SpaceX's next astronaut mission for NASA has been delayed until Sunday due to wind and issues with the rocket-booster recovery

• NASA and SpaceX have delayed the launch of their next astronaut mission to 7:27 p.m. EST on Sunday.
• The launch was scheduled for Saturday but pushed back due to "onshore winds and first-stage booster recovery readiness," according to NASA.
• The Crew-1 mission is SpaceX's first full-length, contracted mission for NASA.
• This was the fourth time NASA announced a delay to the mission's launch date, though the first because of weather.

SpaceX's next human mission for NASA has been delayed due to a combination of weather conditions and a technical issue.

The flight, known as Crew-1, was scheduled to lift off from Cape Canaveral, Florida, on Saturday evening carrying four NASA astronauts. But in a blog on Friday, NASA announced that "onshore winds and first-stage booster recovery readiness" would prevent the crew from taking off as planned.

Instead, Crew-1 is now scheduled to launch on Sunday at 7:27 p.m. ET. The delay will lengthen the astronauts' trip to the International Space Station from eight hours to 27 hours.

The astronauts' launch aboard a Crew Dragon spaceship will mark the start of SpaceX's first full-length, contracted astronaut mission for NASA. The mission the company completed in August, called Demo-2, was considered an experimental demonstration.

The weather delay followed a midweek assessment by the Space Force, which gave a 40% chance that weather would delay a Saturday launch. The Force's 45th Weather Squadron said at the time that the primary concern was cumulus cloud cover associated with Tropical Storm Eta.

Current forecasts for Sunday don't look much better: The Space Force's latest forecast also gives the launch a 40% chance of weather delaying the launch.

The "booster recovery" issue, meanwhile, has to do with SpaceX's reusable, multi-million-dollar, 16-story rocket boosters. The company typically recovers this hardware after it helps propel an upper stage toward orbit. After separating, the booster disconnects and rockets itself to a landing on a ship at sea. Though booster recovery isn't essential to launching astronauts, it appears that some combination of boats, equipment, or staff needed to enable that process wasn't in order for a Saturday launch.

NASA is set to provide more details on the delay in a press briefing Friday evening but did not immediately respond to Business Insider's questions about it.

This is the fourth time NASA has pushed back the launch of Crew-1 — it was originally scheduled for as early as late September. First, officials pushed back the initial launch date to October 23 to better coordinate with the schedules of other cosmonauts and astronauts going to and from the ISS. Then they delayed the launch to Halloween for the same reasons.

After that, SpaceX and NASA delayed the mission to Saturday, November 14 because of a problem found in one of SpaceX's Falcon 9 rocket engines during a test launch. Nearly a month of investigation led SpaceX to the culprit: A red, nail-polish-like residue had clogged a valve that helps regulate the release of fuel and ignition fluid. The substance is used to cover sensitive parts of the rocket while maintenance teams are working on other parts.

Meet the Crew-1 crew

The Crew-1 crew includes NASA astronauts Shannon Walker, Mike Hopkins, and Victor Glover, as well as Japan Aerospace Exploration Agency astronaut Soichi Noguchi. Hopkins is slated to be the mission's commander, Glover the pilot, and Walker and Noguchi mission specialists.

If launch occurs on Sunday as now planned, the crew will spend nearly 27 hours traveling to the space station before docking at about 11 p.m. ET on Monday. Delaying the launch by one day extended the journey to the ISS by 19 hours because the laboratory will be in a less optimal place in its orbit around Earth for the Crew Dragon to sync up with.

Once the spaceship arrives, though, the astronauts plan to kick off a six-month stay on the ISS, during which they'll conduct science experiments and space-station maintenance.

SpaceX's previous mission showed that a Falcon 9 rocket and Crew Dragon capsule could safely ferry astronauts to and from the space station. That paved the way for the company to plan at least six more ISS missions as part of NASA's Commercial Crew Program.

The mission, called Demo-2, kicked off "a new era in spaceflight," as SpaceX founder Elon Musk put it, since NASA hadn't been able to launch its own astronauts since 2011, when it ended the space-shuttle program. Until SpaceX's Crew Dragon became an option, NASA had only one approved option: Russia's Soyuz spacecraft.

Commercial Crew began as a series of competitions to spur private companies to develop astronaut-ready alternatives. In 2014, NASA selected Boeing and SpaceX as the winners. Though cost wasn't a main driver, a spot on the Crew Dragon may be priced at about $55 million (not counting the roughly $3 billion NASA put into the system's development), while Russia has charged the agency up to $90 million per Soyuz seat.

Boeing's new spaceship, the CST-100 Starliner, is slated to do an uncrewed demo mission in December. It will be the company's second attempt, since the first uncrewed test mission of the Starliner capsule hit technical difficulties, and the ship was unable to dock with the space station as planned.

Morgan McFall-Johnsen contributed reporting.