WASHINGTON – NASA remains cautiously optimistic that the first launch of the Space Launch System rocket could take place before the end of the year, despite having to conduct a second rocket test of the core phase of the rocket.
That test, the culmination of the Green Run test campaign for the nuclear phase that began in early 2020, was scheduled for Feb. 25 at the Stennis Space Center in Mississippi. The ignition of the four RS-25 engines on stage is scheduled for around 5pm in the East, assuming the countdown goes according to plan, officials said during a February 19 call with reporters.
This second Green Run fire test takes place because the first one, January 16, ended after 67 seconds, much less than the expected 485 seconds. Program executives later said the early shutdown was caused when the one-engine hydraulic system reached “deliberately conservative” limits in its flight software. NASA announced on January 29 that it would proceed with a second test.
NASA officials initially suggested that they could start preparations for the launch without a second Green Run test, but concluded that a second fuel test could be done with minimal risks for the nuclear phase, which occurred during the Artemis 1 launch will be flown.
The decision was welcomed by NASA’s Aviation Safety Advisory Panel. “We are delighted that NASA has decided to make a second attempt at a full-time combustion of the nuclear division to obtain the key data in the final step in the Green Run series of tests,” said Patricia Sanders, chair of the panel. , said at his public meeting on 18 February. “It was a really good decision, a positive decision to reduce the risk and ultimately succeed.”
At the February 19 briefing, project officials suggested that the second test does not have to take eight minutes to be successful. “The four-minute threshold is something we’ve been looking at for a long time,” said John Honeycutt, SLS program manager at NASA’s Marshall Space Flight Center. “The longer we run, the more data we get.”
Julie Bassler, SLS stage manager at Marshall, said the agency has ten “detailed verification objectives” for the fire test to confirm that the vehicle matches the expected performance required for SLS launches. The previous test achieved three of these objectives, with partial data for six others and no data for the last objective. “If we go four minutes, we’ll collect all the data for those 10.”
Running longer than four minutes will provide data for secondary test purposes, but it is not necessary to meet the “minimum success criteria” for the test, she said. “One of the reasons you want to go for eight minutes is that it would match exactly what we would do for the launch,” she later remarked.
The core phase is ready for testing, despite some complications in recent days due to winter storms and irregular cold weather at Stennis. “The vehicle did not repair much after the first arson. It came out of it in good shape, ”said John Shannon, vice president and SLS program manager at Boeing. He estimated that if the second test went well, the nuclear stage could be refurbished and put on a vessel within about 30 days for dispatch to the Kennedy Space Center.
Once at KSC, the core phase will be integrated with its two five-segment solid rocket amplifiers, top stage and Orion spacecraft for the Artemis 1 launch. NASA had earlier said that the launch would take place in November, but even before the first fuel test in January, it acknowledged that there was a limited margin in the schedule.
Tom Whitmeyer, deputy administrator for exploration systems development at NASA headquarters, said he remains optimistic that Artemis 1 could be launched before the end of the year. He noted that a “deterministic” schedule, assuming everything went well, would make a launch as soon as possible.
However, he later admitted in the call that it was unlikely that everything would go exactly according to plan. “It will take a little longer. We have some learning curve to go, ‘he said, as with first-time operations and complications of the weather and the pandemic. “We’ll see a date later than that, and it’s really hard to predict exactly what that date will be.”
He still expected the launch to take place this year. “We feel we have a fair chance of starting this year,” he said. “First, we really need to get this arson behind us. This is the most important thing we have before us. ”