NASA is examining the results of moon rocket tests

It took four NASA efforts to fully power the new Space Launch System rocket, and although new problems arose during the latest practice countdown on Monday, senior executives said they were pleased with the giant amplifier’s performance.

“We believe we have had a really successful rehearsal,” Tom Whitmeyer, deputy chief of NASA’s Exploration Systems Development, said on Tuesday. “We know we will have a handful of items to deal with … and I think it will take us a few days to get over it and then make a decision on what is the best way forward. “

Assuming repairs to a leaking hydrogen component are successful, managers could decide to run another fuel test of some kind or conclude that they have enough data now to launch a late summer launch campaign without waste time in another rehearsal general. can only offer gradual improvement.

The full moon lands behind the Space Launch System rocket on June 15 at the Kennedy Space Center. / Offer: William Harwood / CBS News

During a press conference on Tuesday, Whitmeyer and other senior officials would not speculate on what would follow. However, Mike Sarafin, Artemis Moon’s director of mission at NASA headquarters, said the SLS rocket had now achieved most of the service’s pre-flight targets, although it had not reached the end of the countdown. of Monday’s practice.

As it was, the team reached the T-minus 29 seconds – just 20 seconds away from the goal – and the engineers understand what caused the early stoppage.

“I would say we are in the 90th percentile of where we need to be overall,” Sarafin said. But “there are still some open objects that we have to see … to say that we are ready in terms of logical flight.”

Running years behind schedule and billions over budget, NASA is in the final stages of testing the giant SLS rocket and its sophisticated systems before launching it into the program’s maiden flight: sending an unmanned Orion crew capsule to a pilot over From the moon and back.

To pave the way for the launch, NASA test launched the first stage rocket engines in March 2021, sent the stage to the Kennedy Space Center in Cape Canaveral, Florida, mounted it on a pair of Rocketne solid fuel boosters and Aer added a senior tier from the United Launch Alliance and then attached an Orion crew capsule, made by Lockheed Martin.

The 330-foot rocket, the most powerful ever built for NASA, was towed from the iconic Vehicle Assembly Building to the 39B launch pad in March for a practical countdown and power test, one of the last major landmarks on the road to launch.

The goal was to load the rocket with 750,000 gallons of supernatant liquid oxygen and hydrogen fuel and then count down to T-minus 9 seconds, the point at which the engines would start to ignite during a real launch, to test complex computer systems, software and hardware in flight day conditions.

The rocket and its target.  / Offer: William Harwood / CBS News

The rocket and its target. / Offer: William Harwood / CBS News

Along with attempting to perform a normal countdown, the team also planned to test its ability to stop the clock and recycle: to make sure the system could handle problems that could cause a last second delay during a real countdown.

But a frustrating series of major ground problems, including a hydrogen leak in the fuel line installation, a problem with a blocked second-stage helium valve, and a lack of nitrogen gas used in fire prevention systems, derailed three consecutive raids. .

The rocket was transported back to VAB for repair and then to the backup earlier this month. During the fourth fuel test on Monday, the engineers finally managed to fully load the SLS, pumping 750,000 gallons of oxygen and hydrogen into the four tanks that make up the first and second stages.

But before the tanks were filled, engineers discovered a new problem: a 4-inch quick-release hydrogen fitting device with a leak. The system is used to inject hydrogen through the four first stage RS-25 engines for proper cooling or pre-ignition adjustment.

The ground countdown sequence computer monitors thousands of parameters, including the status of the 4-inch “bleed line”, and is programmed to stop the clock if the specifications set out in the start-up criteria are violated.

When the gas line problem occurred on Monday, engineers had to quickly find a way to solve the problem so they could continue loading propulsion and get into what is known as “steady refilling,” constantly filling the tanks as hydrogen and oxygen. heat and boil.

They managed to do this by ordering the computers to ignore the leak sensors, and the team eventually filled all four tanks. This laid the groundwork for the countdown phase, the action-packed last 10 minutes before launch. Or, in this case, it leads to a computer-ordered shutdown.

The original goal was to count down to the T-minus 33 seconds, the point where the ground computer would deliver to the SLS embedded flight software and then recycle again at the T-minus 10 minutes. The idea was to test the system’s ability to recover from a problem. The pattern then required the count to be continued and continued until the T-minus 9.3 seconds.

But on Monday, due to a rapid disconnection leak at the hydrogen gas line and a loss of troubleshooting time, administrators chose to drop the recycling to 33 seconds and continue the countdown after the rocket was delivered to the flight computer.

While the ground computer could be said to ignore leak sensors, the flight computer software could not be easily modified, and launch manager Charlie Blackwell-Thompson said engineers expected to stop the countdown as soon as it took over.

“We certainly have the ability within the ground-based sequencer system to suspend tracking of these types of parameters, but we have less on-flight capacity for that,” he said. “And so we knew that as soon as we felt this situation, we would have a cut.”

And that is exactly what happened. The countdown stopped at T-minus 29 seconds, four seconds after delivery.

What happens next is not yet clear. The next realistic lunar launch period, based on the movements of the Earth and the Moon and the planned orbit of the Orion capsule, opens on August 23rd. Another power test could push the flight beyond that, but NASA has not yet considered launch dates.

Meanwhile, Blackwell-Thompson said, “You’re tracking the data. And so we’re going to collect the data and see where the data will lead us.”

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