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SLS started out as the Ares-5, yes. It's still the same first stage core made of space shuttle engines.
Orion is intentionally overweight, to absorb the otherwise lethal thrust vibrations seen with the original 5-segment expansion of the shuttle solid booster. Orion atop one of those was Ares-1.
That same 5-segment booster rocket is used as the boosters on SLS Block-1. I'm guessing that they finally tamed the thrust oscillations in that design, not seen in the 4-segment shuttle design, or else the huge SLS core is enough mass to absorb and attenuate them.
Whether Ares or SLS, this is reusing shuttle components built at the same plants in the same states where the shuttle was built, to the max extent possible, for maximizing senatorial race votes. These vehicle designs are NOT what real engineers would do on a clean sheet of paper! These configurations were dictated by politicians.
All the engineers could do was cope: try to find some way to fly these things and still get to the moon. And THAT is why SLS Block-1/Orion cannot even reprise Apollo-8, much less the other lunar landing missions!
And THAT is what multiple launches to mount 1 mission, from that boondoggle Gateway station, in the idiotic unstable halo orbit about the moon, is all about!
You absolutely do NOT want politicians micromanaging your space program! They are totally (and reliably) technically incompetent! But THAT is exactly where we have been since the 1970's!
GW
PS - that same incompetent micromanaging to optimize votes instead of designing to a sensible spec, is also EXACTLY why it take many years and $billions to get a new airplane, tank, or ship. Military procurement is hobbled by congress the same way, and has been for decades.
The most famous example showing how to do it right was the P-51, way back before congress screwed everything up. About 90-100 days from paper to a flying prototype! And, like SpaceX, there was a fix-it-in-the-field aspect. The P-51 got re-engined with a better engine and a bigger prop, before it was effective enough. The final bubble canopy that fixed the "see the enemy before he sees you" problem did not get fixed until the introduction of the P-51D model, which is the one everybody thinks of.
Artemis II is the Orion atop the SLS with the flawed heat shield discovered on Artemis-I's Orion (which was the first Orion flown atop an SLS), but this one already built before they ran that uncrewed test flight. Orion flew once before, atop a smaller booster, and not under the name "Artemis"; that one (unlike the Artemis-I Orion) had a heat shield that was built and functioned properly. They changed the processing and screwed it up, for Artemis-I, building at least both the Artemis-I and Artemis-II capsules this new way, to save $.
They have decided to fly it anyway, crewed, flawed as it is, even though there has been more than enough time to switch it out with one built "right". It just cost more $ to do that. So now try to tell me NASA top managers value crew safety above $ and schedule, the way that they claim! They claimed that before the Challenger loss (and attempted a cover-up afterward), and they claimed it again before the Columbia loss. They lied, both times. I have seen nothing since to indicate that those attitudes have ever changed since the loss of Challenger.
The Artemis-II mission is a loop around the moon, then heading out into cis-lunar space for a while, before coming home. This is without orbiting the moon. This mission does not even reprise Apollo-8, much less Apollo-10 through 17! That is how uncapable the Orion's service module is, and how uncapable SLS Block 1 is. The closest comparison is Apollo-13, which looped around the moon without orbiting, to save the crew after one of the O2 tanks in their service module blew apart.
The Apollo service module had the dV capability to enter low lunar orbit off the transfer trajectory with both the command module and a lunar module, and enough more dV to get back onto the transfer trajectory from low lunar orbit with just the command module. The Orion service module does NOT have that capability: it is too small, and the Orion capsule is too big and heavy for it. This configuration was selected by politicians, not real engineers! As was the SLS Block-1 configuration.
Artemis-III is another Orion already built, and as I understand it, already being stacked atop an SLS. I do not know if they fixed the flawed heat shield, not having seen a word about that. People should be asking questions about its heat shield! While it is slated to land astronauts on the moon, they do not yet have a working lander to take those astronauts there, with the landing only a year or 2 away, supposedly.
Now I see in the news that Musk has begun a pissing contest with the acting NASA administrator, over NASA re-opening the lander contract to Blue Origin and anyone else, because the Starship variant "HLS" is behind schedule and seems unlikely to be ready in a year or 2 (and I agree with that assessment). Big money correlates with big egos that simply do not know how to behave.
The real problem here is that neither Blue Origin nor anybody else can possibly man-rate a lunar lander in only 1-2 years. It took 4 on Apollo, and that was a crash program where costs were of secondary importance. Blue Origin has built things for its small Blue Moon prototype, but has built nothing for the larger one which was to be the crewed version.
The mistake here is that a serious lander program should have started about 5 or more years ago, maybe even 10 years ago, since this was not to be a "crash" program. But none did. And nobody at the modern NASA seems to have been keeping track of the factors Musk time/real time and Bezos time/real time. There has never been any reality to NASA's Artemis program: contracts, plans, or schedules.
There is plenty of fault here, to go around. A lot of this is the Senate's fault, since they micromanage not only what is to be done, but with what hardware, to be built in whose states. And no one is taking responsibility for all this gross mismanagement. I predict no one will.
Apollo succeeded because NASA and its engineers did the work without much in the way of congressional pork-barrel politics interfering with things and micromanaging things. The Space Shuttle, however, was NOT a fully reusable two-stage airplane, precisely because of congressional mismanagement. And the ISS suffered from the same congressional mismanagement flaws, which is why there were never any human centrifuges aboard it. And why it is in an orbit that is easy for the Russians to reach, but which is quite wrong for dispatching missions to anywhere outside Earth orbit.
The only part of NASA that really worked well in the years after Apollo was JPL with the planetary probes and landers. And now this particular congress and that idiot who is our president have now gutted JPL. 25% laid off, so far. Those idiots are firing the government workers that have demonstrably done good work! Just how STUPID is that?
And everybody forgets what the other A in NASA stands for: "aeronautics". The X-59 has still not yet flown, which was to demonstrate how to fly supersonic with reduced sonic boom. Meanwhile, Boom Supersonic has already accomplished that feat, and on private money. They got there faster. And they did a really good job!
The rot in government that needs rooting-out goes deep, yes, but that process should start in Congress and the White House, not with the general federal workforce.
GW
I found this in today's "Daily Launch" email newsletter from AIAA. It refers to a longer article in the NY Times:
New York Times
With SpaceX Behind Schedule, NASA Will Seek More Moon Lander Ideas
The acting administrator of NASA said on Monday that the agency was looking for a Plan B to carry astronauts to the moon’s surface because SpaceX, Elon Musk’s rocket company, is behind schedule. In appearances on CNBC and Fox News, Sean Duffy, the temporary leader of the space agency, said he would open bidding on a contract to build a new lunar lander to other companies.
-----
my take on it:
I doubt SpaceX will lose its contract to do a "HLS" lunar lander version of Starship, unless Musk does something further to piss off Trump. Big egos seem to go with big money.
The "behind schedule" thing is the inevitable difference due to "Musk time" vs "real time". This is an effect well known and demonstrated to be a factor of about 3, since Musk started SpaceX and almost went bankrupt with it learning to successfully stage supersonic vehicles (Falcon-1, which failed its 1st 3 out of 4 flights).
There is no excuse for NASA not to have known about this effect. They apparently erroneously believed he could do it on a "Musk time" schedule. Which is where we are now.
All the contractors have this time factor schedule lie problem. It's a part of the marketing hype that wins contracts, unfortunately. It's just a different schedule time factor for each one. The government is supposed to track those things and be aware of about how long it will really take.
Boeing's time factor has risen since the merger with McDonnell-Douglas. It is now over 3, approaching 4. (Same goes for Lockheed-Martin.) The difference is that about the same jigger factor now applies to budget estimates with Boeing, not so much at all with SpaceX.
This inevitably pushes back the manned landing. It took 4 years to develop and fly the Apollo LM, and that was a crash program, where cost was secondary. It'll take longer to do this one, because the people who did this before are long-retired or dead, and took their know-how of the unwritten engineering art with them (which is close to half of what you need to know, in order to do what they did). This "plan B" thing should have started about 2-3 years ago.
And that NASA need for a "plan B" also reflects the Blue Origin delay, although nobody said a word about that! They have been funded to build and fly their "Blue Moon" lander, right alongside SpaceX, ever since SpaceX got its contract. Bezos also seems to have a time factor of about 3. And he's been busy trying to get his own big rocket flying, just like Musk.
Surprise, surprise!
GW
In the previous post, the "kaowool" is a low-density ceramic or mineral fiber insulation. That low density means it has a low thermal conductivity, letting the tile get hotter without the tank shell seeing that heat addition so very much. You can only do that if you have a separate means of "tying" the tile in place over the insulation. In SpaceX's case, that is the tile retention pins.
That low density insulation has to be a mineral/ceramic fiber to take the temperatures at the interface with the tile. That way the tile can be a denser and therefore stronger and tougher ceramic (or other material, but apparently not iron-based from Flight 10). Denser is higher thermal conductivity, inherently. Which makes the inner tile face temperature much closer to the outer face temperature. Which is why they need the "kaowool" layer.
The "Pyron" ablative layer is not something I understand yet, except that it is the backup in case the tile is lost. It is related to PICA-X, based on what little there is to be read about it. PICA-X is what the Dragon uses for its ablative heat shield. "PICA" is an acronym for "phenol impregnated carbon ablator". The carbon is likely in a woven fabric form. This was originally a NASA thing, but it was expensive and difficult to fabricate. SpaceX subsequently did a cheaper- and easier-to-fabricate variant, and named it PICA-X. It is still phenolic reinforced with carbon fibers (likely in woven fabric form) and who knows what else, either way. I have seen no material specs for either form, much less "Pyron".
Apparently, the tiles used on Flight 10 were "metallic" in the sense of high iron content in some way. I know NOTHING about the actual material! But apparently it oxidized very fast during the one entry, quite unexpectedly. Whatever Flight 11's tiles were made of, it was something different, likely some kind of firebrick-like material. And those tiles worked a lot better.
Bear in mind that there was no insulation or backup underneath the space shuttle heat shield tiles. Those were a fragile and vulnerable low density ceramic, combining the high temperature resistance of the alumino-sililcate material and the low thermal conductivity of the very low density, into a single material. The new nose and leading edge tiles on X-37B are the first step away from that approach, they being a high-density ceramic locked onto a low-density ceramic underlayer. SpaceX seems to be pioneering yet a different approach. And it would seem to be working.
GW
Update on post 2223 just above:
I saw in today's "Daily Launch" email newsletter from AIAA with a similar very positive assessment of Flight 11. It had a link to a longer Ars Technica article. I looked at that article. About the only new piece of information is that the "crunch wrap" variation of installing heat shield tiles seems to have solved the gap flow problem.
It may be a while before they fly the next one. That will be a version 3 ship with Raptor-3 engines. Who knows what they will do to the booster. They are rebuilding test stands and launch pads for the newer versions. That work is currently ongoing.
GW
I saw this story, too. The South Atlantic Anomaly is growing. That's not good news, as the effective "bottom" of the Van Allen Belts is at lower altitude there, down to LEO itself, instead of generally higher at ~1600 km ~ 900-something miles. Things in higher-inclination orbits (like the ISS) often pass through that lowered bit of Van Allen radiation.
GW
I saw the news story that Starship/Superheavy flew successfully yesterday (Monday), and I went and watched the video of it on SpaceX's website today (Tuesday). It looked to me like they met every objective and suffered less damage than the last flight.
I saw one engine that failed to light for the Superheavy boostback burn, but it lit up for the landing burn.
I did see the heating discoloration on the Starship rear flap trailing edges from the reflected jet blast of the hot staging, but I did not see actual sheet metal damage there, this time. And I saw nothing suggesting any plasma leakage through the rear flap hinge lines, so whatever they did to stop that, seems to have worked.
I didn't see much in the way of pieces coming loose during entry, but I saw lots of small bits coming off as it hit the dense air just before and during its landing burn and splashdown. I did not see a view of the heat shield as it touched down, although I thought I heard words to the effect that such coverage was actually obtained.
All in all, it looked like it got through in even better shape than the last time. Supposedly the next one will be v3 Starship with the Raptor-3 engines. It's pretty close to time for trying to recover them at launch site. They'll learn a lot more, and more quickly, from real hardware with which to do "scratch and sniff" tests, after the flights.
Kudos, SpaceX! You did it again!
GW
If power is beamed as a coherent bean, beam spread is very much reduced. A power density that is quite dangerous leaving the satellite is still rather dangerous 30,000 km away. So you have to aim the beam with utter reliability. This is an inherent phenomenon with coherent beams. We've seen it before, with both laser and maser.
You do not have that risk to mitigate, if you could use an extension cord "fat" enough not to lose very much in I^2*R losses. The problem with that concept is the materials from which to build it do not yet exist! I think I said that when I posed the concept in a post elsewhere on these forums. I used the words "manurium", "unbelievium", and maybe "unobtainium", when I wrote the post.
But once they do exist, one could use the alternate extension cord approach to lower the cost of that electricity further, by simplifying and eliminating so many safety controls and devices.
The danger posed by the extension cord is the same as that posed by a space elevator: what if the thing breaks? Part of it will fall to Earth, ultimately at very high speeds. So you have to build it to reliably not break, if you do it at all, no matter what the available materials are, in the future.
GW
I have actually looked at the Centaur as a possible small space tug. There is a larger version, but it still features the common bulkhead between the LOX and LH2 tanks. Though that is an insulated bulkhead, it still limits the stage life to several hours or maybe a day or so, which is too short to be a useful tug. The periods of the elliptic capture and departure orbits are the best part of a week long.
I really like the steel balloon approach to lighter weight, which depends critically upon control of tank pressure with both evaporation and appropriate venting. I also greatly admire the reliability of the RL-10 engines. Put those together in a scaled-up stage that has separated LOX and LH2 tanks, with anywhere from 2 to 5 RL-10 engines, and cover those tanks with low-density insulation and a very reflective outer foil layer, and you would have a LOX-LH2-powered tug with a stage life long enough to serve as a tug: more than a week or so. Without adding cryocooler equipment, which is not all that heavy, but not all that light either.
SpaceX does not face quite the same stage life problem with its Starship, because the LOX and LCH4 temperatures are not very far apart. They are already doing pressure control of evaporation and venting. But they are not relying upon the inflated balloon approach for strength. At that size scale they cannot, and they also must make this thing a survivable reentry craft, plus land the thing. Centaur does none of those things. SpaceX's design is similar to monocoque construction, with frames and stringers. Their stage life is long enough that a Starship could be a very large space tug. It would have to be fitted for external docking features in one way or another, though.
You would choose a large tug when flinging a large craft into interplanetary space. You would use a small tug (like my conceptual Centaur variant) when flinging a small craft into interplanetary space. The tug (of either size) takes you from LEO speed to just under escape, so that your interplanetary craft need add only a little more to get fully beyond escape to the c3 needed for its mission. The tug (whichever it is) stays on the extended ellipse, and burns (unladen!) back into LEO about a week or so later, then must rendezvous with "something". The unladen burns need not much propellant, despite the large LEO-entry dV (rendezvous budgets are small), precisely because it is unladen (very much lighter in nonpropulsive weight).
GW
Data on the moon's orbit about the Earth, from the "data" worksheet in the "orbit basics spreadsheet" file, part of the "orbits+" course materials available by links from the forums site.
Rmax = 405,506 km, Rmin = 363,299 km, Ravg = ellipse a = 384,403 km, eccentricity = 0.0549 (some 5.49%). speed V at apogee = 0.9632 km/s, V at perigee = 1.0751 km/s, avg V at R = a is 1.0176 km/s. Mean surf gravity 162.3 cm/s^2. Mean surface escape V = 2.376 km/s, mean surf circular orbit V = 1.680 km/s. Mean radius = 1738.3 km, polar radius = 1737.6 km, equatorial radius 1738.7 km. Mass = 7.354 x 10^22 kg.
GW
The moon's orbit about the Earth has a low, but nonzero, eccentricity. That eccentricity will overcome anything based on pure circles. But that effect at low eccentricity is still low.
There is also the issue of local topography. Few places on Earth are really an approximation to the "ideal sphere" used to estimate both sunrise and moonrise, and sunset and moonset, here on Earth. 1 degree of topographical deviation is a deviation of about 4 minutes in sunrise or moonrise, and in sunset and moonset.
Even the adjacent tree-line is a serious effect on this. Locally, the adjacent tree-line variations correspond to angle deviations up to 1.5 degrees (6 minutes) from the "ideal" horizon. Where I am, this is the central Texas prairie. But there really is topological deviation, plus the heights of adjacent tree-lines. Other locations with more pronounced deviations will have even larger time differences for sunrise, moonrise, sunset, and moonset. It is inherent.
Complicating that is some light refraction effects upon what you term sunrise and sunset. Even those definitions have a serious effect: about 2 minutes, whether you use tip-of-sun (or moon) at horizon, or the centerpoint of the disk. Both the sun and the moon are roughly half a degree in diameter as viewed from Earth.
Sorry, but that is the real-world stuff you have to deal with.
Now, who did a better job explaining it. Me, or ChatGPT?
I still say that the term "artificial intelligence" is an oxymoron. Precisely because no computer has any understanding of truth vs falsehood. If all you know is only what others have said, how can you possibly know what is right vs wrong?
Dare trust no machine, and very few real humans!
GW
The Carnot efficiency is an upper bound upon what can be done, from classical thermodynamics. The disparity between what actually can be done and what that upper bound is, is usually quite large: around a factor of 2.
Carnot efficiency is 1 - Tcold/Thot, where the temperatures must be in absolute units.
These low pressure concepts are attractive ONLY if you can tolerate the low inherent energy conversion efficiency. Crudely factor 2 below Carnot efficiency.
Sorry, but that's just the way it is. There have been NO observed exceptions to classical thermodynamics for about 300 years now!
GW
Spacenut:
Here's best notion I've been able to come with yet. Use the Dragon with the bigger trunk, and use a refuelable version of Blue Origin's smaller lander prototype as the LM. I'm not sure, but I think the Blue Origin lander designs were to be 1-stage in order to be reusable. I also think they were going to use LOX-LH2 propellants in order to make 1-stage reusability happen.
Then we need a scaled-up Centaur with the anti-boiloff gear installed, because we are going to use it as a reusable tug, and we need about a 2 week stage lifetime. The lunar trajectory is a 3-body-disturbed ellipse to the moon at its apogee, and LEO at its perigee. The period is about 10 days. If you do not burn for capture at the moon, you will return to LEO, where you can burn to recover there.
Transport the Dragon/big trunk fully loaded with one Starship freighter to LEO, transport the reworked Centaur fully loaded to LEO with another Starship freighter to LEO. After that, you only need to send up propellants for them, and more Dragons with the big trunks. All with Starship freighters to LEO. No big tanker refill flights
Use the modified Centaur to put the loaded Dragon-big trunk/Blue Origin LM onto the lunar trajectory, then detach and let the modified Centaur come back, where it burns unladen to recover into LEO, requiring very little remaining propellant to do so. Thay's about a 3 km/s dV fully laden and another 3 km/s unladen. I am assuming the big trunk has enough propellant to put the whole cluster into low lunar orbit (dV ~ 1 km/s), and to get back onto the trajectory to come home without the lander (another ~1 km/s at a lighter mass), which lander is left in lunar orbit. The trunk is lost and the Dragon makes a direct free return.
The next mission does not need another lander, just the propellant tanks by which to refuel the one left in lunar orbit. All you need are those tanks, and another Dragon with a big trunk. You are out one trunk per mission, and the lander refuel tanks. The Dragon capsule is reusable a few times. Nothing else! Two Starship/Superheavy launches for the first mission, maybe only 1 per mission after that. But no more than 2.
If you can figure out how to use the modified Centaur as a tug, You can course-correct not to make a free entry return with the Dragon/big trunk, but to stay on the ellipse instead. The tug can retrieve you, but that will require another 10 day trip around the ellipse. That's the cost of not losing the Dragon (which is actually reflyable after entry) and the big trunk (which cannot survive entry). Dragon currently has 2 weeks life support for up to a crew of 7. Smaller crews could ride for a longer duration.
If you capture into polar instead of equatorial orbit at the moon, the dV to capture is higher, perhaps double. That would require a really big trunk for Dragon. But that does put the south pole within reach. You capture into an extended equatorial ellipse, instead of low circular. Then you do the 90 degree plane change at its apogee where speeds are low. Then you finally enter low circular polar. There will be a rendezvous budget for rendezvous and dock with the lander, on subsequent missions.
Of course, there is nothing reliable as a cost estimate per launch of Starship/Superheavy. But even if that is $100M per launch, you are looking at no more than $200M per mission in launch costs to go back to the moon. SLS might be able to put these clusters into low lunar orbit with one launch, and it might not, but the price using it is supposedly past $4B per launch.
I'd say my idea not only saves beaucoup launch cost money, but it also saves on mission hardware costs by reusing nearly everything. How could it NOT be a far better idea? Its only fault is that we are not using hardware made in former shuttle-item plants in the states of powerful senators. Which is why under the current government operating procedures, nothing better than SLS will ever be done by NASA.
GW
It's worn out, Spacenut. Particularly the Zvezda module, which keeps cracking and leaking. Sooner or later, something is going to split wide open, and decompress the entire station, killing the entire crew.
It's not pressurization / depressurization cycles like an airplane, but hot-to-cold thermal cycling every orbit. Sunlight vs shadow. That's roughly 4000 cycles per year, for over 2 decades now. 80,000 + cycles? A lot of airplanes were only designed for 40,000 cycles. Same aluminum structures! Unlike most other metals, aluminum does not seem to have a low stress value below which fatigue life is infinite. Or if it does, that value is very low indeed.
You are correct in pointing out that NASA has no valid follow-on space station plan of any credibility! The powerful senators that dominate what NASA's big projects are, are simply too stupid to understand what is really needed next. We do not elect our best and brightest to Congress. Or had you not noticed that?
Myself, I think it is way past time we-the-people got Congress out of the business of micromanaging NASA projects for pork barrel outcomes instead of real space program outcomes. Congress has been doing that to NASA since Apollo. We have NOT seen a logical next-project-notion for NASA, since John F. Kennedy set the moon-landing-objective-before-1970, way back in 1961.
As for this last Cygnus cargo flight, word has it that the trouble was in the flight control software, not the actual engine system hardware. Still, that kind of nonsense is no longer tolerable. Starliner showed that lesson for certain and for true, plus the other lesson about not being so damned cheap.
GW
Spacenut:
Look at it this way. If there were still in existence the Apollo CSM and LM, that entire cluster could fit within the cargo bay of an operational Starship, and be within its anticipated payload capability to LEO. We still do not have a good figure for the cost of a Starship/Superheavy launch, but whatever it finally proves to be, it will be way less than the cost of a Saturn-5, and truly way-to-hell-and-gone less than an SLS (which even makes a Saturn-5 look cheap)!
We could put some sort of Centaur upper stage with an appropriately scaled-up set of propellant tanks into another Starship cargo bay, and send it to LEO to be docked with the Apollo CSM/LM cluster. That scaled-up (slightly) Centaur could put that cluster into the lunar transfer orbit from LEO (doing what the S-IVB did before), and the service module of the CSM has enough dV capability to enter low lunar orbit with the LM, and to return from lunar orbit without the LM. That reprises any of the Apollo missions. You lose the Centaur and the LM, and eventually you lose the service module. But you DO NOT lose a Saturn-5! And you did it with two Starships from LEO without any refueling.
Wanna do it even better? Leave the LM in lunar orbit for the next mission, but modified for refueling in orbit. Substitute a Dragon and the ISS-deorbit trunk with the extra propellant, for the Apollo CSM. Make sure the modified Centaur is just big enough to fetch along propellant tanks for the LM's left in lunar orbit. Do the same mission as before, except refuel and reuse the lander on subsequent missions (maybe 1 or 2 more). All you throw away is the trunk and the extra propellant tanks that refueled the LM in lunar orbit. But you must send a loaded lower LM stage with each subsequent mission!
Wanna do it even better than that? Use the smaller 1-stage Blue Origin lander instead of the old 2-stage Apollo LM. Landing from low lunar orbit requires a lower dV than from that idiotic halo orbit. That way, the smaller Blue Origin lander can carry even more payload down, and maybe even back up, from the lunar surface. Refuel it with the tanks sent for each mission after the very first one that put it there in low lunar orbit. Just make sure your modified Centaur stage can do trans-lunar injection with the Dragon, the bigger trunk for it, and the Blue Origin smaller lander. You still only need two unrefueled Starships to launch the Centaur, and the Dragon/trunk/small Blue Origin lander cluster, to LEO. You throw away only the trunk and the lander refuel tanks. The Blue Origin lander will likely have a longer service life being re-used, than the old Apollo lander ever might have had. Probably much more than 2 missions.
Now think about a third Starship, one that is at least partly refueled in LEO. Use it as a tug to reach the perigee speed of the transfer orbit to and from the moon (just barely under Earth escape at LEO altitude). If you match with the Centaur stage, you can recover it and bring it back to LEO for refuel and re-use. A fourth such Starship could do the same thing to retrieve the big trunk from the Dragon (and maybe even the lander refuel tanks), for refuel and reuse based in LEO. Now, you throw away nothing except maybe the lander refuel tanks! Although, it would help to have a propellant depot and vehicle assembly space station in LEO!
Not even Musk has proposed using Starship as a tug to retrieve returning-from-the-moon things to LEO. But now I have!
And if you do the tug departure thing using yet another partly-refueled Starship, you don't even need the modified Centaur stage!
It's all about thinking outside the usual boxes. Not even Musk does THAT!
GW
Starship/Superheavy is primarily a freighter from the surface of the Earth to low Earth orbit, and back, being reusable, and needing no refueling for those missions. You have to remember what it really is; and even Elon needs to remember that. (I agree with you about his arrogance, he is very definitely NOT an engineer.)
However, given refueling while in low Earth orbit, it does offer the possibility of being a freighter to other destinations, pretty much anywhere in the Solar system, if time-of-travel is not an issue. The faster it has to get there, the more propellant it must use, and the smaller the payload it can carry, simple as that. But, these would be one-way trips, until and unless a propellant manufacturing capability can be established at those destinations!
The advantage of using Starship in that role has absolutely nothing to do with payload fraction or launches per mission or any of the other traditional measures. It is that one (!!!) vehicle can perform multiple roles, if you are willing to pay the cost, primarily in tanker flights for that refueling on orbit. You DO NOT have to develop a new vehicle for each of those missions. And that is unlike anything we have ever seen before!
That is perhaps not what we really need for going back to the moon at small mission scale, I agree. If true, then that is a bad NASA management decision, plain and simple. Blue Origin is too busy trying to make its New Glenn fully operational to be able to get its lunar landers ready in time, either. Which is why I think the possibility of a manned US lunar landing in 2026-2028 is utter BS.
If getting to the moon quickly is the real goal, they should send an uprated Dragon (the one with the bigger trunk that holds the propellant for deorbiting the ISS) to low lunar orbit with a Falcon Heavy, and maybe the smaller demo Blue Origin lander to that same low lunar orbit with another Falcon Heavy or a New Glenn, after doing a crash effort to get the lander flightworthy in time.
All this nonsense about a Gateway station in that weird extended (and unstable) halo orbit about the moon, plus that other nonsense of an overweight Orion and an under-powered service module atop a $4B+ per launch SLS block 1, that cannot even send that Orion into low lunar orbit other than as a 1-way suicide trip, THOSE are why our moon mission plan is fundamentally fatally flawed.
I could say those are ALL very bad NASA management decisions, except that it would not be true! All of that was mandated for political pork purposes, by powerful Senators in whose states the plants are located which built the space shuttle.
The real culprit for all these bad decisions is Congress.
But I will also say that Musk did not help matters by misbehaving so badly for Trump. He pretty much ruined his reputation as a human being, doing all those evil things he did. And THAT is really why Tesla sales have cratered in Europe!
GW
From what I read on the internet, the Merlin 1-D has a bigger expansion ratio than the Merlin 1-C. Design chamber pressure has risen from just under 1000 psia (69 bar) to something near 1400 psia (96-97 bar).
The cycle shows to be something called the "gas generator cycle", and the engine images seem to show a dump pipe or tube for the massflow through that gas generator (to drive the turbopumps). There is NOTHING in anything I read online to suggest what the dumped bleed fraction BF might be. But there clearly is a dumped bleed of some percentage.
Meanwhile, I still have no dimension for the Merlin throat diameter. It is very hard to reverse-engineer the performance of an engine without the very basic data of its nozzle geometry. And I would bet REAL MONEY the reported Isp values are for only the nozzle flow rate, not the total flowrate drawn from stage tankage. I've seen that too many times from other contractors.
Meanwhile, your 5 bar chamber pressure looks awfully low for the solar engine. That's only about 72-73 psia, something not seen since Robert Goddard's experiments in the 1920's.
Let's just say that without the real data, and really-feasible assumptions for the solar rocket, the entire CFD model is suffering from GIGO problems. Extreme GIGO problems! Regardless of whether the OpenFOAM code can model transient ignition behavior or not! And I would bet that it really cannot. Most such codes cannot, even today!
GW
I have not kept up with everything that has been going on. Is Sierra Space the inheritor of the Bigelow inflatable technology? Those designs on the site via your link surely do look like it! Right down to the apparent 1 m thickness around the window openings. Which is not only thermal insulation and meteoroid/debris protection, but also some degree of protection against solar flare radiation.
If you put such a station into Earth orbit somewhere below the Van Allen belts, you are still largely protected from too much solar flare radiation by the Earth's magnetic field. If you want to explore the effects of the radiation and how effective your design is at protecting against it, Van Allen belt radiation is a fair-to-middling surrogate for solar flare radiation. Just put your experimental station (or at least a module) into an orbit that takes it inside the belts. Excepting the South Atlantic anomaly, the nominal lower "edge" of the Van Allen belts is about 900 statute miles = 1600 km altitude. It's a very fuzzy boundary.
I also see that nobody but me is yet proposing to couple a linear stick of such modules together, into a "baton", and then spin it end-over-end for artificial gravity. You can build the decks into the cores of the inflatables as fold-out items. But in baton mode, you can explore the effects of multiple levels of partial gee gravity, all the way up to (and beyond) 1 full gee at the outer 2 modules' outermost decks. That is an experimental answer that we must have for long duration manned missions. And we have ZERO in the way of an answer yet! Which is an unconscionable lack! Traceable directly to nearly all of NASA's significant projects being pork-barrel items dictated by Congress. Since Apollo, actually!
GW
I've said it before and I will say it again: it is too early to be criticizing a design for low payload while it is still in experimental flight test. To do so ignores the changes that will come from the results of those tests. And it ignores other changes that will come from deployed experience.
History has multiple examples. The early models of the B-17 ("Fortress I", prototype model-299 and B-17A through B-17D) had no power gun turrets and no tail gun position. Yet it had about the same range and payload as the later models that did have better self protection ("Fortress II", B-17E, B-17F, and especially B-17G with the chin turret). Fortress I could not have flown missions from England into Germany, the Germans would have simply shot all of them from the sky. Losses were high enough with Fortress II because of a lack of long range fighter escort, but acceptable enough for the bombing campaign to succeed.
If you want to criticize a design, criticize one that has supposedly entered service, with demonstrable shortfalls. Such as SLS Block 1 that has already flown a "real" mission. It is "bigger" than a Saturn-5 in terms of launch thrust, yet with Orion as its payload, cannot reprise Saturn-5's lunar mission performances. Why? Precisely because it was cobbled-together of repurposed Shuttle components and factories for political pork purposes, instead of being purposely designed to return to the moon.
As for Starship/Superheavy, the outcome remains to be seen. It is still deep in experimental flight test. Yet if the payload to LEO projections come true, one can easily estimate a realistic number of tanker missions to refuel a Starship on orbit for any deep space mission, lunar or interplanetary! Let's say Starship finally ends up with a 1300 metric ton propellant capacity (something NOT YET KNOWN FOR SURE). Lets say the payload-to-LEO capacity ends up in the 100-200 metric ton range. At 100 tons, it would take 13 such flights to completely refill a Starship on orbit in LEO. If 150 tons, 8.67 ~ 9 flights (you must round up, not down). If 200 tons, 6.5 ~ 7 flights.
For it to take 20 such flights would imply a payload capacity of only 65 metric tons. For it to take 40 such flights would imply that the payload capacity is only 32.5 metric tons. The bird is still in experimental flight test, and is still undergoing major design changes between tests. Only 4 have made it back from orbit so far, and all of them had problems. None have yet been recovered at all, which will make a huge difference in solving those major problems.
With the bird still that experimental, why on Earth would any sane person be trying to fly those experimental missions all as max-payload capacity demonstration missions? That makes absolutely no sense at all!
First, you make the bird survivable at all (they've done that 4 times now, but with major problems still remaining to be solved). Then you make it recoverable for real "scratch and sniff" evaluations after landing. Then you fix as many problems as you can solve. Then, finally, you start loading it up to see what it might be capable of carrying!
Trying to project what the bird might carry in the future from what it has been carrying on highly-experimental test flights is just utter nonsense!
One more thing: this bird is fully reusable, unlike all previous vehicles with the exception of the Falcon-9/-Heavy. And first stages are far easier to recover, while second stages are really, really hard to recover! It should surprise no one that developing a reusable orbital craft will take far longer than any expendable ever developed before.
The ratio of real time to Musk time is only about 3, demonstrated so during the all-expendable Falcon-1 development. An effort that nearly drove them bankrupt with the first 3 flights in a row all failures. It took a little longer to make Falcon-9 fly, because they were already wanting to re-use the booster. That just reflects what I said in the previous paragraph. And making Falcon-Heavy out of Falcon-9 took a bit longer than it should have, because they did not anticipate at the outset just how bad the structural problems would really be.
So, the apparent ratio of real time to Musk time nearer 6+ actually reflects his fundamental bad guess ratio of 3, compounded by the unanticipated troubles of doing reusability when no one else had ever done it before. And make no mistake, we all share the same bad guess time ratio at one value or another. That is just because we are human.
Actually, I am surprised and pleased by the progress they actually have made toward Starship/Superheavy. It cannot really support a lunar mission in the next year or two, because it will simply take longer than that to get all the bugs out and get started demonstrating a reliable track record in deployed operation to LEO. You have to do that, before flying people in it. Much less landing people on the moon in some variant that is still today just a paper design.
GW
From the AIAA email newsletter “Daily Launch” for Friday 9-26-2025.
AEROSPACE AMERICA
NASA says it’s ‘no longer obligated’ to use Dream Chaser for ISS resupply
NASA announced Thursday it is “no longer obligated” to use the Dream Chaser spaceplane in development by Colorado company Sierra Space for cargo resupply missions to the International Space Station. Both NASA and Sierra said testing and development of the first Dream Chaser, known as Tenacity, would continue toward a test flight planned for 2026, but that flight would be a “free-flyer, demonstration mission.”
----
My take on it: from a technical viewpoint, this was a stupid decision on NASA’s part, driven by the current politically-driven chaos all across our government. NASA needs Dreamchaser, because Starliner is not going to go anywhere. That only leaves them Dragon!
Boeing would just as soon kill Starliner as the money-loser it has been. The only thing holding them back is the costs imposed if they fail to deliver at least one “certified” flight on their contract.
ISS is due to end sometime in 2030. That’s only about 4 to 5 years away. At a crew flight every 6 months, that’s only 8 to 10 more crew flights, and about half of those will fly on the Russian craft. So that’s 4 to 5 flights left for the US to ISS, and Starliner would have only a piece of that (1 or 2 flights), because SpaceX’s Dragon is doing such a good job already.
Even if the Russians never flew another flight, that’s still only 8 to 10 more flights to ISS by the US, with the majority going to the well-proven Dragon. So it’s still only maybe 3-4 flights for Starliner. There is just no money to be made there for Boeing.
As for the follow-on stations, there is Dragon, and Sierra Space will want to offer Dreamchaser for some of those. Why would Boeing want to offer Starliner for that follow-on market, even if they successfully fix it? Especially with the tarnished reputation it already has? Nobody is going to want to ride in it!
GW
Carpet and water do not mix at all, except as a mess out at the curb for trash pickup. I've seen it myself, from a busted toilet valve.
The sellers seem to have left the faucets on which would make the damage their fault, and taking the appliance might be a breach of contract, in addition to the water damage. Just food for thought.
GW
I saw today a story on CBS News indicating the Cygnus (the longer, heavier XL model) has reached the ISS. It turned out to be a software fault that shut the engine down prematurely during its burns. The engine itself was healthy. This was the one I reported about in the previous posting, launched by a Falcon-9.
GW
I see in the AIAA's email newsletter "Daily Launch" that Northrup-Grumman's "Cygnus" cargo craft is no longer launching to the ISS via ULA, now instead riding a Falcon-9 from SpaceX. It used to ride up on ULA's Atlas-5 launcher, which is now essentially gone except for a last few military missions.
I also see that Falcon-9 successfully put the Cygnus onto a transfer trajectory to the ISS, which I think is an ellipse with apogee near the ISS orbit, and perigee just out of the atmosphere. That would be a slightly shorter period, allowing the cargo craft to "wait out" the synchronization of ISS being there when Cygnus reaches its apogee. You circularize, and it's close-in maneuvering from there to docking.
I also see in the newsletter today that the circularization burn failed to work right, because the thruster shut down too early. Shades of Boeing and its Starliner thruster problems! Although, I'm not aware of this having been a problem on earlier Cygnus flights.
GW
I've been working on a stage sizing spreadsheet for TSTO vehicles, that will handle both expendables and reusables. Once I clean it up and finish the user's manual, I plan to add it to the course materials whose links are in this thread.
GW
Responding to, and mostly agreeing with, what Void said in the previous post. I do not usually even look at the politics thread, much less respond anymore. Because I get "flamed" when I do. But this really does need a response!
The conventional notion of left wing vs right wing in political thought is mostly an illusion. It is based upon the notion that political outlook corresponds to a straight line, from far left to far right. It does NOT! It never did!
The better model is a circle, which ranges from "middle of the road" near side, to oppressive military-supported dictatorship, on the far side. There are indeed 2 paths from here to there. But once they get all the way there, there's not a dime's worth of difference between them. It DOES NOT MATTER WHAT THEY SAY, it only matters what they do! ALL professional politicians lie! ALL the time! PERIOD!
I see NO operational difference between Stalin's Russia and Hitler's Germany. Both were military-supported dictatorships, with a secret police (or polices) to "disappear" opponents, concentration camps in which to hold opponents before finally "disappearing" them, total control of all published information, government agencies weaponized to persecute opponents, certain minorities demonized as "the enemy", all the corporate or business heads "bending the knee" to the dictator's every whim, stolen elections amounting to a sham democracy, and absolutely NO accountability upon the "fearless leader" in charge.
There are COUNTLESS other examples besides Stalinist Russia and Hitler's Germany. Putin's Russia today is only one of the latest. Xi's China is another. Kim's North Korea is another. The ruling "mullahs" in Iran are yet another. There are many more.
That ought to sound dangerously familiar to anybody in the US today.
Every one of these dictatorships which has already ended, ended in civil war at one level or another, sooner or later. They always do. And THAT ought to worry everybody in the US, too! Regardless of who you might have voted for!
Extremism is the real evil; left, right, no difference! Does not matter if it is political extremism, religious extremism, or both. And totally unregulated social media are completely rife with it! BELIEVE NOTHING FROM SOCIAL MEDIA, even if they tell you what you want to hear! They lie to you for profit! That is all they do. It is LITERALLY BUILT that way!
GW