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An update on the testing of SLS’s core stage

Link here. The article provides more information on the temperature issue that caused the seventh of eight fueling tests of the core stage to abort early.

The temperature issue arose when NASA transferred superchilled liquid oxygen, to fuel the rocket, from a holding facility to the core stage of the SLS. This procedure has been modeled and verified before, Julie Bassler, SLS stages manager at Marshall, told reporters during the same teleconference. But this was the first time the transfer actually took place.

“We were actually just a few degrees different than what we wanted to see coming in,” she continued, but said the temperature must be precise during the initial phases of filling the tank. The requirement is minus 290.57 degrees Fahrenheit (minus 179.21 degrees Celsius.) But the liquid oxygen was slightly cooler, at minus 296.67 degrees Fahrenheit (minus 182.59 degrees Celsius).

“We filled up [the tank] just enough to pass the phase where we knew we weren’t going to be able to get the temperature to a level that was going to be acceptable to meet the requirement, and that’s when they caught us … in the testing,” Bassler continued.

Despite this issue, NASA still hopes to do the last core stage test, dubbed the Green Run, in the last week in December. During that static fire test they will fuel the core stage entirely and then fire its engines for the full duration of an actual launch — almost ten minutes. If all goes well they will then pack up the stage and ship it to Florida for the planned November unmanned test mission sending Orion around the Moon.

They have no schedule margins, however, because all the components of this very expensive and complex rocket need a lot of time to get anything done. The two solid rocket boosters that will be attached to the sides of the core stage only have a twelve month lifespan once assembled, and they are holding off assembling them pending this test. The core stage itself needs two months to be disassembled, and then two months to be reassembled in Florida. And there remain the issue of a failed power unit in the Orion capsule that could take four to twelve months to repair.

The article however had this telling quote, based on comments from a NASA official, about future launch procedures, that sent a chill up my spine:

Future missions of Artemis will not need a wet dress rehearsal or hot fire test as the SLS will already be certified for flight.

Future Artemis missions will also have people on them. This attitude, similar to NASA’s attitude during the shuttle era, makes too many risky assumptions about the reliability and safety of this new rocket. Just because they have run a single static fire test does not mean they have worked out all the kinks. SpaceX for example does such tests routinely on all engines being built, as well as full dress rehearsal countdowns and engine ignitions prior to every launch, just to make sure there isn’t something they might have missed.

During the shuttle era NASA had the same “No need for further tests” attitude, and this led to the loss of two shuttles, because NASA assumed that once they had achieved one launch they had solved all their engineering issues, and could stop looking. Thus, Challenger was lost during launch because of o-ring problems in the solid rocket boosters, and Columbia was lost on its way back to Earth because of damage sustained during launch by falling foam from the external tank. In both cases the problems had been seen in previous launches, but no one at NASA saw any reason to address them. The shuttle was “certified!” Only after people were killed did NASA fix these engineering faults.

If the Artemis missions do fly as NASA hopes, I will not be surprised if this continuing nonchalant approach causes more launch failures and the lose of more lives.

Conscious Choice cover

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Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
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  • David Eastman

    I believe they’ve announced that they’re going to fly with the malfunctioning PDU rather than trying to replace it. Which is just another amazing example of “do as we say, not as we do” in regards to testing and reliability.

    I find it amazing that the LOX being 6 degrees colder than nominal is a “stop the test” level failure. I could see too warm being a problem, but too cold should be a “bonus! more time before it gets warm!” moment.

  • Ian C.

    Does NASA / FAA apply the “once certified” approach to gov and private launchers/spacecraft equally? Or is the private sector under more regulatory compliance? Or does it depend on the actual case (where political considerations might play a role)?

  • Max

    Bonus indeed, SpaceX takes measures to cool the fuel further, just so they can fit more in.

    I can predict the next delay will be for a refit of all computer components because they’re no longer compatible with today’s software. (Some sensors have an expiration date…)

  • Edward

    Robert wrote: “During the shuttle era NASA had the same ‘No need for further tests’ attitude, and this led to the loss of two shuttles, because NASA assumed that once they had achieved one launch they had solved all their engineering issues, and could stop looking.

    It may be worse than that. In her book “The Challenger Launch Decision,” Diane Vaughan noted that they were already looking at problems with the o-rings, but because one of the problems occurred at room temperature, 72 degrees, many engineers didn’t think it was particularly temperature related. They didn’t make a graph comparing the extent of the 0-ring damage to temperature until after the disaster. The o-rings deviated from the designed performance, but because it hadn’t caused a serious problem it was accepted as a new normal. Vaughan called the acceptance of this problem “normalization of deviance.”

    It was similar for the Columbia. Foam had fallen before, and one time it had broken the thermal tile on the Orbiter down to the metal. Fortunately, that particular location was steel, not aluminum, and the Orbiter reentered intact. Once again, they did not make fixing this problem a priority, and seemed to accept it as another new normal.

    NASA does not just have a problem that they don’t look for problems that need fixing, they don’t seem to fix serious problems that happen in front of their eyes. There were even concerns about the amount of flammable items in the Apollo command module before the Apollo 1 fire. (Apollo 13 was a hidden problem, but caused by human error.)

    Interestingly, Congress gets on NASA’s case after each of these failures, but Congress has not been eager to fund fixes before these problems become tragedies. Congress gets an expensive Space Shuttle that does not do what was promised, but instead of funding a new and improved means of getting to space, they fall for the sunk costs fallacy. They spent so much on something that is not working as intended that they keep using it rather than replace it with something that works better, and perhaps less expensively. Unfortunately, when they finally did fund a replacement, instead of an improved design they went for Apollo technology, with the same solid rocket boosters that destroyed Challenger. *Sigh*.

    Part of the beauty of capitalism in space is that multiple companies have the opportunity to avoid these costly mistakes in order to keep ahead of their competition.

    David Eastman wrote: “I find it amazing that the LOX being 6 degrees colder than nominal is a ‘stop the test’ level failure.

    As the article noted, the design was specific about temperature.

    SpaceX had designed specifically for low temperature, but NASA’s philosophy has been different. NASA has been able to delay launches because they don’t rely upon especially cold oxygen, but SpaceX has to scrub a launch if it cannot launch soon enough after propellant loading. What SpaceX sees as an advantage, denser propellant, NASA sees as a liability, less flexibility for launch window. The need to launch on time has forced SpaceX to Keep It Simple, Stupid (the KISS method).

    Loading propellant before ingressing the crew has been seen as a safety feature since before the first man went into space. In the meantime, several incidents with fueled launch vehicles has suggested that SpaceX could be safer by loading propellants after the crew is aboard — and protected by an abort system.

    Another part of the beauty of capitalism in space is that each company is free to find its own efficiencies and improving safety when it can.

  • Ken

    The Challenger disaster was worse than that. There WAS a launch rule on the books which prohibited launch under the cold conditions that morning. GO fever took over and they waived the very rule that should have saved them – browbeating the Morton-Thiokol team into agreeing with it.

    The entire point of Launch Rules and Flight Rules is that they are put in place ahead of time without time pressure with all the principle stakeholders agreeing that these are the limits to be honored. NASA makes it almost a fetish to get those rules in place, and then ignores them when they become inconvenient.

  • Edward

    Launch occurred when the temperature rose above the limiting temperature. The rule was not violated, and the design was supposed to allow for launch under the conditions that day.

    You are tight that it gets worse than that. Although it was a very complicated situation, Roger Boisjoly, the “whistle blower” who recommended against launch, had a problem that he had created ten months earlier. He realized that those conditions were hazardous, because a year earlier the Shuttle had launched under similar conditions. One o-ring had the worst damage that he had ever seen and showed signs of almost burning through both o-rings, but since such weather conditions were unheard of in Florida, he assumed that it would never happen again and wrote a report to NASA saying that the Shuttle was safe to launch under those conditions.

    This is why the NASA engineers were so confused with the recommendation to not launch. They had his report in their hands saying that it was OK, and when he sent his reasoning in 1986 why it was not OK, he used many of the same pictures, charts, and graphs that were in the report that had convinced them that it was OK. This is why the NASA engineers asked, ‘which is it? Can we launch or not?’ NASA gave Morton-Thiokol time alone to discuss the situation, and Boisjoly was unable to convince his colleagues that he was right that night.

    Many other factors led to that tragic decision. One that stuck in my mind was that at Thiokol some lower level people had information that might help but did not believe they were authority enough to speak up, so they whispered their information to their bosses. Their bosses did not know enough about the information to feel comfortable speaking up.

    NASA was willing to not launch the next morning, but they needed a valid reason. Had Thiokol recommended against launch, that would have been a reason. Not recommending against launch was not a reason to not launch. Thiokol’s big problem was that they had a requirement that the Shuttle be able to launch at 29F, but there design was not adequate if the Solid Rocket Boosters had been soaking in even colder temperatures overnight. Boisjoly had enough concern about launching at 29 degrees in the first place.

    Ultimately, it was too difficult for Thiokol to admit to NASA that their design had limits on their temperature requirement. Those who wore management hats had a hard time being convinced by the conflicting information that was given to them.

  • Michael S. Kelly

    I was the Stage IV engineer for TRW on 16 of the 17 Peacekeeper ICBM development test flights (I missed FTM 16 because I was on my honeymoon). I was astonished when I learned of the temperature-time history of Challenger. We would never have launched a Peacekeeper outside of its qualified temperature limits, period.

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