STENNIS SPACE CENTER, Miss. — For a few moments, it seemed like the Space Launch System saga might have a happy ending. Beneath brilliant blue skies late on Saturday afternoon, NASA’s huge rocket roared to life for the very first time. As its four engines lit and thrummed, thunder rumbled across these Mississippi lowlands. A giant, beautiful plume of white exhaust billowed away from the test stand.
It was all pretty damn glorious until it stopped suddenly.
About 50 seconds into what was supposed to be an 8-minute test firing, the flight control center called out, “We did get an MCF on Engine 4.” This means there was a “major component failure” with the fourth engine on the vehicle. After a total of about 67 seconds, the hot fire test ended.
During a post-flight news conference, held outside near the test stand, officials offered few details about what had gone wrong. “We don’t know what we don’t know,” said NASA Administrator Jim Bridenstine. “It’s not everything we hoped it would be.”
He and NASA’s program manager for the SLS rocket, John Honeycutt, sought to put a positive spin on the day. They explained that this is why spaceflight hardware is tested. They expressed confidence that this was still the rocket that would launch the Orion spacecraft around the Moon.
And yet it is difficult to say what happened Saturday is anything but a bitter disappointment. This rocket core stage was moved to Stennis from its factory in nearby Louisiana more than one calendar year ago, with months of preparations for this critical test firing.
Honeycutt said before the test, and then again afterward, that NASA had been hoping to get 250 seconds’ worth of data, if not fire the rocket for the entire duration of its nominal ascent to space. Instead it got a quarter of that.
Technology So what happened?
Perhaps most intriguing, Honeycutt said the engine problem cropped up about 60 seconds into the test, at one of its most dynamic moments. This was when the engines were throttling down from 109 percent of nominal thrust to 95 percent, Honeycutt said. And it is also when they began to gimbal, or move their axis of thrust.
At approximately 60 seconds, engineers noted a “flash” in the area of a thermal protection blanket around Engine 4, Honeycutt said. The engine section is one of the most complex parts of the core stage, and each of the four main engines has thermal protection to limit heating from the other engines.
Now, engineers from NASA, Boeing and the engine manufacturer, Aerojet Rocketdyne, will study data from the test to determine what exactly went wrong. It is not clear how long this will take, or what problems will need to be fixed.
If there is a serious problem with Engine 4, it could be swapped out. NASA has spare RS-25 engines at Stennis, including backups that are tested and ready, Honeycutt said. Such an engine swap could occur on the test stand itself over the course of a week or 10 days.
A key question is whether another hot fire test will be required. Bridenstine, whose tenure as NASA administrator will end next Wednesday, said it was too early to determine what will happen. He expressed hope that some straightforward problem might be found. Even so, it seems unlikely NASA has enough data from this test to avoid conducting another hot fire test, which would likely require weeks to months of setup time.
All of this casts very serious doubt on NASA’s plans to launch its Artemis I mission—an uncrewed precursor mission to sending humans to the Moon—before the end of this year. Already, the program was on a tight deadline, needing to ship the core stage from Stennis Space Center to Kennedy Space Center in Florida in February to retain any possibility of launching in 2021.
That now seems all but impossible.
Technology What the future holds
The future of NASA’s Space Launch System rocket is not clear. The incoming Biden administration has not released any detailed plans for the space agency. The big rocket’s support has always come from Congress, however, and not the White House. Congress created the booster a decade ago when the Obama administration wanted to rely more on private companies to provide launch vehicles.
The original deal was cut between two senators, Bill Nelson of Florida and Kay Bailey Hutchison of Texas, but they are both now out of office. In recent years, Alabama Senator Richard Shelby—who chairs the powerful Appropriations Committee—has emerged as the rocket’s most potent backer. This is not a surprise given that the rocket is designed and managed at Marshall Space Flight Center in northern Alabama.
However, with Democrats taking a narrow majority in the Senate, Shelby has lost his chair in the upcoming session of Congress. Although he will retain considerable say, he will no longer be able to effectively dictate NASA’s budget.
The SLS has also enjoyed ample support from the Alabama delegation in the House, but they, too, have recently lost some of their clout. Perhaps the most outspoken House backer of the rocket was Alabama Congressman Mo Brooks. But he has gained a measure of infamy for speaking at the pro-Trump rally on January 6, helping to incite rioters to march on the US Capitol. As Brooks spread misinformation about the election, he said, “Today is the day Americans start taking down names and kicking ass.” Of Alabama’s seven US representatives, six are Republicans. All of them, including Brooks, voted to overturn the election results after the Capitol insurrection.
Given these recent events, it seemed likely that the SLS program had a future if it began to execute and deliver on milestones such as Saturday’s test. The weakening political clout of the Alabama delegation may mean that the program has less of a firewall in Congress should it continue to face delays and cost overruns.
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Technology Heritage hardware
Congress created the SLS rocket in its 2010 Authorization Act, declaring it to be a “follow-on launch vehicle to the space shuttle.” The law said NASA must extend or modify existing contracts to build the rocket and ensure the “retention” of critical skills. The legislative intent was clear: keep the shuttle workforce employed.
This led to a design that used modified solid rocket boosters, like those that gave the space shuttle a kick off the launch pad. The SLS rocket would also use the space shuttle main engines, although controversially the expendable rocket would fly the reusable engines just a single time. Eventually, each of the main shuttle contractors got a piece of the SLS rocket.
At the time, proponents of this design argued that relying on space shuttle hardware would keep costs and technical issues to a minimum.
This seemed to make some sense. After all, these engines had flown for three decades. The solid rocket boosters had flown for just as long. This was proven technology. The hardest work would be designing and building large liquid oxygen and hydrogen fuel tanks in the rocket’s core stage. However, liquid hydrogen was hardly a novel fuel to work with. NASA had decades of experience building the shuttle’s large external fuel tank, and US rocket scientists starting with Robert Goddard had been studying the use of liquid hydrogen since before the dawn of the space age.
It has since all gone sideways. By the time Saturday’s test took place, NASA had spent about $17.5 billion developing the rocket, and many billions more on ground systems to launch it. The original launch date was 2016, and now the rocket will likely not fly before 2022. And although much of the hardware has a long heritage, NASA and its contractors have still struggled to integrate it.
Last year, when NASA’s inspector general studied why it had taken so long to develop the SLS rocket, he found that the core stage, booster, and RS-25 engine programs had all experienced technical challenges and performance issues that led to delays and cost overruns.
“We and other oversight entities have consistently identified contractor performance as a primary cause for the SLS Program’s increased costs and schedule delays, and quality control issues continue to plague Boeing as it pushes to complete the rocket’s core stage,” Paul Martin wrote. “Both NASA and contractor officials explained that nearly 50 years have passed since development of the last major space flight program—the Space Shuttle—and the learning curve for new development has been steep as many experienced engineers have retired or moved to other industries.”
So what had been viewed as a strength of the program, using heritage hardware, instead became a liability. Saturday was only the first real hardware test for the rocket. It cannot afford too many more liabilities like those on display.
Listing image by Trevor Mahlmann for Ars
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