Shulou(Shulou.com)11/24 Report--

The National Aeronautics and Space Administration (NASA) cancelled the planned launch of the Space launch system (SLS) rocket again on Saturday, local time. This is the second time in a week that NASA has cancelled the launch of the SLS rocket. NASA officials said the cancellation of the launch was only temporary. Most industry insiders say NASA's caution is wise, given its importance to the entire moon landing program.

NASA executives expressed support for Saturday's decision to cancel the rocket launch and said they would be prepared to wait longer to try again later this month or in October after figuring out the cause of the hydrogen fuel leak and thoroughly resolving the problem.

"the cost of two cancellations is obviously much lower than a failure," NASA Director Bill Bill Nelson said at a news conference on Saturday afternoon.

Although it is nearly 100m high, NASA's new rocket is not too high to fail. But in terms of the importance of SLS rockets to NASA's moon landing, there may not be any difference in rocket launch.

NASA has spent more than $40 billion to develop SLS rockets and Orion spacecraft. The overall progress of the project is several years behind schedule and billions of dollars over budget. Many industry insiders who support commercial manned space missions say companies such as SpaceX, led by Elon Musk, offer more cost-effective and efficient ways for manned space missions.

Because NASA has invested too much money in the SLS rocket, a catastrophic launch failure could delay the moon landing for several years and raise questions about the value of the moon landing.

Even those who don't like SLS rockets say NASA's caution is wise.

Lori Garver, a former deputy director of NASA, once said that rockets are too expensive and prefer to fly in space in a commercial way. "they won't launch prematurely," 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 several weeks of unmanned space flight to test the rocket and the Orion capsule in which astronauts will fly in the future. The next Artemis mission is currently scheduled for 2024, when NASA will send astronauts to the moon, while the third Artemis mission plans to land astronauts near the moon's south pole.

Engineers detected a hydrogen leak at the junction of the hydrogen fuel pipeline to the rocket after the countdown to the launch began on Saturday.

"We know that when the concentration of hydrogen in the surrounding air exceeds about 4 per cent, there is a risk of flammability events," said Mike Salafin, Artemis mission leader.

Salafin said the leak was large, with a concentration of two to three times the 4% limit. The launch was cancelled at 11:17 on Saturday after three failed attempts to plug the leak.

Salafin speculated that the problem could be related to erroneous instructions sent to the launch pad's propellant loading system, which caused the fuel pipeline pressure to reach 60 pounds per square inch (414 KPA) in a few seconds, three times the rated pressure. may have damaged the gasket of the connector.

During the first attempt to launch the rocket last Monday, there was also a hydrogen leak at the same joint, but the leak was small, and engineers came up with a way to keep the leaked hydrogen concentration below 4%. As a result, 537,000 gallons (2 million liters) of ultra-cryogenic liquid hydrogen fuel continue to be injected into the rocket. Last Monday's launch plan was cancelled because of a sensor failure and engineers said one of the rocket's four core-stage engines lacked cooling.

After Saturday's launch was cancelled, NASA officials began to consider plans for the next step in solving the problem. One is to simply disconnect and reconnect the fuel pipeline and try to launch again within a few days. "but given the volume of the leak we see today, we are not confident enough to solve the problem," Salafin said.

The task manager believes that the gasket needs to be replaced. Engineers are considering whether to complete the gasket replacement at the launch pad and directly test the delivery of liquid hydrogen to ensure the success of the repair, or to pull the rocket back to the spacecraft assembly building for maintenance, which is relatively easy, but it is not possible to test the tightness of the pipeline by delivering liquid hydrogen before the rocket returns to the launch pad.

Jim Free, deputy director of NASA, said in a tweet that he and others were "disappointed with the results, but proud that our team kept coming up with solutions".

Although Gaffer said the launch team was right to cancel the launch twice, she was puzzled that the technical design of the SLS rocket dates back more than half a century, using essentially the same motors and solid rocket boosters as the space shuttle.

"choosing to use the shuttle engine directly leads to hydrogen problems, and we all know that hydrogen is prone to leakage," she said. "these are design decisions, and if they continue to affect the launch, they will attract attention."

But Garver added, "assuming they can overcome difficulties in the next round, I think it will be forgotten."

Even some disappointed viewers seem to understand that the rocket launch has been delayed again.

Vincent Anderson (Vincent Anderson), 45, came from Lake Alfred, Florida, last Monday to watch the rocket launch. He went on a boat trip with his son, hoping to see the rocket lift off, but failed. "the Rockets are as picky as cats," he told his 10-year-old son. "

On Saturday morning, Anderson signed up for a cruise with his 15-year-old daughter, and the rocket launch was cancelled. He called the cancellation of the launch "bittersweet", but said they were "all prepared for'it may not happen'at the start of the day."

He said that although the rocket failed to launch again, the outing was always worth it.

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