FThe Space Launch System (SLS), moon rocket, has been more of a monument than a machine for the last 23 days. It stands 32 stories tall at Kennedy Space Center’s launch pad 39B. This is the highest point in the area, towering over flat Florida. On Aug. 29 and again on Sept. 3, the rocket was supposed to take off on an uncrewed mission around the moon—kicking off NASA’s Artemis program, which aims to have Americans back on the lunar surface by 2026. Due to technical issues, both launch failed. Engineers are not giving up.
NASA has reported that work continues at the pad, which could allow the SLS to take flight in one of the two launch windows. This window will be held on September 23, at 6:47 AM. ET or Sept. 27 during a 70 minute period that begins at 11:37 AM. ET. The moon will then be in the best position possible to carry out the intended mission. The repairs will be the first.
Engineers face the greatest challenge in repairing leaks around fuel lines, which supply liquid hydrogen to rocket engines. An 8-inch leak is the first. (20 cm) wide cable that is used for filling the SLS’s massive tanks. This second uses one of the four 4-inch cables. (10 cm) cables that cool the rocket’s main stage engines, conditioning them to the proper temperature so that they can withstand the head of ignition.
It’s a good thing the work can be carried out on the launch pad, since if the SLS had to make the 4 mi. The September launch window windows for the Vehicle Assembly Building (VAB), which is 6.4km away, would be lost. The SLS could still be heading back to the hangar. That’s because the fuel lines aren’t the only problem the massive rocket faces. There’s also the matter of its self-destruct system.
If the SLS goes awry at launch, the rocket’s onboard batteries will trigger an explosion above the Atlantic Ocean. The batteries are certified for 25 days—a period that ends this Sunday—and can only be serviced and recharged in the VAB. NASA is confident that the batteries will be operational through and beyond the launch window. But it’s not up to NASA to green-light extending the certification. That’s up to U.S. Space Force officials, who have not yet responded to the space agency’s request for an extension.
“We did submit our waiver package to them,” Jim Free, NASA’s director of exploration, told CBS News. “They’ve been very gracious and understanding of what we’re trying to do. … It’s our job to comply with their requirements, so we will do that.”
For now it’s a waiting game—both for the space agency and for moon enthusiasts hoping that the SLS candle will at last be lit. America’s era of crewed lunar exploration will eventually resume. There is still the question of when.
The original version of this story appeared in TIME Space. This weekly newsletter covers all things space. Register here.
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