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  SLS: Core stage 'Green Run' test series

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Author Topic:   SLS: Core stage 'Green Run' test series
Robert Pearlman
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Posts: 44772
From: Houston, TX
Registered: Nov 1999

posted 01-23-2020 08:05 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
NASA Artemis Program and Stennis Space Center Set the Stage for Testing in 2020

All eyes are on south Mississippi with this month's delivery and installation of NASA's Space Launch System (SLS) rocket's first core stage to Stennis Space Center for a milestone Green Run test series prior to its Artemis I flight.

The Green Run testing will be the first top-to-bottom integrated testing of the stage's systems prior to its maiden flight. The testing will be conducted on the B-2 Test Stand at Stennis, located near Bay St. Louis, Mississippi, and the nation's largest rocket propulsion test site. Green Run testing will take place over several months and culminates with an eight-minute, full-duration hot fire of the stage's four RS-25 engines to generate 2 million pounds of thrust, as during an actual launch.

"This critical test series will demonstrate the rocket's core stage propulsion system is ready for launch on missions to deep space," Stennis Director Rick Gilbrech said. "The countdown to this nation's next great era of space exploration is moving ahead."

NASA is building SLS as the world's most-powerful rocket to return humans to deep space, to such destinations as the Moon and Mars. Through the Artemis program, NASA will send the first woman and next man to the Moon by 2024. Artemis I will be a test flight without crew of the rocket and its Orion spacecraft. Artemis II will carry astronauts into lunar orbit. Artemis III will send astronauts to the surface of the Moon.

The SLS core stage, the largest rocket stage ever built by NASA, stands 212 feet tall and measures 27.6 feet in diameter. It is equipped with state-of-the-art avionics, miles of cables, propulsion systems and propellant tanks that hold a total of 733,000 gallons of liquid oxygen and liquid hydrogen to fuel the four RS-25 engines during launch. The core stage was designed by NASA and Boeing in Huntsville, Alabama, then manufactured at NASA's Michoud Assembly Facility in New Orleans by lead contractor Boeing, with input and contributions from more than 1,100 large and small businesses in 44 states.

"Delivering the Space Launch System rocket core stage to Stennis for testing is an epic historical milestone," said Julie Bassler, the SLS stages manager. "My team looks forward to bringing this flight hardware to life and conducting this vital test that will demonstrate the ability to provide 2 million pounds of thrust to send the Artemis I mission to space."

The stage was transported from Michoud to Stennis aboard the specially outfitted Pegasus barge. It arrived at the B-2 dock on Jan. 12 and was rolled out onto the test stand tarmac that night. Crews then began installing ground equipment needed for lifting the stage into a vertical position and onto the stand.

The lift was performed Jan. 21-22, which provided optimal weather and wind conditions. Crews now will fully secure the stage in place and to stand systems for testing.

NASA completed extensive modifications to prepare the B-2 stand for the test series. The stand has a notable history, having been used to test Saturn V stages that helped launch astronauts to the Moon as part of the Apollo Program and the three-engine propulsion system of the space shuttle prior to its first flight.

Preparing the stand for SLS core stage testing required upgrades of every major system on the stand, as well as the high pressure system that provides hundreds of thousands of gallons of water needed during a test. It also involved adding 1 million pounds of fabricated steel to the Main Propulsion Test Article framework that will hold the mounted core stage and extending the large derrick crane atop the stand that will be used to lift the SLS stage into place.

Once installed on the stand, operators will begin testing each of the stage's sophisticated systems. Among other things, they will power up avionics; conduct main propulsion system and engine leak checks; and check out the hydraulics system and the thrust vector control unit that allows for rotating the engines to direct thrust and "steer" the rocket's trajectory.

They also will conduct a simulated countdown, as well as a "wet dress rehearsal," in which propellants are loaded and flow throughout the stage system. The rehearsal exercise will end just prior to engine ignition, with the full four-engine hot fire to come in subsequent days.

After the hot fire test, crews plan to perform refurbishment work on the stage and inspect and configure it for shipment to Kennedy Space Center. The stage will be removed from the stand, lowered to its horizontal position on the tarmac and reloaded into Pegasus for the trip to Florida.

At Kennedy, the stage will be joined with other SLS elements and prepared for launch. The next time its four RS-25 engines fire, Artemis I will be taking flight.

Robert Pearlman
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From: Houston, TX
Registered: Nov 1999

posted 05-14-2020 07:15 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
NASA Takes Preliminary Steps to Resume SLS Core Stage Testing Work

NASA resumed Green Run testing activities this week on the first flight stage of its Space Launch System (SLS) rocket, with the return of limited crews to perform work at the agency's Stennis Space Center in Bay St. Louis, Mississippi.

"This is an important step toward resuming the critical work to support NASA's Artemis program that will land the first woman and the next man on the south pole of the Moon by 2024," Stennis Center Director Rick Gilbrech said. "Though Stennis remains in Stage 4 of NASA's COVID-19 Response Framework, we assessed state and local conditions and worked with agency leadership to develop a plan to safely and methodically increase critical on-site work toward the launch of the next great era of space exploration."

Stennis moved to Stage 4 on March 20, with only personnel needed to perform mission-essential activities related to the safety and security of the center allowed on site. NASA's Marshall Space Flight Center in Huntsville, Alabama, and its Michoud Assembly Facility in New Orleans, which are building SLS, also are in Stage 4.

"The test facility has been in standby mode, so we allotted two days to reestablish some facility support of mechanical and electrical systems that will also assist the vehicle contractors in performing their operations," said Barry Robinson, project manager for the B-2 Test Stand SLS core stage Green Run testing at Stennis.

Reestablishing, or "waking up," the Stennis B-2 Test Stand systems in the days ahead includes restoring facility power and controls, as well as ensuring pressurized gas systems are at proper levels for SLS operators to proceed with testing activities.

"Michoud has been cleaning and preparing the rocket manufacturing facility for critical production restart of the SLS core stage and the Orion capsule," said Michoud Director Robert Champion.

According to Julie Bassler, SLS stages project manager responsible for the core stage work at Stennis, Michoud and Marshall, Marshall also is resuming critical flight software and hardware testing.

Returning workers were trained on general safety procedures, personal protective equipment requirements, and self-monitoring. Site personnel also installed signs and markings to indicate where employees should stand and sit during upcoming activities.

"We want to make sure employees are armed with the appropriate information to be effective on the job and return safely to their families," Robinson said.

All sites are closely following CDC guidance to safely operate and protect the health and welfare of all employees. Michoud plans to transition to Stage 3 and operate in that stage for 30 days, in coordination with local government plans. Marshall remains at Stage 4.

Stennis plans for 30 days of limited crew activity on site in anticipation of the center's transition from Stage 4 to Stage 3. Once that transition occurs, increases to on-site work will continue slowly and methodically. The focus then will shift to preparing for the avionics power-up test – the next in a series of core stage Green Run testing milestones. According to Robinson, it's too early to calculate a precise schedule for the various test milestones.

"Like so many others, in so many places, we're operating under a new normal. We're working now to determine exactly what that looks like," he explained. "The virus, and our knowledge of safety as it relates to the virus, will dictate any changes we consider and implement. We will adjust tasks based on the most current information and guidance."

Green Run represents the first top-to-bottom integrated test of all flight core stage systems prior to its maiden Artemis I flight. All testing will be conducted on the B-2 Test Stand in the coming months and will culminate with an eight-minute, full-duration hot fire of the core stage with its four RS-25 engines, as during an actual launch.

Robert Pearlman
Editor

Posts: 44772
From: Houston, TX
Registered: Nov 1999

posted 05-21-2020 08:03 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
NASA's SLS Core Stage Green Run Tests Critical Systems For Artemis I

NASA is resuming work on a series of tests to bring the Space Launch System (SLS) rocket core stage to life for the first time, allowing engineers to evaluate the new complex stage that will launch the Artemis I lunar mission.

In January, engineers began activating the stage's components one by one over several months through a series of initial tests and functional checks designed to identify any issues. Those tests and checks collectively called Green Run will culminate in a test fire replicating the stage's first flight.

"Green Run is the step-by-step testing and analysis of the new SLS rocket core stage that will send astronauts to the Moon," said Richard Sheppard, the SLS Stages Green Run Test Lead from NASA's Marshall Space Flight Center in Huntsville, Alabama. "This testing will reduce risks for, not only the first flight, but also for the Artemis mission that will land astronauts on the Moon in 2024."

Above: Teams at NASA's Stennis Space Center near Bay St. Louis, Mississippi, completed the first test of the eight-part core stage Green Run test series for NASA's Space Launch System (SLS) rocket on Jan. 30, 2020. (NASA)

The Green Run test series, conducted in the historic B-2 Test Stand at NASA's Stennis Space Center near Bay St. Louis, Mississippi, is a collaborative effort between the SLS program, the Stennis test team, core stage manufacturer Boeing and engine manufacturer Aerojet Rocketdyne. On March 18, work was temporarily suspended on Green Run when Stennis Space Center went to Stage 4 on the Agency Response Framework in response to a rise in COVID-19 cases in the area near Stennis.

Prior to pausing test operations, engineers completed the modal test, the first of the eight tests in the Green Run series, to understand the vibration charateristics of the core stage. Now, work is slowly and methodically starting back, as workers return to prepare the facility and resume testing.

"The team connected the facility with the rocket earlier this year, both electrically and mechanically," said Ryan McKibben, Green Run test conductor at Stennis. "We are now preparing for the second test, which will power on the vehicle's avionics and the three computers that control the rocket's flight as it soars into space."

The avionics are distributed throughout the stage. Engineers at Marshall designed software similar to the flight software for Green Run. A special stage controller will be used to simulate the Launch Control Center operations that will control the actual launch at Kennedy Space Center in Florida.

"The core stage avionics along with Green Run software have successfully completed tests in our test laboratories at Marshall, said Lisa Espy, the core stage avionics lead at Marshall. "I am excited to see the flight systems come to life that will control the rocket as it sends the first Artemis mission to the Moon."

Above: The massive core stage for NASA's Space Launch System (SLS) rocket is in the B-2 Test Stand at NASA's Stennis Space Center near Bay St. Louis, Mississippi, for the core stage Green Run test series. (NASA)

Green Run tests minimize risk to the core stage and ensure the stage satisfies design objectives and validates design models:

  • Test 1- Modal Test: The first test in the Green Run series, a modal test was conducted in January. This test used shakers to impart dynamic forces on the suspended stage to identify primary bending modes of the stage. Information from the modal test will help engineers verify vehicle models needed for the operation of the rocket's guidance, navigation and control systems.

  • Test 2- Avionics: The rocket's avionics, which are distributed throughout the stage, will be turned on and checkout out. This includes not only flight computers and electronics that control the rocket but also those that collect flight data and monitor the overall health of the core stage.

  • Test 3- Fail-Safes: Engineers will check out all the safety systems that shut down operations during testing. To do this, they will simulate potential issues.

  • Test 4- Propulsion: This will be the first test of each of the main propulsion system components that connect to the engines. Command and control operations will be verified, and the core stage will be checked for leaks in fluid or gas.

  • Test 5- Thrust Vector Controls: Engineers will ensure that the thrust vector control system can move the four engines and check all the related hydraulic systems.

  • Test 6- Countdown: This test simulates the launch countdown, including step-by-step fueling procedures. Core stage avionics are powered on, and propellant loading and pressurization are simulated. The test team will exercise and validate the countdown timeline and sequence of events.

  • Test Case 7- "Wet" Dress Rehearsal: Engineers will demonstrate loading, controlling and draining more than 700,000 gallons of cryogenic propellants into the two test stand run tanks and then returning the stage to a safe condition.

  • Test Case 8- Hot Fire: The core stage's four RS-25 engines will operated for up to 8 minutes, generating 1.6 million pounds of thrust, the amount of thrust the engines produce at sea level on the launch pad at liftoff.
After the hot fire test, engineers will refurbish the core stage and configure it for its journey to Kennedy for launch preparations. The next time the RS-25 engines fire, the SLS will launch in an epic debut of Artemis I — the first in a series of increasingly complex missions that will enable human exploration to the Moon and Mars.

Robert Pearlman
Editor

Posts: 44772
From: Houston, TX
Registered: Nov 1999

posted 08-10-2020 10:22 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
Four Down, Four to Go: Artemis I Rocket Moves Closer to Hot Fire Test

The Space Launch System (SLS) rocket core stage for the Artemis I lunar mission has successfully completed its first four Green Run tests and is building on those tests for the next phase of checkout as engineers require more capability of the hardware before hot-firing the stage and its four powerful engines.

Green Run is a demanding series of eight tests and nearly 30 firsts: first loading of the propellant tanks, first flow through the propellant feed systems, first firing of all four engines, and first exposure of the stage to the vibrations and temperatures of launch.

"We are methodically bringing several complex systems to life and checking them out during the first seven tests," explained SLS Stages Manager Julie Bassler. "Then it is show time for the eighth test when we put it all together and fire up the rocket's core stage, just like we'll fire it up for the Artemis I launch to the Moon."

On Aug. 5, engineers at NASA's Stennis Space Center near Bay St Louis, Mississippi, where the stage is loaded into the B-2 Test Stand, completed the fourth of eight planned tests of the 212-foot-tall core stage. For Test 4, engineers performed the initial functional checkout of the main propulsion system components to verify command and control operability (valve response, timing, etc.) and performed leak checks on the core stage-to-facility umbilical fluid and gas connections.

"With test gases flowing through this many parts of a complex rocket stage, we expected the test team to encounter some issues," said Jonathan Looser, who manages the SLS core stage main propulsion system. "Historically, there's never been a NASA human-rated launch vehicle flown without one or more full-up tests before flight, and they have all encountered first-time issues. As expected, we found a few with valves and seals and addressed them, and now we're ready to complete the next four Green Run tests."

The Green Run testing series formally started in January with modal testing to verify computer models and support guidance and navigation control systems. In March, the test series was interrupted by a shutdown related to COVID-19 cases in Mississippi. When testing resumed in May with appropriate safety measures in place, the team completed Test 2, activation of computers, data collection health monitoring and other "avionics" that make up the brains and nervous system of the core stage. Test 3 was a check of the fail-safe systems that shut down the stage in a contingency situation. Each test builds on the prior test and is longer than the previous one, adding new hardware activations to those already completed.

For Test 4, functional and leak checks of the stage main propulsion systems and engines lasted three weeks. Engineers were able to conduct the test with gaseous nitrogen and helium, which is more efficient than using liquid hydrogen and oxygen propellants, which are only needed for the actual hot-fire test. As these gases flowed through systems, special instrumentation monitored for any leaks or poor connections.

Next up for the Green Run team is Test 5. It will ensure the stage thrust vector control system works correctly, which includes huge components that steer the four RS-25 engines, called actuators, and provides hydraulics to the engine valves.

Test 6 simulates the launch countdown to validate the countdown timeline and sequence of events. This includes the step-by-step fueling procedures in addition to the previous test steps of powering on the avionics and simulated propellant loading and pressurization.

As one final checkout before the full firing test, Test 7 is called the "wet dress rehearsal," meaning it builds on the simulations in Test 6 and includes fueling the rocket. After once again powering on the avionics, hydraulic systems, fail-safe systems, and other related systems that have been checked out in the prior six tests, the team will load, control, and drain more than 700,000 gallons of cryogenic, or super cold, propellants.

Only after passing these seven tests will it be time for Test 8, a full countdown and hot fire test for up to eight minutes. During the test, all four RS-25 engines will be firing at a full, combined 1.6 million pounds of thrust just as they will on the launch pad. Test 8 will be the final checkout to verify the stage is ready for launch. Afterward, engineers will prepare the stage for its trip to Kennedy Space Center in Florida.

"We want to find any issues here on the ground at Stennis, where we've added hundreds of special ground test sensors to the stage for Green Run," said Ryan McKibben, one of the Stennis Green Run test conductors. "We have great access to the stage on the B-2 Test Stand and have engineers and technicians on hand who are familiar with this stage."

By the time all eight Green Run tests are complete, Boeing, the prime contractor for the core stage, estimates it will collect 75-100 terabytes of data, not including voice and video data collected. And that's a lot of homework considering that all the data in the Library of Congress amounts to just 15 terabytes.

Robert Pearlman
Editor

Posts: 44772
From: Houston, TX
Registered: Nov 1999

posted 09-14-2020 06:11 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
Engineers Complete 5th Green Run Test of Space Launch System Core Stage

Engineers have completed the fifth of eight Green Run tests on the core stage of NASA's new Space Launch System (SLS) rocket, continuing progress toward a milestone hot fire test this fall.

Operators concluded a test of the stage's thrust vector control system on the historic B-2 Test Stand at NASA's Stennis Space Center near Bay St. Louis, Miss., on Sept. 13. The test provided critical verification of the control system and its related hydraulics as operators gimbaled the stage's four RS-25 engines just as they must move during flight to steer the rocket and maintain a proper trajectory.

The stage now is set for two more tests – a simulated countdown demonstration and wet dress rehearsal – directly leading to the hot fire of all four RS-25 engines, just as during an actual flight. In the countdown demonstration, engineers will simulate the launch countdown and procedures to validate the established timeline and sequence of events. In the wet dress rehearsal, engineers will conduct another countdown exercise and actually load, control and drain more than 700,000 gallons of cryogenic propellants to ensure all is set for the final test of the Green Run series.

The concluding test will activate all stage systems and fire the four RS-25 engines to generate the same combined 1.6 million pounds of thrust that will help launch the SLS rocket when it flies on its maiden Artemis I mission.

Robert Pearlman
Editor

Posts: 44772
From: Houston, TX
Registered: Nov 1999

posted 10-06-2020 10:52 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA release
NASA Moon Rocket Stage Passes Simulated Countdown Test

Engineers at NASA's Stennis Space Center near Bay St. Louis, Mississippi, completed a simulated launch countdown sequence on Oct. 5 for the sixth test of the eight-part core stage Green Run test series for NASA's Space Launch System (SLS) rocket.

During the simulated countdown, NASA engineers and technicians, along with prime contractors Boeing, and Aerojet Rocketdyne, monitored the stage to validate the timeline and sequence of events leading up to the test, which is similar to the countdown for the Artemis I launch.

The countdown sequence for an actual Artemis launch begins roughly two days prior to liftoff. In addition to all the procedures leading up to the ignition of the four RS-25 engines, the SLS core stage requires about six hours to fully load fuel into the two liquid propellant tanks.

The simulated countdown sequence test at Stennis began at the 48-hour mark as if the stage was first powered up before liftoff. Engineers then skipped ahead in the sequence to monitor the stage and procedures of the stage 10 minutes before the hot fire.

The simulated countdown sequence is one of the final tests of the SLS Green Run campaign. The series of tests is designed to gradually bring the rocket stage and all its systems to life for the first time.

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