Why does NASA not rush to launch the Artemis moon rocket?

KENNEDY SPACE CENTER, Florida – For the second time in a week, NASA officials on Saturday called off the test launch of a rocket that would one day carry astronauts to the moon. It was another setback for the iconic National Space Flight Program, although NASA officials expressed confidence that it would only be temporary.

But senior NASA officials stood behind their decision to call off the launch on Saturday, and said they were prepared to wait a little longer, and possibly try again later this month or in October, after understanding and resolving the cause of the hydrogen leak.

“The cost of two scrubs is a lot less than failure,” NASA Administrator Bill Nelson said during a Saturday afternoon news conference.

Despite its height of 322 feet, NASA’s new rocket isn’t literally too big to fail. But in terms of the craft’s importance to the space agency’s lunar plans, it probably is.

NASA has already spent more than $40 billion developing the rocket known as the Space Launch System and the capsule known as Orion. The program is years behind schedule and billions of dollars on budget. It has faced criticism from proponents of a more commercial approach to spaceflight, who say companies like Elon Musk’s SpaceX offer the most cost-effective and efficient way to propel human spaceflight.

Since NASA has invested so much in this one rocket, a catastrophic failure would delay the lunar program for years and possibly call its value into question.

Even people who aren’t fans of the Space Launch System said NASA’s caution is wise.

“They’re not going to launch prematurely,” said Laurie Garver, a former NASA deputy administrator during the Obama administration, who said the rocket was too expensive and favored commercial methods of space flight. “do not worry about that.”

Moon landings half a century ago were part of NASA’s Apollo program. The effort to return to the new moon was named Artemis. In Greek mythology, Artemis was the twin sister of Apollo.

The omitted launch is for Artemis 1, a weeks-long unmanned mission that will test the rocket and capsule where future astronauts will ride. The next Artemis mission, currently scheduled for 2024, will carry astronauts aboard, and the third Artemis mission will be to land astronauts near the south pole of the moon.

As the countdown to launch approaches Saturday, a hydrogen leak has been detected in a conductor along the hydrogen fuel line leading to the rocket.

“We know that when you exceed approximately 4 percent of the hydrogen concentration in ambient air, you are at risk of experiencing a flammability event,” said Mike Sarafin, Artemis mission manager.

For this leak, which Mr. Sarrafin described as significant, concentrations were two to three times the 4 percent limit. After three attempts to close the leak failed, the launch attempt was called off at 11:17 AM ET by the launch director, Charlie Blackwell Thompson.

Mr. Sarrafin said the problem may have been related to an incorrect command sent to the fuel-loading system on the operating panel, causing extremely high pressures – 60 pounds per square inch instead of 20 – in the fuel line for a few seconds. This can damage the gasket in the connector.

A hydrogen leak appeared in the same conductor during Monday’s first launch attempt, but it was smaller, and engineers figured out how to keep the hydrogen concentration below 4 percent, and they were able to fill the rocket with 537,000 gallons of super-cold liquid. hydrogen. The launch was called off on Monday when a faulty sensor reported that one of the rocket’s four primary stage engines had not been cooled enough.

After canceling Saturday’s launch, NASA officials considered options for what to do next. One was simply to disconnect and reconnect the fuel line and try to get it working again in a couple of days. “But our confidence level, given the scale of the leak we saw today, was fairly low that would solve the problem,” said Mr. Sarafin.

Mission managers decided the gasket would need to be replaced, and the engineers were considering whether this work might best be done on the launch pad, where they could then run liquid hydrogen through the line to ensure a successful repair, or first roll the rocket back into a gigantic structure known as the Vehicle Assembly Building. . It would be easier to do repair work there, but engineers won’t be able to test the line with liquid hydrogen until the rocket is back on the launch pad.

Jim Frey, associate administrator at NASA, said in a tweet that he and others at the agency were “disappointed with the result but proud of our team for consistently coming up with solutions.”

While Ms. Garver said the launch teams did the right thing by canceling the launch both times, she questioned the design of the Space Launch System, which uses pretty much the same engines and solid rocket boosters that power the space shuttles – a technology that goes back in history. It goes back more than half a century.

“The choice to use shuttle engines has been shown to be in hydrogen, and we know the hydrogen is leaking,” she said. “These are all design decisions that, if they continue to muddy us, will be a concern.”

But she added, “Assuming they can get past it in the next round, I think it will be forgotten.”

Even some frustrated onlookers seemed to understand.

It was the second time in days that throngs of people along Central Florida’s waterways and beaches were disappointed by their missed opportunity to launch the first more powerful rocket since the Saturn 5 took astronauts to the moon in the 1960s and 1970s.

last monday, Vincent Anderson, 45, of Lake Alfred, Florida, took a boat ride with his son in hopes of seeing the missile launch. It used to not be.

“Rockets are as ungainly as cats, they go up when they want to,” he told his 10-year-old.

Then the scene came up again this morning, when Mr. Anderson scored for another boat ride, this time with his 15-year-old daughter. He described the scrub as “bittersweet” but hedged that they started the day with “the same expectations that probably won’t happen.”

The launch never happened again, he said, but the outings were still worth it.

Kristen Chong Contribute to the preparation of reports.