The loss of hydrogen derails NASA’s second attempt to launch the moon rocket

The loss of hydrogen derails NASA’s second attempt to launch the moon rocket

The loss of hydrogen derails NASA’s second attempt to launch the moon rocket

On Saturday, the star-crossed lunar rocket Space Launch System was grounded for the second time in five days, this time by a large hydrogen leak in a fuel line quick release fitting that will delay flight by several weeks. inaugural of the $ 4.1 billion booster, probably in October.

The latest delay was a frustrating disappointment for the Kennedy Space Center’s workforce, who invited guests and thousands of area residents and tourists who lined the area’s streets and beaches to witness the takeoff of NASA’s most powerful rocket. raising the curtain on the agency’s Artemis lunar program.

But faced with a large hydrogen leak and without enough time to make repairs before the current lunar launch period ends Tuesday, NASA executives had no choice but to order a delay for the Artemis 1 test flight.

Oxygen vapor escapes from the Space Launch System rocket while the engineers, working via remote control, tried to stop a leak of hydrogen in a quick release fitting at the base of the rocket where the ultra-cold propellant is fed into the first stage of the booster.  After three unsuccessful attempts, the launch was canceled.  / Credit: NASA

Oxygen vapor escapes from the Space Launch System rocket while the engineers, working via remote control, tried to stop a leak of hydrogen in a quick release fitting at the base of the rocket where the ultra-cold propellant is fed into the first stage of the booster. After three unsuccessful attempts, the launch was canceled. / Credit: NASA

Engineers are considering two options for solving the last problem: replace components in the suspect fitting on the launch pad and perform a liquid hydrogen refueling mini test to verify leak-free performance. Or take the rocket back to the vehicle assembly building and perform repairs there.

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

Both options indicate a launch delay of multiple weeks. The next lunar launch period begins on September 19th and will last until October 4th. But NASA plans to launch a new crew on the International Space Station aboard a SpaceX capsule on October 3, and the agency wants to avoid a conflict.

This means that the SLS launch will likely slip into the next launch period, which opens on October 17 and runs until Halloween, unless a solution can be found to expedite the repair work.

“This is an incredibly difficult business,” said Mike Sarafin, mission manager at Artemis 1. “Our goal is to understand the problem. … We will follow up next week when we have these options further eliminated.”

During Saturday’s countdown, engineers made three attempts to correctly “place” a suspicious seal in the 8-inch quick release fitting, but none of them worked. After a “no-go” recommendation from the engineers who worked on the problem, launch director Charlie Blackwell-Thompson canceled the countdown at 11:17 EDT.

“We’ll go when it’s ready,” NASA administrator Bill Nelson said. “We won’t go until then, especially now, on a test flight.”

It is not yet clear what caused the leak, but Sarafin said a valve was inadvertently actuated during the initial moments of the fuel loading operation, briefly pressurizing the lines and quick release fitting.

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

“But there is a possibility that the soft products, or the seal in the eight-inch quick disconnect have seen some effects, but it’s too early to tell … What we do know is that we have seen a big leak.”

The Space Launch System lunar rocket atop Pad 39B on Monday while refueling for its first test flight.  The rocket was blocked by a leak of hydrogen in the system that supplies propellant to the first stage tanks.  / Credit: NASA

The Space Launch System lunar rocket atop Pad 39B on Monday while refueling for its first test flight. The rocket was blocked by a leak of hydrogen in the system that supplies propellant to the first stage tanks. / Credit: NASA

The goal of the Artemis 1 mission is to take 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 unmanned 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 next man near the moon’s south pole in period 2025-26. But it all depends on a successful Artemis 1 test flight.

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

To complicate planning, flight planners want to avoid putting the solar-powered spacecraft in the shadow of the moon for long periods and want to ensure a daytime splashdown.

The current launch window closes on Tuesday, the same day the battery certification in the rocket’s self-destruct system expires. This alone would have required returning to the vehicle assembly building for maintenance already planned because the batteries cannot be accessed from the launch pad.

NASA attempted to launch the SLS rocket on its maiden flight on Monday after four countdown tests and refueling tests, they all ran into multiple technical hitches, including hydrogen leaks in different systems.

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

Additionally, the same leaked fitting on Saturday also leaked during Monday’s launch attempt, but concentrations were much lower and engineers were able to have the hydrogen tank filed before the engine cooling problem occurred.

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

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