Artemis I launch scrubbed as engine problem defies fast fix

NASA was forced to scrub the much-anticipated first flight of its Space Launch System rocket early Monday after a series of problems with the rocket and the fueling procedures prevented it from lifting off.

The space agency had been planning to launch the massive rocket and the Orion spacecraft, without any astronauts on board, on a trajectory toward the moon as part of its Artemis program. Now it will have to stand down and reassess problems with the complicated vehicle that has suffered delays and setbacks for years.

Engineers struggled to get one of the booster’s RS-25 engines chilled to the correct temperature by running liquid hydrogen, kept at minus 423 degrees Fahrenheit, through it. Engineers tried a series of fixes, but none worked.

NASA ran into a similar problem in June during a fueling test known as a “wet dress rehearsal,” when there was a leak of liquid hydrogen in one of the lines leading from the ground supplies to the rocket. Knowing the fueling lines could pose a problem, NASA officials said the moment would be a key hurdle to clear before launch.

“This is something they wanted to test during wet dress four but were unable to,” Derrol Nail, a NASA broadcaster, said during the agency’s livestream of the launch attempt. “So this was the first opportunity for the team to see this live in action. It’s a particularly tricky issue to get that temperature dialed in.”

In the days leading up to the flight, NASA officials had tried to manage expectations, saying repeatedly that the flight was a test to see how the rocket performs in real-world conditions and warned they would likely encounter problems along the way.

In an interview last week, NASA Administrator Bill Nelson said that despite all the excitement surrounding the launch, “I want to remind people this is a test flight. We’re going to stress this thing in a way that we would never do with humans on board. And so I just want to bring everybody back to reality.”

On Saturday, Mike Sarafin, NASA’s Artemis mission manager, said that the launch “could scrub for any number of reasons. We're not going to promise that we're going to get off on Monday. We could have weather, we could have technical issues or we could have a range and public safety hold and or a combination of those.”

Still, it is a setback for the agency, which very much wanted the launch to go well. NASA has backup launch dates on Sept. 2 and 5th, but it was not immediately clear when it might try to launch again.

NASA got a late start to fueling the rocket when a thunderstorm came within five miles of the launch pad at about midnight Monday. Once the storm passed, engineers began fueling the rocket, first the liquid oxygen, which was going well, and then the liquid hydrogen. But soon afterward, sensors at the base of the rocket detected a leak. NASA stopped the fueling, then started and stopped again in a fitful effort to keep the launch on track.

NASA was able to fully fuel the first stage and was nearly done with the rocket’s second stage.

“The team did fantastic job working through that problem and get us past it,” Jeremy Graeber, the Artemis I assistant launch director, said during NASA’s live broadcast.

But it ran into a problem when it attempted to prep the engines for launch. Liquid hydrogen was not running through one of the four RS-25 engines mounted to the base of the rocket. As a result, it did not reach the correct temperature needed for launch.

The SLS rocket has been in development for years, derided by critics as a waste of money but supported at every turn by Congress.

Read The Post’s deep dive into the history of the rocket, and the story it tells about how NASA, and Washington, works.

NASA engineers had feared that a crack had formed on a section of the rocket known as the intertank because they noticed a line of ice forming. But they now believe it’s only a crack in the foam on the outside of the rocket to insulate the tank and not in the intertank itself.

They now believe the ice formed because ambient air is being chilled by the tank and then getting sucked into the crevice in the foam. “It looks like air is leaking, but in fact it’s not,” Derrol Nail, NASA’s launch commentator, said during a live broadcast.

He added that NASA has experience with this phenomenon going back to the space shuttle, and it even has a name: cryopumping.

Liquid hydrogen, the fuel that powers the RS-25 engine, is a fickle propellant. It’s kept at minus-423 degrees Fahrenheit, a temperature that would be a shock to the system as it’s loaded into the tanks and then cycles through pumps to the engines.

To prepare the systems for the blast of super-chilled hydrogen, engineers condition the system ahead of time by bleeding liquid hydrogen through it. But in one of the three engines, a bleed line isn’t functioning properly, and so the engine is not dropping to the needed temperature.

Engineers are trying to figure out how to solve the problem, and the launch director has added a 10-minute hold to the countdown, so they can try to fix it.

NASA has big plans for its broadcast of the Artemis I launch, a show featuring astronauts and special guests who would talk about the space agency’s enthusiasm for its plans to return human beings to the moon.

It was to feature a series of celebrity appearances by Jack Black, Chris Evans, and Keke Palmer, as well as a special performance of “The Star-Spangled Banner” by Josh Groban and Herbie Hancock. It also planned to feature a performance of “America the Beautiful” by the Philadelphia Orchestra and cellist Yo-Yo Ma, conducted by Yannick Nézet-Séguin.

But all that has been put on hold while engineers attempt to get the huge Space Launch System rocket in a condition for launch.

Until the problems are resolved, NASA is providing a feed to its operational channel where it offers occasional updates on the progress of readying the rocket.

NASA engineers are troubleshooting a problem with one of the four RS-25 engines that power the rocket. They had attempted to run cryogenic propellant through the engine to get it to the right temperature for flight but were having problems with the line.

The liquid hydrogen is kept at minus-423 degrees Fahrenheit.

They have since opened and closed the valves, and added pressure, but that doesn’t seem to be working to cool the engine. NASA ran into a similar problem during a fueling test in June and had hoped they had fixed the problem.

Additionally, engineers have noticed the buildup of frost on the intertank, which connects the liquid oxygen and liquid hydrogen tanks. That could be the result of a crack, and engineers are assessing that as well.

NASA got a late start on fueling the rocket overnight when a thunderstorm came within five miles of the launchpad around midnight Eastern time. Once the storm passed, crews began fueling the rocket: First, the liquid oxygen, which was going well, and then the liquid hydrogen. That’s when sensors at the base of the rocket detected a leak. NASA stopped the fueling, then started and stopped again in a fitful effort to keep the launch on track.

The supercooled liquid hydrogen is extremely light and kept at minus-423 degrees Fahrenheit, which makes it a difficult propellant to control. It’s so cold that when the 130-foot-tall hydrogen tank in the main booster stage is fully fueled with 538,000 gallons of liquid hydrogen, it shrinks six inches, according to NASA.

A little before 5 a.m. Eastern time, NASA started filling the upper-stage tanks and, shortly thereafter, the main-stage tanks had been fully fueled without additional leaks.

“The team did fantastic job working through that problem and get us past it,” Jeremy Graeber, the Artemis I assistant launch director, said during NASA’s live broadcast.

In the meantime, NASA has been pressing ahead. The problems are likely to force NASA to move the launch time to later in the two-hour window. But the agency has not set a new launch time.

“We have a lot of work to get to that point,” Graeber said.

Later, NASA commentator Derrol Nail said NASA was investigating a crack on a part of the rocket that connects the liquid hydrogen and liquid oxygen tanks, and serves as a connection point for the rocket’s solid rocket boosters.

“The intertank is built differently from the rest of the core stage,” according to NASA’s website. “It is bolted together, not welded, with ribs on the outside for strength.”

Engineers are also working a problem with one of the booster’s engines that is not at the correct temperature that would allow it to launch.

Vice President Harris is scheduled to visit NASA’s Kennedy Space Center in Florida and attend the Artemis I launch. She’s also scheduled to deliver a speech about the nation’s effort to return to the moon and tour the facilities where the hardware is being built for upcoming missions.

The Artemis program, which aims to send the first woman and person of color to the lunar surface, was an initiative started by the Trump administration. However, it has been embraced by the Biden White House as well, making it the first deep-space human spaceflight program to survive subsequent administrations since Apollo.

Earlier this month, Harris, who chairs the National Space Council, met with space leaders in the private sector. The next Space Council meeting is scheduled for Sept. 9.

The weather forecast for the beginning of the two-hour launch window, which opens at 8:33 a.m. Eastern time, looks good: an 80 percent chance of go. Later in the window, however, clouds and possible showers could move into the area near the Kennedy Space Center, lowering the probability of launch to 60 percent.

There are all sorts of other technical issues that could delay the mission, and since this is the first flight of the rocket, NASA is still learning how it operates, even after years of development. In the past, the space agency had trouble loading the vehicle with the liquid hydrogen and liquid oxygen that serve as its propellant. But it hopes that all of those issues have been resolved.

On Saturday, Mike Sarafin, NASA’s Artemis mission manager, was blunt in assessing the probability of launch, but he also said he was optimistic.

“We’re not going to promise that we’re going to get off on Monday,” he said. “We could have weather. We could have technical issues, or we could have a range and public safety hold and/or a combination of those. But we do feel good about our attempt on Monday in terms of our overall setup.”