The planned Wednesday launch of four civilians on a privately chartered spaceflight featuring the first commercial spacewalk has been delayed again, this time because of predicted bad off-shore weather where the crew capsule will splash down at the end of the flight, SpaceX announced late Tuesday.

The company said the Polaris Dawn launch was off until at least Friday, weather permitting.

"Our launch criteria are heavily constrained by forecasted splashdown weather conditions," mission commander Jared Isaacman said in a post on X. "With no ISS (space station) rendezvous and limited life support consumables, we must be absolutely sure of reentry weather before launching.

"As of now, conditions are not favorable tonight or tomorrow, so we'll assess day by day. As Elon (Musk) mentioned, Polaris Dawn is a challenging mission with critical objectives, so we'll wait for the best opportunity to ensure success."

Already running two days late because of ground launch processing issues, liftoff on the historic Polaris Dawn flight had been targeted for 3:38 a.m. EDT Wednesday. But Tuesday night, before the countdown began, mission managers reviewed the forecast and ordered another delay.

"Due to unfavorable weather forecasted in Dragon's splashdown areas off the coast of Florida, we are now standing down from tonight and tomorrow's Falcon 9 launch opportunities of Polaris Dawn," SpaceX said in a statement posted to social media. "Teams will continue to monitor weather for favorable launch and return conditions."

The launch was originally planned for Monday, but the flight was delayed 24 hours to complete normal pre-flight processing. Another 24-hour slip then was ordered Tuesday after engineers discovered a leak in a launch pad umbilical that delivers helium to the booster to push propellants to the rocket's engines.

But all systems appeared "go" Tuesday afternoon, with good launch weather expected along Florida's Space Coast. Those hopes were dashed after the late Tuesday weather review.

"Sometimes, the hardest journeys require the most patience, and we're ready to wait for the right moment," Isaacman wrote on social media. "We know many have traveled to see the launch, and we're grateful for your support. Alongside @SpaceX, we'll do our best to keep you updated."

Isaacman's crewmates are former F-16 pilot Scott Poteet and two SpaceX engineers, Anna Menon and Sarah Gillis. They plan to launch into a highly elliptical orbit that will carry them higher than any astronauts have flown since the Apollo moon program.

The flight is the second SpaceX trip to low-Earth orbit chartered by Isaacman, who at 16 founded what became one of the nation's leading credit card transaction processors. In 2021, he financed and commanded the Inspiration4 mission, the first all-civilian commercial flight to orbit.

The Polaris Dawn mission is the first of three more SpaceX flights Isaacman is funding in cooperation with Musk and the first ever featuring non-government, civilian spacewalks.

Using a scaffold known as the "Skywalker," Isaacman and Gillis will take turns floating up through the Crew Dragon's forward hatch to reach open space, connected at all times by 12-foot-long tethers.

Because the ship does not have an airlock, its cabin will be vented to vacuum before the hatch is opened. Poteet and Menon will also be wearing SpaceX-designed pressure suits, and even though they will not get to stick their helmeted heads outside, they will be counted among the world's spacewalkers.

The primary goals of the demonstration are to test the new suit's joints, mobility and comfort to help SpaceX engineers develop lower-cost, easier-to-produce spacesuits for large numbers of people who SpaceX says will one day be venturing to the moon and Mars.

The crew also plans to test a high-speed laser communications system and will carry out a battery of bio-medical experiments throughout the five-day flight to help researchers from more than 30 institutions learn more about the effects of weightlessness.

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