NASA confirms EUS for SLS Block IB design and EM-2 flight

[jarmumd]

It could go well, we have to see.  But you are wrong to state that: "They have already demonstrated transfer of cryogenic propellants between tanks on-orbit, and docking is well proven."  They have demonstrated nothing that we know of, because none of it is public.

There's a NASA paper (public) on the transfer between tanks demo. It definitely happened.

Not exactly a paper, but a presentation: In-Space Cryogenic Propellant Transfer: Modeling and Validation of Two-Phase Flow Dynamics in Low-Gravity, it has a lot of technical details wrt the test.

I stand corrected.  I apologize for the dart, and appreciate the information.  I forgot about the presentation, and had a beer too many to keep me from posting.

[nethegauner_reloaded]

Now I'm confused.  I thought the point of Block 2 and EUS was to put co-manifested payloads in orbit, specifically gateway. 

it can and I-HAB is to be delivered by it.

As well as ESA's refueller module — and I understand, the UAE airlock also.

[CoolScience]

Before I reply to the rest of this message, I want to thank you for acknowledging your mistake, which for some reason is rare for people to do so I want to say this right up front.

And which flight is the milestone of an uncrewed test flight of the EUS? No amount of analysis can substitute for a real world test of a complex system, and launch of a new stage simply should not be done with crew aboard. LAS is not something to rely solely on, so please don't waste time with an argument like that.

Not to jump in here, but we launched Shuttle for the first time with crew.  All rockets launch successfully with analysis.  Testing validates simulation, it doesn't validate success.

There is a lot to unpack there, and you just demonstrated a misunderstanding that is super important to clarify. Some of what I am about to say might not be new to you but I think this is important to clarify for anyone reading this who works in engineering or even with people who do engineering of complex systems in any capacity.

To start with the shuttle and STS-1, and I should preface this by saying I loved the shuttle, like any spaceflight fan I know, but also it had serious problems, and some of the best things about the shuttle are things it taught us, like that reuse of solid rocket boosters has limited benefit, and the importance of optimizing the heat shield of a reusable entry vehicle for refurbishment cost.

They had no choice except to launch STS-1 with crew because the shuttle was not designed in a way that allowed for a fully autonomous flight. Many reasons for this including limitations of 1970s technology, but if they had a choice crewed first flight should not have been done. This also ended up as the perfect demonstration of why this is a bad idea, as there were potentially catastrophic issues that occurred during the flight. (wikipedia has a summary of some issues.)

Saying that all rockets launch successfully with analysis is simply untrue, as in this context it implies that analysis alone can ensure a safe launch. Somewhere around half of first launches of a rocket fail. which trivially shows that analysis alone is not good enough. Shuttle again provides a good example of how analysis does not actually prove safety. The failure modes that killed crews weren't things that any safety estimate would normally account for (such as management operating the system outside of its operating parameters, combined with a design flaw where it was actually making use of a redundancy on every flight and no one knew.)

Testing sometimes can be used to validate a simulation. It can also be used to determine answers that cannot be simulated in a practical way. More flight-like tests are better but are not always doable. For example a satellite could have a requirement to survive the on-orbit radiation environment for five years. The only true way to prove that is to have it put it in orbit operating and wait 5 years. A combination of analysis and accelerated ground tests usually would be used instead, depending on the system details, but the final test is still it operating on-orbit. Analysis only ever approximates reality, and while important the one and only final test of a system is it actually operating as designed while performing its mission. Success is only validated by operational tests. anything short of that (including ground tests of satellites, rockets, etc.) is simply not complete proof.

This applies to human rated systems and not, but when the system is critical for the safety of humans, it should be operationally tested without humans present.

It could go well, we have to see.  But you are wrong to state that: "They have already demonstrated transfer of cryogenic propellants between tanks on-orbit, and docking is well proven."  [Edited for my ignorance]  The scale of what they are doing, and they way they are doing has never been done before, don't make it trivial.  Further, docking on that scale, with that system has never been done before.  Their system is so large it can't even be tested at full scale on the ground, which is something we always do.  We can't even test interactions between slosh and docking unless it's on orbit for the first time ever.

Scale is not on its own a description of a technical issue that needs to be solved, or a problem that could occur.

"tested at full scale on the ground, which is something we always do." What "we" are you talking about here? Ground tests should be done to the extent practical, but nothing in space is fully tested until it flies. There will always be things that aren't fully tested on the ground and flight is the real test. SpaceX is demonstrating how to avoid getting trapped in analysis paralysis on the ground and go just get the real answers. There are no humans on board the first tests, it doesn't matter if it doesn't work the first time, but there is no reason to think it won't get working quickly. That is what happens when you design a system for low costs and frequent uses.

But stop reducing the tremendous amount of work that went into SLS (so they they could launch, orbit the moon, and land successfully on the first attempt).

I am not "reducing" the amount of work that went into SLS/Orion. 10s of billions of dollars too much worth of work went into them, with only 1 flight test that still revealed problems. They are not capable of a sufficient flight rate for safety or useful work, and they are too expensive as well, just to name the biggest problems.

[jarmumd]

I also want to say that I appreciate good discussion.

Before I reply to the rest of this message, I want to thank you for acknowledging your mistake, which for some reason is rare for people to do so I want to say this right up front.

Saying that all rockets launch successfully with analysis is simply untrue, as in this context it implies that analysis alone can ensure a safe launch. Somewhere around half of first launches of a rocket fail. which trivially shows that analysis alone is not good enough. Shuttle again provides a good example of how analysis does not actually prove safety. The failure modes that killed crews weren't things that any safety estimate would normally account for (such as management operating the system outside of its operating parameters, combined with a design flaw where it was actually making use of a redundancy on every flight and no one knew.)

Testing sometimes can be used to validate a simulation. It can also be used to determine answers that cannot be simulated in a practical way. More flight-like tests are better but are not always doable. For example a satellite could have a requirement to survive the on-orbit radiation environment for five years. The only true way to prove that is to have it put it in orbit operating and wait 5 years. A combination of analysis and accelerated ground tests usually would be used instead, depending on the system details, but the final test is still it operating on-orbit. Analysis only ever approximates reality, and while important the one and only final test of a system is it actually operating as designed while performing its mission. Success is only validated by operational tests. anything short of that (including ground tests of satellites, rockets, etc.) is simply not complete proof.

I say this as someone who has worked many, years in loads and dynamics for launch vehicles early in my career.  Yes, rockets are tested.  But to design them, to ensure that they can meet qualifications, that's done in simulation.  Preferably test validated simulation, but sometimes it's all analytic.  Case in point, SLS modal test was done at the VAB for cost.  As opposed to Saturn 5 and Shuttle tested at MSFC.

Normal docking tests are done for real at JSC's SDTS facility.  Failure cases, which make up the bulk of the work to approve a docking system cannot be tested practically and are only done analytically.  The one exception I can think of was NDS-B1 did a test of the emergency release at the end of testing.  Analysis by test correlated models is what provides margin so that we can approve mechanisms for use.

"tested at full scale on the ground, which is something we always do." What "we" are you talking about here? Ground tests should be done to the extent practical, but nothing in space is fully tested until it flies.

We is the Commercial and NASA Docking community.  Every docking system used for human spaceflight has been tested on the ground first.  You cannot wait until it's in space to find out if it's right.  You do a battery of tests, validate models, analyze where appropriate.  This is what SpaceX will do as well, I'm making the point that they are further away from norms than typical.  But, like the example I gave before with modal testing of SLS, it's likely that with enough analysis, they can get away without full testing.

But stop reducing the tremendous amount of work that went into SLS (so they they could launch, orbit the moon, and land successfully on the first attempt).

I am not "reducing" the amount of work that went into SLS/Orion. 10s of billions of dollars too much worth of work went into them, with only 1 flight test that still revealed problems. They are not capable of a sufficient flight rate for safety or useful work, and they are too expensive as well, just to name the biggest problems.

I agree they are very expensive, and I think contracting and contractors play a big role in that.  But be weary that despite SLS cost and delays, it's the only vehicle of it's size and human rated.  I believe many others will match that class and human rating, but just be aware they aren't there yet, and we need to see what the final cost is.

[CoolScience]

Success is only validated by operational tests. anything short of that (including ground tests of satellites, rockets, etc.) is simply not complete proof.

I say this as someone who has worked many, years in loads and dynamics for launch vehicles early in my career.  Yes, rockets are tested.  But to design them, to ensure that they can meet qualifications, that's done in simulation.  Preferably test validated simulation, but sometimes it's all analytic.  Case in point, SLS modal test was done at the VAB for cost.  As opposed to Saturn 5 and Shuttle tested at MSFC.

Normal docking tests are done for real at JSC's SDTS facility.  Failure cases, which make up the bulk of the work to approve a docking system cannot be tested practically and are only done analytically.  The one exception I can think of was NDS-B1 did a test of the emergency release at the end of testing.  Analysis by test correlated models is what provides margin so that we can approve mechanisms for use.

I kept the most important part of my quote that you seem to have missed the point of. You use models and analysis to design so that something has a good chance of working, but it never is enough on its own. For example, if a supplier has an unreliable process and a small percentage of struts are defective and have lower strength than expected, worse than the standard factor of safety used in the design, then the system will still catastrophically fail. (This is of course a real example from Falcon 9.) The only way to have complete confidence in a system is to actually use the system.

You cannot know that your models are good enough or complete enough. Thinking otherwise is a dangerous type of arrogance for engineers. It is the type of organizational arrogance that led to the space shuttle disasters.

"tested at full scale on the ground, which is something we always do." What "we" are you talking about here? Ground tests should be done to the extent practical, but nothing in space is fully tested until it flies.

We is the Commercial and NASA Docking community.  Every docking system used for human spaceflight has been tested on the ground first.  You cannot wait until it's in space to find out if it's right.  You do a battery of tests, validate models, analyze where appropriate.  This is what SpaceX will do as well, I'm making the point that they are further away from norms than typical.  But, like the example I gave before with modal testing of SLS, it's likely that with enough analysis, they can get away without full testing.

You cannot know if something is right until it is in space. SpaceX is not doing anything away from the norms. Claiming otherwise is an insult to SpaceX engineers, as you are not citing any actual problem with what they are doing. The only thing they are doing different than historically, is that they are allowing for more and earlier flight tests. The reason for this difference is that they have reduced the costs enough that they can afford to do more thorough on-orbit testing, where it is ok if it doesn't work the first time, they can just repeat the test. As long as consequences of failure are small enough, more complete testing earlier in the development is better. Some in the space industry seem to have forgotten this due to the high confidence before a first test that historically has been required due to the expense of building and launching another copy of a system in the case of problems.

SLS/Orion (They are for all relevant purposes a combined system) is what is blatantly violating the norms by planning to put astronauts on the first flight of EUS, and by making a change to heat shield material on Orion because of its poor performance on the previous test flight, but putting astronauts on the next mission anyway. This ultimately is driven by the cost and schedule problems with the system that do not allow for testing that absolutely must be done for safety, and management allowing those concerns to override safety.

You say that "it's likely with enough analysis, they can get away without full testing." This is again the type of inappropriate logic that leads to astronaut deaths. SpaceX will be doing full testing, they just may do less of it on the ground, because they can afford to do more of it in flight. The more flight-like a test, the better, and nothing is more flight-like than flight. SLS simply is not doing full testing, and that is simply not acceptable, no amount of analysis changes that. (There are of course always risks you have to accept at some point for things that logically can't be tested before the full up mission with humans, but launching a stage unmanned or a flight-tested heat shield aren't on that list.)

I am not "reducing" the amount of work that went into SLS/Orion. 10s of billions of dollars too much worth of work went into them, with only 1 flight test that still revealed problems. They are not capable of a sufficient flight rate for safety or useful work, and they are too expensive as well, just to name the biggest problems.

I agree they are very expensive, and I think contracting and contractors play a big role in that.  But be weary that despite SLS cost and delays, it's the only vehicle of it's size and human rated.  I believe many others will match that class and human rating, but just be aware they aren't there yet, and we need to see what the final cost is.

It is not human rated according to general standards, as significant problems with a critical system on the previous test mean that it is not proven. Even without that, SLS itself is only good for 2 more flights before it loses its human rating by changing out a stage. A change like that without a flight test is simply not consistent with the basic principles of human safety.

[Coastal Ron]

I agree they are very expensive, and I think contracting and contractors play a big role in that.  But be weary that despite SLS cost and delays, it's the only vehicle of it's size and human rated.  I believe many others will match that class and human rating, but just be aware they aren't there yet, and we need to see what the final cost is.

Not getting into the middle of the rest of the conversation, but I did want to respond to this comment you made, especially the part I bolded.

For a long time SLS supporters have been pointing out that the SLS is "the only" vehicle certified and available, yet NASA uses different rules for itself than for other launch providers regarding the potential safety of the SLS for human use. And sure, NASA claims that is because they are themselves in charge of the design of the SLS, but we have two Shuttle accidents that prove that NASA is not immune from making critical errors in judgement. Putting humans on top of the 2nd SLS to launch is a huge risk, and one that is driven by politics, not good science.

As to the "only vehicle of its size" part, that is irrelevant. We could have returned humans to the Moon using our existing fleet of commercial launchers, and ULA even released a study back in 2009 to support such a plan. From the summary page:

The use of smaller, commercial launchers coupled with orbital depots eliminates the need for a large launch vehicle. Much is made of the need for more launches- this is perceived as a detriment. However since 75% of all the mass lifted to low earth orbit is merely propellant with no intrinsic value it represents the optimal cargo for low-cost, strictly commercial launch operations. These commercial launch vehicles, lifting a simple payload to a repeatable location, can be operated on regular, predictable schedules. Relieved of the burden of hauling propellants, the mass of the Altair and Orion vehicles for a lunar mission is very small and can also be easily carried on existing launch vehicles. This strategy leads to high infrastructure utilization, economic production rates, high demonstrated reliability and the lowest possible
costs.

Building the SLS has never been about space exploration, because we have never needed the SLS for human space exploration. Building the SLS has always been about spending money in the right states and with the right companies.

Continuing the build the SLS will not result in America being in better shape for science and political goals, and investing in the EUS is just more money to be thrown away or turned into expensive museum displays...

[jarmumd]

Success is only validated by operational tests. anything short of that (including ground tests of satellites, rockets, etc.) is simply not complete proof.

I say this as someone who has worked many, years in loads and dynamics for launch vehicles early in my career.  Yes, rockets are tested.  But to design them, to ensure that they can meet qualifications, that's done in simulation.  Preferably test validated simulation, but sometimes it's all analytic.  Case in point, SLS modal test was done at the VAB for cost.  As opposed to Saturn 5 and Shuttle tested at MSFC.

Normal docking tests are done for real at JSC's SDTS facility.  Failure cases, which make up the bulk of the work to approve a docking system cannot be tested practically and are only done analytically.  The one exception I can think of was NDS-B1 did a test of the emergency release at the end of testing.  Analysis by test correlated models is what provides margin so that we can approve mechanisms for use.

I kept the most important part of my quote that you seem to have missed the point of. You use models and analysis to design so that something has a good chance of working, but it never is enough on its own. For example, if a supplier has an unreliable process and a small percentage of struts are defective and have lower strength than expected, worse than the standard factor of safety used in the design, then the system will still catastrophically fail. (This is of course a real example from Falcon 9.) The only way to have complete confidence in a system is to actually use the system.

You cannot know that your models are good enough or complete enough. Thinking otherwise is a dangerous type of arrogance for engineers. It is the type of organizational arrogance that led to the space shuttle disasters.

"tested at full scale on the ground, which is something we always do." What "we" are you talking about here? Ground tests should be done to the extent practical, but nothing in space is fully tested until it flies.

We is the Commercial and NASA Docking community.  Every docking system used for human spaceflight has been tested on the ground first.  You cannot wait until it's in space to find out if it's right.  You do a battery of tests, validate models, analyze where appropriate.  This is what SpaceX will do as well, I'm making the point that they are further away from norms than typical.  But, like the example I gave before with modal testing of SLS, it's likely that with enough analysis, they can get away without full testing.

You cannot know if something is right until it is in space. SpaceX is not doing anything away from the norms. Claiming otherwise is an insult to SpaceX engineers, as you are not citing any actual problem with what they are doing. The only thing they are doing different than historically, is that they are allowing for more and earlier flight tests. The reason for this difference is that they have reduced the costs enough that they can afford to do more thorough on-orbit testing, where it is ok if it doesn't work the first time, they can just repeat the test. As long as consequences of failure are small enough, more complete testing earlier in the development is better. Some in the space industry seem to have forgotten this due to the high confidence before a first test that historically has been required due to the expense of building and launching another copy of a system in the case of problems.

SLS/Orion (They are for all relevant purposes a combined system) is what is blatantly violating the norms by planning to put astronauts on the first flight of EUS, and by making a change to heat shield material on Orion because of its poor performance on the previous test flight, but putting astronauts on the next mission anyway. This ultimately is driven by the cost and schedule problems with the system that do not allow for testing that absolutely must be done for safety, and management allowing those concerns to override safety.

You say that "it's likely with enough analysis, they can get away without full testing." This is again the type of inappropriate logic that leads to astronaut deaths. SpaceX will be doing full testing, they just may do less of it on the ground, because they can afford to do more of it in flight. The more flight-like a test, the better, and nothing is more flight-like than flight. SLS simply is not doing full testing, and that is simply not acceptable, no amount of analysis changes that. (There are of course always risks you have to accept at some point for things that logically can't be tested before the full up mission with humans, but launching a stage unmanned or a flight-tested heat shield aren't on that list.)

I am not "reducing" the amount of work that went into SLS/Orion. 10s of billions of dollars too much worth of work went into them, with only 1 flight test that still revealed problems. They are not capable of a sufficient flight rate for safety or useful work, and they are too expensive as well, just to name the biggest problems.

I agree they are very expensive, and I think contracting and contractors play a big role in that.  But be weary that despite SLS cost and delays, it's the only vehicle of it's size and human rated.  I believe many others will match that class and human rating, but just be aware they aren't there yet, and we need to see what the final cost is.

It is not human rated according to general standards, as significant problems with a critical system on the previous test mean that it is not proven. Even without that, SLS itself is only good for 2 more flights before it loses its human rating by changing out a stage. A change like that without a flight test is simply not consistent with the basic principles of human safety.

As someone who does spacecraft loads and dynamics and docking dynamics, and has put human rated hardware in space...  I think we are talking past each other.  We approve systems based upon correlated models and simulations.  That correlation comes from real world testing of parts, components, and systems.  Often we cannot test everything altogether and we have to test parts separately.  Orbital operations can be used to adjust models based upon flight data, but we don't do operations unless we are confident in our models in the first place.

[jarmumd]

I agree they are very expensive, and I think contracting and contractors play a big role in that.  But be weary that despite SLS cost and delays, it's the only vehicle of it's size and human rated.  I believe many others will match that class and human rating, but just be aware they aren't there yet, and we need to see what the final cost is.

Not getting into the middle of the rest of the conversation, but I did want to respond to this comment you made, especially the part I bolded.

For a long time SLS supporters have been pointing out that the SLS is "the only" vehicle certified and available, yet NASA uses different rules for itself than for other launch providers regarding the potential safety of the SLS for human use. And sure, NASA claims that is because they are themselves in charge of the design of the SLS, but we have two Shuttle accidents that prove that NASA is not immune from making critical errors in judgement. Putting humans on top of the 2nd SLS to launch is a huge risk, and one that is driven by politics, not good science.

As to the "only vehicle of its size" part, that is irrelevant. We could have returned humans to the Moon using our existing fleet of commercial launchers, and ULA even released a study back in 2009 to support such a plan. From the summary page:

The use of smaller, commercial launchers coupled with orbital depots eliminates the need for a large launch vehicle. Much is made of the need for more launches- this is perceived as a detriment. However since 75% of all the mass lifted to low earth orbit is merely propellant with no intrinsic value it represents the optimal cargo for low-cost, strictly commercial launch operations. These commercial launch vehicles, lifting a simple payload to a repeatable location, can be operated on regular, predictable schedules. Relieved of the burden of hauling propellants, the mass of the Altair and Orion vehicles for a lunar mission is very small and can also be easily carried on existing launch vehicles. This strategy leads to high infrastructure utilization, economic production rates, high demonstrated reliability and the lowest possible
costs.

Building the SLS has never been about space exploration, because we have never needed the SLS for human space exploration. Building the SLS has always been about spending money in the right states and with the right companies.

Continuing the build the SLS will not result in America being in better shape for science and political goals, and investing in the EUS is just more money to be thrown away or turned into expensive museum displays...

Look I get it, you don't like SLS.  And I agree that SLS is very expensive and has taken too long.  I'm also saying keep track of the cost to get that size vehicle+human rated.  It's not that we have to do it that way, and I'm not saying that's the best way to do it.  I'm saying keep track of the cost and schedule when these new vehicles are human rated and launching.

[pochimax]

I just want to add to the interesting debate that the EUS stage will be tested in a full ground ignition, the Green Run.

[Coastal Ron]

...
Building the SLS has never been about space exploration, because we have never needed the SLS for human space exploration. Building the SLS has always been about spending money in the right states and with the right companies.

Continuing the build the SLS will not result in America being in better shape for science and political goals, and investing in the EUS is just more money to be thrown away or turned into expensive museum displays...

Look I get it, you don't like SLS.

I don't like taxpayer money wasted, and I don't like NASA forced to go down a path that doesn't make it easier and less costly to expand humanity out into space. And as it turns out, the SLS program qualifies for all of that.

And I agree that SLS is very expensive and has taken too long.

Doing things that have never been done before means that it is not unusual for costs and schedules to exceed their initial estimates. This is NOT related to why the SLS (and by extension, the EUS) are a waste of taxpayer money.

I'm also saying keep track of the cost to get that size vehicle+human rated.

Why? How much did it cost to human rate Falcon 9? How much did it cost to human rate Atlas V? Explain what you mean...

It's not that we have to do it that way, and I'm not saying that's the best way to do it.

"It" being what? Flying humans on the 2nd SLS flight? That is a political decision, not a safety one. The SLS is so hideously expensive, and now so far behind on schedule, that NASA is being forced to fly humans on the 2nd ever flight of the SLS despite there only being ONE flight data point for all the major components of the SLS.

I'm saying keep track of the cost and schedule when these new vehicles are human rated and launching.

Again, why are you saying this? What do you mean? How does that related to the SLS and EUS?

[CoolScience]

As someone who does spacecraft loads and dynamics and docking dynamics, and has put human rated hardware in space...  I think we are talking past each other.  We approve systems based upon correlated models and simulations.  That correlation comes from real world testing of parts, components, and systems.  Often we cannot test everything altogether and we have to test parts separately.  Orbital operations can be used to adjust models based upon flight data, but we don't do operations unless we are confident in our models in the first place.

Yes, definitely seem to be talking past each other on some points so to clarify what I am saying:

I think we agree that approval (requirements sell-off) will involve analysis (models and simulations) for many requirements. Test is also used, but for total end-to-end type requirements good tests get hard or impossible to do on the ground.

I disagree with your statement that we don't do flight operations if we aren't first confident in our models. The issue is that statement is too broad, and in part comes from history where any test of something on-orbit is extremely expensive and therefore must have high confidence. The confidence required is proportional to the consequences of failure. I have worked on an extremely thoroughly tested satellite that had an operational need, long lead times and therefore had to work on the first try, and I have worked on a related one that was built far cheaper and barely tested on the ground, because it just needed to prove the technology functioned as expected. The latter's results save a lot of ground tests, analysis, and questions for building an operational version of it.

My main point is that there are always things that you do not know until you actually fly something. If you can afford to try multiple times (as SpaceX obviously can for Starship refueling, Starship heat shield, etc.) it is actually beneficial to just do that. If you are doing something with extremely high consequence (flying humans) then the only way you get sufficient confidence is by actually flying.

It may have been lost in the back and forth, but what I originally said is:

And which flight is the milestone of an uncrewed test flight of the EUS? No amount of analysis can substitute for a real world test of a complex system, and launch of a new stage simply should not be done with crew aboard. LAS is not something to rely solely on, so please don't waste time with an argument like that.

Human rating of a rocket or capsule can only happen after at least one flight test, and for a new rocket, even just one flight test is questionable no matter how much ground analysis is done. In fact, NASA's own standards demand 3 prior flights for important payloads.

https://nodis3.gsfc.nasa.gov/NPD_attachments/AttachmentA_7C.pdf

Changing out an upper stage? That is a new configuration that needs to be proven, preferably with 3+ flights. Changing a heat shield material should be reasonable to approve after 1 test flight if the results are good, but there is no way that is acceptable with ground test only when it was just demonstrated the previous set of ground tests was not good enough to find a major problem.

[jarmumd]

Again, why are you saying this? What do you mean? How does that related to the SLS and EUS?

Nevermind.  I should know better than to post.

[eeergo]

Cross-posting from the original EUS thread:

Restart of a ten-year-old thread.

https://twitter.com/DerekdotSpace/status/2001753241529311613

Derek Newsome
@DerekdotSpace
The Exploration Upper Stage Structural Test Article is now well into production at the Michoud Assembly Facility ahead of a planned completion early next year.

This is the first EUS to be manufactured, and will be used for testing at the Marshall Spaceflight Center in Alabama.