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A Good First Step

45 Comments

Not as good as a cancellation of SLS, but it’s a redirection toward some semblance of programmatic sanity.

[Update a couple minutes later]

Eric Berger has the story.

And, of course, Boeing continues the lies: ” “The SLS core stage remains the world’s most powerful rocket stage, and the only one that can carry American astronauts directly to the moon and beyond in a single launch.”

[Update a while later]

45 thoughts on “A Good First Step”

  1. I do wonder if it isn’t too late, but yeah. If you aren’t going to cancel SLS, then at least make it effective. There’s not walking away from sunk costs but worse, NASA was continuing the same strategy hoping it may one day work out for them. Glad to see the shakeup.

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  2. Unless one or the other are dragging the SLS out behind the VAB to shoot it dead, it’s not an improvement.

    It’s arranging deck chairs on RMS Titanic.

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    1. I just finished watching Scott Manley’s YouTube report on this “reimagining” of Artemis. The top comment on his video was:

      “There’s a point when you changed plans so many times, you can’t even call them plans anymore. They’re just future cancellations.”

      That drew 310 “likes” in four hours, including mine.

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  3. Without analyzing the announcement a lot, it seems to me like something of a mild compromise…a way to use up the SLS hardware (keeping Ted Cruz happy), while eliminating stupidities like Gateway and the new mobile pad, eliminating a lot of risk to the Artemis II astronauts, and doing things that actually work towards getting to the Moon.

    Without much analysis it seems to me that they could accomplish all the goals of the new SLS mission set with other vehicles, but maybe I’m wrong.

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    1. Every time Isaacman does an interview or makes a post on X, he alludes to SLS making some launches but going away while Artemis continues on.

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      1. It would pretty much have to be. Centaur 5 is the only hydrolox upper stage that could conceivably be built in sufficient quantity on the newly accelerated Artemis schedule. The only conceivable alternative would be the New Glenn stage 2 which is too big for the job, is a much poorer fit to extant infrastructure and is not exactly a mass-producible item to the extent Centaur 5 is. Blue is going to need all of the NG2 stages it can crank out for its own revised contribution to the Artemis architecture in addition to all of the other jobs already slated for New Glenn.

        So we might as well start calling the SLS-ized Centaur 5 the SCPS (Standardized Cryogenic Propulsion Stage). You heard that here first.

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          1. Haven’t the French already given the name SCALP for one of their “weapon systems”, so this name is taken?

          2. Only in the singular not the plural. OTOH:

            J’aimerais que les Français aient des relations sexuelles avec eux-mêmes, avec ou sans leur cuir chevelu.

  6. One of the clues is apparently, the upper stage is a dual engine Centaur V.

    Would a Centaur V be able to carry enough fuel and loiter long enough to put the Orion into LLO?

    Because Orion appears to have enough propellant to either to LOI or TEI but not both.

    If Centaur could do the insertion, that means the lander doesn’t have to drag its ass all the way back to NRHO and can be smaller and/or lighter as a consequence…

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    1. I just burned a couple of hours trying to come up with an alternate mode, but am still short of a viable mission.

      I started out with the idea of using the ICPS for the LOI burn. Normally the ICPS with Orion and its ESM (Euro service module) has a delta V of about 2950 m/sec, but only about 750 m/sec is needed for LOI into LLO. So that allows a much bigger final mass, with the lander coming in at 79 tonnes. But that required too much LEO weight, even though the Orion/ESM/and ICPS were delivered to LEO separately.

      So instead I went with the Blue Origin lander weight target of 45 tonnes. That gives the ICPS + lander + Orion + ESM a delta V of nearly 1400 m/sec, which mean the ICPS only had to use part of it’s fuel for the 750 m/sec LOI, and could use the rest as a 650 m/sec adder to the TLI burn somewhere mid-course. That cuts the TLI burn from about 3200 m/sec to 2550 m/sec, which drops the initial part of the boost (done with a different upper stage) from 2.03 to 1.76, assuming the upper stage uses RL10 engines.

      But that still doesn’t get things in the range of an existing upper stage, or a non-refueled Starship with its lower ISP.

      And as part of my attempts at it, I even assumed that the lander goes up on a big booster, with the lander also enclosed by some struts inside the payload shroud that mate to the back of the Orion’s ICPS to act as an interstage for a new stack built with LEO rendezvous. Then the lander’s upper stage booster is expended doing most of the delta V for TLI, which then is discarded after the Orion stack with the ICPS separates, turns around, and conventionally docks with the lander. Then the ICPS fires to give a 650 m/sec boost to finish up the TLI insertion.

      But we don’t have the right upper stage booster to pull off the intial TLI burn.

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      1. I’m not concerned about the lander, it can get there on its own. Just the Orion. Would a dual-engine Centaur V, which I assume makes sense over a four engine since it stages almost in orbit, have enough total impulse and loiter time to brake the Orion into LLO as well as doing the initial TLI burn? Would this leave the Orion service module with enough ass to get it back home from LLO?

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        2. ‘Would this leave the Orion service module with enough ass to get it back home from LLO?’

          No. The upper stage doesn’t matter for that. The Orion service module has to handle inserting into, and exiting out of, lunar orbit. The upper stage (whichever one it is) on SLS is always discarded after the TLI burn.

          This is why Orion is only ever supposed to use NRHO or a similarly high orbit. Because it’s too underpowered (total of only 1,050 m/s) to insert into or out of any lower lunar orbit. (Apollo had over 2,800 m/s.)

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          2. Thus my approach of using the ICPS for Lunar Orbit Insertion. The ICPS is now the only SLS upper stage since the SLS-1B variant with the Exploration Upper Stage just got cancelled.

            https://en.wikipedia.org/wiki/Exploration_Upper_Stage

            The Orion and its ESM service module have the delta V to do a Trans-Earth Injection from low lunar orbit. But only just. The service module can’t both do that and do a Lunar Orbit Insertion from TLI. But the ICPS could do the LOI as long as it’s not tasked with trying to do the whole TLI burn.

            So something needs be attached beneath the ICPS to do most of the TLI burn. The TLI takes about 2950 m/sec, which is what the ICPS attached to the Orion and Orion ESM provides. But the LOI burn needs about 750 or so m/sec, so the TLI and LOI need 3700 m/sec, of which the ICPS only has 2950 m/sec. But where to scrounge up an extra upper stage, and how do they attach it to what they’ve already got? Maybe a Centaur launched on a Vulcan or New Glenn could handle the job.

            What NASA should build is an upscale SLS with a bigger LEO payload, with a larger core diameter, more lift-off mass, and five RS-25 engines. They could call it the Ares V and point out that it will be cheaper and faster to develop than the SLS, on top of eliminating the need for the Quik-E-Stop in the crazy rectilinear halo orbit.

          3. But I was hoping the Centaur could brake it into LOI. Would have enough extra total impulse vs IUS. No dice, can’t deploy the solar panels till it drops the stage.

          4. You know, rumor has it that SpaceX has in development a capsule capable of docking with either a Starship HLS or the ISS. Supposedly being capable of being launched on a far cheaper booster based on some fantasy about it being partially reusable…

      2. George, the ICPS (which I was incorrectly calling the IUS), is tot, kaput, the production line is pinnin’ for the fjords, decommissioned and scattered to the four winds.

        That’s why they are considering the Centaur V as the closest substitute.

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          1. More NASA foresight? Say it isn’t so!

            Maybe they still have the design schematics for the ICPS hidden in a warehouse somewhere.

            So all they lack for the lunar mission at this point is a working command module (the Orion still hasn’t flown with a human crew), a service module (they’ll run out of upper stages before the landing), a lander, and a launch system that can get them to the moon.

        2. George, it’s ain’t the design, it’s the loss of tooling and the staff being scattered to other projects like EUS and Centaur V.

          Sure, with enough money, you could re-establish the line, it would just cost more time and money than finishing the EUS or adapting the Centaur.

          That ship has sailed, like it did with the F-22 production line.

          The fact that they would consider adapting the Centaur after all the time and money has already been dropped on the EUS speaks volumes on NASA’s confidence that Boeing can deliver the goods in a timely fashion.

          Even worse when you consider historically, the engines are the hardest and most expensive part and it’s (the RL-10) essentially an already off the shelf item.

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  7. It was always . . . uh, *bold* to just go straight from a circumlunar mission straight to a landing. But I think we all know the pitiful reasons why NASA planners felt they had to do it that way.

    One aspect of this previously planned big leap that does not get discussed much is the matter of *docking*. Because, you see, Artemis III will literally be the first mission where Orion even has a docking port or docking software, let alone even use them. (Lockheed is still working on the port.) With Apollo, they had already done docking on two missions (Apollo 9, Apollo 10) before they even tried a landing. Here, NASA *had* been planning to do it for the very first time in lunar orbit, with a commercial lander, right on the first landing attempt mission.

    So, this is another advantage of switching Artemis III to an Apollo 9 style Earth orbit test flight. They can test out the docking stuff in a lower risk profile mission. That is no small matter, as the Boeing Starliner team can tell you.

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    1. Another advantage of the new plan is that both of the lunar landers used for Artemis 3 could, after all of the docking and crew transfer tests are done and the crew are back on Orion, make their way to the Moon, uncrewed, and conduct landing, surface loiter and ascent tests rather than do these as separate missions.

      For HLS Starship that would mean that a fully topped-off depot Starship needs to be waiting in LEO before the Artemis 3 SLS-Orion lifts off.

      There will, doubtless, be comparable preparatory steps needed anent Blue’s lander as well, I just don’t know exactly what those would need to be, though the rumored architecture of the notional BlueMoon 1.5 is said to include multiple transfer stages launched separately from the lander.

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      1. Orbital propellant transfer is a huge force multiplier. It means not throwing away any stages, just refueling a transfer stage at each end. Between manned missions you ship fuel to propellant depots at each end, using the same transfer stages.

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    1. Fortunately the Artemis docking system is compatible with the ISS, and I hope NASA has the wisdom to do the LEO test mission with the landers in a plane compatible with reaching the ISS, just in case the Artemis crew needs to hitch a ride home on a Crew Dragon.

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  9. While the spectacularly slow launch cadence is certainly ONE of the complaints about SLS-Orion, and I’m glad they’ve recognized it, it’s not the only one.

    The first problem is of course that the thing is unaffordable at any flight rate, so now we’re just going to unafford it faster, I guess.

    But the industrial supply base was specifically intended to turn these out at a glacial pace. Can we make these three times as fast? I question whether we can make tanks and interstages that fast; recent history is not encouraging. I openly doubt that Lockheed-Martin can make their overweight and heat-shield-compromised space capsules three times as fast. And I’m pretty certain AeroPratoDyne, or whatever they’re calling themselves today, can’t make and qualify an extra 8 SSME’s by next year, even if 4 (?) of them can be pulled out of storage. They didn’t make them that fast in the Shuttle era, and that was when they more or less knew what they were doing.

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    1. What if they switch the SLS core stage to use stainless steel instead of aluminum, so they could use more conventional and faster welding instead of friction stir welding? While they’re at it, maybe they could pack more impulse per volume by switching to liquid methane instead of liquid hydrogen, which of course would require new engines.

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      2. LoL While we’re at it and now that George has me in the mood why not switch from Helium to Nitrous Oxide*as the propellant pressurizer? Leaks would be a riot…

        *Just kidding you all… 🙂

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      4. Read about a company working on something like this who might be willing to license their technology to them

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  10. The elegance of the politics at play here is at least as impressive as the engineering improvements to be made. Isaacman has figured a way to stay within the legal mandate to use SLS through at least the Artemis 5 mission while simultaneously excising the dangerous tumor that was EUS from the entire architecture. Boeing has so badly blighted its escutcheon that Isaacman had the maneuvering room to deliver a roundhouse kick to its bollocks by cancelling the EUS outright.

    Along with it goes the planned flying of a crew on the EUS maiden mission. Artemis 4 will now be the first landing mission and will fly using an upper stage – Centaur 5 – with four missions worth of flight heritage at the moment and much more by the time Artemis 4 lifts off.

    If Boeing is in grin-and-bear-it mode, the rest of the major Artemis contractors should be all smiles. Given its recent SRB problems with Vulcan, ULA should be happy to get contracts for at least a pair of SLS-ized Centaur 5s.

    SpaceX should be pleased too. Launching the first flight test article of the HLS Starship lander next year as part of the revised Artemis 3 mission also potentially allows SpaceX to then send the already-in-LEO lander to a depot Starship that has been filled asynchronously, refill the HLS and dispatch it Moonward for landing, surface loitering and ascent tests.

    Blue, for its part, has the opportunity to pull much closer to even with SpaceX, though I think SpaceX will still get the lander nod for Artemis 4 and Blue for Artemis 5 as previously specified.

    There will be much of interest to watch over the next two or so years where Artemis is concerned. It’s going to be march or die for all of the affected contractors.

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  11. So, with all these changes, is Artemis II still slated to head to the Moon?

    Using the weights of the pieces that made up Apollo it would seem to me that you could have planned to launch 1) a Command and Service Module, then a 2) EM, then a 3) TLI burn module with individual Falcon 9 and/or Falcon Heavy flights. Assembled it all in Earth orbit with 2 docks. Check it all out, then fire up the TLI module, dump it, land on the moon and come back.

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      1. Modern electronics and materials (no carbon fiber in the 1960’s) could likely reduce those weights for more consumables.

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