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It looks like the "improvement" to EUS allows it to bring a minimum of 10 metric tons of comanifested payload on Block 1B, and their graphic shows 11t.

That's what it was always supposed to be, anyway? Perhaps the 10-11t was a target they could not reach with the other version?

Up thread it was said that "we know" it exceeds 37t... I'm not seeing that. Hopefully NASA can tell us more at some point. BTW, assuming they are able to exceed what NSF is saying above, it would be the result of optimizing EUS for TLI, vs an attempt to make it generic (presumably adjusting prop load for different goals on a larger tank). This demonstrates a truism: the mission for any system that is not grossly over-capable for any likely target needs to be established FIRST, and the vehicle designed to fit that mission.

Of course of that extended to the core stage, it would very simply not exist as a hydrolox sustainer, but would be a hydrocarbon booster, and they'd have hydrolox stage 2 (and could likely dump the SRBs and do TSTO).

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I have acquired a graphic listing the EUS specs as of 2018.

J5XlbQm.jpg

I will compare it to the one @tater showed.

  • Dry weight is roughly 1,000 lbs lighter for the new EUS (28,940 lb versus 30,000 lb to 31,000 lb)
  • Propellant weight actually seems to be a fair bit lower (though this may have been an oversight or mistake in the new graphic, as the number seems nonsensically low if it's truly referring to the "wet" weight of the whole stage and not just the weight of the propellant itself).
  • Stage height has decreased (~17.6 m versus 17.8 m)

Overall, the new EUS design is actually a bit smaller than the old one, even though it has greater performance.

Edited by jadebenn

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Steven Pietrobon at NSF posted some numbers for different versions, and suggested that the 2018 version no only took 2 tons more to TLI, but that it might have been planned to do LOI as well since it has excess dv compared to TLI. I wonder how much dv it needs to place the payload in an Earth parking orbit, however, that might explain the extra ~1.3 km/s.

An EUS capable of taking a payload to the Moon and doing LOI would be a useful thing, actually, since if it was a lander for example, the lander would not have to carry the excess tank mass to the surface. Also, RL-10c3 vs any other engine (Isp of 460.2s).

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The first SLS core is preparing to leave Michoud Assembly Facility.

exvMRW4.jpg

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On 1/1/2020 at 4:51 PM, jadebenn said:

The first SLS core is preparing to leave Michoud Assembly Facility.

It took a week to roll it to the barge?

Your image it was on blue lifts, now yellow. Guess they had to change what it was attached to.

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1 hour ago, tater said:

It took a week to roll it to the barge?

For every action a worker does (“tie-down secured, sir!”) two others have to verify it was done properly and fill out the associated paperwork, which then needs to be reviewed before moving on to the next tie-down.... Or something like that...

Or else expensive space hardware ends up falling on the floor (insert old image of fallen weather satellite on the clean-room floor here)

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I know they dot all the "i"s and cross all the "t"s, but they tweet out an image of it rolling out of the building, then the next tweet is a week later, and it's still rolling out of the building, lol.

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35 minutes ago, tater said:

I know they dot all the "i"s and cross all the "t"s, but they tweet out an image of it rolling out of the building, then the next tweet is a week later, and it's still rolling out of the building, lol.

Well I guess it must be a really long rocket then.

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Spoiler

  

13 hours ago, StrandedonEarth said:

For every action a worker does (“tie-down secured, sir!”) two others have to verify it

The security officer and the translator.

 

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On 1/8/2020 at 1:39 PM, tater said:

Your image it was on blue lifts, now yellow. Guess they had to change what it was attached to.

One of the NASA image captions states that the initial transporters were only designed for internal factory use (well, to be more precise, the blue equipment siting on top of them was) and can't navigate inclines. The ones it's on now collectively act as the equivalent of the strongback used in the STS days, capable of navigating the (comparatively) rough road surfaces to the barge.

They also had to attach some rigging to it for transit. I don't know the exact details there, though.

On 1/8/2020 at 3:55 PM, tater said:

but they tweet out an image of it rolling out of the building, then the next tweet is a week later, and it's still rolling out of the building, lol.

The first tweet was actually of it rolling into the building. They were moving it to a place where they could prep for ship.

Edited by jadebenn

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6 hours ago, jadebenn said:

The first tweet was actually of it rolling into the building. They were moving it to a place where they could prep for ship.

Gotcha, the "preparing to leave" up thread is what got me.

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11 hours ago, tater said:

Gotcha, the "preparing to leave" up thread is what got me.

To be fair, I was under that impression at first as well. It's only upon further reading that I realized they meant they hadn't left quite yet.

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A little birdie told me of a big find of his, and oh man, this is some pretty exciting tech.

As part of the modifications made to 39B for SLS, NASA is building a new LH2 tank to replace the Apollo-era one currently in use. This tank is being built to utilize a new NASA-developed technology called Integrated Refrigeration and Storage (IRaS). Not only does this allow for zero-boiloff storage of LH2, but it allows it to be cooled further below boiling temperature to a densified, or even solid, state. In fact, according to a NASA paper on the technology, "It is estimated that densification at the 46% fill level produced the largest single batch of solid hydrogen in history: 1,020 kg, with a solid-to-liquid mass fraction of 25%, or around 11,780 L of solid material."

Similar to the RP-1 densification employed by SpaceX, this would allow greater performance of hydrogen rocket stages. With this capability soon to be available to them with the new LH2 sphere at 39B, NASA appears to be investigating the possibility of using it to further boost the performance of SLS. The NASA paper from 2016 that set out the project in the first place stated it would, "...culminate with an operational demonstration of the loading of a simulated flight tank with densified propellants." The page of a follow-up project investigating the use of densified LH2, the Autonomous Propellant Loading Project, includes the claim that a 10% or more gain in SLS ascent performance(!!!) is possible.

Overall, this really exciting technology! It's unfortunate it seems to have mostly flown under the radar 'till now.

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Could this technology be used in space? Can we have liquid hydrogen fuel without boiloff? :o

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1 hour ago, Scotius said:

Could this technology be used in space? Can we have liquid hydrogen fuel without boiloff? :o

That was my first thought too. The potential increase in SLS capability is not to be sniffed at but it’s the possibility of using hydrogen as a more general-purpose propellant that I’m excited by. 

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What does the performance boost do to payload for B1b? (Block 1 is still a dead end, it can't comanifest anything, and for cargo it has a uselessly tiny fairing).

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Unfortunately, figuring out the benefits of densified hydrogen is non-trivial. The Core will have more dv, but will also mass more, as a result, the SRBs might not be enough (ceetainly not enough to fly an identical flight profile as the TWR of the stack will change). Dunno what the thrust bump would be on the RS-25s and if this would make up for the lower stack TWR. I think for a cargo version, it's likely a decent gain, but I think the issue with the crew version is that it has a narrow possible flight profile to deal with abort contingencies.

Edited by tater

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9 hours ago, tater said:

but I think the issue with the crew version is that it has a narrow possible flight profile to deal with abort contingencies.

How so?

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1 hour ago, jadebenn said:

How so?

They have to be concerned about the trajectory WRT entry after an abort. This is why the CST-100 has to fly the profile it flies, for example, and why the downrange pitch is different for Crew Dragon (shallower, in all cases with a capsule).

This limits what can be done with SLS as long as Orion is on top. If they can use densified props and still fly an acceptable trajectory, woot! I'm merely saying the envelope is narrow for such a trajectory. (the point is that if they have an abort short of making orbit, they need to be able to have a survivable EDL profile)

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1 hour ago, tater said:

They have to be concerned about the trajectory WRT entry after an abort. This is why the CST-100 has to fly the profile it flies, for example, and why the downrange pitch is different for Crew Dragon (shallower, in all cases with a capsule).

This limits what can be done with SLS as long as Orion is on top. If they can use densified props and still fly an acceptable trajectory, woot! I'm merely saying the envelope is narrow for such a trajectory. (the point is that if they have an abort short of making orbit, they need to be able to have a survivable EDL profile)

Ah, okay. I misunderstood and thought you were definitively stating it would cause an unsafe trajectory with crew.

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New NSF article:

Boeing negotiating with NASA on future SLS Core Stage production

Interestingly, this says the first core stage actually came out underweight compared to what they were expecting. I'd imagine that's part of the reason they're looking at trading a decent bit of mass margin to simplify component designs and manufacturing, which should hopefully help bring costs down.

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