Author Topic: Prediction: Technical realities will result in selection of SLS-launched HLS  (Read 55281 times)

Offline jadebenn

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It's late at night, so I'll keep this brief.

Consider the following:
1. To maximize payload, a 3-stage lander design will need to use slow, low-energy transfers
2. Slow, low-energy transfers are not compatible with cryogenic fuels
3. Non-cryogenic fuels are not compatible with Artemis objectives of Lunar ISRU and the "soft" objective of maximal reuse of landing architecture
4. 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

In addition, the new head of HEOMD has been reviewing the Lunar architecture, and was supposed to have released a new plan internally on the 14th, with a public release upcoming sometime in March. I'm putting my money on the possibility we're going to be seeing some heavy revision in regards to HLS, EUS, and the SLS flight manifest and cadence in general.

Anyway, I know this will probably be an unpopular prediction, but 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.
« Last Edit: 02/19/2020 04:15 am by jadebenn »

Offline Proponent

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If the NRHO used has an altitude varying between 3000 and 7000 km, then a worst-case Hohmann-like transfer to LLO would be a approximately a 8700x1800-km ellipse (radii, not altitudes, at apolune and perilune).  Half the orbital period of such an ellipse is about 5 h.  That's not terribly long, and is certainly much shorter than the minimum acceptable maximum surface stay time.  I mean, you're going to want your crews to hang out on the moon for at least a few days.  Hence, I think it's surface stay times rather than orbital transfers that affect propellant choices.  That's to say that the ascent stage in a 2-stage lander and both the transfer and ascent stages in a 3-stage lander will need lengthy viability times.  The descent stage in either architecture may not, and, indeed, the Blue Origin/Lockheed/Northrop Grumman/Draper plan involves a hydrolox descent stage.  Methalox is nominally space storable and was originally baselined for Constellation's Orion capsule and Altair lander.  The BO/Lock/NG/D lacks a suitably sized methalox engine, however, so I would guess its transfer and ascent stages will burn the usual hypergols.

It's not clear to me that ISRU is going to be part of Artemis.  It's explicitly not part of H.R. 5666 (the House's proposed NASA authorization bill), and S. 2800 (the Senate's) refers to the vague term "sustainability" but not to ISRU.  Both bills require EUS and neither mentions 2024: two good reasons to believe that neither 2024 nor anything close to it will happen.

I think you may be right that 3-stage landers will fade from discussion.  Boeing wants 2 stages, and Congress seems to listen to Boeing.  Not that Congress should be specifying architectures at all, but....

Offline Lar

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

Fixed that for you.

The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.
« Last Edit: 02/19/2020 02:51 pm by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline su27k

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Non of the technical reasons given make any sense:

1. NASA's DAC2 architecture analysis has 2-stage and 3-stage landers (IP 08 and 17) that do not use slow transfer to NRHO
2. DAC2 has a SLS based architecture that requires keeping LOX/CH4 fuel cool for 8 to 12 months (IP 03), so cryogenic fuel is compatible with slow transfer to NRHO
3. ISRU doesn't even appear in the HLS RFP. Reusability was mentioned as an option for post-2024 landing in early draft, but it was removed from the final version. So none of these will be used in selecting the winners.
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.
« Last Edit: 02/19/2020 04:29 pm by su27k »

Offline jadebenn

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

Fixed 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.
« Last Edit: 02/19/2020 05:43 pm by jadebenn »

Offline jadebenn

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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.
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.

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.
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.

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.
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.

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.
I could see the benefits of dissimilar redundancy, here, but it'd depend a lot on the specifics of the proposals and the weightings NASA uses, methinks.

Offline meberbs

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

Fixed 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.
If you didn't want this to be political, you shouldn't have based your argument on a political 2024 date (and Congress rejecting that date out of politics,) and ISRU (removed in part by politics) etc. You jumped straight into the politics of the situation with your justification. The parts that you mention which are actually technical are also wrong as pointed out above.

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.
As I know you are aware, I have already covered examples of how commercial rockets today provide better architectures than the SLS. While Starship clearly would be better in every way, and is developing at a rapid pace, it is fine to ignore it as a ground rule. It remains unreasonable from my perspective to even use SLS to launch Orion to the moon, but it is simply contradictory to the facts in evidence to think that SLS would somehow have spare capacity to launch other hardware as well if you stick to the 2024 timescale, and there is no plan to have EUS ready by then.

Offline armchairfan

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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.
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.

Offline su27k

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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.
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.

Yeah, Steven Pietrobon also estimated 20.8t through TLI in this post.

Offline GWH

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While not a bidder that we know of, Tory Bruno of ULA has made many comments implying long stage life of ACES like this one
https://www.reddit.com/r/ula/comments/96uoax/what_is_aces/e44r8a9/

Quote
Also 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.


Offline su27k

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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.
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.

Each element of the two stage lander on SLS will need its own propulsion systems too, and there needs to be a sort of "docking" interface between them so that the two can be separated, so some of that mass penalty applies to SLS single launch architecture too.

Quote
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.
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.

See discussion above about possible TLI capability of stock FH.

As far as I can see all the NASA planning for the CLV launched lander used FH as reference LV, so I don't see why fairing would be an issue.

Quote
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.
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.

NASA is part of the administration, they're the same thing. The president's budget request is basically NASA's answer to congress about how much it would cost to do Artemis, there's no way NASA didn't have a say in what's in the budget.

The bids were submitted months ago, I don't think bidders can change it before winners are selected. It is possible that they can change it after being selected, but then given NASA really doesn't like to rely on EUS for 2024, I don't see why they would want to given the alternatives.

Offline Proponent

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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.
The transfer stage shouldn't have too much problem fitting in a 15t payload. The ascent and descent stages are another story.

What about refueling with non-cyro propellants?  It:

    1. Makes the stages much lighter;
    2. Is a demonstrated technology; and
    3. Is required anyway for truly sustainable operations (though admittedly we don't really know what the Senate's authorization bill means by "sustainable":  if it's meant in a political sense, then probably anything that continues to fund Orion and SLS is "sustainable").

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.
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.

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.
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.

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.
I could see the benefits of dissimilar redundancy, here, but it'd depend a lot on the specifics of the proposals and the weightings NASA uses, methinks.
[/quote]

Offline TrevorMonty

While not a bidder that we know of, Tory Bruno of ULA has made many comments implying long stage life of ACES like this one
https://www.reddit.com/r/ula/comments/96uoax/what_is_aces/e44r8a9/

Quote
Also 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.
A long life ACES stage can take slow route (3months) and deliver payload direct to Gateway for 3.1km/s compared to 3day 3.7km/s. That is significant performance increase for no additional mass to US as IVF system saves mass compared to current Centuar systems.

Also payload doesn't need propulsion and avionics for TLI - Gateway trip so more mass savings.



Offline Lar

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

Fixed 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.
My take on the technical reasons put forward is that none of them hold up to scrutiny, so I'm comfortable with the recharacterization, but you go ahead and have fun trying...

Quote
I refuse to let this devolve into another Starship vs. SLS "discussion,"
People don't own threads. They go where they will. We mods will try to help keep things focused but only to a point. You can't wall off people pointing out that other alternatives are better.  PS, putting scare quotes around things doesn't make your case for you at all.
Quote
so all I'll say is it will not be available for a crewed Lunar mission on this timescale.
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....
« Last Edit: 02/20/2020 06:35 pm by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline JohnFornaro

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If 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.
Sometimes I just flat out don't get it.

Offline meberbs

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If 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.
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.

Online Coastal Ron

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If 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.

The first two of those were driven "need by" dates, they were "this is when it happened" dates. NOT politically driven.

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But 2024 is the date we have to work with at the moment.

Not if Congress doesn't fund it.

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Whether or not 2024 is "agressive" or not depends on the willingness of the aerospace community to work towards that date.

1. Why should the "aerospace community" care about the 2024 date? In this current effort they assume risk that doesn't translate into reward regardless if they meet the 2024 date or not. I see ZERO incentive for them.

2. In time of war or acknowledged "National Imperative" the private sector has stepped up to support their country in a time of need. This 2024 goal is NOT something the nation "needs", it is a political desire.

Quote
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.

The repeated use of gender pronouns is not enough for the private sector to risk $Millions on a political activity. And that is what the current NASA plan is, a "co-investment" strategy that requires private companies to risk their own money to attain a purely political goal. No wonder there is hesitation...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline JohnFornaro

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If 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.

Well, maybe jadebenn could have tightened up his summary.

I'm not addressing the technical problems other than to broadly, but not specifically, agree that cryo boil-off would be a technical problem with low energy, *lazy* transfers.  It takes three and a half days to get to the Moon's surface. Go ahead and add an extra day to assemble pieces in LEO, then send 'em up to the Moon post haste.  If that's not the plan, then they're not really trying to get back to the Moon, as I see it.

I think it was Planetary Resources who proposed using low energy orbits for their project?  I skyped the lead tech guy once, and questioned him on the economic viability of six month transfer orbits, to find out that they hadn't considered the tinme value of money, but I digress.

I think what we're seeing at HEOMD and all, is simply the same-old same-old.  Sigh.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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If 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?
« Last Edit: 02/21/2020 04:49 pm by JohnFornaro »
Sometimes I just flat out don't get it.

Offline rakaydos

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If 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.

Online Coastal Ron

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If 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?

Congress writes the funding laws, and Presidents can only sign them or veto them. There is some flexibility, but for the most part an administration can award all the contracts they want, but there won't be money to pay the contractors unless Congress authorizes the programs.

So sure, a President can propose any date they want, and any activity they want. But funding laws - how and when money is spent - that comes from Congress.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline jadebenn

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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....
Well, you've got one now.
« Last Edit: 02/22/2020 06:36 pm by jadebenn »

Offline jadebenn

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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.
Good point that a larger LV doesn't necessitate SLS. It's in the latest phase of development for a vehicle of its size, but you also have slightly less-powerful designs that are around the same maturity and should be available by 2024, such as Vulcan and New Glenn. Starship is a bit of a wild card here, as cargo Starship could be ready to launch a separate lander payload by then, I think, but I don't think SpaceX would find that option very attractive.

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.
« Last Edit: 02/22/2020 06:12 pm by jadebenn »

Offline ZChris13

Prediction: Technical Political realities will result in selection of SLS-launched HLS
Fixed that for you.
The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.
I don't think Starship is a good choice for Lunar Lander beyond the fact that it would:
A. exist
B. be able to send itself to the surface and back with significant payload via a refueling scheme

There are black marks against it too, I personally don't understand the exhaust impingement crater issue well but there are a lot of very smart people doomsaying regarding it. Using Starship as a TLI stage or maybe even a command/reentry module is a much more promising architecture, but requires additional development, which would negate the primary benefits so I guess we're back to letting better be the enemy of good enough.

I hope the first lunar cargo Starshp attempt is soonish, should be enlightening.

EDIT: whoops I forgot to make this on-topic.
I disagree with the ideas presented in the OP. Cryo boil-off doesn't seem to be as big of an issue as people think it is when you're not trying to use liquid hydrogen.
« Last Edit: 02/22/2020 06:38 pm by ZChris13 »

Offline GWH

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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.

Short answer, not really. They state 13 tonnes to GTO, somewhere I saw 10-12 tonnes to TLI recently but I can't remember where for the life of me.

As big of a rocket it is, the 1st stage will have to stage at a lower velocity than say Delta IV or Atlas V, so its very large 2nd stage starts dropping in capabilities fast.

Of course other threads suggest they may be sandbagging:
https://forum.nasaspaceflight.com/index.php?topic=41146.1520
https://forum.nasaspaceflight.com/index.php?topic=43073.100

They also need to deliver class C payloads for NSSL of 6.6 tonnes direct to GEO, which doesn't really correspond with the payload ration between the LEO and GTO figure. 
This suggests 2 possibilities: either they really are sandbagging or they have something else up their sleeve. BE-7 is very well suited for used as a 3rd stage, which they plan to use for the transfer element and is pretty much the ideal 3rd stage/tug. See my thoughts on that here: https://www.reddit.com/r/BlueOrigin/comments/eukh8g/thoughts_on_the_blue_originnorthrop_grumman/


« Last Edit: 02/22/2020 09:51 pm by GWH »

Offline Lar

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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....
Well, you've got one now.
Check your PMs.  I'll try to remember where that thread we used was.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline JohnFornaro

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If 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. 
Sometimes I just flat out don't get it.

Offline JohnFornaro

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If 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 ....

Thanks for sharing your enthusiasm.  With your help, mankind will surely stay on Earth.  Have a nice planet.
Sometimes I just flat out don't get it.

Offline Markstark

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I agree with your prediction that one of the HLS selections will be an SLS launched lunar lander. Furthermore, it will likely be a two stage lander. The SLS will feature a different upper stage and but not necessarily a Boeing-EUS.

Offline GWH

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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.

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?

Offline rakaydos

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If 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.
Let me introduce you to the Golden Rule.

He who has the gold, makes the rules.

Congress has the power of the purse, recent constitutional crisis concerning "national state of emergency" aside, which means they decide if anyone gets paid to get to the moon by 2024.

We are in a capitalist society. If noone's getting paid to do something, it wont happen. (hence the need for social saftey nets in capitalisim, to make sure the money is there for basic humanitarian concerns)

On the other hand, Elon must definately has the will, and is expected to have the money, to practice moon landings while waiting for mars windows to open. Starship isnt at all optimised for the moon, but it has the capacity to brute force a solution in any number of ways. (dropping skycrane pad builders via apollo 10 trajectory, or intentional crashes of various kinds that lets a pad builder emerge safely, or additional nose (vertical) or belly (horizontal) mounted landing engines, or other approaches)

Once Elon's figured out landing on the moon (and mars), well, he's got no reason to go back to the moon unless someone pays him. But I bet the price will be less than an SLS launch, if anyone's interested.
« Last Edit: 02/23/2020 05:10 pm by rakaydos »

Offline jadebenn

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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.

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?
I believe he's referring to the several different reference architectures in one of the attachments.

Offline JohnFornaro

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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.

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.


I'm gonna write that one down.

Quote from: rakaydos
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.

In turn, let me introduce you to another saying:

Do not bite the hand that feeds you.
Sometimes I just flat out don't get it.

Offline envy887

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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.

A lot of interesting stuff here, and I think this post could be a full page of itself.

Is Appendix H or another summary of the considered architectures available anywhere public? In particular, I wonder if increasing the AE wet mass to the 15+ t limit and using part of that on descent was considered, to mitigate DE mass growth.

Offline FiniteBurn

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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.

Offline rakaydos

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

Quote
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.
Why would you believe that? Congress has no problem throwing NASA money, but not for 2024 moon missions. They throw NASA money because it's welfare that they can pretend isnt welfare, and those "good paying jobs" might vanish if we ever actually accomplished anything.
« Last Edit: 02/26/2020 03:59 pm by rakaydos »

Offline GWH

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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.

Thank you, Second BAA draft, Attachment A12 Architecture Analysis of Alternatives (August 7 2019) https://beta.sam.gov/opp/cd53a248201b96671d9599dd268fdc47/view
PDF Download Link

Coles notes:
Considered Alternatives:
- Sub-TLI launch, individual elements finish the burn
- Make the transfer element do more (partial crasher stage, or pick up the ascent element in LLO)
- Higher capacity launch vehicle
- in space propellant transfer
- 4 element launch is also considered
- Passive Cryogenic Fluid Management with deployable sun shield to reduce boil off rates of cryogens
- Active Cryogenic Fluid Managenement
- Launch vehicle upper stage derived transfer element (this includes Centaur specifically)
- Reusable landing gear as part of the ascent element
- Drop tanks for the ascent element or a combined Ascent/Decent element
- Combined ascent/descent element and 2 transfer elements
- "Super tug" built off launch vehicle upper stage. Pretty deep split kind of contradicts a statement about not considering deep dV splits

Not considered alternatives
- Single stage
- Any kind of Earth Orbit rendezvous including single stage*
- Deep split ascent/descent elements (aka a true crasher stage)
- SEP tugs

Commercial launch vehicle graphics are initially a very Falcon Heavy looking outline, then on slide 41 on are New Glenn's with the logo stripped off (strakes and all).

*Earth Orbit rendezvous wasn't considered due to high thermal loads and orbital debris concerns.



Overall this makes me more excited and curious to see these proposals come out. The sub-TLI launch option I think would be favorable to Blue Origin's proposal as a BE-7 would have great ISP and New Glenn's second stage is going to have a lot of dry mass due to its shear size. Drop tanks and re purposed upper stages both would make for some very neat architectures.
« Last Edit: 02/24/2020 10:33 pm by GWH »

Offline JohnFornaro

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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.

Quote from: JF
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.  ...

Quote from: rakaydos
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.

Well, yeah.  I have this old fashioned idea that success is rewarded, failure not.
Sometimes I just flat out don't get it.

Offline ZChris13

Quote from: rakaydos
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.
Well, yeah.  I have this old fashioned idea that success is rewarded, failure not.
It's important to keep in mind Congress' definition of success and failure in this matter.

Offline RonM

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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. Vice President Pence pulled the 2024 date out of his you know what just so President Trump could have a moon landing during his second term (assuming he is reelected). 2024 will get us a flag and footprints mission because of the rush to get it done. 2028 could lead to a sustainable program.

Getting back on topic, I think political realities will have SLS used to launch crew on Orion while everything else will be done on commercial launchers. HLS will not be launched on SLS because of cost.

Offline rakaydos

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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.

Offline su27k

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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.

Offline JohnFornaro

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... 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: rakaydos
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.
« Last Edit: 02/27/2020 11:58 am by JohnFornaro »
Sometimes I just flat out don't get it.

Offline rakaydos

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... 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: rakaydos
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.

Offline JohnFornaro

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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.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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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.
« Last Edit: 02/27/2020 12:34 pm by JohnFornaro »
Sometimes I just flat out don't get it.

Offline RonM

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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.

Offline JohnFornaro

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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.
Sometimes I just flat out don't get it.

Offline rakaydos

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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.

Offline Proponent

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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.

Offline FiniteBurn

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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. 

Offline GWH

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^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:

Quote
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/

Offline su27k

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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.

Offline FiniteBurn

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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.
« Last Edit: 02/28/2020 02:56 am by FiniteBurn »

Offline JohnFornaro

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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.
« Last Edit: 02/28/2020 01:08 pm by JohnFornaro »
Sometimes I just flat out don't get it.

Offline su27k

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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.

Offline JohnFornaro

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I'm not interested in word plays...

Fair.

Quote from: 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...

Quote from: su27k
I'm more interested in concrete discussion on technical details.

... as has been explained above.

Sometimes I just flat out don't get it.

Offline JohnFornaro

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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
Sometimes I just flat out don't get it.

Offline su27k

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Quote from: 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...

Quote from: su27k
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.

Online dglow

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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.

Offline JohnFornaro

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

Constellation slowed down SLS.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Sometimes I just flat out don't get it.

Offline woods170

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

Constellation slowed down SLS.

That's one way of looking at it. In that SLS is the second attempt to create Ares V.

Online dglow

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so 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.
« Last Edit: 03/02/2020 05:43 am by dglow »

Offline Steven Pietrobon

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The 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. :-)
« Last Edit: 03/02/2020 08:29 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline JohnFornaro

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so 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?
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Offline JohnFornaro

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The 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.
Sometimes I just flat out don't get it.

Offline rakaydos

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The 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.
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.

Online dglow

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so 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?

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.
« Last Edit: 03/02/2020 01:59 pm by dglow »

Offline JohnFornaro

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so 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.  Was there some point to Program "A", which, in this context, is Ares and Constellation?  Short answer, yes.  Constellation and Ares were meant to support a return of Americans to the Moon, somehow making SLS work better.  IOW, program A was a "technical reality" which delayed program B.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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The 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.

Going back to the beginning of the thread:
...

Consider the following:
1. To maximize payload, a 3-stage lander design will need to use slow, low-energy transfers
2. Slow, low-energy transfers are not compatible with cryogenic fuels
3. Non-cryogenic fuels are not compatible with Artemis objectives of Lunar ISRU and the "soft" objective of maximal reuse of landing architecture
4. 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.

1. SLS has not yet been proposed for supporting "slow, low energy transfers" supporting a lunar mission.

2. Whatever the word is which describes the vehicle which performs the "slow, low energy transfers", has not yet been proposed to fly on SLS.

3. My sense is that the lander will use hypergolic propellant, at least at first.  We still don't know how many landings there need to be in order to set up an ISRU plant on the Moon.  Heck, NASA cannot even use IRSU techniques to tear down the old launch tower and build a new one here on Earth's surface.

4. All dates are political, and if the NASA machine has no intent upon realizing the date, it will not happen.

5. Extreme mass? 
« Last Edit: 03/02/2020 09:05 pm by gongora »
Sometimes I just flat out don't get it.

Online dglow

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so 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>

Ah. Is that the same context in which people remove part of their own post from the quoted thread?   ::)

Offline jadebenn

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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.
It has nothing to do with the not-so-subtle "intent" you allege. I'll show you the difference in one image:

Offline Lar

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For a thread supposedly focused on technical aspects, this sure is political seeming. Let's try to get back to technical...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online dglow

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mod:
For a thread supposedly focused on technical aspects, this sure is political seeming. Let's try to get back to technical...

fan?  ;)
Prediction: Technical Political realities will result in selection of SLS-launched HLS

Fixed that for you.

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Ah. Is that the same context in which people remove part of their own post from the quoted thread?   ::)

haha.
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Offline JohnFornaro

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It 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.
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Offline jadebenn

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It 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.
It is not the height of the graph I am referring to, but the shape of it. That's why SLS is taking longer.
« Last Edit: 03/03/2020 04:54 pm by jadebenn »

Offline JohnFornaro

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It 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
It is not the height of the graph I am referring to, but the shape of it. That's why SLS is taking longer.

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
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Offline rakaydos

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The 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.

False. It can be ACCURATELY modeled, but not PRECICELY modeled.

A precice shooter has a tight shot group. An accurate shooter is centered on the target.

Offline jadebenn

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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
Development naturally wants to follow a bell curve. The more you squash it flat, the more you must spread out tasks. The more you spread out tasks, the slower development goes. The slower development goes, the more money you're spending on personnel and losing to inflation.

Congress prefers the consistency of a relatively flat budget, so a flat budget the SLS gets. Keeps the yearly slice of the NASA budget pretty much the same, but inflates the total cost. Literally.
« Last Edit: 03/03/2020 11:56 pm by jadebenn »

Offline JohnFornaro

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It can be ACCURATELY modeled, but not PRECICELY modeled.

Yeah, right.  No.  There is simply no accurate nor precise mathmeatic  model of human intention.

SLS is not failing because of technical realities and we're watching HLS die off because of "accurate" and "precise" miscalculations based on false premises.  The major false premise is that no metal will be bent until every option has been "accurately" and "precisely" modeled.  They are creating an always expanding tree of alternatives.  It's not as bad as that famous rice grain on the chessboard example. Day one, one grain, day 2 , two grains, day 3, four grains, etc, but they're working on that.

The simplest HLS solution is posted up above by Lar:

The technically "right" lander is a one stage lander. It's being built in Boca Chica as we speak.

The mission should be planned around this strategy, and let the winner be the party which delivers.

Thoreau:  Simplify, simplify, simplify.

As to your analogy of the precise and accurate shooter.  You forgot to include the guy who draws a bull's eye over the group he shot.  Hint:  Look at these precisely accurate calcs on a three piece HLS.  Woo-hoo!
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Offline JohnFornaro

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For a ~100 day mission...

There will be no 100 day missions.
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Offline Lar

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mod:
For a thread supposedly focused on technical aspects, this sure is political seeming. Let's try to get back to technical...

fan?  ;)
Prediction: Technical Political realities will result in selection of SLS-launched HLS

Fixed that for you.
Absolutely correct. Early in the thread I gave my fan opinion. I didn't spend a lot of walls of text on explaining all the politics in detail, I just opined that it wasn't going to be technical reasons.

Now, I'm wearing my mod hat and saying that while you might want to say what I did, or not, (and leave it at that) actually dissecting all the politics is off topic.   Savvy? I get to wear two hats if I want to.

THAT SAID: is anyone actually saying anything new that's on topic? Mod reports about this thread are on the increase, which is often a sign that the thread's played out.

Funding is not a technical reality. Stay out of funding, or politics. Stick to whether there is technical justification for SLS-launched HLS or not.
« Last Edit: 03/04/2020 01:40 pm by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline JohnFornaro

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Stick to whether there is technical justification for SLS-launched HLS or not.

Well, there's nothing "technical" forbidding HLS in principle being a payload for SLS, always assuming mass to be the restraint.  The discussion seems to me to be more about whether HLS should be one, two, or three part.  Heck, the second post started discussing the dang NRHO orbit!
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Offline Stan-1967

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Stick to whether there is technical justification for SLS-launched HLS or not.

I'm really trying to understand the differing views in this thread, & the underlying assumptions do indeed make this very frustrating.  So here is my attempt to make sense of it all & add something:

What is meant by "technical realities" or  "technical justification"?
1.  A technical reality based on a unique capability ( i.e safety, payload to LEO, TLI, etc.)
2.  A technical reality based on a unique requirement?  This requirement can be technical, financial, or political ( i.e humans must go to wherever in the Orion spaceship, budget for the mission is capped at some lowball number, or "go to the moon" & Congress gives you infinity money)
3.  A technical reality based on a political circumstance ( i.e we will only fund program 'X") Not having any money to pursue a technical solution is the worst of all "technical" problems.  Way worse than being at TRL=0.

SLS can reasonably be argued to meet many technical realities based across a spectrum of value based assumptions. ( Thank you JadeBenn & other SLS advocates for voicing these)   Alternately it can also fail to meet an array of countering technical problems based on very real technical realities, also rooted in value based assumptions.

I am left feeling that while both sides of this argument have singular coherency, overall the argument becomes incoherent because of the internal contradictions at the root of the question, which I think are correctly pointed out to be the lack of defined "need" and "purpose" of HLS efforts in the first place.  Coastal Ron has been beating this horse mercilessly & correctly for years, & he is right to do so.  The incoherency at the political headwaters ( US Congress & Executive branch) cannot explain how their funding & programatic decisions align to what they think it is what they need.  Their failure to define a need & then fund a program aligned to that is not surprising.   
   
Private entities ( not to be named..keep this thread pristine from them..)  can partially bypass this morass if they steer clear of entangling themselves, however financial forces inevitably push them to align themselves to the flow of money, & they become subject to the politics.  If they shun the money with the political strings attached, it is a very real technical handicap, & they risk relegating their efforts to side-show status.  I would also add that private entities have no margin for tolerating the incoherence of government led efforts.  They simply don't have the money or time to participate unless the government guarantees payment for whatever piece of the pie they win.



Offline rakaydos

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The problem isnt that SLS is somehow technically incapable.

The problem is that the thread title is specifying that there is a TECHNICAL reason NO OTHER launcher will be able to handle HLS. This is patently absurd and his post fails to eliminate all other launchers the way it would need to.


Offline Kerb

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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.
« Last Edit: 03/05/2020 12:06 pm by Kerb »

Offline meberbs

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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.
Even the assumption of an integrated lander does not justify the claim. Existing and soon to exist vehicles could get it to 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.

Offline Kerb

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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.
« Last Edit: 03/06/2020 11:39 am by Kerb »

Offline JohnFornaro

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Jadebenn is assuming an integrated lander. Thus, there IS a technical reason that no other launcher cannot handle a integrated HLS.

Please reword this so there aren't quite so many negatives?

Quote from: kerb
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.

Your language is confusing.  To me, "to TLI" means launching a spacecraft from Earth to the point where trans lunar injection would take place but no further, implying a lunar tug or a TLI stage.  I would say, 'thru TLI', implying that the spacecraft is launched from Earth all the way into lunar orbit.

BONG is an unfortunate acronym seemingly made famous by Cheech and Chong.
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Offline JohnFornaro

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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.

What I think I hear you saying is that there's no way to get humans on the Moon and return them safely, using one launch.  Obviously, that has been done, even tho Saturn had some what more capacity than SLS.  Today, however, there are mass constraints which preclude an "integrated lander", starting with the mass of the Orion capsule.  It seems like it will take two or three launches to LEO of the various pieces, which will then have to be assembled in LEO and then sent off to the Moon.

So I think I agree with you.

In this thread, however, there are several undefined terms:  "technical realities"; "integrated landers"; "unique capabilities"; and a few other terms which mean what the poster wants them to mean, which limits the broader utility of the conversation.
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Offline Proponent

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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.

Of course, both Constellation and  Boeing had or have reasons  of their own to require particular large-diameter launch vehicles.

Offline jadebenn

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Jadebenn 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.
« Last Edit: 03/06/2020 02:19 pm by jadebenn »

Offline JohnFornaro

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Jadebenn 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.

What is the chief downside of a lander that "could get you to the Moon and back", and why is this not a satisfactory goal?

And a point of clarification.  What law of physics is it such that all landers launching on other than SLS will be engineered "into a dead-end with near-zero future extensibility"?
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Offline GWH

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I really fail to see how an integrated SLS lander becomes more reusable than the alternatives.

You have a larger 2 stage lander, all NASA plans state the lander will not be reused, but it could happen one day. Due to established mass limits that justify SLS use, that lander is too massive to launch on anything other than a dedicated SLS launch. Cost of the larger lander replacement remain higher.

With either system, the ascent element would be solvable to be refueled and reused. Orion can act as a tug to carry a prop load when flying on EUS, ap point to SLS there.

The transfer element may be able to cycle back to Gateway for reuse,  so potentially no loss there.

The 3 stage landers all require propellant delivery to close off 2 of 3 stage reuse, so at least one flight plus a prop load with Orion. 

If ISRU comes about then there really isn't some magic thing accomplished in a 2 stage system that can't be done in a 3 stage.

Offline GWH

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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. 
It's better than SLS since it can deliver equal or more mass thru TLI than an extremely expensive dedicated launcher with no other "customers".
It's better than a 3 component solution where 2 unnecessary stages worth of dry mass are put thru TLI just to be expended.

2 stage integrated or 3 stage aggregated at Gateway, both solutions are still attacking the wrong problem.

Offline meberbs

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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.
This logic is all so backwards, that it seems like it must be nothing other than motivated reasoning.

If it is reusable/refuelable, propellant can be sent separately, and any discussion of limitations on fuel type based on trajectory to the moon are simply nonsense. Restricting the fuel type just so the first launch is constrained to launch on SLS is an actual example of "engineering the lander into a dead-end with near-zero future extensibility" for a short term preference.

At the same time the whole paragraph where I quoted that phrase from is backwards. All lander designs are multi-part. I don't think anything I have heard of proposed (not counting Starship) involves full reuse of the stages, not without ISRU capabilities that there has been no evidence of any plan to implement, and certainly would require multiple landings first. Since replacement pieces of the lander will need to be launched anyway, then there is no reason that the 1st launch would have to be all-up integrated either. Requiring the all up configuration on first launch which will never be needed again is just adding a configuration which potential could cause mass growth.

Offline JohnFornaro

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I really fail to see how an integrated SLS lander becomes more reusable than the alternatives.

Is that a failure of imagination, or a failure of political will?  Askin' for a friend who throws away his car after each round trip.

One of the mistakes on threads like this, is the refrain that the first next landing of humans on the Moon, has to be like the second one, and the third one, and so forth.  NASA keeps this refrain going by pretending to have already *cough* scheduled 10 Artemis launches!  See?  It's *cough* sustainable, because there's ten of 'em!  As if to imply that all is known about the future of American human lunar missions, and that new launchers won't happen, new landers won't be designed, no innovation will take place, yada yada.
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Offline JohnFornaro

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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.

You're getting dangerously close to arguing for a lunar tug, which is not mentioned as being included in the next ten Artemis flights.  Because re-usability?  Sustainability?  NASA doesn't say.
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Offline JohnFornaro

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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.

While I would have put that slightly differently, this is broadly in agreement with my objection to jadebenn's suggestions.  Each successive mission will be different as the knowledge base increases, as lessons are learned, and as new innovations come on line.  the first launch is different from all subsequent launches.
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Offline Markstark

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Is there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?

Offline rakaydos

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Is there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?
wasn't there something about Boeing needing to demonstrate that an additional SLS launch for a lunar lander would not affect the Artemis SLS rate? If Boeing does not get the lunar lander bid, I do not see them taking the steps needed to produce an extra SLS for a lander.

Offline jadebenn

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Is 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.

Offline Markstark

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Is 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.

Offline jadebenn

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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.
« Last Edit: 03/24/2020 03:03 am by jadebenn »

Online Coastal Ron

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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.

Contractors have no say over how the U.S. Government uses its own assets, even if the contractor builds that asset.

So I'm not even sure why anyone would think that Boeing has a say regarding what flies on the SLS - NASA doesn't have to ask permission from Boeing for which payloads fly on the SLS.
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Is there a scenario that HLS-1 launches indeed launches on Block 1B but the lander contractor is not Boeing ?

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.

Offline Proponent

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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.

Couldn't a non-Boeing lander contractor simply sub-contract integration to Boeing?

Offline DreamyPickle

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Quote
1. To maximize payload, a 3-stage lander design will need to use slow, low-energy transfers
2. Slow, low-energy transfers are not compatible with cryogenic fuels
3. Non-cryogenic fuels are not compatible with Artemis objectives of Lunar ISRU and the "soft" objective of maximal reuse of landing architecture
4. 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

This whole argument relies on "Lunar ISRU" being an important goal but it doesn't seem to be a requirement for 2024 landing. The political imperative seems to be to perform a landing as soon as possible and NASA should pick an architecture using storable propellants if it can get boots on the moon faster with lower tech.

It could take many manned missions to get an ISRU system up and running and those missions could very well be based on storable propellants. Hell, even if you have a base that can produce hydrolox it makes sense to have a backups ascent vehicle based on hypergolics.

Another aspect is that current plan is for NASA to make two awards. It's not clear where they would find the budget for this but it is clearly the way to go for a "sustainable" system because it provides dissimilar redundancy. Setting up a race between an SLS-based HLS and one based on commercial vehicles would also help with the goal of landing as soon as possible.

Offline su27k

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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.

Couldn't a non-Boeing lander contractor simply sub-contract integration to Boeing?

That could work, but I have trouble seeing this happening in the proposal stage. Maybe it could happen post award, after some persuasion from Loverro. A new national team of Blue + LM + Boeing sounds pretty good politically.

Offline Vahe231991

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Is 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.
SpaceX won the first HLS contract in April 2021, and it was awarded an HLS contract in November 2022 for the Artemis 4 mission. That Blue Origin was just awarded the third HLS contract this month rather than SpaceX shows that there will be not one, but two companies for providing the HLS systems for the first three manned Artemis missions.

Links:
https://techcrunch.com/2021/04/16/spacex-wins-nasa-contract-to-develop-human-landing-system-for-returning-to-the-moon/
https://www.nasa.gov/press-release/nasa-awards-spacex-second-contract-option-for-artemis-moon-landing-0
https://www.nasa.gov/press-release/nasa-selects-blue-origin-as-second-artemis-lunar-lander-provider

Offline jadebenn

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Why must you dig up my old shame.  :'(

Offline Zed_Noir

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Why must you dig up my old shame.  :'(
Because he is a tusker (wild boar) who like digging up old and buried threads.  >:(

Offline woods170

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Why must you dig up my old shame.  :'(
Because he is a tusker (wild boar) who like digging up old and buried threads.  >:(

Threads are not buried until they are archived. Which btw. never happens on this forum. That is one feature of the NSF forums. Another major feature is that the NSF forums has a very good collective memory.

I've made some pretty stupid mistakes on this very forum over the years. They are still there for all to see. What sets forum members apart is the capability to "own" their mistakes.

Those who accept that they screwed up and are willing to admit it, won't have much problems here. Those who are ashamed of having made mistakes will probably be forgiven. But those who try to hide their mistakes, or deny that they made them, will eventually be exposed for what they truly are. Some of them even got axed for it permanently. ParabolicArc comes to mind for example.


But I digress.
« Last Edit: 05/23/2023 07:53 am by woods170 »

Tags: HLS Artemis 
 

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