NASA is just days away from a key refueling test of its new mega-rocket that could make or break the space agency’s chances of launching its Artemis 1 mission to the moon next week.
The refueling test, which NASA will attempt on Wednesday (September 21), will test repairs to two hydrogen leaks on the rocket, called the Space Launch System, as well as a new, slower way to refuel the 32-stage booster. at Pad 389A of the Kennedy Space Center in Florida. If all goes well, NASA will make its third attempt to launch the Artemis 1 SLS rocket to the Moon on September 27 after two false starts in recent weeks.
“We are not just preparing for the September 27 launch, we are preparing for the future of this vehicle,” Tom Whitmeyer, NASA’s deputy associate administrator for joint exploration systems development, told reporters during a conference call Monday (September 19). “That’s why we take the time and effort to make sure we understand the vehicle.”
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NASA’s Artemis 1 refueling test comes after two failed attempts to launch the Artemis 1 mission – the SLS rocket’s first uncrewed test flight with its Orion capsule – on August 29 and September 3, first in due to an engine temperature problem related to a bad sensor, then due to a major hydrogen leak. The space agency has since repaired an 8-inch (20 centimeter) hydrogen pipe and a smaller 4-inch (10 cm) pipe.
The 8-inch line was of particular concern due to its heavy leak during the September 3 launch test. Engineers replaced the soft seals on both lines and even found a small indentation in the seal of the larger line which may or may not have been caused by a piece of debris (although no debris was found on launch pad). The tiny divot measured just under 0.01 inches long (0.002 cm), NASA said.
“Now that doesn’t seem like a lot, but we’re dealing with hydrogen, the smallest particle on the atomic map,” Mike Sarafin, NASA’s Artemis 1 mission manager, said on the conference call. “It provides the opportunity for pressurized gas to leak through it.”
To make things easier on the SLS fuel lines, NASA will attempt what it calls a “softer, gentler” liquid hydrogen charging process in this week’s test. This process will fuel the rocket approximately 30 minutes slower than normal to alleviate stress on fuel lines and pressure seals. (It usually takes up to four hours to fuel the rocket.)
“At the end of the day, we’ve mitigated everything we can think of, and we’ll know in about 36 or 48 hours, how well these mitigations work,” said John Blevins, NASA SLS chief engineer at Marshall Space. Flight Center in Huntsville, Alabama. , told reporters.
The agency also automated all but five manual controls for the refueling process and added launch crew training to prevent accidental overpressure of a fuel line, such as in an incident during the September 3 attempt.
During the Artemis 1 refueling test on Wednesday, NASA will fill the rocket’s core and upper stages with the 736,000 gallons (3.3 million liters) of supercooled liquid hydrogen and liquid oxygen it has needed for launch. This is not a full dress rehearsal for launch (the Artemis 1 Orion space capsule and two solid rocket boosters will not be powered), but is designed to check for fuel leak patches and new refueling process work, NASA officials said.
Space Force dispensation is still needed
Even if the refueling test is successful, it is not certain that NASA will be able to launch on September 27.
The space agency is currently requesting a waiver from the US Space Force on the SLS rocket’s flight termination system, whose batteries must be checked every 25 days to ensure they are functioning properly. The Flight Termination System is a safety device designed to detonate the SLS rocket to protect the public in the event of a deviation. Ensuring it’s working properly is required by the US Space Force, which oversees the Eastern Range for rocket launches off the coast of Florida. The 25-day period for Artemis 1 ended on September 6.
Rechecking the Flight Termination System can only be performed inside the huge hangar of the Vehicle Assembly Building where the SLS was assembled. To do so, NASA would have to roll the 322-foot-tall (98-meter) rocket off the launch pad, which could add weeks of additional delays.
“At this time we are still having technical discussions with the Range,” Whitmeyer said. “It’s been very productive and collaborative.” NASA has not yet received a decision on whether it will obtain the waiver and does not expect to be notified before the September 21 refueling test.
If Artemis 1’s refueling test goes well and NASA gets the waiver it requests from the Space Force, its next launch attempt would be set for Sept. 27 at 11:37 a.m. EDT (3:37 p.m. GMT). NASA would have a 70-minute window to launch the mission.
It’s possible that a backup launch date could be Oct. 2, but that also depends on getting the Space Force waiver and the health of the Artemis 1 launch system, Sarafin said.