Tropical Storm Ian, strengthening over the central Caribbean, is moving toward Florida and could become a major hurricane. NASA said Saturday that it would "stand down" on preparations for a Tuesday launch attempt.
The agency is still deciding whether to haul the rocket off the pad and back to the hangar, saying a final decision would come Sunday as teams watch the forecast and gather more data.
"This step-wise approach gives our employees time to address the needs of their families while preserving a launch opportunity if conditions improve," NASA administrator Jim Free said on Twitter.
It's unclear when the next launch attempt would be — whether October or even November — if the rocket must seek shelter indoors. If the rocket remains at the pad, NASA could aim for a launch attempt on Oct. 2. The next launch window after a two-week blackout period would open Oct. 17.
It takes three days of preparations to get the rocket back into Kennedy Space Center's mammoth Vehicle Assembly Building, a 4-mile trip lasting several hours.
The 322-foot rocket can withstand gusts of 85 mph at the pad, but only 46 mph once it’s on the move.
This would have been the third launch attempt for the Space Launch System rocket, the most powerful ever built by NASA. Fuel leaks and other technical problems scrapped the first two tries, in late August and early September.
Managers on Friday had declared that the rocket was ready to blast off on its first test flight, after overcoming more hydrogen leaks during a fueling test earlier in the week. It would be the first time a crew capsule orbits the moon in 50 years; the spacecraft will carry mannequins but no astronauts.
Although hydrogen fuel seeped past newly installed seals during Wednesday's dress rehearsal, the launch team got the leakage down to acceptable levels by slowing the flow and reducing the pressure in the lines. That gave the launch team the confidence to proceed with a Tuesday launch attempt, officials said.
Managers said that the 30-year space shuttle program also saw plenty of hydrogen fuel leaks and hurricane-related rollbacks. The moon rocket's main engines are actually upgraded versions of what flew on shuttles.
Also, the Space Force has extended the certification of on-board batteries that are part of the flight safety system — at least through the beginning of October.
Astronauts would climb aboard for the second test flight around the moon in 2024. The third mission, targeted for 2025, would see a pair of astronauts landing on the moon.