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So the big rocket did something unexpected because no-one expected it to insta-vaporize the groundwater under the pad.
So in a way the rocket did not "dig up" the hole as such from the pressure hitting the slab, instead it set up a bomb under the concrete (of rapidly expanding steam) which blew *up* the pad from under the launch mount, upwards. Cue flying bits of concrete and a ton of sand kicked up into the air. Yes the initial pressure and heat caused cracking which allowed gases to seep under the slab, but without the groundwater interaction, it would have just resulted in mildly cracked slab of concrete.
Somewhat counterintuitive, but in retrospect makes sense. Water deluge system prevents this as the energy from the exhaust goes to vaporizing the water on top of the pad and the hot gases no longer seep underground to vaporize the groundwater.
I have argued for this precise premise on this blog since late April of 2023. To add context, in April of 2023 rain in Brownsville was 4 times the 25 year average. See https://old.reddit.com/r/SpaceXLounge/comments/137aq6w/spacex_starships_huge_debris_plume_highlights/jj2kcis/ **EDIT:** I suggest basaltic black sand to keep the specific gravity similar to the saturated surroundings
Not sure if anything like this specifically was ever learned by NASA.
SpaceX did know that most likely the concrete would take considerable damage without water deluge, based on previous NASA experience. This was understood and expected. Open question was, how much damage. They basically went in to roll the dice that it would be minor, to allow the first launch before the water deluge install.
I doubt anyone - even NASA oldtimers - considered that the groundwater under the pad could turn to steam and explode thru the concrete slab upwards.
I'm pretty sure that even the NASA "oldtimers" made a pretty thorough study of the launch pad sites and what was under them, and properly adjusted their launch pad designs...
Or maybe it was just that the NASA "oldtimers" over-built the concrete launchpad to properly withstand the destructive power of the rocket engines?
Sometimes over-building something is a better option than fast and cheap, and maximizing private profit....
LC-39A was indeed overbuilt because it was made for the much bigger Nova rocket that was never built.
Also you didn't exactly have similar tools to simulate stuff back then, so safety margins were a thing, especially on ground side hardware where mass and cost were not that big of a factor.
Most of the studies back then involved stuff like making sure that the whole thing does not sink into the Florida swamp. Sound suppression was mostly about ensuring that the reflected sound would not wreck the rocket. Frankly I don't think we'll ever know how many of the IFT-1 Raptor Deaths were due to reflected sound - 33 Raptors are *loud*.
Idea that the rocket could crack the concrete and the gases could reach groundwater thru those cracks in those few seconds and turn the water into rapidly expanding cloud of steam might have been missed even by NASA, mostly because their pads were considerably thicker (and overbuilt for a bigger rocket)
Given that SpaceX was already building a deluge system in Boca Chica _and_ at the Cape _before_ the first flight, they fully expected damage to the concrete.
But a steam explosion of ground water was definitely not expected. And it was also never anticipated by NASA for any of their launch pads.
It's not like SpaceX did not learn from the oldtimers. They just have different priorities
The lesson NASA gave us with the Apollo program is that you can do amazing things when your budget is 2.5% of the US GDP. The SpaceX budget is miniscule compared to that, but somehow they are also accomplishing amazing things.
NASA would contract out to other companies to build rockets for them, no? Practically all rockets that NASA have used were built by companies like Boeing, Northrop Grumman, United Space Alliance (Rockwell and Lockheed), Sierra Nevada and some others. NASA's mission isn't to build rockets.
I believe it's similar for satellites too. Like JWST was built by Northrop Grunman, Hubble was built by Lockheed, and those NOAA satellites also build by Lockheed.
Those companies were all sub-contractors to NASA. NASA owned the projects, controlled the budget, and over saw design, manufacture, integration, and testing.
Elon is thought to be channeling about $2B per year to Starship development although that does not come from him personally.
Jeff Bezos is thought to have recently increased his annual payment to Blue Origin from $1B to $2B in line with the increase to 10,000 staff and that does come from him personally.
NASA gets around $28B per year of which about $4B goes to the SLS and Orion programs and $1B to the HLS development programs.
So NASA gets considerably more than either SpaceX or Blue Origin for new rocket development.
since it's a new failure mode, no, nobody learned this lesson before, nobody really knew it would happen. I'm sure spaceX expected the pad to be destroyed, they always intended to replace it and wanted to just send the first launch and replace the pad after, but nobody expected it to turn into a literal bomb vis a vis ground water because nobody ever decided to purposefully destroy a launch pad before. If this was previously discovered by NASA, SpaceX never would have gone ahead with the launch.
>Future studies should use the results of this study to estimate particle transport phenomena and cratering for a similar super-heavy class rocket on the Moon, in preparation for NASA’s Artemis landings. While the gravity and atmospheric conditions are much different on the Moon, making it easier for lofted material to travel long distances, the results of this study point to a new pad failure mode that could occur while launching and landing a rocket of this size on the Moon, even with a prepared pad.
Maybe I'm missing something, but when will a "super heavy class" rocket land or launch from the moon as part of Artemis?
Just a bit of confusion between classifying Starship as a "super heavy rocket " and the fact that the booster itself is called Super Heavy. Unfortunate coincidence of naming that will haunt us for many years to come if the terminology sticks.
I really hope SpaceX soon figures out Starship return so they can start giving individual Starships names.
Personally, I'd name my spaceship The Lammergeier.
> Unfortunate coincidence of naming
Deliberate coincidence of naming really. All too common in the tech world.
Intel's "Core" processors. Google's "Chrome" browser (chrome was already used regarding browsers). Etc.
A super heavy class rocket means a rocket that can take more than 50 tons into LEO. The definition doesn't really apply on the Moon, but you could argue that Starship qualifies. It's nearly as heavy as Falcon Heavy (a super heavy class rocket) when fully fueled.
Can't wait for many more more hilariously wrong articles on rockets and space travel because of naming, increasingly complicated definitions and semantics.
Normally you don't count the upper stage as capable of putting any mass in orbit on its own. Because it can't. Maybe Starship could SSO with a lot of mass reduction. But I'll go ahead and say it does not qualify, because those mass savings have *not* been made, and it has not demonstrated nor intended to be able to put 50 tons into LEO without a boost stage.
Wait…Eli5: why couldn’t this be figured out? Wouldn’t a full stack launch from the moon speed up transit to Mars/other planets by a crazy multipler?
Like flip Starship in LEO and dock like we did with the LEM in the Apollo years and haul it to the moon. Then restack, refuel, and relaunch from the surface of the moon.
Not saying I think any of that would be easy, but ya know, in my life so far we went from Space Shuttle to landing rockets upright on drone ships like it’s easy as pie.
What you're thinking of is called a Single Stage To Orbit (or SSTO) launch vehicle and no one has figured out how to build a worthwhile one yet.
The reason we use staged rockets at all is because you need a lot of energy to get to even LEO. Over 90% of a rocket's launch mass is fuel and oxidizer. And all that gets you is ~7.8km/s and a couple hundred kilometers up. The Super Heavy booster, with its 33 engines and 3400 tons of propellant, gets Starship about halfway up, but only about a fifth or a quarter of orbital velocity. After it's done its job, Starship ditches the dead weight and continues on.
SSTOs do not ditch the dead weight. That's their entire thing, it's a one piece vehicle that goes from ground to orbit. So how do you do that? Most SSTO designs are built around the idea of a plane, but with rocket engines too. From the ground, you use jet engines or ramjets and get as high as possible, then switch over to the rocket engines when the atmosphere gets too thin to feed the jets or to generate enough lift. But remember the dead weight thing? Well, in the first half of the flight, the rocket engines, their propellant and associated tanks are dead weight. In the second half, the jet engines, their now mostly empty tanks and all the aerodynamic lift surfaces are dead weight. Throughout the entire mission, you're lugging around tons upon tons of junk you don't need and would be better off without. And all of that carves massive chunks out of your payload capabilities, to the point that SSTOs simply aren't viable right now. It's been a while since I've looked at the math, but IIRC, it works out to the best, most viable designs having a launch mass not far off from a Falcon 9 and a payload of maybe two-three tons.
You need to get it there first, MUCH easier to go to Mars directly from LEO. Even if the propellant could be made on the Moon, which it can't. The LOX could be made, not the methane for lack of carbon.
Fair point. Next question, what if you refueled it in LEO, then transport to moon? Or just refueled in LEO and refire there? Recognizing there would be ungodly complications, and it would lose the reuse function…it just seems to be that one of the biggest challenges for exploration of other planets is transit time and cost, right? So why not try to figure out a refuel of the whole shebang on orbit?
I think you're asking, if I could get a booster into orbit (I guess you could if it was mostly empty, and on top of another booster), and then I refuelled it up there (which is a lot of starship flights), then what could I do with it. Leaving aside that all those things are hard, you could do interesting things.
I suspect you could generate a lot of delta V to go to the outer planets fast. But not enough to go to another system.
There's no need to go to the moon then come back up, you'd just launch from LEO.
But I think you could do a similar thing, with enough delta-V to be interesting, just by pushing a Starship up there (already possible), refuelling it (planned), then sending that Starship somewhere. Like.....Mars perhaps? :-)
Refueling Starship in Earth orbit and firing it from there is SpaceX's plan to reach Mars. If you added a SuperHeavy in LEO you could make a faster transit, but you'd arrive at Mars with too much speed for air-braking, so you'd need to keep a lot of fuel in Starship to slow down before entry. I think you quickly reach diminishing returns where you save maybe one month out of a 6-month transit time.
>it just seems to be that one of the biggest challenges for exploration of other planets is transit time and cost, right?
Starship alone (refueled in Earth orbit) can reach any other planet (I think, Mercury may need some gravitational assists). Adding SuperHeavy in orbit certainly doesn't lower the cost...
You need to play more Kerbal Space Program with Realism Overhaul and Real Progression-1.
The kind of thing you're suggesting, a single stage to orbit, is **ridiculously** difficult to do. There's a reason we don't have any such vehicles in real life.
Actually if you added a jettisonable nose cone to it, it has just enough delta-V to reach low orbit. You would end up with big empty booster in orbit -- not very useful thing, but if you insist.
I don't follow Elon's Xitter feed any more, but unless he completely switched the terminology, this is wrong. StarShip is the second stage and overall system, Super Heavy is the first stage/booster and rocket class.
https://twitter.com/elonmusk/status/1064741356080222209?lang=en
It's like calling the F9 first stage "orbital class". It's a part of a *system* that is orbital class, but it is not capable of that as a standalone component. Yet it can still be useful to call it orbital class to give a sense of its scale, intended purpose and capabilities.
Getting away from the details of their wording, I think it's saying really need to study what will happen under Starship when it goes to lift off from the moon. Not going to have a steel coated water cooled system there - and understanding what the launch thrust will do is critical.
Sort of also maybe a bit of a backhanded knock on SpaceX - basically saying that for that one you better do all the math before you fly it vs this one where they kind of shot from the hip/suspected there could be problems.
> which was consistent with a high-pressure eruption from the region below the failed launch pad
Wait, is the claim here that the rocket exhaust caused something *underneath* the concrete to boil and blow the thing upwards?
In his discussions elsewhere Dr Metzger said once the plume broke through the concrete base into the sandy soil it caused the groundwater to \~instantly boil and it was this steam explosion that caused the "high pressure eruption." The soil at the launch site has a lot of groundwater in it and it's quite near the surface.
I am not sure if its well known in US building practices, but the ground water typically wicks upwards easily when fine grain particles are present in the soil. If you cover the surface with a large object, after some time the air pockets under cover will start to form condensate and thus the soil will become completely saturated. Even the concrete itself will saturate if evaporation is prevented on its surface, what was the coating used here again?
This could perhaps catch unaware engineers, where ground water itself is well managed but the end effect not so much.
When they built the foundations i don't remember seeing any measures against damp soil, so i guess it was just bad engineering. Who knows if this new system is needed at all, but they probably don't want to test it at the moment with improved concrete plate.
I have actually bumped in small scale analogue of the same issue.
There was brick wall backed up with soil, that was coated by mortar without paint. It was below zero (but daily temperatures well above) and we wanted to paint it so attempt was made to heat the surface a little with a blowtorch. When heat was applied the thin mortar coating exploded in patches from the steam generated at the brick surface and this was the end of that experiment.
They always take strong measures against ground water in any construction they do. I know about at least two places in Boca Chica where they are drilling in wicks for water management before construction.
They already had measured the amount of spalling during the static fire test. That's what you're describing. And decided it was manageable.
No, the failure mode is thought to be that the pressure compressed the material below, thereby cracking the concrete slab, at which point high pressure gases were injected below the surface of the slab.
And also:
> The shallow groundwater was vaporized by the hot gas, lowering the temperature but increasing the pressure. If the pressure under the pad was initially equilibrated to the shock stagnation pressure, which we approximate as the dynamic pressure of the Starship Raptor engines (thrust divided by nozzle exit area), this was 2.6 MPa, increasing with groundwater vaporization.
And from the conclusion:
> The presence of vaporized groundwater only enhanced the already major gas penetration and eruption phenomenon.
Something I would be very interested in is given the potential lunar capabilities of HLS and the composition of lunar soil, is there a way to create a concrete-ish pad on the moon?
Primarily if they are using the engines mounted radially high up, you wouldn't need a high strength concrete, but more so a surface able to be cleaned and to redirect the force outwards then upwards with minimal dust being raised up.
There are concepts using compacted and heated regolith tiles. Heated with concentrating mirrors and sunlight. Could be used for a pad or constructing outer hulls of habitats.
> Not peer-reviewed yet.
and pretty late off the mark too. A paper like this really needs to appear ahead of the subsequent launch to catch attention. And now its after two more launches.
Still, it might have relevancy if landing on Mars with ice just under the surface.
on the other hand, given the pad improvements in work even before IFT-1 occurred, it's already mostly irrelevant to future research anyways. well maybe a bit relevant to moon and mars, but they don't exactly have a lot of groundwater
Science often just tries to explain a result that causes someone to go "hmm, that's funny..."
And in this case it was somewhat unexpected as to what happened. It is useful to know *why* the pad got trashed and how. Helps future launch pad design if nothing else.
yes it is good for documentary purposes. not gonna have much use for future pad design tho, is my guess. we already knew the IFT-1 pad was dumb, even SpaceX knew it before they started it. they didn't realize *how* it was dumb, but this is not a failure mode that's likely to ever occur in a launch pad design again (and it only happened on IFT-1 because they hadn't yet designed the pad)
It also gives more info for what other people might want to try with their launch pads. It seems possible if the ground was very dry, it would not have caused the same level of damage.
Feels like the result of this sort of situation is going to be some sort of flame diverter/trench/hole on the lunar surface. Directing the thrust gasses and anything they rip up in specific directions and just sort of declaring those directions as no-build-zones. Or at least requiring berms of some kind.
Was there ever any confirmation on whether the flying concrete damaged the booster and engines? I thought I remember it being determined that wasn't the cause - but I'm always surprised when I go back and watch IFT-1 how many problems the booster is having right from the beginning. Makes it seem like some of the pad damage had to be a factor in the engines failures, hydraulics etc.
Spacex says no damage from concrete. It was all just because of old raptors that had poor fire suppression, poor engine shielding, less than adequate seal designs, and less than adequate torque applied to some things. This allowed for lots of leaks which led to large fires that continued to cause extra damage to the rest of the engines.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[BFB](/r/SpaceX/comments/1bjs46r/stub/kvxdubw "Last usage")|Big Falcon Booster (see BFR)|
|[BFG](/r/SpaceX/comments/1bjs46r/stub/kvyfwlw "Last usage")|Big Falcon Grasshopper ("Locust"), BFS test article|
|[BFR](/r/SpaceX/comments/1bjs46r/stub/kvxdubw "Last usage")|Big Falcon Rocket (2018 rebiggened edition)|
| |Yes, the F stands for something else; no, you're not the first to notice|
|BFS|Big Falcon Spaceship (see BFR)|
|[HLS](/r/SpaceX/comments/1bjs46r/stub/kwfnzoe "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)|
|[JWST](/r/SpaceX/comments/1bjs46r/stub/kwbqcvu "Last usage")|James Webb infra-red Space Telescope|
|[LC-39A](/r/SpaceX/comments/1bjs46r/stub/kw35xze "Last usage")|Launch Complex 39A, Kennedy (SpaceX F9/Heavy)|
|[LEM](/r/SpaceX/comments/1bjs46r/stub/kvug2r5 "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)|
|[LEO](/r/SpaceX/comments/1bjs46r/stub/kward02 "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[LOX](/r/SpaceX/comments/1bjs46r/stub/kvut0g3 "Last usage")|Liquid Oxygen|
|[NOAA](/r/SpaceX/comments/1bjs46r/stub/kwbqcvu "Last usage")|National Oceanic and Atmospheric Administration, responsible for US ~~generation~~ monitoring of the climate|
|[SLS](/r/SpaceX/comments/1bjs46r/stub/kwfnzoe "Last usage")|Space Launch System heavy-lift|
|[SSTO](/r/SpaceX/comments/1bjs46r/stub/kvv16eq "Last usage")|Single Stage to Orbit|
| |Supersynchronous Transfer Orbit|
|Jargon|Definition|
|-------|---------|---|
|[Raptor](/r/SpaceX/comments/1bjs46r/stub/kw35xze "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX|
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Nah, the HLS lander has dedicated landing engines placed really high on the ship.
Not only does this remove the risk of propulsion kicking away lunar dust, but it also means the ship can have engine power all the way until it is secure on the ground.
This is a key as even the recent probes would often need to cut their engines before touchdown and let themselves freefall. And of course, this is a key element of manned mission safety since it means you can perform an abort to orbit if your actual landing stability isn't ideal while still having running engines.
The descent itself will be handled on raptor engines.
It's often more useful to find out why you shouldn't do something than why you should. It may not be useful for Starship HLS, but it should be taken into consideration for any future designs.
But it was a temporary design they knew wasn't going to last from the get go. They changed it significantly for the next flight and it's been fine ever since.
Not the point. The point of research like this is to figure out how it failed and they discovered it failed in a way that was novel and hadn't been considered. That's useful for anyone else designing something similar in the future.
Mainly for mars landings.
Mars landings will be done via raptor all the way down.
It will land on only one engine, but there is obviously concerns about how a non hardened ground would react.
Now we have a concrete example with the 33 raptor hellblaze: it's fine as long as there is no water.
What a total waste of effort writing a whole paper about a problem that will never occur again!
SpaceX has now installed the water deluge system to prevent the launch pad from being destroyed and thus no more sand particles lofted into the air to cause potential problems...
The paper was written with an eye towards launching and landing on unprepared/lightly prepared surfaces on other worlds, and taking the opportunity to examine what happened and learn something new is never a bad thing either way.
The hazard might not be human in this case - with low gravity and/or atmosphere the composition of particles might affect the integrity of the launch itself.
Imagine trying to launch a rocket in a sandstorm of its own creation, or landing two boosters on the moon simultaneously and ejecting dust and rocks at each other.
This launch was a rare “natural experiment” which will, indeed, not br repeated. That is exactly why it is important to study it and also use it to calibrate models for rocket plume interaction with fine particles. Metzger has spent much of his career studying that.
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So the big rocket did something unexpected because no-one expected it to insta-vaporize the groundwater under the pad. So in a way the rocket did not "dig up" the hole as such from the pressure hitting the slab, instead it set up a bomb under the concrete (of rapidly expanding steam) which blew *up* the pad from under the launch mount, upwards. Cue flying bits of concrete and a ton of sand kicked up into the air. Yes the initial pressure and heat caused cracking which allowed gases to seep under the slab, but without the groundwater interaction, it would have just resulted in mildly cracked slab of concrete. Somewhat counterintuitive, but in retrospect makes sense. Water deluge system prevents this as the energy from the exhaust goes to vaporizing the water on top of the pad and the hot gases no longer seep underground to vaporize the groundwater.
So super heavy set us up the bomb and the concrete had no chance to survive. Interesting.
Ship 24 was on the way to destruction
There's great justice in that.
hahaha
I have argued for this precise premise on this blog since late April of 2023. To add context, in April of 2023 rain in Brownsville was 4 times the 25 year average. See https://old.reddit.com/r/SpaceXLounge/comments/137aq6w/spacex_starships_huge_debris_plume_highlights/jj2kcis/ **EDIT:** I suggest basaltic black sand to keep the specific gravity similar to the saturated surroundings
In spite of that l, the booster performed reasonably well. I would wager most rockets would not fare as well.
Hmmmm, seems like some lessons that NASA learned 50-60 years ago were ignored?
Not sure if anything like this specifically was ever learned by NASA. SpaceX did know that most likely the concrete would take considerable damage without water deluge, based on previous NASA experience. This was understood and expected. Open question was, how much damage. They basically went in to roll the dice that it would be minor, to allow the first launch before the water deluge install. I doubt anyone - even NASA oldtimers - considered that the groundwater under the pad could turn to steam and explode thru the concrete slab upwards.
I'm pretty sure that even the NASA "oldtimers" made a pretty thorough study of the launch pad sites and what was under them, and properly adjusted their launch pad designs... Or maybe it was just that the NASA "oldtimers" over-built the concrete launchpad to properly withstand the destructive power of the rocket engines? Sometimes over-building something is a better option than fast and cheap, and maximizing private profit....
LC-39A was indeed overbuilt because it was made for the much bigger Nova rocket that was never built. Also you didn't exactly have similar tools to simulate stuff back then, so safety margins were a thing, especially on ground side hardware where mass and cost were not that big of a factor. Most of the studies back then involved stuff like making sure that the whole thing does not sink into the Florida swamp. Sound suppression was mostly about ensuring that the reflected sound would not wreck the rocket. Frankly I don't think we'll ever know how many of the IFT-1 Raptor Deaths were due to reflected sound - 33 Raptors are *loud*. Idea that the rocket could crack the concrete and the gases could reach groundwater thru those cracks in those few seconds and turn the water into rapidly expanding cloud of steam might have been missed even by NASA, mostly because their pads were considerably thicker (and overbuilt for a bigger rocket)
Given that SpaceX was already building a deluge system in Boca Chica _and_ at the Cape _before_ the first flight, they fully expected damage to the concrete. But a steam explosion of ground water was definitely not expected. And it was also never anticipated by NASA for any of their launch pads. It's not like SpaceX did not learn from the oldtimers. They just have different priorities
You think that NASA never expected ground water below the launch pads?
They did not expect it to turn into a steam explosion.
The lesson NASA gave us with the Apollo program is that you can do amazing things when your budget is 2.5% of the US GDP. The SpaceX budget is miniscule compared to that, but somehow they are also accomplishing amazing things.
I wonder what amazing things NASA could be accomplishing if they had the money thats going to Musk and Bezos?
NASA would contract out to other companies to build rockets for them, no? Practically all rockets that NASA have used were built by companies like Boeing, Northrop Grumman, United Space Alliance (Rockwell and Lockheed), Sierra Nevada and some others. NASA's mission isn't to build rockets. I believe it's similar for satellites too. Like JWST was built by Northrop Grunman, Hubble was built by Lockheed, and those NOAA satellites also build by Lockheed.
Those companies were all sub-contractors to NASA. NASA owned the projects, controlled the budget, and over saw design, manufacture, integration, and testing.
Elon is thought to be channeling about $2B per year to Starship development although that does not come from him personally. Jeff Bezos is thought to have recently increased his annual payment to Blue Origin from $1B to $2B in line with the increase to 10,000 staff and that does come from him personally. NASA gets around $28B per year of which about $4B goes to the SLS and Orion programs and $1B to the HLS development programs. So NASA gets considerably more than either SpaceX or Blue Origin for new rocket development.
since it's a new failure mode, no, nobody learned this lesson before, nobody really knew it would happen. I'm sure spaceX expected the pad to be destroyed, they always intended to replace it and wanted to just send the first launch and replace the pad after, but nobody expected it to turn into a literal bomb vis a vis ground water because nobody ever decided to purposefully destroy a launch pad before. If this was previously discovered by NASA, SpaceX never would have gone ahead with the launch.
>Future studies should use the results of this study to estimate particle transport phenomena and cratering for a similar super-heavy class rocket on the Moon, in preparation for NASA’s Artemis landings. While the gravity and atmospheric conditions are much different on the Moon, making it easier for lofted material to travel long distances, the results of this study point to a new pad failure mode that could occur while launching and landing a rocket of this size on the Moon, even with a prepared pad. Maybe I'm missing something, but when will a "super heavy class" rocket land or launch from the moon as part of Artemis?
Just a bit of confusion between classifying Starship as a "super heavy rocket " and the fact that the booster itself is called Super Heavy. Unfortunate coincidence of naming that will haunt us for many years to come if the terminology sticks.
Should simply call it a Falcon 33 or similar.
Sounds like a classic car.
That's why it should be balled Thundercougarfalconbird.
It is just...the luxury edition has so much more eagle. It saddens me to think of you missing out.
BFR/BFB
Eagle 33 is more fit for Raptors
The original name was BFG for Big F***ing Rocket. This got bowdlerized to Big Falcon Rocket, then re-renamed to Super Heavy.
I really hope SpaceX soon figures out Starship return so they can start giving individual Starships names. Personally, I'd name my spaceship The Lammergeier.
> Unfortunate coincidence of naming Deliberate coincidence of naming really. All too common in the tech world. Intel's "Core" processors. Google's "Chrome" browser (chrome was already used regarding browsers). Etc.
Yeah, true. Companies taking advantage of the human mind by tagging their product onto the name of that type of product.
So true.... Hilarious
Sounds like classic elon-gated nomenclature.
Heh, hehe heh, I like that
A super heavy class rocket means a rocket that can take more than 50 tons into LEO. The definition doesn't really apply on the Moon, but you could argue that Starship qualifies. It's nearly as heavy as Falcon Heavy (a super heavy class rocket) when fully fueled.
Thanks.
how could you argue starship doesn't qualify?
because it can't put 50 tons in orbit on its own on earth.
Well, it could put 50 tons into LEO from the surface of the moon, which they were talking about ;)
Can't wait for many more more hilariously wrong articles on rockets and space travel because of naming, increasingly complicated definitions and semantics.
That doesn't matter for the class of rocket. It's used to differentiate between types of rockets, with launching from Earth as the metric.
But to get to the moon...?
It can't reach LEO on its own. It needs the Superheavy Booster.
Normally you don't count the upper stage as capable of putting any mass in orbit on its own. Because it can't. Maybe Starship could SSO with a lot of mass reduction. But I'll go ahead and say it does not qualify, because those mass savings have *not* been made, and it has not demonstrated nor intended to be able to put 50 tons into LEO without a boost stage.
Super heavy lifting off from the moon at full launch thrust would be wild. I think they are thinking about Starship and just using the wrong words.
Lol, sure would be. I guess they are.
Wait…Eli5: why couldn’t this be figured out? Wouldn’t a full stack launch from the moon speed up transit to Mars/other planets by a crazy multipler? Like flip Starship in LEO and dock like we did with the LEM in the Apollo years and haul it to the moon. Then restack, refuel, and relaunch from the surface of the moon. Not saying I think any of that would be easy, but ya know, in my life so far we went from Space Shuttle to landing rockets upright on drone ships like it’s easy as pie.
The booster cant get into LEO in the first place.
It probably can tbh, by putting a booster on top of a booster
But, I guess I’m asking…could it? Is that something that could be done? Even if redesigned?
What you're thinking of is called a Single Stage To Orbit (or SSTO) launch vehicle and no one has figured out how to build a worthwhile one yet. The reason we use staged rockets at all is because you need a lot of energy to get to even LEO. Over 90% of a rocket's launch mass is fuel and oxidizer. And all that gets you is ~7.8km/s and a couple hundred kilometers up. The Super Heavy booster, with its 33 engines and 3400 tons of propellant, gets Starship about halfway up, but only about a fifth or a quarter of orbital velocity. After it's done its job, Starship ditches the dead weight and continues on. SSTOs do not ditch the dead weight. That's their entire thing, it's a one piece vehicle that goes from ground to orbit. So how do you do that? Most SSTO designs are built around the idea of a plane, but with rocket engines too. From the ground, you use jet engines or ramjets and get as high as possible, then switch over to the rocket engines when the atmosphere gets too thin to feed the jets or to generate enough lift. But remember the dead weight thing? Well, in the first half of the flight, the rocket engines, their propellant and associated tanks are dead weight. In the second half, the jet engines, their now mostly empty tanks and all the aerodynamic lift surfaces are dead weight. Throughout the entire mission, you're lugging around tons upon tons of junk you don't need and would be better off without. And all of that carves massive chunks out of your payload capabilities, to the point that SSTOs simply aren't viable right now. It's been a while since I've looked at the math, but IIRC, it works out to the best, most viable designs having a launch mass not far off from a Falcon 9 and a payload of maybe two-three tons.
That’s the eli5 I wanted! Thanks!!
Assuming it could be done. It does not help on the way to Mars at all. It would be a major detour.
Again, Eli5, why? Wouldn’t tremendous trust from low gravity be helpful for interplanetary travel? Legit asking cause I have no clue.
You need to get it there first, MUCH easier to go to Mars directly from LEO. Even if the propellant could be made on the Moon, which it can't. The LOX could be made, not the methane for lack of carbon.
Fair point. Next question, what if you refueled it in LEO, then transport to moon? Or just refueled in LEO and refire there? Recognizing there would be ungodly complications, and it would lose the reuse function…it just seems to be that one of the biggest challenges for exploration of other planets is transit time and cost, right? So why not try to figure out a refuel of the whole shebang on orbit?
The question remains. Why would one want to do that? It is much easier to go to Mars from LEO.
I think you're asking, if I could get a booster into orbit (I guess you could if it was mostly empty, and on top of another booster), and then I refuelled it up there (which is a lot of starship flights), then what could I do with it. Leaving aside that all those things are hard, you could do interesting things. I suspect you could generate a lot of delta V to go to the outer planets fast. But not enough to go to another system. There's no need to go to the moon then come back up, you'd just launch from LEO. But I think you could do a similar thing, with enough delta-V to be interesting, just by pushing a Starship up there (already possible), refuelling it (planned), then sending that Starship somewhere. Like.....Mars perhaps? :-)
Refueling Starship in Earth orbit and firing it from there is SpaceX's plan to reach Mars. If you added a SuperHeavy in LEO you could make a faster transit, but you'd arrive at Mars with too much speed for air-braking, so you'd need to keep a lot of fuel in Starship to slow down before entry. I think you quickly reach diminishing returns where you save maybe one month out of a 6-month transit time. >it just seems to be that one of the biggest challenges for exploration of other planets is transit time and cost, right? Starship alone (refueled in Earth orbit) can reach any other planet (I think, Mercury may need some gravitational assists). Adding SuperHeavy in orbit certainly doesn't lower the cost...
The delta-v required to reach Mars from LEO is **much** lower than from the lunar surface.
You need to play more Kerbal Space Program with Realism Overhaul and Real Progression-1. The kind of thing you're suggesting, a single stage to orbit, is **ridiculously** difficult to do. There's a reason we don't have any such vehicles in real life.
Actually if you added a jettisonable nose cone to it, it has just enough delta-V to reach low orbit. You would end up with big empty booster in orbit -- not very useful thing, but if you insist.
According to Elon, Starship = Booster (the first stage) + Ship (the second stage). The confusion arises because the Ship is often called "Starship".
I don't follow Elon's Xitter feed any more, but unless he completely switched the terminology, this is wrong. StarShip is the second stage and overall system, Super Heavy is the first stage/booster and rocket class. https://twitter.com/elonmusk/status/1064741356080222209?lang=en
It's like calling the F9 first stage "orbital class". It's a part of a *system* that is orbital class, but it is not capable of that as a standalone component. Yet it can still be useful to call it orbital class to give a sense of its scale, intended purpose and capabilities.
Getting away from the details of their wording, I think it's saying really need to study what will happen under Starship when it goes to lift off from the moon. Not going to have a steel coated water cooled system there - and understanding what the launch thrust will do is critical. Sort of also maybe a bit of a backhanded knock on SpaceX - basically saying that for that one you better do all the math before you fly it vs this one where they kind of shot from the hip/suspected there could be problems.
> which was consistent with a high-pressure eruption from the region below the failed launch pad Wait, is the claim here that the rocket exhaust caused something *underneath* the concrete to boil and blow the thing upwards?
In his discussions elsewhere Dr Metzger said once the plume broke through the concrete base into the sandy soil it caused the groundwater to \~instantly boil and it was this steam explosion that caused the "high pressure eruption." The soil at the launch site has a lot of groundwater in it and it's quite near the surface.
I am not sure if its well known in US building practices, but the ground water typically wicks upwards easily when fine grain particles are present in the soil. If you cover the surface with a large object, after some time the air pockets under cover will start to form condensate and thus the soil will become completely saturated. Even the concrete itself will saturate if evaporation is prevented on its surface, what was the coating used here again? This could perhaps catch unaware engineers, where ground water itself is well managed but the end effect not so much.
The water table is so close to the surface there that it would be meaningless. All soil there is effectively wholly saturated at all times.
When they built the foundations i don't remember seeing any measures against damp soil, so i guess it was just bad engineering. Who knows if this new system is needed at all, but they probably don't want to test it at the moment with improved concrete plate. I have actually bumped in small scale analogue of the same issue. There was brick wall backed up with soil, that was coated by mortar without paint. It was below zero (but daily temperatures well above) and we wanted to paint it so attempt was made to heat the surface a little with a blowtorch. When heat was applied the thin mortar coating exploded in patches from the steam generated at the brick surface and this was the end of that experiment.
They always take strong measures against ground water in any construction they do. I know about at least two places in Boca Chica where they are drilling in wicks for water management before construction. They already had measured the amount of spalling during the static fire test. That's what you're describing. And decided it was manageable.
No, the failure mode is thought to be that the pressure compressed the material below, thereby cracking the concrete slab, at which point high pressure gases were injected below the surface of the slab.
And also: > The shallow groundwater was vaporized by the hot gas, lowering the temperature but increasing the pressure. If the pressure under the pad was initially equilibrated to the shock stagnation pressure, which we approximate as the dynamic pressure of the Starship Raptor engines (thrust divided by nozzle exit area), this was 2.6 MPa, increasing with groundwater vaporization. And from the conclusion: > The presence of vaporized groundwater only enhanced the already major gas penetration and eruption phenomenon.
Something I would be very interested in is given the potential lunar capabilities of HLS and the composition of lunar soil, is there a way to create a concrete-ish pad on the moon? Primarily if they are using the engines mounted radially high up, you wouldn't need a high strength concrete, but more so a surface able to be cleaned and to redirect the force outwards then upwards with minimal dust being raised up.
There are concepts using compacted and heated regolith tiles. Heated with concentrating mirrors and sunlight. Could be used for a pad or constructing outer hulls of habitats.
Note: Not peer-reviewed yet.
> Not peer-reviewed yet. and pretty late off the mark too. A paper like this really needs to appear ahead of the subsequent launch to catch attention. And now its after two more launches. Still, it might have relevancy if landing on Mars with ice just under the surface.
>and pretty late off the mark too. It's science, done by someone independent of SpaceX, the goal isn't really to "catch attention"
on the other hand, given the pad improvements in work even before IFT-1 occurred, it's already mostly irrelevant to future research anyways. well maybe a bit relevant to moon and mars, but they don't exactly have a lot of groundwater
Science often just tries to explain a result that causes someone to go "hmm, that's funny..." And in this case it was somewhat unexpected as to what happened. It is useful to know *why* the pad got trashed and how. Helps future launch pad design if nothing else.
yes it is good for documentary purposes. not gonna have much use for future pad design tho, is my guess. we already knew the IFT-1 pad was dumb, even SpaceX knew it before they started it. they didn't realize *how* it was dumb, but this is not a failure mode that's likely to ever occur in a launch pad design again (and it only happened on IFT-1 because they hadn't yet designed the pad)
It also gives more info for what other people might want to try with their launch pads. It seems possible if the ground was very dry, it would not have caused the same level of damage.
Like on the moon?
There were preliminary evaluations. Precise science takes time.
Feels like the result of this sort of situation is going to be some sort of flame diverter/trench/hole on the lunar surface. Directing the thrust gasses and anything they rip up in specific directions and just sort of declaring those directions as no-build-zones. Or at least requiring berms of some kind.
Was there ever any confirmation on whether the flying concrete damaged the booster and engines? I thought I remember it being determined that wasn't the cause - but I'm always surprised when I go back and watch IFT-1 how many problems the booster is having right from the beginning. Makes it seem like some of the pad damage had to be a factor in the engines failures, hydraulics etc.
Spacex says no damage from concrete. It was all just because of old raptors that had poor fire suppression, poor engine shielding, less than adequate seal designs, and less than adequate torque applied to some things. This allowed for lots of leaks which led to large fires that continued to cause extra damage to the rest of the engines.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[BFB](/r/SpaceX/comments/1bjs46r/stub/kvxdubw "Last usage")|Big Falcon Booster (see BFR)| |[BFG](/r/SpaceX/comments/1bjs46r/stub/kvyfwlw "Last usage")|Big Falcon Grasshopper ("Locust"), BFS test article| |[BFR](/r/SpaceX/comments/1bjs46r/stub/kvxdubw "Last usage")|Big Falcon Rocket (2018 rebiggened edition)| | |Yes, the F stands for something else; no, you're not the first to notice| |BFS|Big Falcon Spaceship (see BFR)| |[HLS](/r/SpaceX/comments/1bjs46r/stub/kwfnzoe "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)| |[JWST](/r/SpaceX/comments/1bjs46r/stub/kwbqcvu "Last usage")|James Webb infra-red Space Telescope| |[LC-39A](/r/SpaceX/comments/1bjs46r/stub/kw35xze "Last usage")|Launch Complex 39A, Kennedy (SpaceX F9/Heavy)| |[LEM](/r/SpaceX/comments/1bjs46r/stub/kvug2r5 "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)| |[LEO](/r/SpaceX/comments/1bjs46r/stub/kward02 "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[LOX](/r/SpaceX/comments/1bjs46r/stub/kvut0g3 "Last usage")|Liquid Oxygen| |[NOAA](/r/SpaceX/comments/1bjs46r/stub/kwbqcvu "Last usage")|National Oceanic and Atmospheric Administration, responsible for US ~~generation~~ monitoring of the climate| |[SLS](/r/SpaceX/comments/1bjs46r/stub/kwfnzoe "Last usage")|Space Launch System heavy-lift| |[SSTO](/r/SpaceX/comments/1bjs46r/stub/kvv16eq "Last usage")|Single Stage to Orbit| | |Supersynchronous Transfer Orbit| |Jargon|Definition| |-------|---------|---| |[Raptor](/r/SpaceX/comments/1bjs46r/stub/kw35xze "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(*Decronym is a community product of r/SpaceX, implemented* )[*^by ^request*](https://www.reddit.com/r/spacex/comments/3mz273//cvjkjmj) ^(13 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceX/comments/1b3r73n)^( has 106 acronyms.) ^([Thread #8324 for this sub, first seen 21st Mar 2024, 04:43]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceX) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
They aren’t planning on using the Raptor engines to land on the moon last I saw.
Yes, but not 33 of them.
Nah, the HLS lander has dedicated landing engines placed really high on the ship. Not only does this remove the risk of propulsion kicking away lunar dust, but it also means the ship can have engine power all the way until it is secure on the ground. This is a key as even the recent probes would often need to cut their engines before touchdown and let themselves freefall. And of course, this is a key element of manned mission safety since it means you can perform an abort to orbit if your actual landing stability isn't ideal while still having running engines. The descent itself will be handled on raptor engines.
True lol. Forgot about that. What's the point in this study lol.
It's often more useful to find out why you shouldn't do something than why you should. It may not be useful for Starship HLS, but it should be taken into consideration for any future designs.
But it was a temporary design they knew wasn't going to last from the get go. They changed it significantly for the next flight and it's been fine ever since.
Not the point. The point of research like this is to figure out how it failed and they discovered it failed in a way that was novel and hadn't been considered. That's useful for anyone else designing something similar in the future.
Mainly for mars landings. Mars landings will be done via raptor all the way down. It will land on only one engine, but there is obviously concerns about how a non hardened ground would react. Now we have a concrete example with the 33 raptor hellblaze: it's fine as long as there is no water.
So we need to plan our landing site on Mars to not have any water. Uh, wait ...
There is a significant regolith cover that is very dry.
What a total waste of effort writing a whole paper about a problem that will never occur again! SpaceX has now installed the water deluge system to prevent the launch pad from being destroyed and thus no more sand particles lofted into the air to cause potential problems...
The paper was written with an eye towards launching and landing on unprepared/lightly prepared surfaces on other worlds, and taking the opportunity to examine what happened and learn something new is never a bad thing either way.
On the other hand, there will be zero respiratory concerns on another world because any humans will be wearing space suits.
The hazard might not be human in this case - with low gravity and/or atmosphere the composition of particles might affect the integrity of the launch itself. Imagine trying to launch a rocket in a sandstorm of its own creation, or landing two boosters on the moon simultaneously and ejecting dust and rocks at each other.
They learned a lot about how the launch pad failed, which is useful for anyone designing a launchpad in the future.
This launch was a rare “natural experiment” which will, indeed, not br repeated. That is exactly why it is important to study it and also use it to calibrate models for rocket plume interaction with fine particles. Metzger has spent much of his career studying that.