NASA encountered some trouble early in the day Wednesday as the space agency conducted a tanking test to determine if a fuel leak on the Artemis-1 rocket is fixed, which scrubbed the space agency’s most recent launch attempt earlier this month of the mega moon rocket from Kennedy Space Center in Florida.
The Space Launch System rocket with the uncrewed Orion spacecraft is slated to launch on its maiden voyage known as the Artemis-1 mission, sending Orion around the moon and back.
A fueling test is underway at KSC on Wednesday morning to determine if a fuel leak is fixed on the giant moon rocket, however soon after the liquid hydrogen “fast fill” began on the rocket’s core stage, another leak popped up.
During the test, NASA is trying a “kinder and gentler” approach using lower pressure to fill the 322-foot-tall SLS rocket with thousands of gallons of cryogenic fuel to determine if fixes to a liquid hydrogen leak were successful.
NASA’s deputy associate administrator for Exploration Systems Development Tom Whitmeyer explained that unlike liquid oxygen, which is “pumped” into the rocket, hydrogen requires pressure to move the light molecules.
“We’re taking these transitions at a slower rate. The crunch in pressure and temperature changes will be more gradual,” Whitmeyer said.
Hydrogen leak well outside safety limit
After a brief delay due to a person within the blast danger zone, Launch Director Charlie Blackwell-Thompson gave the “go” to begin fueling at 7:30 a.m., about a half hour behind the original timeline.
During the test, both the SLS core and upper stages will go through all three phases of fueling, including slow fill, fast fill and replenish.
The liquid oxygen fill in the core stage was underway by mid-morning and teams began slow fill of liquid hydrogen.
However, when the team moved to fast-fill of liquid hydrogen, NASA commentator Derrol Nail said a leak was detected of about 7%, much higher than the 4% safety limit.
The SLS requires more than 700,000 gallons of super-cold liquid hydrogen and liquid oxygen fuel to lift the 322-foot-tall rocket off the launchpad and into space. While an efficient rocket fuel, hydrogen is a tiny molecule that easily leaks. It has previously created problems for the space shuttle program.
SLS has also experienced hydrogen leaks during wet dress rehearsal tests and a small leak during the first launch attempt.
Teams at KSC launchpad 39B worked for the past two weeks to replace two quick-disconnect seals to the rocket in hopes of fixing the leak, which NASA managers described as a “major leak” well above the 4% limit.
At one point during fueling, the leak “spiked” to over 8%, KSC Exploration Ground Systems Program deputy manager Jeremy Parsons said about the Sept. 3 attempt.
“The reason where 4% is set is its kind of the flammability of hydrogen and air. So that’s where you start to enter a certain amount of risk of flammability,” Parsons said.
“It’s really a relatively conservative limit,” he added.
NASA SLS Chief engineer John Belvins said after reviewing all possible causes on the fault tree, he doesn’t believe any one thing caused the leak.
On the 8-inch seal, engineers found an “indentation” that could have been caused by a hit from what NASA calls FOD, which stands for “foreign object debris.” However, no FOD was found near the seal.
Forecasters will be watching for lightning
NASA requires certain weather criteria before the SLS rocket can be fueled or launched.
Forecasters with the Space Force 45th Weather Squadron will continue to monitor the weather during the test.
On Wednesday, launch weather officers were monitoring some storm cells a few miles off the coast of the launch complex. However, rain won’t stop the test.
“Meteorologists currently predict favorable weather for the test with a 15% chance of lightning within 5 nautical miles of the area, which meets criteria required for the test,” NASA said in a blog Tuesday.
The FOX Forecast Center is tracking potential rain showers in the morning and storms later during Wednesday’s cryo-loading test.
The launch director will not give the “go” to begin tanking of the rocket’s core stage if lightning chances are greater than 20% within 5 nautical miles of the launch area.
Fueling also cannot start if the 24-hour temperature is less than 41.4 degrees Fahrenheit or above 94.5 degrees, but that should not be a problem in mid-September. The forecast high on Wednesday will be in the low 80s.
Next SLS launch depends on this test and Space Force‘s decision
If the fueling test is successful, teams are targeting Sept. 27 for liftoff during a 70-minute window opening at 11:37 a.m. However, that all rides on the outcome of Wednesday’s cryo-loading and if NASA gets approval from the Space Force.
“Ultimately, we’ve mitigated everything that we can think of, and we will know in the (next) 36 hours or so, or 48 hours, how effective those mitigations were,” Belvins said Monday.
The Sept. 27 launch date and a backup window on Oct. 2 are under review by the Space Force, which manages the Eastern launch range.
Previously, NASA said the moon rocket would need to roll back to the Vehicle Assembly Building (VAB) due to safety requirements to replace flight termination system (FTS) batteries. The FTS is required on all rockets and would cause the vehicle to self-destruct if it veers off course and threatens the public.
“They’re responsible for all the vehicles they launch, not just ours,” Blevins said of Space Force. “And they’ll make a decision whether we meet the requirements for public safety or not and will adhere to that decision.”
The agency submitted a waiver to extend the FTS certification and is waiting to hear back from Space Force.