Hydrogen leak derails NASA’s second moon launch attempt

NASA’s Space Launch System’s moon rocket landed for the second time in five days on Saturday, this time due to a major hydrogen leak in a fuel line quick disconnect that will delay the maiden flight of the $4.1 billion booster by several weeks. probably in October.

The latest delay was a heartbreaking disappointment for the Kennedy Space Center workforce, invited guests and thousands of local residents and tourists who lined area streets and beaches to watch NASA’s most powerful rocket blast off, raising the curtain on the program. Artemis moon of the organization.

But faced with a major hydrogen leak and not enough time for repairs before the current lunar launch period ends on Tuesday, NASA managers had no choice but to order a delay for the Artemis 1 test flight.

Oxygen vapor flows away from the Space Launch System rocket as engineers, working by remote control, tried to stop a hydrogen leak at a quick-detach fitting at the base of the rocket, where supercooled propellant is fed into the first stage of the booster. After three unsuccessful attempts, the launch was aborted. / Credit: NASA

Engineers are evaluating two options to resolve the latest problem: replacing components on the suspect component on the launch pad and conducting a mini-test of liquid hydrogen fueling to verify leak-free performance. Or roll the rocket back to the Vehicle Assembly Building and make repairs there.

While the VAB would provide shelter from the weather and would not require the assembly of an environmental enclosure to protect sensitive components during repair work, engineers would not be able to test emplacement with cryogenic hydrogen. And that’s when leaks are most likely to occur.

Either option means a launch delay of several weeks. The next lunar launch period begins on September 19th and lasts until October 4th. But NASA is scheduled to launch a new crew to the International Space Station in a SpaceX capsule on Oct. 3, and the agency wants to avoid a collision.

That means the SLS launch will likely roll over to the next launch period, which opens Oct. 17 and runs through Halloween, unless a solution is found to speed up repair work.

“This is an incredibly difficult operation,” said Artemis 1 mission manager Mike Sarafin. “Our focus is on understanding the problem … We will continue next week when we have these options further.”

During Saturday’s countdown, engineers made three attempts to properly seat a suspected seal on the 8-inch quick-disconnect fitting, but none of them worked. After a “no traffic” recommendation from troubleshooting engineers, Launch Director Charlie Blackwell-Thompson stopped the countdown at 11:17 a.m. EDT.

“We’ll go when it’s ready,” NASA Administrator Bill Nelson said. “We’re not going until then, especially now, on a test flight.”

It’s not yet clear what caused the leak, but Sarafin said a valve inadvertently released during the first moments of the fuel loading operation, briefly due to pressure from the lines and the quick-disconnect fitting.

“There was an unintended compression of the hydrogen transfer line that exceeded what we had designed, which was about 20 pounds per square inch,” he said. “It came to about 60 pounds per square inch. The flight hardware itself, we know it’s fine, we didn’t exceed the maximum design pressure.

“But there’s a possibility that the soft products or the seal on the eight-inch quick disconnect saw some results from that, but it’s too early to tell. . . . What we do know is that we saw a big leak.”

The Space Launch System's moon rocket at pad 39B Monday during fueling for its maiden test flight.  The rocket landed due to a hydrogen leak in the system that carries propellant to the first stage tanks.  / Credit: NASA

The Space Launch System’s moon rocket at pad 39B Monday during fueling for its maiden test flight. The rocket landed due to a hydrogen leak in the system that carries propellant to the first stage tanks. / Credit: NASA

The goal of the Artemis 1 mission is to propel an unmanned Orion capsule into a distant orbit around the moon, testing the spacecraft in the deep space environment before returning it to Earth for a high-speed, high-temperature reentry.

If the initial uncrewed test flight goes well, NASA plans to launch four astronauts on a shakedown flight around the Moon — Artemis 2 — in 2024 and land the first woman and the next man near the Moon’s south pole in that time frame 2025-26. But all of this depends on a successful test flight of Artemis 1.

The long-awaited mission must lift off during specific launch periods based on the ever-changing positions of the Earth and the Moon, the desired lunar orbit for the Orion spacecraft, and the power of the SLS rocket to put it into orbit.

Complicating the design, flight planners want to avoid putting the solar-powered spacecraft in the moon’s shadow for extended periods and want to ensure a drop in daylight.

The current launch window closes on Tuesday, the same day the batteries in the rocket’s self-destruct system expire. That alone would require a return to the Vehicle Assembly Building for already scheduled maintenance because the batteries are not accessible from the launch pad.

NASA attempted to launch the SLS rocket on its maiden flight on Monday after four countdown rehearsals and power trials, which encountered multiple technical obstacles, including hydrogen leaks in different systems.

During Monday’s launch attempt, a faulty temperature sensor led to uncertainty as to whether the SLS rocket’s four RS-25 first-stage engines were receiving proper cooling before launch.

In addition, the same component that leaked on Saturday also leaked during Monday’s launch attempt, but the concentrations were much lower and engineers were able to put in the hydrogen tank before the engine cooling problem occurred.

As it turned out, the engines were in fact properly cooled and a faulty temperature sensor was responsible for misleading the engineers.

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