SpaceX set to blast billionaire's private crew into space on Polaris Dawn mission

Private astronaut crew members are in the final stages of preparations for a groundbreaking SpaceX mission on Tuesday that aims to execute the first-ever private spacewalk using the company's new spacesuits and a redesigned spacecraft.

According to Reuters, the crew — including a billionaire entrepreneur, a retired military fighter pilot and two SpaceX employees — is scheduled to launch at 3:38am ET from the National Aeronautics and Space Administration's (Nasa) Kennedy Space Center in Florida.

They will be embarking on the space agency's fifth and riskiest private space mission as they blast into space aboard the Crew Dragon capsule on Tuesday.

The mission, named Polaris, was previously postponed due to a minor helium leak but has now been permitted to proceed. However, the launch faces a 40% chance of favourable weather, according to the US Space Force launch weather modeling.

SpaceX has other launch opportunities Tuesday at 5:23am and 7:09am.

"Crew safety is absolutely paramount and this mission carries more risk than usual, as it will be the furthest humans have traveled from Earth since Apollo and the first commercial spacewalk!," Elon Musk, SpaceX's CEO, wrote about the mission last month on his social media site X.

What is Polaris Dawn mission?

The SpaceX mission, called Polaris Dawn, will last about five days in an oval-shaped orbit that passes as close to Earth as 190kilometre and as far as 1,400km, the farthest any humans will have traveled since the end of the US' Apollo moon program in 1972.

The spacewalk is planned for the mission's third day at 700km in altitude and will last around 20 minutes.

SpaceX's Crew Dragon craft will slowly depressurise its entire cabin — it has no airlock like the ISS — and all four astronauts will rely on their slimmed-down, SpaceX-built spacesuits for oxygen.

Jared Isaacman, 41, a pilot and the billionaire founder of electronic payment company Shift4, is bankrolling the Polaris mission but has declined to say how much he is paying for the missions. However, they are likely to cost hundreds of millions of dollars.

Joining him is mission pilot Scott Poteet, 50, a retired US Air Force lieutenant colonel; and SpaceX employees Sarah Gillis, 30, and Anna Menon, 38, both senior engineers at the company.

For the spacewalk, Isaacman and Gillis will exit the spacecraft tethered by an oxygen line while Poteet and Menon stay in the cabin.

The four-person crew are effectively test subjects for an array of scientific experiments that will aim to shed light on how cosmic radiation and the vacuum of space affect the human body, adding to decades of studies on astronauts living aboard the ISS.