NASA’s Interstellar Space Launch System’s lunar rocket was grounded for the second time in five days Saturday, this time due to a large hydrogen leak in one of the fuel line’s quick disconnect fixtures that will delay the first $4.1 billion booster flight by several weeks, likely in October.
The recent delay was a frustrating disappointment for the workforce at the Kennedy Space Center, as he invited guests and thousands of area residents and tourists who lined the area’s roads and beaches to watch NASA’s most powerful rocket lift off, unveiling the agency’s Artemis moon program.
But in the face of a major hydrogen leak and no time to make repairs before the current lunar launch period expires Tuesday, NASA administrators had no choice but to request a delay in the lunar launch date.test flight.
Engineers are evaluating two options to fix the latter problem: replace components in the suspected installation at the launch pad and perform a small fuel test with liquid hydrogen to verify leak-free performance. Or roll the missile into the vehicle assembly building and make repairs there.
While the VAB will provide shelter from the weather and will not require the assembly of an environmental enclosure to protect sensitive components during repair work, engineers will not be able to test the installation with cooled hydrogen. This is when leaks are most likely to surface.
Either option means a launch delay of several weeks. The next lunar launch period begins on September 19 and lasts until October 4. But NASA is scheduled to launch a new crew to the International Space Station aboard the SpaceX capsule on October 3, and the agency wants to avoid a conflict.
That means the SLS launch will likely slip into the next launch period, which begins on October 17 and runs through Halloween, unless a solution is found to speed up repair work.
“This is very hard work,” said Mike Sarafin, Artemis 1 mission manager. “Our focus is on understanding the problem… and we will follow up next week when we have more of these options.”
During Saturday’s countdown, engineers made three attempts to properly “place” a suspect seal in the 8-inch quick-disconnect fittings, but none succeeded. Following a “ban” recommendation from the engineers working on the problem, launch manager Charlie Blackwell-Thompson canceled the countdown at 11:17 AM EDT.
“We’ll go when we’re ready,” said NASA Administrator Bill Nelson. “We’re not going until then, especially now, on a test flight.”
It’s not yet clear what caused the leak, but Sarafin said the valve was inadvertently rotated during the initial moments of the fuel loading process, briefly due to excessive pressure on the lines and a quick disconnect installation.
“There was unintended pressure to the hydrogen transmission line that went beyond what we had planned, which was about 20 pounds per square inch,” he said. “It was going up to about 60 psi. The fly machine itself, we know it’s good, we didn’t go over the maximum design pressure.
“But there’s a possibility that Soft Commodity, or the seal in the eight-inch quick-disconnect has seen some effects from that, but it’s too soon to tell…what we do know is that we saw a major leak.”
The goal of the Artemis 1 mission is to propel the unmanned Orion capsule into distant orbit around the Moon, testing the spacecraft in a deep space environment before returning it to Earth for high-speed, high-temperature reentry.
If the initial unmanned test flight goes well, NASA plans to launch four astronauts on an extortionate flight around the moon – Artemis 2 – in 2024 and land the first woman and the next man near the moon’s south pole in the 2025-26 time frame. But it all depends on a successful test flight of Artemis 1.
The long-awaited mission must take off during specific launch periods based on the ever-changing positions of the Earth and Moon, the lunar orbit required for the Orion spacecraft and the power of the SLS rocket to put it on the right track.
Complicating planning, flight planners want to avoid placing the solar-powered spacecraft in the moon’s shadow for extended periods and want to ensure that daylight is emitted.
The current launch window closes on Tuesday, on the same day the certificate for the batteries in the missile’s self-destruct system expires. This alone would have required returning to the vehicle assembly building for the already planned service because the batteries at the launch pad were not accessible.
After four countdown drills and fuel-supply tests, they all ran into multiple technical hurdles, including hydrogen leaks in various systems.
During Monday’s launch attempt, a faulty temperature sensor led to uncertainty about whether the SLS rocket’s four RS-25 first-stage engines were receiving proper pre-launch cooling.
In addition, the same installation that leaked on Saturday also leaked during Monday’s launch attempt, but concentrations were much lower and engineers were able to get the hydrogen tank off before the cooling problem arose.
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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