— NASA's next attempt to launch its new megarocket on a test flight to the moon could still happen this month, but only if the agency fixes a leak and receives a critical waiver from the U.S. Space Force.

Jim Free, NASA's associate administrator for exploration systems development, said Thursday (Sept. 8) that the space agency is targeting Sept. 23 or Sept. 27 for the launch of its first Space Launch System (SLS) rocket on the Artemis I mission. Those launch dates, though, depend on a number of requirements, including securing a waiver to extend the time needed to check batteries on the SLS's flight termination system (FTS), which is used to destroy the rocket if it veers off course during its climb to space.

The U.S. Space Force, which oversees the Eastern Range used for Florida rocket launches, requires NASA to test the FTS every 25 days, a process that requires the 322-foot-tall (98 meters) SLS to leave the launchpad and roll back to Kennedy Space Center's Vehicle Assembly Building. Extending that time frame could allow NASA to avoid weeks of additional delay that would push the Artemis 1 launch into October.

Free said Artemis 1 mission managers submitted a waiver request to the Eastern Range this week.

"After meeting with us several times, they've been very gracious and understanding of what we're trying to do," Free said during a call with reporters on Thursday. "Our job is to live to their requirements. That is their range. And it's our job to comply with their requirements."

Free did not say how long of an extension NASA is seeking. The agency already had secured one such FTS waiver, pushing the limit from 20 to 25 days.

Artemis I is NASA's first mission in its program to return astronauts to the moon. The uncrewed flight will test the SLS and its Orion spacecraft to verify that both are ready to fly with people on board. The first crewed mission, Artemis II, will fly astronauts around the moon in 2024, with Artemis III landing astronauts at the lunar south pole a year later, pending the success of Artemis I.

Even with the FTS test waiver, NASA has a lot to do to get Artemis I ready for what will be its third launch attempt. NASA first tried to launch the mission on Aug. 29 but stood down due to an engine cooling issue that was traced to a bad sensor. A persistent liquid hydrogen leak led to a second scrub on Sept. 3.

NASA will attempt to fix that leak by replacing a seal around an 8-inch (20 cm) quick disconnect fuel line that leads into the SLS' core stage. Agency engineers are also working on a smaller connector that saw a different leak before the first scrub on Aug. 29. That work is ongoing this week at the Artemis I launch site, Pad 39B at Kennedy.

A kinder and gentler fueling approach

The SLS must then pass a cryogenic fueling test to check if the seal fix worked. That test is currently scheduled for no earlier than Sept. 17, but the timing is tight, Mike Bolger, NASA's exploration ground systems manager, said in Thursday's press call.

"I would not be surprised to see it slip a day or two," Bolger said, adding that even if it slips a few days, NASA would still be able to pursue the September windows.

NASA has not yet confirmed if an "inadvertent" manual command that briefly overpressurized the liquid hydrogen line caused the leak, but the agency is investigating the incident. Bolger said new manual processes replaced automated ones during the second attempt and the launch team could have used more time to practice them.

"So we didn't, as a leadership team, put our our operators in the best place we could have," Bolger said. During the Sept. 17 fueling test, NASA will try out a slower, "kinder and gentler" process that should avoid such events.

"We all own the process," Free added. "As far as I was concerned, everybody's finger was on that switch."

Fueling the SLS with its 736,000 gallons (2.79 million liters) of super-cold liquid hydrogen and liquid oxygen propellant has been a challenge for NASA. Before the two launch attempts, the agency performed four test runs, called "wet dress rehearsals," but didn't manage to check all the desired boxes during any of them.

The next fueling test will be used to check that the leak repairs worked, Bolger said.

"This is the first time we're operating this vehicle," Free said, noting that NASA saw fueling challenges during its space shuttle and Apollo programs. "There are challenges when you try and do this."

Finally, NASA must fit the Artemis I launch in when its Deep Space Network (DSN) communications assets can support the moon flight.

NASA's DART asteroid probe is scheduled to purposely impact a small asteroid on Sept. 26 and will need to use the DSN to relay its results back to Earth. NASA's Artemis I target dates of Sept. 23 and Sept. 27 should avoid any conflict with that mission, Free said.

Meanwhile, SpaceX is planning to launch its next astronaut mission, called Crew-5, to the International Space Station on Oct. 3. That's another constraint for when Artemis I can fly, Free said.

NASA technically has launch windows for Artemis I that run from Sept. 16 to Oct. 4, and then again from Oct. 17 to Oct. 31, with some cutout days in each window.

If NASA is able to pursue a Sept. 23 launch for Artemis I, liftoff would occur during a 120-minute window opening at 6:47 a.m. EDT (1047 GMT). The mission would return to Earth on Oct. 18.

A Sept. 27 launch would lift off during a 70-minute window opening at 11:37 a.m. EDT (1537 GMT). A launch on that day would lead to a return to Earth on Nov. 5.

A version of this article, as written by Tariq Malik, first ran on Space.com. Read the original here.

collectSPACE is grateful to film and TV company Haviland Digital for supporting our Artemis I coverage. Their team has produced and supported titles such as the award-winning "Last Man on the Moon," "Mission Control: The Unsung Heroes of Apollo" and "Armstrong."