Why did NASA cancel the launch of the SLS rocket again? NASA chief: Cancellation obviously costs much less than failure
NASA executives expressed support for Saturday’s decision to cancel the rocket launch and said they will be prepared to wait longer and try again later this month or in October after the cause of the hydrogen leak is figured out and the problem is completely resolved. .
“The cost of two cancellations is obviously much lower than one failure,” NASA Administrator Bill Nelson said at a news conference Saturday afternoon.
Despite being nearly 100 meters tall, NASA’s new rocket isn’t too tall to fail. But in terms of the importance of the SLS rocket to NASA’s lunar program, the rocket launch probably couldn’t make any difference.
NASA has spent more than $40 billion developing the SLS rocket and Orion spacecraft. The overall progress of the project is several years behind schedule and billions of dollars over budget. Companies such as Elon Musk’s SpaceX offer a more cost-effective and efficient way for human spaceflight, many industry insiders who support commercial human spaceflight say.
With NASA spending so much money on the SLS rocket, a catastrophic launch failure could delay the moon landing by several years and raise questions about its value.
Even people who don’t like the SLS rocket say NASA’s caution is a wise move.
Lori Garver, a former NASA associate administrator, has said that rockets are too expensive, preferring a commercial approach to spaceflight. “They’re not going to launch too soon,” she said of the SLS rocket launch. “I’m not worried about that.”
The SLS rocket was originally scheduled to launch to complete the Artemis I mission, which will take a few weeks of uncrewed spaceflight to test the Orion space that the rocket and astronauts will ride in the future cabin. The next Artemis mission is currently scheduled for 2024, when NASA will send astronauts to the moon; a third Artemis mission is planned to land astronauts near the moon’s south pole.
On Saturday, as the countdown to launch began, engineers detected a hydrogen leak at the junction of the hydrogen fuel line leading to the rocket.
“We know that when the hydrogen concentration in the surrounding air exceeds about 4 percent, there is a risk of a flammable event,” said Mike Sarafin, the Artemis mission leader.
Sarafin said the leak was large, with concentrations two to three times the 4 percent limit. The launch was canceled at 11:17 a.m. Saturday after three failed attempts to seal the leak.
Sarafin speculates that the problem may be related to erroneous instructions sent to the launch pad’s propellant loading system, which caused the fuel line to overpressure, reaching 60 pounds per square inch (414 kilopascals) for a few seconds, which is rated Three times the pressure may damage the gasket of the connector.
During the first attempt to launch the rocket last Monday, the same joint also had a hydrogen leak, but the leak was not large. Engineers figured out a way to keep the leaked hydrogen concentration below 4% and continue to inject into the rocket. 537,000 gallons (about 2 million liters) of ultra-low temperature liquid hydrogen fuel. Last Monday’s launch was canceled because of a malfunctioning sensor and what engineers said was insufficient cooling of one of the rocket’s four core-stage engines.
After Saturday’s launch was canceled, NASA officials began to consider plans for next steps to solve the problem. One is to simply disconnect and reconnect the fuel lines and try to launch again in a few days. “But given the volume of leaks we’re seeing today, we’re not confident enough to fix the problem,” Sarafin said.
Mission managers felt the gasket needed to be replaced. Engineers are considering whether to complete the gasket replacement on the launch pad and directly test delivery of liquid hydrogen to ensure the repair is successful; Test the tightness of the pipeline by delivering liquid hydrogen.
NASA associate administrator Jim Free said in a tweet that he and others were “disappointed by the results, but proud of our team’s continued efforts to come up with solutions.”
While Garver said the launch team was right to cancel the launch twice, she was puzzled that the SLS rocket had a technical design that dates back more than half a century and uses essentially the same engines and solid rocket boosters as the space shuttle.
“The choice to use a space shuttle engine led directly to the hydrogen problem, which we all know is prone to leaks,” she said. “These are design decisions that will be of concern if they continue to affect launches.”
But Garver added, “Assuming they can get over it in the next round, I think that’s going to be forgotten.”
Even some disappointed viewers seemed to understand that the rocket launch was delayed again.
Vincent Anderson, 45, came from Lake Alfred, Florida, to watch the rocket launch last Monday. He went on a boat trip with his son, hoping to see the rocket lift off, but that didn’t happen. He said to his 10-year-old son: “The rocket is as picky as a cat, and it only gets promoted when it wants to.”
On Saturday morning, Anderson signed up for another boat trip with his 15-year-old daughter, only to have the rocket launch canceled. He called the cancellation of the launch “bittersweet,” but said they started the day “with a ‘maybe it won’t happen’ mentality.”
While the rocket again failed to launch, the outing was always worth it, he said. (Chen Chen)