Prediction: Technical Political realities will result in selection of SLS-launched HLSFixed that for you. The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.
4. 3 CLV launches can put more mass through TLI than a single SLS Block 1B, so it is Block 1B solution that is mass constrained.
Note everybody in the public has been using the 15t to TLI number, which is a conservative value from NASA LSP for FH. That number was published before the first Block 5 FH even flew, very likely the current FH can put a few more tons than this, that's assuming they don't uprate it, which I think is quite possible. I think this will be the biggest surprise once HLS bids are revealed: It would turn out the 15t to TLI constraint is wrong.
As for Doug Loverro's review, I don't think it will change anything major to HLS, since if he did, it would require a re-compete, which will slow things further (it's already slowed comparing to their original target date). And if NASA really wants to use SLS Block 1B, they wouldn't propose to postpone EUS in president's budget.
I'm betting if NASA does select more than one provider, then at least one provider won't be using SLS Block 1B, that's just common sense, otherwise SLS becomes a single point of failure.
Quote from: Lar on 02/19/2020 02:50 pmPrediction: Technical Political realities will result in selection of SLS-launched HLSFixed that for you. The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.I actually originally wanted to title this thread "Technical (not political) realities will result in selection of SLS-launched lander," but the character limit was too low for it, and I figured the meaning was well enough implied. I guess not.
I refuse to let this devolve into another Starship vs. SLS "discussion," so all I'll say is it will not be available for a crewed Lunar mission on this timescale.
Quote from: su27k on 02/19/2020 04:08 pmNote everybody in the public has been using the 15t to TLI number, which is a conservative value from NASA LSP for FH. That number was published before the first Block 5 FH even flew, very likely the current FH can put a few more tons than this, that's assuming they don't uprate it, which I think is quite possible. I think this will be the biggest surprise once HLS bids are revealed: It would turn out the 15t to TLI constraint is wrong.Would be interesting, but how much more could be realistically squeezed out of it? 1t? 2t?An expendable FH bid would also be interesting, but I don't expect to see that. Not with its fairing.
Quote from: jadebenn on 02/19/2020 05:41 pmQuote from: su27k on 02/19/2020 04:08 pmNote everybody in the public has been using the 15t to TLI number, which is a conservative value from NASA LSP for FH. That number was published before the first Block 5 FH even flew, very likely the current FH can put a few more tons than this, that's assuming they don't uprate it, which I think is quite possible. I think this will be the biggest surprise once HLS bids are revealed: It would turn out the 15t to TLI constraint is wrong.Would be interesting, but how much more could be realistically squeezed out of it? 1t? 2t?An expendable FH bid would also be interesting, but I don't expect to see that. Not with its fairing.My quick-n-dirty guestimate would be that Falcon Heavy Expendable could push more than 20t through TLI. That's just based on comparing NASA's LSP performance curve with the "16.8t to Mars" currently mentioned on the SpaceX capabilities webpage and assuming a Mars C3 of 12 km2/s2. That's a 5t difference between the LSP and SpaceX payload figures for trans Mars injection. Since the curve is steeper for low C3 (TLI C3 ~ -3), it's probably more than 15+5=20t. Expending (only) the center core takes about a 10% hit though perhaps more at TLI C3. So I'd just call it 20t even.There are probably better estimates elsewhere on this forum. There's been a lot of reverse sleuthing trying to figure out various stage dry masses and the like from the published payload mass and velocity profile from prior missions.
Also inherent longevity of 5 years in space without refueling. And electrical power availability of around 20x of a conventional stage
Quote from: su27k on 02/19/2020 04:08 pm4. 3 CLV launches can put more mass through TLI than a single SLS Block 1B, so it is Block 1B solution that is mass constrained.You're not considering the mass penalties making each element autonomous and free-flying imposes. I'll admit the impact isn't equal on every module. The transfer stage shouldn't have too much problem fitting in a 15t payload. The ascent and descent stages are another story.
Quote from: su27k on 02/19/2020 04:08 pmAs for Doug Loverro's review, I don't think it will change anything major to HLS, since if he did, it would require a re-compete, which will slow things further (it's already slowed comparing to their original target date). And if NASA really wants to use SLS Block 1B, they wouldn't propose to postpone EUS in president's budget.NASA didn't propose the end of EUS, the administration did, and there's virtually no chance that sticks (it didn't the last time they tried).You're also not considering the possibility that this is on the bidder side. There's nothing stopping a bidder from changing their LV at this point in time if they make the trades and they come up positive.
Quote from: su27k on 02/19/2020 04:08 pm4. 3 CLV launches can put more mass through TLI than a single SLS Block 1B, so it is Block 1B solution that is mass constrained.The transfer stage shouldn't have too much problem fitting in a 15t payload. The ascent and descent stages are another story.
While not a bidder that we know of, Tory Bruno of ULA has made many comments implying long stage life of ACES like this onehttps://www.reddit.com/r/ula/comments/96uoax/what_is_aces/e44r8a9/QuoteAlso inherent longevity of 5 years in space without refueling. And electrical power availability of around 20x of a conventional stage I believe most of that life was due to the Multi Layer Insulation they intend to use and less so how ACES deals with boil off.At least some in industry think they can deal with boil off, I would expect that to have been one of the first items bidders looked at before proposing an architecture.
I refuse to let this devolve into another Starship vs. SLS "discussion,"
so all I'll say is it will not be available for a crewed Lunar mission on this timescale.
If you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...
Quote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Whether or not 2024 is "agressive" or not depends on the willingness of the aerospace community to work towards that date. In my view, the first two women could certainly land on the Moon by 2024, if the damn community would simply work together instead of fighting each president since, I guess, George Washington.
Quote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No.
But 2024 is the date we have to work with at the moment.
Whether or not 2024 is "agressive" or not depends on the willingness of the aerospace community to work towards that date.
In my view, the first two women could certainly land on the Moon by 2024, if the damn community would simply work together instead of fighting each president since, I guess, George Washington.
Quote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Of course all dates are political, but my point was just that the claim from jadebenn that the arguments were purely technical and not political was inherently wrong.I agree that despite the politics, 2024 could happen, but the limited flight rate of SLS means that adding to the role of SLS will make the date slip, conversely reducing its role can increase schedule confidence depending on what it is replaced with.
Quote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.
Quote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.
Quote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Really? What role does Congress play in all this? You're saying that the President cannot propose a date?
I'm willing to put my money where my mouth is, and (in a well structured way) bet that it will be ready for a crewed lunar mission before SLS will be... I never get any takers on my offers to bet, no idea why....
I'm seeing a whole lot of "should" and "believe". Now, I am by no means the sole authority on the subject, but I know some things that may be of use for grounding this conversation. Some of my observations, in no particular order:The reference design I am most familiar with had a descent element over the 15 t limit, and the transfer element was right at the edge. Both designs were working with some relatively low TRL inclusions. The amount of hydrogen boiled off over the 100+ day mission is low enough to justify using a passive system and accepting some boiloff, rather than using an active system (cryocoolers) to try and get ZBO.The 15 t limit is the "updated" number. The internal estimate was higher.Even before accounting for the 15 t launch vehicle restriction, the performance of this HLS design was not particularly reassuring, with landed payload mass far less than some of the AE sizing I saw in Appendix H solicitation. I would have to go back and look more carefully to see why that is. I also don't know enough about AE design closure to say how much of a problem that would be. I am not aware of any analysis on stack height and how that relates to the crew. That could pose a risk if the lander needs to be squatter and fatter. Switching to storables would require accelerating development of a pump-fed engine. Most of the research dollars have gone to cryogenic systems. Methane and Liquid Hydrogen have very different implications for thermal design. A hydrogen design may end up with design closure issues that the methane design does not have. It is not as bianry as cryogenic vs storable. 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. Things that produce power also produce heat. That heat has to go somewhere and generally the propellant is not where you want to put it. Exceptions exist. Total mass is, IMHO, not as relevant as the mass of the DE element, which is really what is going to drive most of the architecture decisions. If you want my opinion, designs are going have severe difficulty closing under the 15 t limit without an extra "something" even with some of the low TRL bells and whistles baked in. The Appendix H reference documentations have several examples of what that extra something can be. It is my intuition that the larger launch vehicle is probably going to be substantially easier than some of the other "somethings". Note that larger launch vehicle doesn't necessarily mean SLS, but SLS is one option.
Do we know New Glenn's payload to TLI, actually? I'd imagine, considering the rocket's size and its use of an LH2 upper stage, that it would be able to throw more mass to lunar orbit than non-expendable FH. That might be enough for the National Team to stick with the 3-element design with little difficulty. Of course I already believed they were the least likely to switch out of all the bidders, considering the specifics of their partnership.
Quote from: Lar on 02/20/2020 06:30 pmI'm willing to put my money where my mouth is, and (in a well structured way) bet that it will be ready for a crewed lunar mission before SLS will be... I never get any takers on my offers to bet, no idea why....Well, you've got one now.
Quote from: JohnFornaro on 02/21/2020 04:47 pmQuote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Really? What role does Congress play in all this? You're saying that the President cannot propose a date?Without congressional support, the president proposing a date has considerbly less weight than Elon Musk proposing a date. It's federal Separation of Powers at work.
Quote from: JohnFornaro on 02/21/2020 04:47 pmQuote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? ... 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.... You're saying that the President cannot propose a date?... So sure, a President can propose any date they want ....
Quote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? ... 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.... You're saying that the President cannot propose a date?
Quote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? ... 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.
Quote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? ... 2024 is the date we have to work with at the moment.
If you want my opinion, designs are going have severe difficulty closing under the 15 t limit without an extra "something" even with some of the low TRL bells and whistles baked in. The Appendix H reference documentations have several examples of what that extra something can be. It is my intuition that the larger launch vehicle is probably going to be substantially easier than some of the other "somethings". Note that larger launch vehicle doesn't necessarily mean SLS, but SLS is one option.
Quote from: rakaydos on 02/22/2020 03:11 pmQuote from: JohnFornaro on 02/21/2020 04:47 pmQuote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmQuote from: meberbs on 02/19/2020 07:22 pmIf you didn't want this to be political, you shouldn't have based your argument on a political 2024 date...Is there some magical date that is NOT political? 1776? 1492? 2001? Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Really? What role does Congress play in all this? You're saying that the President cannot propose a date?Without congressional support, the president proposing a date has considerbly less weight than Elon Musk proposing a date. It's federal Separation of Powers at work.It's not a matter of weight. It's a matter of date. 2024, first woman on the Moon. All the pieces are well underway, but they lack integration and coordination, and most importantly, the will to achieve the proposed landing date, 2024.Look at this thread. Who is arguing to return humanity to the Moon in 2024? A tiny mainority. It appears that most of NASA's rank and file, like NASA's leadership, simply do not want there to be a lunar landing by 2024. Prove me wrong.
Quote from: FiniteBurn on 02/21/2020 03:58 pmIf you want my opinion, designs are going have severe difficulty closing under the 15 t limit without an extra "something" even with some of the low TRL bells and whistles baked in. The Appendix H reference documentations have several examples of what that extra something can be. It is my intuition that the larger launch vehicle is probably going to be substantially easier than some of the other "somethings". Note that larger launch vehicle doesn't necessarily mean SLS, but SLS is one option.As much as I love trying to unravel a good mystery, there look to be a few dozen attachments in the Appendix H bid solicitation. Any hints as to which ones to look at?
Quote from: JohnFornaro on 02/23/2020 01:39 pmQuote from: rakaydos on 02/22/2020 03:11 pmQuote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmIs there some magical date that is NOT political? ... Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Without congressional support, the president proposing a date has considerbly less weight than Elon Musk proposing a date. ...It's not a matter of weight. It's a matter of date. ... All the pieces are well underway, but they lack ... the will to achieve the proposed landing date, 2024.... Who is arguing to return humanity to the Moon in 2024? Let me introduce you to the Golden Rule. He who has the gold, makes the rules.
Quote from: rakaydos on 02/22/2020 03:11 pmQuote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmIs there some magical date that is NOT political? ... Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Without congressional support, the president proposing a date has considerbly less weight than Elon Musk proposing a date. ...It's not a matter of weight. It's a matter of date. ... All the pieces are well underway, but they lack ... the will to achieve the proposed landing date, 2024.... Who is arguing to return humanity to the Moon in 2024?
Quote from: Coastal Ron on 02/21/2020 03:01 pmQuote from: JohnFornaro on 02/21/2020 02:12 pmIs there some magical date that is NOT political? ... Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.Without congressional support, the president proposing a date has considerbly less weight than Elon Musk proposing a date. ...
Quote from: JohnFornaro on 02/21/2020 02:12 pmIs there some magical date that is NOT political? ... Short answer: No. But 2024 is the date we have to work with at the moment.Not if Congress doesn't fund it.
Is there some magical date that is NOT political? ... Short answer: No. But 2024 is the date we have to work with at the moment.
We are in a capitalist society. If noone's getting paid to do something, it wont happen.
No. Capitalism does not explain, in a short, non-exhaustive list, the failure of Constellation, the gratuitous change of the OML for Orion, the slow process of SLS, the continuing delays of JWST, yada yada. People are getting paid plenty; they end up wasting the money they are given.
In my view, Congress would be more generous with the purse strings if they thought NASA would accomplish the goal that the President has stated. As it stands, NASA's budget is rising, but on this site and elsewhere, that budgetary increase is mocked.
The Appendix H solicitation included a number of reference documents under Attachment A. One of them is the Analyses of Alternatives. I believe it has been posted and discussed on this forum before.
Quote from: JohnFornaro on 02/24/2020 01:20 pmNo. 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.
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.
In my view, Congress would be more generous with the purse strings if they thought NASA would accomplish the goal that the President has stated. ...
Why would you believe that? Congress has no problem throwing NASA money, but not for 2020 [2024?] moon missions. They throw NASA money because it's welfare that they can pretend isn't welfare, and those "good paying jobs" might vanish if we ever actually accomplished anything.
Quote from: rakaydosWhy would you believe that? Congress has no problem throwing NASA money, but not for 2020 [2024?] moon missions. They throw NASA money because it's welfare that they can pretend isn't welfare, and those "good paying jobs" might vanish if we ever actually accomplished anything.Well, yeah. I have this old fashioned idea that success is rewarded, failure not.
Well, yeah. I have this old fashioned idea that success is rewarded, failure not.
Quote from: rakaydos on 02/24/2020 08:03 pmQuote from: JohnFornaro on 02/24/2020 01:20 pmNo. 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.
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.
Quote from: JohnFornaro on 02/26/2020 02:58 pm... 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 it's not the President's "lack of ability" to secure funding. As everybody here knows, the President proposes, and Congress disposes.
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.
Quote from: rakaydos on 02/26/2020 03:58 pmQuote from: JohnFornaro on 02/26/2020 02:58 pm... 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.Quote from: rakaydosAnd 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.
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!
Me, I prefer the 1960 Corvette OML...
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!
Quote from: JohnFornaro on 02/26/2020 02:58 pmWell, 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.
Quote from: RonM on 02/26/2020 03:55 pmQuote from: JohnFornaro on 02/26/2020 02:58 pmWell, 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.
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.
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
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) 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
Quote from: su27k on 02/27/2020 02:08 amThis 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.
Upper stage is a spacecraft, and a TE has a lot more in common with an upper stage than with Cassini.
Quote from: su27k on 02/28/2020 01:55 amUpper 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.
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.
Quote from: su27kI 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...Quote from: su27kI'm more interested in concrete discussion on technical details.... as has been explained above.
Quote from: RedSky on 03/09/2006 03:18 pmAlso, 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.
so this impacted Constellation, but wouldn't have affected the SLS schedule. Good to know - thank you.
... more word play ...
Quote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. Good to know - thank you.Constellation slowed down SLS.
The development of SLS is taking longer than the Apollo/Saturn V program actually flew.
Quote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. Good to know - thank you.Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B, which only began after program A's termination.
Quote from: Mr. Scott on 03/02/2020 04:14 amThe development of SLS is taking longer than the Apollo/Saturn V program actually flew. Yes, but if Saturn V was funded at the same level as SLS, it would have first launched in the 1980s. :-)
Quote from: Steven Pietrobon on 03/02/2020 08:28 amQuote from: Mr. Scott on 03/02/2020 04:14 amThe development of SLS is taking longer than the Apollo/Saturn V program actually flew. Yes, but if Saturn V was funded at the same level as SLS, it would have first launched in the 1980s. :-)Maybe there's a good math model supporting this intuitively realistic counterfactual. But. And there's always a but. The difference between then and now was not money, but intent. They intended to complete Apollo. Now, not so much. Intent cannot be accurately modeled.
Quote from: dglow on 03/01/2020 09:59 pmQuote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. Good to know - thank you.Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B, which only began after program A's termination.Huh. Program A was sold as supporting and furthering Program B. BTW, Shuttle was sold as having a two week turnaround, back in the day. Maybe the premise of Program A was sold in the same fashion as shuttle? What was the purpose of Constellation supposed to be?
Quote from: JohnFornaro on 03/02/2020 12:28 pmQuote from: dglow on 03/01/2020 09:59 pmQuote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. ...Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B ...Huh. Program A was sold as supporting and furthering Program B. ... What was the purpose of Constellation supposed to be?Constellation is program A. It came first. It was cancelled. SLS, aka program B, came second.And no, I don't think either SLS or Ares were sold in the same fashion as Shuttle.
Quote from: dglow on 03/01/2020 09:59 pmQuote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. ...Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B ...Huh. Program A was sold as supporting and furthering Program B. ... What was the purpose of Constellation supposed to be?
Quote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. ...Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B ...
Quote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. ...Constellation slowed down SLS.
so this impacted Constellation, but wouldn't have affected the SLS schedule. ...
Quote from: JohnFornaro on 03/02/2020 12:28 pmQuote from: Steven Pietrobon on 03/02/2020 08:28 amQuote from: Mr. Scott on 03/02/2020 04:14 amThe development of SLS is taking longer than the Apollo/Saturn V program actually flew. Yes, but if Saturn V was funded at the same level as SLS, it would have first launched in the 1980s. :-)Maybe there's a good math model supporting this intuitively realistic counterfactual. ... The difference between then and now was not money, but intent. They intended to complete Apollo. Now, not so much. Intent cannot be accurately modeled. it can be modeled, but political sciences inherently softer than the technical sciences. Beating the Soviets to the moon was in the national interests, going back to the moon before the next reelection campaign is not.
Quote from: Steven Pietrobon on 03/02/2020 08:28 amQuote from: Mr. Scott on 03/02/2020 04:14 amThe development of SLS is taking longer than the Apollo/Saturn V program actually flew. Yes, but if Saturn V was funded at the same level as SLS, it would have first launched in the 1980s. :-)Maybe there's a good math model supporting this intuitively realistic counterfactual. ... The difference between then and now was not money, but intent. They intended to complete Apollo. Now, not so much. Intent cannot be accurately modeled.
...Consider the following:1. To maximize payload, a 3-stage lander design will need to use slow, low-energy transfers2. Slow, low-energy transfers are not compatible with cryogenic fuels3. Non-cryogenic fuels are not compatible with Artemis objectives of Lunar ISRU and the "soft" objective of maximal reuse of landing architecture4. The aggressive 2024 deadline makes in-space cryogenic refueling non-viable, and to change the fuel type at a later date would require a total redesign of most of the lander.5. The extreme mass constraints imposed by launching each of the three fueled components on existing CLVs leaves them with very little growth potential{snip}Anyway, ... I think it's fairly likely we might see one of the currently-announced bidders that was angling for a three-stage design come out with a newer two-stage revision that launches on a cargo Block 1B SLS, considering all the difficulties with the 3-stage approach.
Quote from: dglow on 03/02/2020 01:58 pmQuote from: JohnFornaro on 03/02/2020 12:28 pmQuote from: dglow on 03/01/2020 09:59 pmQuote from: JohnFornaro on 03/01/2020 12:19 pmQuote from: dglow on 03/01/2020 03:26 amso this impacted Constellation, but wouldn't have affected the SLS schedule. ...Constellation slowed down SLS.Constellation may have slowed down the arrival of a NASA-designed HLLV, sure. But program A did not impact the schedule of program B ...Huh. Program A was sold as supporting and furthering Program B. ... What was the purpose of Constellation supposed to be?Constellation is program A. It came first. It was cancelled. SLS, aka program B, came second.And no, I don't think either SLS or Ares were sold in the same fashion as Shuttle.The term "same fashion" in this context, means that the program was sold under false premises. <snip>
Maybe there's a good math model supporting this intuitively realistic counterfactual. But. And there's always a but. The difference between then and now was not money, but intent. They intended to complete Apollo. Now, not so much. Intent cannot be accurately modeled.
For a thread supposedly focused on technical aspects, this sure is political seeming. Let's try to get back to technical...
Prediction: Technical Political realities will result in selection of SLS-launched HLSFixed that for you.
Ah. Is that the same context in which people remove part of their own post from the quoted thread?
It has nothing to do with the not-so-subtle "intent" you allege. I'll show you the difference in one image:
Quote from: jadebenn on 03/02/2020 07:40 pmIt has nothing to do with the not-so-subtle "intent" you allege. I'll show you the difference in one image:There is a difference between being first, and having to intentionally invent the entire infrastructure to achieve the goal of landing humans on the Moon, and now. Technical realities are not the problem with SLS. YMMV.
Quote from: JohnFornaro on 03/03/2020 12:43 pmQuote from: jadebenn on 03/02/2020 07:40 pmIt has nothing to do with the not-so-subtle "intent" you allege. I'll show you the difference in one image:There is a difference between being first, and having to intentionally invent the entire infrastructure to achieve the goal of landing humans on the Moon, and now. Technical realities are not the problem with SLS. YMMVIt is not the height of the graph I am referring to, but the shape of it. That's why SLS is taking longer.
Quote from: jadebenn on 03/02/2020 07:40 pmIt has nothing to do with the not-so-subtle "intent" you allege. I'll show you the difference in one image:There is a difference between being first, and having to intentionally invent the entire infrastructure to achieve the goal of landing humans on the Moon, and now. Technical realities are not the problem with SLS. YMMV
Quote from: rakaydos on 03/02/2020 01:00 pmQuote from: JohnFornaro on 03/02/2020 12:28 pmQuote from: Steven Pietrobon on 03/02/2020 08:28 amQuote from: Mr. Scott on 03/02/2020 04:14 amThe development of SLS is taking longer than the Apollo/Saturn V program actually flew. Yes, but if Saturn V was funded at the same level as SLS, it would have first launched in the 1980s. :-)Maybe there's a good math model supporting this intuitively realistic counterfactual. ... The difference between then and now was not money, but intent. They intended to complete Apollo. Now, not so much. Intent cannot be accurately modeled. it can be modeled, but political sciences inherently softer than the technical sciences. Beating the Soviets to the moon was in the national interests, going back to the moon before the next reelection campaign is not. In this context, "inherently softer" means exactly that intent cannot be "accurately modeled". Thanks for confirming.
What about the area under the curve? You have not explained "why" SLS is "taking longer". Anyhow, here's the oracle: https://en.wikipedia.org/wiki/Space_Launch_System"The Space Launch System (SLS) is a US super heavy-lift expendable launch vehicle, which has been under development since its announcement in 2011..." As is well known Apollo started from nothing, and achieved its goal between 1961 and 1969. SLS, not so much, eh?The oracle gives another excellent lesson in word thinking, tho: "The initial variant of SLS, Block 1, was required by the US Congress to lift a payload of 70 metric tons (150,000 lb) to low Earth orbit (LEO), but exceeded that requirement with a rated payload capacity of 95 metric tons ..."Interesting technical definition of "exceeded" which doesn't require an actual, like, launch of any actual, like, mass, FWIW.Stop me if you've heard this before: Technical realities are not the problem with SLS. YMMV
It can be ACCURATELY modeled, but not PRECICELY modeled.
The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.
For a ~100 day mission...
mod:Quote from: Lar on 03/02/2020 09:10 pmFor a thread supposedly focused on technical aspects, this sure is political seeming. Let's try to get back to technical...fan? Quote from: Lar on 02/19/2020 02:50 pmPrediction: Technical Political realities will result in selection of SLS-launched HLSFixed that for you.
Stick to whether there is technical justification for SLS-launched HLS or not.
Jadebenn is assuming an integrated lander. Thus, there IS a technical reason that no other launcher cannot handle a integrated HLS. No other currently or soon to be available launch vehicle (Excluding Starship), is capable of sending an integrated lander to TLI, or fitting a integrated lander within its fairing. BONG could potentially fit a integrated lander (IDK tbh), but we know that a integrated lander can fit within a 8m SLS fairing. Of course other launchers could launch a three element lander, but those elements would have to be launched separately, and docked together, at Gateway.
Jadebenn is assuming an integrated lander. Thus, there IS a technical reason that no other launcher cannot handle a integrated HLS.
No other currently or soon to be available launch vehicle (Excluding Starship), is capable of sending an integrated lander to TLI, or fitting a integrated lander within its fairing.
Even the assumption of an integrated lander does not justify the claim. Existing and soon to exist vehicles could get it to TLI [Again, I would say 'thru TLI'.] by simply using a dual launch architecture. For example, the PPE for the gateway also can serve directly or as the basis for a transfer stage from LEO to lunar orbit. The Falcon family should have a plan for a larger fairing for NSSL, which is relatively trivial problem compared to getting people to the moon, and New Glenn's fairing should be plenty.Of course, since there isn't any technical reason to assume an integrated lander, the point is moot.
I would think that an integrated lander would have an overall higher safety level, and an integrated lander easily provides enormous surface capability, due to the larger mass margins from launching on SLS, and not requiring each stage to have its own rendezvous and docking capabilities. If you look at Constellation's Altair, or Boeing's HLS proposal, it shows that an integrated lander would need a far larger fairing than Falcon or New Glenn could provide, unless BO propose a hammerhead fairing of some sorts.
Jadebenn is assuming an integrated lander.
Quote from: Kerb on 03/05/2020 12:05 pmJadebenn is assuming an integrated lander.To clarify: I'm not.My point of contention is that going with the 3-stage approach would require a lot more design compromises than the integrated approach; The limitations on fuel type and element mass being chief among them.Sure, it could get you to the Moon and back, but where's the evolution path? The Artemis landers are supposed to be able to evolve into fully-reusable beasts capable of bringing all 4 crew down from Gateway and refueling using ISRU. There's no better way to ensure that won't happen than by engineering the lander into a dead-end with near-zero future extensibility just so it can fit on something other than SLS.
My point of contention is that going with the 3-stage approach would require a lot more design compromises than the integrated approach; The limitations on fuel type and element mass being chief among them.Sure, it could get you to the Moon and back, but where's the evolution path? The Artemis landers are supposed to be able to evolve into fully-reusable beasts capable of bringing all 4 crew down from Gateway and refueling using ISRU. There's no better way to ensure that won't happen than by engineering the lander into a dead-end with near-zero future extensibility just so it can fit on something other than SLS.
I really fail to see how an integrated SLS lander becomes more reusable than the alternatives.
Ultimately any HLS method that sends mass direct thru TLI and aggregated in deep space will be an inferior trade to one where an optimized reusable transfer stage hauling components from LEO thru TLI, to Gateway and out to LLO will be far superior.
Requiring the all up configuration on first launch which will never be needed again is just adding a configuration which potentially could cause mass growth.
Is there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?
Quote from: Markstark on 03/22/2020 01:34 pmIs there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?Yes. Boeing will not be sole-sourced the lander contract even if it's decided to go with an integrated lander.
I agree. I don’t anticipate that the HLS contract will be sole sourced to Boeing. I anticipate two or three HLS contracts. My question is, is there a scenario where the first HLS for 2024 landing is launched on a B1B but the HLS vendor is someone other than Boeing. They still get a contract, but it would be for a later date.
I believe NASA has the ability to force Boeing to make an SLS rocket available to another contractor since SLS is a government-owned system, so I think that scenario is possible.
The lander contractor who uses SLS is supposed to be the prime for the extra SLS since NASA is not going to do the integration for them, I don't see anyone else can do this besides Boeing.
1. To maximize payload, a 3-stage lander design will need to use slow, low-energy transfers2. Slow, low-energy transfers are not compatible with cryogenic fuels3. Non-cryogenic fuels are not compatible with Artemis objectives of Lunar ISRU and the "soft" objective of maximal reuse of landing architecture4. The aggressive 2024 deadline makes in-space cryogenic refueling non-viable, and to change the fuel type at a later date would require a total redesign of most of the lander.5. The extreme mass constraints imposed by launching each of the three fueled components on existing CLVs leaves them with very little growth potential
Quote from: su27k on 03/24/2020 03:18 amThe lander contractor who uses SLS is supposed to be the prime for the extra SLS since NASA is not going to do the integration for them, I don't see anyone else can do this besides Boeing.Couldn't a non-Boeing lander contractor simply sub-contract integration to Boeing?
Quote from: jadebenn on 03/24/2020 02:36 amQuote from: Markstark on 03/22/2020 01:34 pmIs there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?Yes. Boeing will not be sole-sourced the lander contract even if it's decided to go with an integrated lander.I agree. I don’t anticipate that the HLS contract will be sole sourced to Boeing. I anticipate two or three HLS contracts. My question is, is there a scenario where the first HLS for 2024 landing is launched on a B1B but the HLS vendor is someone other than Boeing. They still get a contract, but it would be for a later date.
Why must you dig up my old shame.
Quote from: jadebenn on 05/22/2023 05:28 amWhy must you dig up my old shame. Because he is a tusker (wild boar) who like digging up old and buried threads.