Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-31-2020 04:52 PM
Please use this topic to discuss NASA's Space Launch System (SLS) Green Run test series, the top-to-bottom integrated testing of the core stage's systems prior to the SLS's maiden flight.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-31-2020 04:54 PM
From NASA Administrator Jim Bridenstine, via Twitter:
The first test in the Green Run series of the Artemis I Space Launch System Core Stage COMPLETE at Stennis Space Center. Data from this modal testing will be used to verify critical flight control parameters and structural models.
oly Member
Posts: 1450 From: Perth, Western Australia Registered: Apr 2015
posted 02-24-2020 06:26 PM
Are there any image or data releases from the first green run test as of yet?
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 02-24-2020 06:54 PM
The "modal test" does not sound like it was very photogenic. As I understand it, it involved lifting the core stage with a crane so that it was isolated from the stand and then striking with a metal hammer-like device so that the sensors installed on the stage recorded the frequency generated.
If correct, this type of test and its data are generally not something meriting a public release.
oly Member
Posts: 1450 From: Perth, Western Australia Registered: Apr 2015
posted 02-25-2020 01:49 AM
Thanks Robert, yes, the modal tests are where they ring the vehicle like a bell to determining the vehicles natural frequencies so that such data can be used in subsequent tests. I thought it would be interesting to observe such tests in progress.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 05-21-2020 08:05 AM
NASA has released this photo from the first modal test:
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.
Headshot Member
Posts: 1221 From: Vancouver, WA, USA Registered: Feb 2012
posted 05-21-2020 10:24 AM
Is there a schedule of the test cases with tentative dates for the seven remaining test cases?
I am wondering if there is any audio recording of the first test? My imagination tells me the core stage rang like a bell for all of Stennis to hear. I am certain that reality was probably far less dramatic.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 05-21-2020 10:56 AM
I am not aware of a schedule. At a recent NASA Advisory Committee meeting, it was said the final test, the hot fire, will likely be in the Thanksgiving-ish timeframe this year.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 07-15-2020 11:50 AM
Boeing's Space Launch System manager John Shannon said today (July 16) that a wet dress rehearsal is planned for September, followed by the full duration hot fire test in October.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 08-06-2020 11:30 AM
From NASA Administrator Jim Bridenstine (via Twitter):
Progress! The fourth test of the Space Launch System core stage Green Run test series is complete. Teams finished testing the main propulsion system components within the core stage that connect to the rocket's four RS-25 engines on August 5.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 10-13-2020 09:20 AM
Per John Shannon, Boeing's vice president and program manager for the Space Launch System, in a call with reporters today, the wet dress rehearsal (loading the core stage with propellants) is targeted for Oct. 30 and the hotfire is targeted for Nov. 14.
The core stage would then ship to the Kennedy Space Center to be prepared for the Artemis I mission on or before Jan. 14, 2021.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 10-28-2020 02:26 PM
NASA update on the Green Run testing status:
NASA is progressing through the Green Run test series for the Space Launch System (SLS) rocket at the agency's Stennis Space Center in Mississippi and has completed six of the eight tests. The team is preparing to stand down for another tropical weather system that is heading to the area.
The pause in work comes ahead of the most complex tests: wet dress rehearsal, when propellant will be loaded for the first time, and hot fire, when all four engines will be fired and every system within the stage will operate. During the pause, engineers will continue to assess data from recent tests to ensure the team is ready to proceed to the next phase of testing.
Green Run testing is a complex series of tests to methodically and thoroughly check all the rocket’s core stage systems together for the first time to ensure the stage is ready for flight. NASA will provide an update on adjusted dates for the Green Run wet dress rehearsal and hot fire tests after the storm has passed.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 11-06-2020 07:41 PM
NASA update on the Green Run testing status:
NASA has conducted an initial assessment of the impact from Hurricane Zeta at the agency's Stennis Space Center near Bay St. Louis, Mississippi and Michoud Assembly Facility in New Orleans.
While storm appraisals are continuing, teams have determined that Stennis did sustain some damage on the center, but the B-2 test stand and the Space Launch System (SLS) rocket's core stage for Artemis I, currently in the stand, were not damaged. Michoud experienced damage to the outside and roof of buildings, but there is no damage to the SLS rocket or Orion spacecraft hardware being manufactured at the facility.
Widespread power outages in the area have made assessments difficult at both locations, and some buildings are still without power. While no personal injuries have been reported by NASA employees, many team members are also still without power, have experienced damage to personal property, and have not been able to return to work. Despite stopping work for the pandemic, as well as six Gulf Coast storms, and while working under pandemic-imposed restrictions, NASA and contractors Boeing and Aerojet Rocketdyne continue to make progress on Green Run testing of the SLS core stage at Stennis.
NASA has completed six of the eight core stage Green Run tests and is in the final stage of testing, which will operate the entire stage and its propulsion systems together for the first time.
During the pause of on-site work due to the storm, engineers were able to take a closer look at data from recent testing. The team identified one of eight valves, which supply liquid hydrogen to the RS-25 engines, had inconsistent performance during recent tests. The valve is called a prevalve and is part of the core stage main propulsion system.
NASA conducts ground testing on the core stage to demonstrate it is ready for flight, and the expert team of problem solvers is prepared to resolve any issues. Engineers have inspected the valve, understand the reason it is not working properly, and plan to repair the valve while the core stage remains in the B-2 test stand. Following a successful repair, the team plans to conduct the Green Run wet dress rehearsal and hot fire testing before the end of the year.
Headshot Member
Posts: 1221 From: Vancouver, WA, USA Registered: Feb 2012
posted 11-07-2020 11:13 AM
I assume that subsequent SLS core stages will not undergo the same rigorous Green Run tests as this first stage. Is there going to be a plan implemented to search for potential prevalve anomalies in future core stages and will it be Boeing's or NASA's responsibility?
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 11-18-2020 08:49 PM
NASA update
Engineers Move Forward with SLS Green Run Testing, Valve Repair Complete
Over the weekend, engineers at NASA's Stennis Space Center near Bay St. Louis, Mississippi, successfully repaired a valve inside the core stage of the agency's Space Launch System (SLS) rocket. The team designed an innovative tool to remove and replace the valve's faulty clutch while the core stage remained in the B-2 test stand, and without removing the entire valve. Subsequent testing of the repaired valve confirmed that the system is operating as intended.
This week, the team is preparing for the seventh Green Run test, called the wet dress rehearsal, when the stage will be loaded with cryogenic, or super-cold, propellant for the first time. NASA is now targeting the week of Dec. 7 for the wet dress rehearsal and the week of Dec. 21 for the hot fire test. During the hot fire test, all four engines will fire to simulate the stage's operation during launch. The Green Run test series is a comprehensive test of the rocket's core stage before it launches Artemis missions to the Moon. NASA remains on track to launch Artemis I by November 2021.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 12-04-2020 12:53 PM
Per NASA, the wet dress rehearsal will begin Saturday (Dec. 5) and take place over several days.
Engineers will power up all the core stage systems and load and drain more than 700,000 gallons of cryogenic, or supercold, propellant into the tanks for the first time.
Following the completion of the wet dress rehearsal, NASA will set a date for the hot fire test. During the hot fire test, all four engines will fire to simulate the stage's operation during launch.
Blackarrow Member
Posts: 3604 From: Belfast, United Kingdom Registered: Feb 2002
posted 12-04-2020 04:06 PM
When the fuel and oxidiser for this test has been removed after the test, is it all "thrown away" or is it stored for use during the actual hot-firing test?
Would filling the tanks and then draining them not produce minute amounts of contaminant flaking off the interiors of pipes, tanks and from insulation? Would that not make the fuel and oxidiser slightly less "clean" if used later? Or does the system tolerate a tiny amount of contaminants?
Headshot Member
Posts: 1221 From: Vancouver, WA, USA Registered: Feb 2012
posted 12-23-2020 01:03 PM
Whenever it occurs, will Test #8, the hot fire test, be broadcast live on NASA television?
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 12-23-2020 01:39 PM
Yes, at last word from NASA, the hot fire will be broadcast live.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-05-2021 07:03 PM
NASA is targeting the final test in the Green Run series, the hot fire, for as early as Jan. 17.
NASA conducted the seventh test of the SLS core stage Green Run test series – the wet dress rehearsal – on Dec. 20 ...
The end of the test was automatically stopped a few minutes early due to timing on a valve closure. Subsequent analysis of the data determined the valve's predicted closure was off by a fraction of a second, and the hardware, software, and stage controller all performed properly to stop the test. The team has corrected the timing and is ready to proceed with the final test of the Green Run series.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-11-2021 06:00 PM
NASA is now targeting Saturday, Jan. 16, for the Green Run hot fire test. A pre-test news briefing will stream online at 1 p.m. EST on Tuesday (Jan. 12).
Participating in the briefing are:
John Honeycutt, SLS program manager, NASA's Marshall Space Flight Center
Julie Bassler, SLS stages manager, Marshall
Ryan McKibben, Green Run test conductor, Stennis
John Shannon, vice president and SLS program manager, Boeing
Jeff Zotti, RS-25 program director at Aerojet Rocketdyne
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-13-2021 09:50 AM
NASA is targeting a two-hour test window that opens at 5 p.m. EST on Saturday (Jan. 16), for the hot fire test of NASA's Space Launch System (SLS) rocket core stage at the Stennis Space Center in Mississippi.
Live coverage will begin at 4:20 p.m. EST on NASA Television and the agency's website, followed by a post-test briefing approximately two hours after the test concludes.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-16-2021 10:16 AM
NASA update
Test team gives 'Go' to proceed with tanking
The test team conducted a pre-test briefing in the Test Control Center at the B test complex at NASA's Stennis Space Center near Bay St. Louis, Mississippi, and gave a "go" to proceed with testing and to fill the propellant tanks.
Over the next several hours, the teams will monitor the systems and load more than 700,000 gallons of cryogenic, or supercooled, liquid oxygen and liquid hydrogen that will be fed to the four RS-25 engines.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-16-2021 01:45 PM
NASA update
Because test preparation is running ahead of schedule, NASA TV coverage will begin at 3:20 p.m. EST for a test start time of 4 p.m.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-16-2021 04:32 PM
The planned 485-second hot fire lasted about 60 seconds before an early shutdown. Prior to the test, Boeing SLS program manager John Shannon said that at least 250 seconds were needed for the test to be a success.
Just before the shutdown, there was a call out of an "MCF on engine 4," though all four engines appeared to be still firing (at the time). From former space shuttle flight diretor Wayne Hale (via Twitter):
Well MCF was not a call this ascent flight director ever wanted to hear: Major Component Failure is detected by the SSME controller.
posted 01-16-2021 07:00 PM
An educated guess that they have to do it again.
OV-105 Member
Posts: 901 From: Ridgecrest, CA Registered: Sep 2000
posted 01-17-2021 01:20 AM
Don’t know if it is the lighting but the exhaust on the right engine in the photo doesn’t look as clean as the others, wonder if that is any indication.
Posts: 3604 From: Belfast, United Kingdom Registered: Feb 2002
posted 01-18-2021 08:58 AM
It occurs to me that the only premature shutdown of an SSME in flight was the fault of (from memory) a temperature sensor, not the engine itself. If NASA is saying that all four engines are in good shape, might that not suggest over-zealous sensors or software?
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-19-2021 09:40 AM
From a NASA update released today:
During gimballing, the hydraulic system associated with the core stage's power unit for Engine 2, also known as engine E2056, exceeded the pre-set test limits that had been established. As they were programmed to do, the flight computers automatically ended the test. The specific logic that stopped the test is unique to the ground test when the core stage is mounted in the B-2 test stand at Stennis. If this scenario occurred during a flight, the rocket would have continued to fly using the remaining CAPUs to power the thrust vector control systems for the engines.
During the test, the functionality of shutting down one CAPU and transferring the power to the remaining CAPUs was successfully demonstrated. This gimballing test event that resulted in shutting down the CAPU was an intentionally stressing case for the system that was intended to exercise the capabilities of the system. The data is being assessed as part of the process of finalizing the pre-set test limits prior to the next usage of the core stage...
Initial data indicate the sensor reading for a major component failure, or MCF, that occurred about 1.5 seconds after engine start was not related to the hot fire shutdown.
Blackarrow Member
Posts: 3604 From: Belfast, United Kingdom Registered: Feb 2002
posted 01-23-2021 10:07 AM
As a non-engineer, I realise that the following question might make engineers roll their eyes, but please bear with me: Obviously, nothing lasts for ever. A SSME has a design life, which implies that if you use it for long enough, it must eventually fail. If a SSME has a tiny, sub-microscopic flaw that is too small to be spotted in any scans or inspections, but will eventually end that engine's life earlier than expected, then surely if you keep testing it to make sure it doesn't have any faults, you bring forward the day when that fault manifests itself?
Putting that into simpler (and hopefully not too simplistic) terms: if any one of those four SSMEs on the core stage has another 12 minutes of life left, it might not be a good idea to do a further "Green Run" test of 8 minutes in case that engine "has its moment" half-way to orbit on the real Artemis 1 mission.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 01-23-2021 10:15 AM
The SSMEs had a lifetime rating of 27,000 seconds, or roughly 55 missions. Of the four engines on the core stage, the most that one has been used is for 12 missions. Even with the RS-25 expendable modifications and static hot fires, the engines are no where near the end of their design life.
The engines were designed with the knowledge they would be put through multiple hot fires.
Blackarrow Member
Posts: 3604 From: Belfast, United Kingdom Registered: Feb 2002
posted 01-24-2021 11:22 AM
That is certainly reassuring, as is NASA's explanation for the premature shutdown. It doesn't really address my hypothetical situation, but we obviously can't go through life basing decisions on worst case scenarios.
It was much easier with the Saturn V. It wasn't that I discounted the possibility of a catastrophic failure during a launch to the moon. It just never occurred to me that a Saturn V might fail. Of course, I was barely 14 when Apollo 8 was launched.
GACspaceguy Member
Posts: 2954 From: Guyton, GA Registered: Jan 2006
posted 01-24-2021 12:44 PM
quote:Originally posted by Blackarrow: If a SSME has a tiny, sub-microscopic flaw that is too small to be spotted in any scans or inspections, but will eventually end that engine's life earlier than expected...
What you describe here is the science of metallurgy and metal fatigue. Rest assured that your scenario is taken into account during design and analysis. Then a safety factor is applied that for aircraft is four times the expected life. I am sure it is even more for a rocket engine.
Jim Behling Member
Posts: 1815 From: Cape Canaveral, FL Registered: Mar 2010
posted 01-24-2021 07:45 PM
quote:Originally posted by Blackarrow: It was much easier with the Saturn V...
Not really, the same situation applies to the Saturn V. Its non "reusable" engines had an even shorter life and they were test still fired multiple times, singly and on stages, which used up some their remaining "life."
Blackarrow Member
Posts: 3604 From: Belfast, United Kingdom Registered: Feb 2002
posted 01-25-2021 08:03 AM
Jim, we're slightly at cross-purposes on this. It WAS much easier for me, as a 14-year-old who believed that NASA could do no wrong, to take it for granted that the Saturn V would always succeed in launching its crews to the moon. It's only as I got older and, I hope, wiser and more knowledgeable, that I realised that complex machines like rocket engines can and do actually fail (even if they are designed not to!).
However, I appreciate your comment about metallurgy and metal fatigue, which builds on Robert's earlier comment.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
The Green Run team scrutinized data from the first hot fire test and determined that a second hot fire lasting approximately at least 4 minutes would provide significant data to help verify the core stage is ready for flight.
oly Member
Posts: 1450 From: Perth, Western Australia Registered: Apr 2015
posted 01-29-2021 09:26 PM
Until the SLS core stage completes a successful full duration test, each failed test brings the structure closer to its design fatigue limit. I hope that there is not another mid-test shutdown and delay to the program.
Robert Pearlman Editor
Posts: 50516 From: Houston, TX Registered: Nov 1999
posted 02-17-2021 10:18 AM
NASA is targeting Thursday, Feb. 25, for the hot fire. The date will be confirmed following a test readiness review later this week.