NASA halted a second attempt to launch the Artemis 1 mission into lunar orbit early Saturday after engineers failed to seal a hydrogen leak that occurred when loading propellant into the rocket’s core-stage fuel tanks. After a failed second launch attempt, NASA likely won’t make a third attempt in September.
NASA said the hydrogen leak occurred “at the interface between the liquid hydrogen fuel supply line and the Space Launch System (SLS) rocket.” SLS has the unique ability to deliver Orion spacecraft, astronauts and supplies to the Moon on a single mission.
The second launch of the Artemis 1 mission, an uncrewed test, is scheduled for Saturday at 2:17 p.m. ET (11:17 a.m. PT) at the Kennedy Space Center in Florida.
The SLS core stage, built by Boeing, is 212 feet (64.6 meters) tall and 27.6 feet (8.4 meters) in diameter. It stores cryogenic liquid hydrogen and liquid oxygen, as well as a system for fueling the stage’s four R2-25 engines.
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NASA’s Artemis mission team had previously called off an Aug. 29 launch attempt when engineers were unable to cool all four RS-25 engines to minus 420 degrees Fahrenheit (-250C) — a measure to ensure the core stage wouldn’t be affected on eight. Necessary steps for damage – a minute journey to low earth orbit. After reaching low-Earth orbit, the core stage is separated from the upper stage and the Orion spacecraft.
During the second launch attempt, one of the four engines showed higher temperatures than the others, according to NASA. This so-called “emission test” occurs before ultracold liquid hydrogen flows into the rocket’s core stage.
Engineers also discovered a hydrogen leak on the “purge tank” during the first launch attempt, but at that stage it could be controlled by manually adjusting the propellant flow rate.
After the unsuccessful launch of the Artemis 1 mission on Saturday, NASA revealed it made three attempts to plug the leak.
“Engineers saw a leak in the cavity between the ground side plate and the rocket side plate, which surrounds an 8-inch line used to fill and drain liquid hydrogen from the SLS rocket. Three attempts to reinstall the seal were unsuccessful,” NASA said in an update Saturday night.
NASA is investigating whether an “unintentional command” issued during the early stages of hydrogen loading could temporarily raise system pressure and possibly cause a leak in the seal.
“Although during the early stages of a hydrogen loading operation called cooling, when the launch controller was cooling the lines and propulsion system before pouring ultra-cold liquid hydrogen into the rocket tank at minus 423 degrees Fahrenheit, an inadvertent command was sent that temporarily raised the The pressure is in the system. While the rocket remains safe, it’s too early to tell if the boost shock is the cause of the seal leak, but engineers are working on it,” NASA said.
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At about 11:17 a.m. ET, about three hours before Saturday’s launch window, Artemis launch director Charlie Blackwell-Thompson chose to cancel the second attempt.
NASA has set aside a spare launch time for Monday or Tuesday this week, but concluded it would take longer to fix the new hydrogen leak, Reuters reported. The next available time is Sept. 19-30 or another window in October, NASA associate administrator Jim Free said at a media briefing.
NASA’s Artemis mission manager Mike Sarafin said it would take “weeks of work” to fix the current technical issues. If that involves pushing the SLS back into the assembly building, any launch could be delayed until mid-October.
According to NASA’s Artemis mission availability webpage, there are 11 launch opportunities between Oct. 17 and Oct. 31. A rocket can’t just be launched on any one day — four key criteria need to be met.
- The launch day must take into account the moon’s position in its lunar cycle so that the upper stage of the SLS rocket can time the jet burn across the moon to intercept the “ramp” of the moon’s far retrograde orbit.
- The resulting trajectory must ensure Orion is not in the dark for more than 90 minutes at a time so that the solar array wings can pick up sunlight and convert it into electricity.
- It must support the orbit to allow Orion’s planned “jump entry” technology during its return to Earth, which sees the spacecraft enter the upper part of Earth’s atmosphere, slow down and jump out of the atmosphere, and then re-enter for its final descent and splashdown.
- The launch date must mean a sunsplash from Orion to make it easier to retrieve the spacecraft from the Pacific Ocean.