than from a built-in system.

While this makes the suits far more mobile, it also means that the 12-foot (3.7m) umbilical will be the only thing preventing the spacewalkers from drifting off or asphyxiating. 

Mission pilot and former Air Force commander Scott Poteet and medical officer Anna Menon will remain seated the entire time to monitor the vitals of the two spacewalkers. 

Since the Dragon spacecraft does not have an airlock, the entire craft will need to be depressurized at once so Poteet and Menon will also need to wear EVA suits during the spacewalk. 

That will expose all four crew members to the harsh conditions of low orbit and will break the current record for most people simultaneously in the vacuum of space.

Previously only state-backed space agencies have sent astronauts on spacewalks due to the extremely high risks involved.

Floating beyond the protective walls of a spacecraft is considered to be one of the most dangerous tasks an astronaut can undertake.

In this case, that risk will only be heightened by the fact that none of the crew except for Isaacman have ever been in space before.  

An hour after the spacewalk begins, the hatch will be closed and the spacecraft will slowly repressurise over the next hour. 

This needs to be done extremely slowly so that the huge changes in pressure do not cause any health complications for the astronauts onboard. 

Just like deep-sea divers, when astronauts enter the vacuum of space the sudden drop in pressure can cause dissolved nitrogen in the blood to expand into bubbles.

These bubbles can cause a condition called decompression sickness, otherwise known as the Bends, which can be fatal in severe cases.

To avoid decompression sickness the Polaris Dawn crew have spent the last two days going through a pre-breath procedure by breathing a high-oxygen gas mix to purge their blood of Nitrogen. 

This is significantly longer than the two hours normally taken by astronauts on the ISS before spacewalks as the cabin slowly decreased pressure and raised the level of oxygen. 

On social media, commenters shared their excitement and well-wishes for the crew before the start of the spacewalk.

One commenter wrote on X, formerly Twitter, 'Let's go!! Praying for a safe spacewalk for Polaris dawn.'

Another commenter wrote: Absolutely breathtaking. Another achievement!'

'Humanity once again reaching out towards the stars', another commenter said.

SpaceX CEO Elon Musk, meanwhile, shared a simple excited statement, writing: 'Spacewalk!!' 

Some commenters also shared their amazement at the technological advancements behind this impressive feat.

One commenter wrote on X: 'History in the making on so many fronts.. let's go. Godspeed and good luck to all the Astronauts!'

'Amazing technical accomplishment to get crystal clear video and audio back to earth. Much better than 50 years ago,' another wrote.  

The Polaris Dawn mission launched from the Kennedy Space Centre in Florida on September 10 at 5:23 am ET after days of delay due to weather and a helium leak.

Yesterday, the SpaceX Dragon Crew spacecraft carried its crew to an altitude of 870 miles (1,400 km) above Earth - the highest any human has been since NASA's Apollo missions. 

At that altitude, the Dragon capsule briefly entered Earth's Van Allen Belt - a region where magnetic fields trap highly radiating charged particles.

Entering the Van Allen Belt means the crew received a hefty dose of space radiation, getting as much in a few hours as they would in 20 years on the Earth by one estimate.  

NASA has noted that it is crucial 'to fly through this region quickly to limit exposure to radiation,' since high doses of space radiation can increase astronauts' long-term risk of cancer by damaging cellular DNA.

By stepping out beyond the protection of the spacecraft, Isaacman and Gillis will once again expose themselves to harmful radiation, albeit in a far smaller dose.   

While in space, the crew's sole protection will be SpaceX's new EVA suits.

These suits have been designed using thermally resistant materials borrowed from the Dragon's trunk section and includes a 'Faraday' layer which insulates the astronaut from any electrical fields.

The new helmets also include a 'heads-up display' (HUD) and a camera which can stream video to Earth via the Dragon spacecraft.

While in space, Polaris Dawn will also conduct nearly 40 scientific experiments some of which will measure the harmful effects of exposure to radiation.

These also include testing contact lenses embedded with microelectronics to continuously monitor changes in eye pressure and shape.

The Polaris Dawn crew will also take the opportunity to trial SpaceX's latest laser-based communication system nicknamed the 'Plug and Play-ser'. 

They will attempt to communicate between the spaceship and Starlink - SpaceX's more than 6,000-strong constellation of internet satellites, in a bid to boost space communication speeds.

This mission also marks an important landmark for SpaceX's goal of making the Dragon spacecraft the go-to option for orbital flights.

The same Dragon used for this mission is the exact same craft used by Isaacman on the Inspiration4 mission and on NASA's Crew 1 mission.  

After six days in space, the mission will conclude with a splashdown off the coast of Florida.