SpaceX Postpones Historic Mission Again

A civilian quartet was set to blast off into space from Florida on Wednesday morning, on their way to the first spacewalk ever by private citizens, but that mission has now been postponed. The BBC reports that Elon Musk's SpaceX, just hours before liftoff, cited "unfavorable weather forecasted" in the spot where the Polaris Dawn capsule was set for its splashdown, just a day after the expedition was aborted due to a leak in a helium line. More:

• The crew: Billionaire entrepreneur Jacob Isaacman, 41, who founded the payment processing platform Shift4, has spearheaded the mission, though he hasn't yet said how much cash he's pumped into it. He'll serve as captain of the expedition and will be joined by former Air Force pilot Scott Poteet and SpaceX engineers Sarah Gillis and Anna Menon. More here on Isaacman.

• The mission: When the SpaceX Dragon capsule, attached to a Falcon 9 rocket, does eventually launch, it will spend five days in space. The two-hour spacewalk, carried out by a tethered Isaacman and Gillis, is scheduled for the third day. They hope to reach an altitude of up to 870 miles, which the BBC notes "would be the highest point reached by any crewed mission since NASA's Apollo program" over a half-century ago.
• Perils: Besides the usual dangers of space flight, CNN reports that the crew's orbit will be high enough to send them into the deadly Van Allen radiation belts. In addition, this will be the first time that nongovernment astronauts will be exposing themselves "to the vacuum of space," a mission for which they've been training for more than two years. They'll wear spacesuits designed just for this journey. "Anytime you try something for the first time there are significant risks," former NASA astronaut Garrett Reisman, a SpaceX consultant, tells CNN. "I'll feel much better when they are back inside with the hatch closed and latched."
• Crew's take: "Absolutely zero reservations," says Poteet. Gillis and Menon, meanwhile, say they feel confident due to their years working for SpaceX.
• Isaacman's take: "SpaceX is doing all the hard work to be at the tip of the spear of commercial space," he tells the Washington Post. "Star Wars or The Jetsons is the future we're aiming for."
• What's next: It hasn't yet been indicated when the mission will be rescheduled, but CNN notes that Thursday was also a possible date if any delays happened on Wednesday. Much more here and here on the fascinating upcoming voyage.

(More Polaris Dawn stories.)