Stuck propulsion valve delays second SLS test-firing – Spaceflight Now

One of many SLS core stage’s 4 RS-25 engines throughout a moist gown rehearsal in . Credit score: NASA

A difficult liquid oxygen valve on the Launch System’s first flight-rated core stage will maintain NASA from performing a second test-firing of the ’s 4 engines this week.

NASA hoped to conduct the second hotfire check on SLS core stage Thursday, however the company introduced Monday that the engine firing will likely be postponed to judge a misbehaving valve within the rocket’s propulsion system.

The house company mentioned Monday that engineers recognized the issue over the weekend. Certainly one of eight “prevalves” within the core stage propulsion system was not working correctly, NASA mentioned.

The prevalve provides liquid oxygen to one of many rocket’s 4 RS-25 major engines. The engines are left over from the house shuttle program, and devour liquid oxygen gas together with super- liquid oxygen. All eight prevalves functioned correctly in the course of the first SLS core stage hotfire check Jan. 16, officers mentioned.

“NASA and the core stage lead contractor Boeing will establish a path ahead within the days forward and reschedule the recent hearth check that was initially scheduled for Feb. 25,” NASA mentioned Monday.

The Jan. 16 hotfire check was imagined to final greater than eight minutes, however the 4 RS-25 engines shut down slightly greater than a minute after ignition. Engineers traced the reason for the untimely shutdown to a hydraulic system parameter that tripped an overly-conservative setting for the check, the final part of a “Inexperienced Run” check and checkout marketing campaign for the SLS core stage at NASA’s Stennis Area Heart in Mississippi.

The core stage hydraulics drive actuators that pivot, or gimbal, the 4 RS-25 engines to steer the rocket after liftoff. The Area Launch System will fly with two stable rocket boosters mounted on all sides of the 212-foot-tall (64.6-meter) core stage. An higher stage and Orion crew capsule on prime of the core stage will deliver the overall launcher top to 322 ft (98 meters) tall.

NASA officers determined to redo the Inexperienced Run test-firing after the early cutoff final month. Managers need to get at the least 4 minutes of run time on the RS-25 engines on the second hotfire check to collect sufficient information to construct confidence within the rocket’s efficiency earlier than delivery the stage to the Kennedy Area Heart in Florida for launch preparations.

However the aim for the second hotfire check is to burn the engines for greater than eight minutes, the period they’ll hearth on an actual SLS flight.

Kathy Lueders, affiliate for NASA’s human spaceflight division, mentioned Wednesday that engineers had been having hassle getting the liquid oxygen prevalve to totally open throughout checkouts earlier than the second Inexperienced Run hotfire check.

“It’s very irritating,” Lueders mentioned in a panel dialogue on the 47th Spaceport Summit.

“In your LOX (liquid oxygen) system, if you happen to’re attempting to run your engines on the energy degree we’re attempting to run our engines, you must have that prevalve open,” she mentioned.

The Inexperienced Run hotfire check has been delayed greater than six months for the reason that SLS core stage arrived at Stennis in January 2020. A brief suspension of labor brought on by the COVID-19 pandemic initially delayed preparations for the check, and a collection of hurricanes and tropical storms that impacted the Gulf Coast final 12 months additionally slowed work on the Stennis Area Heart.

An exhaust erupts from the B-2 check stand throughout a test-firing of the Area Launch System core stage Jan. 16. Credit score: NASA/Robert Markowitz

Engineers aimed to carry out the hotfire check earlier than the top of the 12 months, however an issue throughout a fueling check in December pushed the engine firing into January. With the newest delay, the earliest the -duration core stage test-firing is a while in March.

The primary SLS check launch will carry an unpiloted Orion crew capsule into house on NASA’s 1 mission. The Orion spacecraft will fly into orbit across the moon on a multi-week check flight earlier than returning to Earth for a splashdown within the Pacific Ocean. If profitable, the mission will pave the best way for Artemis 2, the primary crewed SLS/Orion mission, to hold 4 astronauts across the moon and again to Earth as quickly as 2023.

The Artemis program is NASA’s initiative to return astronauts to the moon. NASA was tasked by the Trump administration with a crew close to the south pole of the moon by the top of 2024. The Biden administration has expressed help for the Artemis program, however has not set a timetable for a crewed lunar touchdown mission.

The 2024 schedule aim was already slipping away earlier than the top of the Trump administration. Congress authorised solely a fraction of the funding NASA requested in fiscal 12 months 2021 for the Artemis program’s human-rated lunar lander growth.

Lueders, a former supervisor of NASA’s business crew program, mentioned the SLS Inexperienced Run delays had been “very, very powerful.”

“That is the one final piece that now we have ready for us to get all the way down to the Cape for us to go fly,” Lueders mentioned.

She mentioned NASA continues to be “hoping” to fly the primary SLS rocket on the finish of this 12 months.

“Like I used to say with the business crew program, we’re going to fly after we’re prepared,” Lueders mentioned Wednesday.

Email the writer.

Comply with Stephen Clark on Twitter: @StephenClark1.



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