Prediction: Technical realities will result in selection of SLS-launched HLS

[rakaydos]

No.  Capitalism does not explain, in a short, non-exhaustive list, ... yada yada.  People are getting paid plenty; they end up wasting the money they are given.

Nothing to do with the 2020 date, and the president's lack of ability to back it up with money.

And by 2020, you mean 2024, right?  And it's not the President's "lack of ability" to secure funding.  As everybody here knows, the President proposes, and Congress disposes.

Fixed, apologies for the typo. And yes, it is the Office of the Presidency's legal inability, under the constitution, to provide funding that is exactly the problem, regardless who holds that office. It means that the president doesn't get to reward success or punish failure- congress does. And congress, as ZChris13 alluded to, has very different ideas as to what success and failure are.

[su27k]

Regardless of how many pieces there are and how they fit together, the elements are going to have a reasonably large structural component that is not tanks and feed systems. Making comparisons to launch vehicle stages is likely going to end in disappointment.

This came up again in SLS thread, but I think it's better to address it here: I don't think this is the correct take. There is an example in space history where a lunar tug becomes a upper stage: The Soviet Blok D, it was originally designed to do lunar orbit insertion and part of the descent, later it was used as upper stages on Proton and Zenit. BTW, Blok D is kerolox and has a PMF of ~0.87, a lot lower than Falcon 2nd stage's 0.96 

That's the TRL 9 example, there're more recent examples on powerpoint, for example:
1. ULA and Bigelow proposed to send a BA330 to LLO using ACES: ULA and Bigelow expand association with lunar depot plan, the ACES will pick up the BA330 in LEO and insert it to LLO, basically the same thing a transfer stage will do in HLS.
2. This was also mentioned by GWH in the SLS thread: NASA's DAC2 study also included an example (IP 08) of utilizing modified upper stage as super tug.

[JohnFornaro]

... And it's not the President's "lack of ability" to secure funding.  As everybody here knows, the President proposes, and Congress disposes.

Fixed, apologies for the typo.

No problemo.  I made a typo back in 1977, so I know how you must feel.

And yes, it is the Office of the Presidency's legal inability, under the constitution, to provide funding that is exactly the problem, regardless who holds that office. It means that the president doesn't get to reward success or punish failure- congress does. And congress, as ZChris13 alluded to, has very different ideas as to what success and failure are.

I think you're putting the blame for NASA's program failures in returning Americans to the Moon on Congress, which is true to a certain extent. You've forgotten how the revolving door from NASA into the corporate world has had decades of success in keeping the pipeline to Treasury open, while staying securely planted here on Earth.  It is hardly the case that NASA's upper level management and program directorates are making staff and resource decisions which further the stated goals of various presidents over the past, now fifty, years.  At least, not without corporate approval.

But if instead, you're arguing that this president is "legally" restricted from being a dictator, free to order NASA in all of its details, no matter the cost, hence the unrealistic return to the Moon date, then I have to say:

Shirley, you jest.

[rakaydos]

... And it's not the President's "lack of ability" to secure funding.  As everybody here knows, the President proposes, and Congress disposes.

Fixed, apologies for the typo.

No problemo.  I made a typo back in 1977, so I know how you must feel.

And yes, it is the Office of the Presidency's legal inability, under the constitution, to provide funding that is exactly the problem, regardless who holds that office. It means that the president doesn't get to reward success or punish failure- congress does. And congress, as ZChris13 alluded to, has very different ideas as to what success and failure are.

I think you're putting the blame for NASA's program failures in returning Americans to the Moon on Congress, which is true to a certain extent. You've forgotten how the revolving door from NASA into the corporate world has had decades of success in keeping the pipeline to Treasury open, while staying securely planted here on Earth.  It is hardly the case that NASA's upper level management and program directorates are making staff and resource decisions which further the stated goals of various presidents over the past, now fifty, years.  At least, not without corporate approval.

But if instead, you're arguing that this president is "legally" restricted from being a dictator, free to order NASA in all of its details, no matter the cost, hence the unrealistic return to the Moon date, then I have to say:

Shirley, you jest.

A bit of both. And don't call me Shirley- even our current administration needs a paper thin "national emergency" to reallocate funding, which is difficult to justify as an uncontested leader in spaceflight.  And even that excuse is only a few months old, it's not something commercial partners could have expected, let alone planned on.

[JohnFornaro]

You mentioned OML changes for Orion. I'm not familiar with this piece of history, and search is turning up anything useful. Is there topic or link you can share? Thank you!

The outer mold line.  Basically the profile of the vehicle.

Me, I prefer the 1960 Corvette OML...

One of the best posters here.

The search function on NSF is better than nothing.  Here's the top hit this morning, on the phrase "outer mold line", in quotes, any poster, oldest first.

Also, if the 2nd stage diameter is reduced from 5.5 to 5m, wouldn't it have to be lengthened to compensate and hold the same amount of fuel?  Its already gone to a 5-segment SRB.... and with a lengthened and thinner 2nd stage,  sounds like it'll wind up being a 300-foot pencil shaft of a rocket!

This will get you started.

In short, they changed the diameter of the capsule a small amount, late in the design phase; heck, after metal had been bent, even.  Then, in an OMG moment, they realized that the design change trickled down into the design of the launch system in almost every design category.

The expected delays and cost increases resulted just as planned.   The president's proposal to land, if he follows my advice, the first black American woman on the Moon in 2024 is a realistic plan that is being slow-walked and denigrated for no rational engineering reason.

[JohnFornaro]

Well, yeah.  I have this old fashioned idea that success is rewarded, failure not.

Then you should be supporting a 2028 moon landing instead of 2024.

We were all wondering what a "non-political" date for the next American human return to the Moon would be.  Mucho thankso.

[RonM]

Well, yeah.  I have this old fashioned idea that success is rewarded, failure not.

Then you should be supporting a 2028 moon landing instead of 2024.

We were all wondering what a "non-political" date for the next American human return to the Moon would be.  Mucho thankso.

2028 was the date being discussed before Pence surprised everyone with 2024 at NSC. Congress isn't going to support a 2024 crewed landing and the president isn't going to waste political capital to get it. He doesn't care enough about it. Time to face reality.

[JohnFornaro]

2028 was the date being discussed before Pence surprised everyone with 2024 at NSC. Congress isn't going to support a 2024 crewed landing and the president isn't going to waste political capital to get it. He doesn't care enough about it. Time to face reality.

Wait, what? "Surprised everyone"?  When did they change it from 2015?  or 2020?

https://www.nasa.gov/missions/solarsystem/bush_vision.html

"Our third goal," Bush said, "is to return to the moon by 2020, as the launching point for missions beyond." He proposed sending robotic probes to the lunar surface by 2008, with a human mission as early as 2015, "with the goal of living and working there for increasingly extended periods of time."

TBH, he said "'return to the moon by 2020"; didn't specify what would be returned there. As to 2015, it was just a "human mission", destination not specified in the same sentence.  So I guess 2028's official?   Not sayin' official for what. 

We're all  really tired of all the verbal shenannigans year after year.  Time to "face reality".  NASA won't be landing the first American woman on the Moon by 2028 either, if they have their way.

[rakaydos]

We're all  really tired of all the verbal shenannigans year after year.  Time to "face reality".  NASA won't be landing the first American woman on the Moon by 2028 either, if they have their way.

Of course not. Congress gets more from "technology development jobs" in their district than someone else claiming credit for putting a person somewhere outside (very outside!) their district.

[Proponent]

2028 was the date being discussed before Pence surprised everyone with 2024 at NSC. Congress isn't going to support a 2024 crewed landing and the president isn't going to waste political capital to get it. He doesn't care enough about it. Time to face reality.

And Ted Cruz has just expressed skepticism that a NASA appropriation will pass this year.  If NASA enters FY 2021 on a continuing resolution, then a year and a half will have elapsed since Pence's announcement without NASA receiving the major funding boost needed.

[FiniteBurn]

This came up again in SLS thread, but I think it's better to address it here: I don't think this is the correct take. There is an example in space history where a lunar tug becomes a upper stage: The Soviet Blok D, it was originally designed to do lunar orbit insertion and part of the descent, later it was used as upper stages on Proton and Zenit. BTW, Blok D is kerolox and has a PMF of ~0.87, a lot lower than Falcon 2nd stage's 0.96 

It's the correct take. And your example starts to chip away at why. In-space vehicles have additional needs that a launch vehicle doesn't. For the example of the TE, it needs to be kept pointed in the correct orientation to minimize heating. For a ~100 day mission, that requires a lot of RCS propellant. It may also have to perform more sensitive maneuvers like correction burns and rendezvous maneuvers. That possibly requires a more complex RCS system, that adds more mass. It needs more power than even an extended LV mission, that means solar panels or some other power source. More mass. An in-space cryogenic vehicle will have an entire CFM system than a typical launch vehicle doesn't. That's not only more mass, but if you want an active system,  more power, which is more mass. More power is also more heat, which means more radiators, which means more mass. All this extra stuff has to be packaged somehow, so your vehicle structure has to make room to accommodate it. That's mass. You also need to consider that your structure affects the thermal loads into the tank, and that's something you need to design for up-front. Launch vehicles with big, beefy structural components add large heat loads that are not conducive for keeping propellant in liquid form for weeks at a time.

What you are left with is something that looks more like an actual spacecraft (like Cassini) without the instruments than a launch vehicle stage with stuff sticking off it. At least for smaller vehicles. And that is also part of the challenge. Bigger vehicles can get better propellant mass fractions for reasons I don't think I need to explain. But a lot of these vehicles aren't particularly large, with even a "large" vehicle like a Mars propulsion stage carrying substantially less propellant than something S-IVB-sized. So, while pmfs in the range of .9 are pretty common for launch vehicles, the range is far lower once you get into these long-duration missions. I would say that personally, .85 is a "good" pmf, .75-.8 is more typical, and those will be on the higher end for small vehicles.

Anyway, the long and short of it is that launch vehicles are designed for missions of a few hours, which does not translate well into missions of several weeks. Some of the things that are desirable for launch vehicle stages are not desirable for in-space vehicles. This is why "rendezvous with stage" concepts like the super-tug keep the mission duration to a minimum, and that opens a can of worms with regards to launch windows and mission design. Hence, why they never make it off the powerpoint.

This is only a brief overview based a bit on my experience. There's a lot here I haven't even delved into like MLI and whether it needs to be inside a fairing. But I think you can get a flavor for some of the trades behind it. 

[GWH]

^Good post, expands on what I expected (increased dry mass).

This is only a brief overview based a bit on my experience. There's a lot here I haven't even delved into like MLI and whether it needs to be inside a fairing. But I think you can get a flavor for some of the trades behind it.

I'll quote Bernard Kutter of ULA on the above:

1) As you observed, ACES has been updated to an inline design. Tank pressure requirements to satisfy ascent structure are similar to that required to prevent engine cavitation, thus ACES will still achieve the high mass fraction.

2) Yes, we will use a common docking interface for both the Distributed Launch propellant tanks and the B330.

3) ACES will be encapsulated in MLI (multi-layer insulation) to reduce the LH2 & LO2 boil off. MLI that can survive ascent aerodynamic forces is one of the many innovations being incorporated into ACES to enable refueling, long mission durations and numerous burns.

Bernard Kutter ULA Chief Scientist

Source: https://www.reddit.com/r/ula/comments/76ysr9/bigelow_aerospace_and_united_launch_alliance/doova5k/

[su27k]

This came up again in SLS thread, but I think it's better to address it here: I don't think this is the correct take. There is an example in space history where a lunar tug becomes a upper stage: The Soviet Blok D, it was originally designed to do lunar orbit insertion and part of the descent, later it was used as upper stages on Proton and Zenit. BTW, Blok D is kerolox and has a PMF of ~0.87, a lot lower than Falcon 2nd stage's 0.96 

It's the correct take. And your example starts to chip away at why. In-space vehicles have additional needs that a launch vehicle doesn't. For the example of the TE, it needs to be kept pointed in the correct orientation to minimize heating. For a ~100 day mission, that requires a lot of RCS propellant. It may also have to perform more sensitive maneuvers like correction burns and rendezvous maneuvers. That possibly requires a more complex RCS system, that adds more mass. It needs more power than even an extended LV mission, that means solar panels or some other power source. More mass. An in-space cryogenic vehicle will have an entire CFM system than a typical launch vehicle doesn't. That's not only more mass, but if you want an active system,  more power, which is more mass. More power is also more heat, which means more radiators, which means more mass. All this extra stuff has to be packaged somehow, so your vehicle structure has to make room to accommodate it. That's mass. You also need to consider that your structure affects the thermal loads into the tank, and that's something you need to design for up-front. Launch vehicles with big, beefy structural components add large heat loads that are not conducive for keeping propellant in liquid form for weeks at a time.

What you are left with is something that looks more like an actual spacecraft (like Cassini) without the instruments than a launch vehicle stage with stuff sticking off it. At least for smaller vehicles. And that is also part of the challenge. Bigger vehicles can get better propellant mass fractions for reasons I don't think I need to explain. But a lot of these vehicles aren't particularly large, with even a "large" vehicle like a Mars propulsion stage carrying substantially less propellant than something S-IVB-sized. So, while pmfs in the range of .9 are pretty common for launch vehicles, the range is far lower once you get into these long-duration missions. I would say that personally, .85 is a "good" pmf, .75-.8 is more typical, and those will be on the higher end for small vehicles.

Anyway, the long and short of it is that launch vehicles are designed for missions of a few hours, which does not translate well into missions of several weeks. Some of the things that are desirable for launch vehicle stages are not desirable for in-space vehicles. This is why "rendezvous with stage" concepts like the super-tug keep the mission duration to a minimum, and that opens a can of worms with regards to launch windows and mission design. Hence, why they never make it off the powerpoint.

This is only a brief overview based a bit on my experience. There's a lot here I haven't even delved into like MLI and whether it needs to be inside a fairing. But I think you can get a flavor for some of the trades behind it.

1. I showed the PMF difference between Blok D and Falcon 2nd stage exactly because the mass concerns. Modern upper stage is much more efficiently designed, this means you can add more mass while still achieve a reasonable PMF. For example, you can add 10t dry mass to Falcon 2nd stage and it still has a PMF of 0.87, on par with Blok D.
2. Upper stage is a spacecraft, and a TE has a lot more in common with an upper stage than with Cassini. For starters, you stated a TE would likely have PMF in .75 to .8 range, which is not far from older upper stage like Blok D, while Cassini has a PMF of 0.54.
3. The upper stages for the new reusable LVs are not small at all, Falcon 2nd stage has a propellant load of 105t, this is basically the same as S-IVB. New Glenn upper stage is likely to be even larger given it has two BE-3U which provides a lot more thrust than a MVac.
4. You're still ignoring the example of ACES, which is proposed by the most trusted LV manufacturer in the US and someone quoted Tory Bruno as saying its mission duration is basically unlimited. I wonder if this is why Boeing is putting a stop to ACES, because just the proposal itself would poke a hole through argument like yours.

[FiniteBurn]

I am just offering my insight based on my experience working on the matter. I have little to no interest in going back and forth with you over all of the details the “but what about...”s.

Edit: also, my statement on small vehicle is talking about the DE/TE, not launch vehicles. They have propellant loads that are about half of that of the common cryogenic upper stages.

I said what I said and I stand by it. You can start wherever you want but you end up in the same place at the end. That applies to everyone.

[JohnFornaro]

Upper stage is a spacecraft, and a TE has a lot more in common with an upper stage than with Cassini.

Excuse me for jumping in, but this is an example of word thinking.  I have a baseball, and I just threw it up into LEO.  Now, that baseball is a spacecraft.  A spacecraft is a function, not just a word and not just a location.  The obvious example is that Cassini is a spacecraft, and the lunar lander is also a spacecraft.  That these two artifacts are both in space, have mass, and have propellant, does not make them equivalent in any way.

Just because an upper stage makes it to LEO or further, doesn't mean that, because it is a... *spacecraft*, that it is interchangeable with a lunar tug, ACES, the Glenn upper stage, etc.

One word:  Function.

[su27k]

Upper stage is a spacecraft, and a TE has a lot more in common with an upper stage than with Cassini.

Excuse me for jumping in, but this is an example of word thinking.  I have a baseball, and I just threw it up into LEO.  Now, that baseball is a spacecraft.  A spacecraft is a function, not just a word and not just a location.  The obvious example is that Cassini is a spacecraft, and the lunar lander is also a spacecraft.  That these two artifacts are both in space, have mass, and have propellant, does not make them equivalent in any way.

Just because an upper stage makes it to LEO or further, doesn't mean that, because it is a... *spacecraft*, that it is interchangeable with a lunar tug, ACES, the Glenn upper stage, etc.

One word:  Function.

I'm not interested in word plays, I gave 3 examples of how upper stage can fill the role of TE, including one real world example from decades ago, I'm more interested in concrete discussion on technical details.

[JohnFornaro]

I'm not interested in word plays...

Fair.

I gave 3 examples of how upper stage can fill the role of TE, including one real world example from decades ago,

And they're wrong...

I'm more interested in concrete discussion on technical details.

... as has been explained above.

[JohnFornaro]

Like I was saying...

The president's proposal to land, if he follows my advice, the first black American woman on the Moon in 2024 is a realistic plan that is being slow-walked and denigrated for no rational engineering reason.

" 'Black in Space' looks at final frontier of civil rights"

https://www.nbcnews.com/news/nbcblk/black-space-looks-final-frontier-civil-rights-n1139736

[su27k]

I gave 3 examples of how upper stage can fill the role of TE, including one real world example from decades ago,

And they're wrong...

I'm more interested in concrete discussion on technical details.

... as has been explained above.

"they're wrong" without explanation is not concrete discussion on technical details, it's just more word play which reduces the SNR of this thread.

[dglow]

Also, if the 2nd stage diameter is reduced from 5.5 to 5m, wouldn't it have to be lengthened to compensate and hold the same amount of fuel?  Its already gone to a 5-segment SRB.... and with a lengthened and thinner 2nd stage,  sounds like it'll wind up being a 300-foot pencil shaft of a rocket!

This will get you started.

In short, they changed the diameter of the capsule a small amount, late in the design phase; heck, after metal had been bent, even.  Then, in an OMG moment, they realized that the design change trickled down into the design of the launch system in almost every design category.

The expected delays and cost increases resulted just as planned.   The president's proposal to land, if he follows my advice, the first black American woman on the Moon in 2024 is a realistic plan that is being slow-walked and denigrated for no rational engineering reason.

2006... so this impacted Constellation, but wouldn't have affected the SLS schedule. Good to know - thank you.