By Joey Roulette and Gerry Doyle

WASHINGTON (Reuters) -Four private astronauts blasted into space early on Tuesday in a modified SpaceX Crew Dragon capsule, kicking off the company’s five-day Polaris Dawn mission, which aims to test new spacesuit designs and conduct the first private spacewalk.

The crew, a billionaire entrepreneur, a retired military fighter pilot and two SpaceX employees, lifted off from NASA’s Kennedy Space Center in Florida about 5:23 a.m. EST (0923 GMT).

The capsule reached orbit about nine and a half minutes later, and the crew batted around a small plush astronaut toy dog as free fall – zero gravity – became apparent. Crew Dragon separated from its support trunk three minutes after that, with onboard cameras revealing a spectacular view of the capsule over the sunlit Earth.

“As you gaze toward the North Star remember that your courage lights the map for future explorers,” SpaceX Launch Director Frank Messina told the crew by radio. “We trust your skills, your bravery and your teamwork to carry out the mission ahead. … We are sending you hugs from the ground.”

The mission’s Falcon 9 booster landed safely on a seaborne pad.

It is Crew Dragon’s fifth – and riskiest – private mission so far. The spacecraft will eventually settle into an oval-shaped orbit, passing as close to Earth as 190 km (118 miles) and as far as 1,400 km (870 miles), the farthest any humans will have ventured since the end of the U.S. Apollo moon program in 1972.

An attempt to launch last month was postponed hours before liftoff over a small helium leak in ground equipment on SpaceX’s launchpad. SpaceX fixed the leak, but the company’s Falcon 9 was then grounded by U.S. regulators over a booster recovery failure during an unrelated mission, further delaying the Polaris launch. The launch on Tuesday was delayed about two hours because of unfavorable weather.

Only highly trained, well-funded government astronauts have done spacewalks in the past. There have been roughly 270 on the International Space Station (ISS) since its creation in 2000, and 16 by Chinese astronauts on Beijing’s Tiangong space station.

SPACEWALK PLANNED FOR THIRD DAY

The Polaris Dawn spacewalk is planned for the mission’s third day at 700 km in altitude and will last about 20 minutes. SpaceX’s Crew Dragon craft will slowly depressurize 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.

The first U.S. spacewalk was in 1965, aboard a Gemini capsule, and used a similar procedure to the one planned for Polaris Dawn: the capsule was depressurised, the hatch opened, and a spacesuited astronaut ventured outside on a tether.

Jared Isaacman, 41, a pilot and the billionaire founder of electronic payment company Shift4, is bankrolling the Polaris mission, as he did for his Inspiration4 flight with SpaceX in 2021. He has declined to say how much he is paying for the missions, but they are likely to cost hundreds of millions of dollars.

Joining him is mission pilot Scott Poteet, 50, a retired U.S. 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 mission is the first in Isaacman’s private Polaris program that includes a follow-on Crew Dragon mission in the future, followed by a flight on SpaceX’s Starship, a giant rocket the company has spent billions of dollars developing as a flagship moon and Mars vehicle.

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.

Since the retirement of the Space Shuttle in 2011, NASA has relied heavily on the company and its Crew Dragon, which has flown nine astronaut missions to and from the ISS for the agency as the only U.S. crew-grade vehicle in operation.

The company has previously flown four private missions: Isaacman’s Inspiration4, and three private astronaut flights arranged by Houston-based mission broker Axiom Space.

Boeing is struggling to develop a similar spacecraft, Starliner, that could rival Crew Dragon. But Starliner’s latest NASA test mission that began in June – its first time flying a crew – left its astronauts on the ISS last week because of issues with its propulsion system.

(Reporting by Joey Roulette in Washington and Gerry Doyle in Singapore; Editing by Sandra Maler and Alex Richardson)