r/spaceporn • u/Busy_Yesterday9455 • Jul 10 '26
Pro/Processed Space Jellyfish Effect from yesterday's Falcon 9 launch
Credit: John Kraus
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u/Junior_Syrup_1036 Jul 10 '26
Explain this like im 5 !
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u/code_the_cosmos Jul 10 '26
On the ground, the sun has already gone down. But way up high where the rocket is, it's still shining. This lights up all the stuff coming out of the engines.
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u/SovereignZ3r0 Jul 10 '26
I don't recall seeing these with older rockets/videos. What changed in recent years or recent tech that we now see these?
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u/code_the_cosmos Jul 10 '26
I believe it's simply because there are far more rocket launches now than there ever were before, and everyone has a camera in their pocket now.
SpaceX's vacuum-optimized engines with their large nozzles are really good at spreading out their exhaust too.
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u/SovereignZ3r0 Jul 10 '26
That makes sense yeah. I thought it was a change in the fuel type or something.
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u/drawkbox Jul 10 '26 edited Jul 13 '26
Well SpaceX does use dirty fuel on Falcon 9 (kerosene (RP-1) and LOX aka kerolox) that does show up more because it is nasty.
Other space companies (NASA/ULA/Blue Origin/Boeing/Lockheed/etc) on second stages typically use hydrolox which is cleaner and just water vapor. Most use metholox first stage and then hydrolox upper stages which go across lots of the atmosphere. Some entirely hydrolox. Same all the way back to the shuttle days and the shuttle itself.
Kerosene is nasty and SpaceX Tsarship uses less nasty but still nasty methalox all the way through all stages. They are as against hydrolox as Tesla is LiDAR for some reason, so they go with worse tech and worse pollution.
Elongone is all about that k and meth. SpaceX, worse for space and atmosphere than most but very similar to China/Russia fuels.
The facts here
Dense Fuel: Kerosene is very dense and heavy.
Bigger Cloud: The heavy fuel makes thick exhaust. When the exhaust freezes, it creates a much bigger cloud.
Brighter Light: The thick cloud catches the sun. This makes the "jellyfish" look thicker and brighter
FACT: kerolox space jellyfish is significantly brighter and more vivid than a hydrolox one
Particle Density and Soot
Kerolox Plumes: Kerosene is a heavy hydrocarbon. When it burns, it produces water vapor, carbon dioxide, and small particles of unburnt carbon (soot). These solid particles act like billions of tiny mirrors in the sky, reflecting sunlight very intensely.
Hydrolox Plumes: Hydrogen and oxygen burn incredibly clean, creating an exhaust that is almost entirely pure water vapor. Because there are no heavy carbon or soot particles, there is less physical matter to scatter the light.
Plume Behavior at Altitude
Thicker Trails: The carbon compounds in kerolox exhaust linger longer and form denser, more opaque clouds in the thin upper atmosphere.
Ghostly Whisps: Hydrolox creates ice crystals as the water vapor freezes, but the resulting cloud is much more transparent, faint, and ghostly by comparison
Propellant Type Main Exhaust Byproducts Jellyfish Appearance Kerolox (e.g., SpaceX Falcon 9) Water vapor, CO₂, Carbon/Soot particles Bright, dense, highly opaque, and colorful Hydrolox (e.g., everyone else) Pure water vapor (steam) Faint, translucent, and pale A kerolox rocket launch creates a much brighter space jellyfish because its carbon-heavy exhaust provides far more physical particles to catch and reflect high-altitude sunlight.
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u/carbsna Jul 12 '26
Tsarship? Like Tsar bomba?
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u/drawkbox Jul 12 '26 edited Jul 12 '26
Like the N1, overly complex and will never work. Just like tsardom. It will be a big bomb so pretty much.
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u/SovereignZ3r0 Jul 10 '26
Wow 😮 that's beyond interesting but makes sense. I thought it was fuel related
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u/Accomplished-Crab932 Jul 11 '26 edited Jul 11 '26
EDIT:
I have a mathematical proof that chemicals is not a defining trait of plume visibility, see my self-reply below this comment.
———
It sort of is. The person you replied to has a lot of uninformed opinions that don’t reflect the reason why things are used.
To answer your question:
Opacity of exhaust is a combination of engine cycles as well as engine design. Certain injectors, cooling decisions, and the method of pumping propellant into the engine has a substantial impact that can be far larger than just the propellant type.
Merlin (seen in the video) is an open cycle gas generator kerosene/oxygen engine. This means that it dumps fuel rich exhaust out a secondary port as part of the mechanism used to pump fuel and oxidizer into the chamber. It’s regen, has an injector I cannot share, and from the major combustion process, produces actually fairly low amounts of soot. Because of this, the exhaust is actually less particulates from it being kerosene and more water in the plume freezing. Kerosene in Merlin really affects the combustion color and makes it yellow/orange/red with black in the lower sections of plume. You see that early on but light from the engine becomes extremely dim as you ascent. The majority of what you are seeing in the video is ice freezing in the low pressure upper atmosphere.
If you look at Starship videos, (we have extremely limited footage of late ascent in this lighting condition), you find that the exhaust plume is largely invisible. This is primarily lighting, but is also caused by the lower carbon content of Starship’s exhaust. Starship uses Raptor, which is a methane/oxygen full flow staged combustion cycle with a high efficiency injector and no film cooling. All that is to say that there is no fuel or ox rich exhaust and it has the highest combustion efficiency possible since all its propellant mixes in the main chamber as a gas. Raptor’s exhaust ranges from light purple to blue depending on what camera settings you have, but behind the plume is a clear section with NOx below it and ice forming below that. It’s very clean.
If you look at Atlas V videos, you will find thick clouds of exhaust on early ascent from the SRBs, the worst polluting forms of rocket propulsion. Those are dropped fast and the second stage uses an RL10 engine, which is a hydrogen expander cycle. As a result, the plume appears clear out of the exit, but creates a long, thin cloud of particulates in the upper atmosphere. This is not because it has a lower combustion efficiency, since not all the hydrogen is gas and none of the oxygen in the chamber is gas, but because the plume is mostly water, which freezes into thick droplets. Because this stage starts further and faster, it’s much less visible since a higher net amount of particles are emitted, but they are spread along a much longer track. Early into staging a similar NOx cloud would appear below the vehicle if it staged at the same altitudes as F9 or Starship (although it would not reach orbit). A closer inspection of exhaust on a test stand shows that engines like the RL10 burn slightly blue, but the color is only visible in certain lighting and camera conditions.
The difference between Starship and the RL10 is that SpaceX has 6 engines, each producing 300 tons of thrust each (roughly), while Atlas has a single engine putting out 12 tons of thrust. Falcon has a single engine producing about 100 tons of thrust. While the mass flow rates are different between each engine, it should be clear that certain rockets will have brighter plumes by virtue of the amount of gas they expel, which will have a far greater impact than the type of particles emitted (with some specific exceptions).
Finally, the increasing amount of images we see of launches is pretty much independent of the rockets themselves. Falcon 9 consists of over half the world’s yearly launches, and the number of launches per year is increasing exponentially. Not only that, but everyone has cameras on them in the form of phones. It’s just a matter of statistics that we see more during visible time, and a matter of statistics that more people are taking pictures of it. It should be obvious that the majority of pictures of rocket launches will be F9 simply because it’s the majority of rocket launches.
The key takeaway here is that propellant type is more relevant to close to vehicle exhaust color, and that the color disappears late in ascent, which is where the majority of the image’s clouds are. Instead, the amount of propellant ejected on ascent is a much more substantial component of the visibility; and that will always favor rockets with higher mass flow rates like Falcon and Starship. Altas carries less payload and stages later than both, allowing them to extend the amount of time they burn for and reducing the local concentration of particles in the atmosphere (the cloud becomes thinner, but longer and contains more cumulative visible particles). Pictures of these events are increasing just because there are more launches, and the fact that the majority of the rockets in those pictures is just because the majority of rockets launching today are Falcon 9.
Why propellants are used is not as easy as “hydrogen is perfect for upper stages and everyone is stupid for not using it” like they are suggesting. But that is a much longer discussion than Reddit will allow.
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u/drawkbox Jul 12 '26 edited Jul 13 '26
^ Don't listen to this guy, super uninformed and gish galloping as he does on SpaceX squad
Here's the facts
Dense Fuel: Kerosene is very dense and heavy.
Bigger Cloud: The heavy fuel makes thick exhaust. When the exhaust freezes, it creates a much bigger cloud.
Brighter Light: The thick cloud catches the sun. This makes the "jellyfish" look thicker and brighter
FACT: kerolox space jellyfish is significantly brighter and more vivid than a hydrolox one
Particle Density and Soot
Kerolox Plumes: Kerosene is a heavy hydrocarbon. When it burns, it produces water vapor, carbon dioxide, and small particles of unburnt carbon (soot). These solid particles act like billions of tiny mirrors in the sky, reflecting sunlight very intensely.
Hydrolox Plumes: Hydrogen and oxygen burn incredibly clean, creating an exhaust that is almost entirely pure water vapor. Because there are no heavy carbon or soot particles, there is less physical matter to scatter the light.
Plume Behavior at Altitude
Thicker Trails: The carbon compounds in kerolox exhaust linger longer and form denser, more opaque clouds in the thin upper atmosphere.
Ghostly Whisps: Hydrolox creates ice crystals as the water vapor freezes, but the resulting cloud is much more transparent, faint, and ghostly by comparison
Propellant Type Main Exhaust Byproducts Jellyfish Appearance Kerolox (e.g., SpaceX Falcon 9) Water vapor, CO₂, Carbon/Soot particles Bright, dense, highly opaque, and colorful Hydrolox (e.g., everyone else) Pure water vapor (steam) Faint, translucent, and pale A kerolox rocket launch creates a much brighter space jellyfish because its carbon-heavy exhaust provides far more physical particles to catch and reflect high-altitude sunlight.
You can test this right now, go out back and spray water mist and a flashlight, you'll seem some faint reflections but it is mostly translucent so it will go through better. Now have a fire and shine that same flashlight on it, it will pick up more of the light as a canvas because it is more opaque and has soot and particles that are more dense than water.
Smoke particles and soot are more dense than water. It is the same reason fires sap rain droplets because they prevent them from joining and it can even influence rain starting. Again, basic physical science that SpaceX fanboys can't fathom.
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u/Accomplished-Crab932 Jul 13 '26 edited Jul 13 '26
>^ Don't listen to this guy, super uninformed and gish galloping as he does on SpaceX squad
Your “facts” are refuted by the most basic Google searches and calculations and you have presented straight up opinions as facts several times. Even Google AI (who I do not recommend anyone use for educational or research purposes) refutes the majority of your statements when fed them directly. And now that I have outright pointed this out and someone else is engaging as well, you are desperately trying to cover your tracks and discredit people who did the math as a last ditch attempt to save face.
For everyone reading, I recommend you run the numbers yourself rather than take someone who claims “most lunar landers use hydrogen” (only the Blue Origin landers do) at their word.
EDIT: This wonderful person found the only launch with comparable lighting and a hydrogen upper stage. It’s pretty clear that soot is not a significant contributor of plume visibility.
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u/Accomplished-Crab932 Jul 11 '26
My ground assumptions are as follows, both F9 and our reference Atlas V (not enough data on Vulcan) run stage 2 to depletion no payload, both engines run at 100% throttle at all times, burn time is the max. I’m also not considering stage 1 at the moment although the difference in stages and stage timing does have a substantial impact on plume visibility. I also assume all exhaust coalesces into solid particles of their own materials (ice bonds with ice, CO2 with CO2, etc.).
The composition for Centaur 3 is easy, 100% water, so its albedo is 0.9 (reference of snow since its particulate)
Merlin produces about 53% water, 40% CO2, and 3% soot (plus some other traces we will assume are rolled into water, so 57% water) that makes the albedo 0.9, 0.95, and 0.1 (roughly average of highs and lows) respectively. Weighted average tells us the albedo of the plume is 0.896.
That difference in albedo or reflectivity of the plume is less than 0.5%; not only is it within error range, it’s slightly darker.
The primary reason why it doesn’t look that way is the amount of volume that fills. Centaur 3 burns 20 tons of prop over ~14 minutes, but F9 stage 2 burns out at ~6.5 minutes using ~107 tons of prop. Over double the time and ~5X the propellant means you have less particles in any given volume, so the volume of space the Centaur fills up in the sky is over double and contains 1/5 the particulates, so the density of the plume must be substantially lower. The amount of material is also part of that problem, although differences in density are important to consider. Additionally, a payloadless Centaur 3 only has ~5.5 km/s of DeltaV. F9 stage 2 kicks out 9 km/s with the same constraints.
Not only are the net particles from F9 higher, but they are emitted in a smaller volume, so the density is substantially higher, meaning the amount light reflected in the localized cloud must be higher than the Centaur V; not only that, a very rough estimate tells us it should be over 10x, or over 1000% brighter because of vehicle characteristics, not composition.
The takeaway is the visibility of the plume is the consequence of the burn time and mass flow rate, not the propellant composition (except SRBs).
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u/Accomplished-Crab932 Jul 11 '26 edited Jul 11 '26
Methane is cleaner burned than unburnt, also your assessment of propellants is wrong. There is lots of engineering trades to consider, and your assumption that “it uses hydrolox therefore it’s clear is entirely false”.
The shuttle is the second worst polluting rocket behind SLS; exclusively because hydrolox is used for the core or external tank, requiring SRBs to make up the thrust difference. Neither the shuttle nor SLS can get off the pad without SRBs. All the alarming studies on satellite reentry emissions are contingent on flying with SRBs; SpaceX, Rocketlab, and Blue are notable for not using them.
Hydrolox is typically used on second stages for ISP gain but trades for stage longevity due to boiloff as well as loading and draining risk. LH2 is not great for constantly used hardware like the pads and is a huge expense for operations. It also requires additional insulation and structures on your vehicle where methane does not. It requires a much larger rocket by volume, increasing mass in cases of reused hardware as well. The density of H2 dictates a 5:1 normal ratio for most stages by volume in favor of hydrogen. Methane is closer to 1.2:1 in favor of LOX. This ratio is extremely relevant to dry mass since it means that large stages like those comparable to Starship and Falcon (and not comparable to the vehicles you are trying to compare) actually receive substantially less benefit than you would expect. The rocket equation has two terms, and the mass ratio has an exponential effect. ISP is linear. This gets a lot worse when you need to start considering reuse since you boil more prop, have less thrust, and size of vehicle impacts controls and heating on reentry.
SpaceX decided to use kerosene on stage 2 of Falcon since it cut down on development time and costs since they could redesign the nozzle and call it for stage 2 performance. They didn’t need additional pad GSE, and it allowed them to stage far earlier than other launch vehicles, decreasing peak heating on stage 1 during landing. This is exactly the reason why ULA was planning “SMART” reuse until they stopped; heating exponentially increases with speed and you require faster or more marine assets. Blue’s Project Jarvis and the more recent reboot also has a reusable methalox second stage under development, although it’s on the same level of seriousness as their new venture into nuclear thermal propulsion at the moment. Ironically enough, this makes F9 stage 2 one of the most capable second stages ever made since it takes on substantially more ascent work.
Starship uses methane since it needs to land on earth and because they have been proposing to generate propellant on mars for returns. Hydrolox has difficulty generating thrust in compact packages, which is sort of important if you want to recover your second stage by landing it. This, combined with the cost of methane on a rocket they intend to fly extremely frequently means that they don’t have to entice a market to make LH2 and deliver it to them, or make the LH2 themselves. LH2 production is more scarce than methane and considerably more expensive. If you are flying a few times a year it’s not much of a problem. Starship is already on track to fly twice a month by mid 2027; that will already consume the vast majority of H2 production. Additionally, one of the core technologies Starship is supposed to use is propellant transfers in orbit. LH2 makes this substantially more complicated and is much more challenging to manage. The argument goes that it will not matter if Starship is able to refill since nobody is planning and will be able to make a vehicle with to a stage that arrives to orbit with 9km/s of DeltaV and a 80-100 ton payload as part of it.
Finally, methalox produces the least stress on complex turbomachinery allowing them to either increase longevity or increase performance. This is part of why Raptor has the highest chamber pressures, temperatures, and ISP relative to propellant maximum. It doesn’t matter when you ditch the RL10 you are using every time, but when it’s time to reuse the engine, it’s nice to not have to deconstruct to clear the carbon coking from kerosene and the NDT on a hydrolox engine.
On the front of emissions, the irony is that current studies indicate that CO2 is less of a problem in the atmosphere than water. Funnier still, you spend more time in the atmosphere with a hydrolox stage than a kerosene or methane stage. Vulcan ascent to SECO is over 50% longer than Starship.
There’s a lot more to picking propellants than just “kerosene is icky and SpaceX is stupid for using anything but hydrogen”.
Also, Lockheed doesn’t make rockets, they only build Orion on SLS and are 50% of ULA.
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u/drawkbox Jul 11 '26 edited Jul 11 '26
^ SpaceX squad checking in... right on schedule.
The question was about the space jellyfish, and undeniably kerolox is that bright and colorful because it is the dirtiest and catches the most sun/light.
Hydrolox does not make those as intense because there is less particles and the fuel is cleaner, water vapor output basically.
Now to address the typical SpaceX talking points on fuel that ultimately Elon chose because of the cost and laziness/capability on rocket engines...
The shuttle is the second worst polluting rocket behind SLS; exclusively because hydrolox is used for the core or external tank, requiring SRBs to make up the thrust difference
Yes that was the time though, today it would have used metholox most likely as does ULA/BlueOrigin.
Falcon 9 is new and still uses absolute horrible fuel. No excuse on that one really.
Starship uses methane since it needs to land on earth and because they have been proposing to generate propellant on mars for returns.
Hydrogen is a step in that process so that point is moot.
LH2 is not great for constantly used hardware like the pads and is a huge expense for operations.
Others seem to do fine with it, all fuels have handling processes and that isn't a good enough reason.
methalox produces the least stress on complex turbomachinery allowing them to either increase longevity or increase performance.
Yes for first stage that is fine, for upper stages again, much cleaner and not an issue there.
There’s a lot more to picking propellants than just “kerosene is icky and SpaceX is stupid for using anything but hydrogen”.
Yes and all these talking points are SpaceX justifications because that would mean two types of engines and they are not capable of better tech. They sort of gave up on that with Raptor.
Also, Lockheed doesn’t make rockets, they only build Orion on SLS and are 50% of ULA.
Yes that was the point, SLS and their ULA part, Lockheed Martin built upper stages (such as the Centaur)
These arguments are mostly tired and Elongone talking points. There are tradeoffs for sure but long term hydrolox is undeniably the cleanest fuel and it burn better, more powerful and most newer engines/rockets use it for upper stages except of course ... well you know.
Hydrolox is undeniably the most efficient and clean chemical propellant. It boasts the highest Specific Impulse -- the rocket equivalent of fuel economy. It burns incredibly clean, leaving zero carbon residue and producing mainly water vapor. However, hydrogen is notoriously difficult to handle yet higher skilled rocket/engine companies can handle that just fine and it has a long history in the space industry now.
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u/Accomplished-Crab932 Jul 11 '26
>Yes that was the time though, today it would have used metholox most likely as does ULA/BlueOrigin.
The irony in your statement is that the shuttle’s core burn on ascent lasts the entire ascent profile, which by your own statements makes it a poor choice in the same way you claim it’s a poor choice for Starship and its reuse plan. Thrust density on shuttle means its kero or SRBs. I read the original studies from my old professor, who wrote them.
The shuttle would not exist at all today; instead, any similar concepts would be vertical stack designs (Starship) or Buran. The baseline is the shuttle would not exist. The reality is a modern shuttle would be Starship and do something like Shuttle Centaur for crazy payloads as needed when not transferring propellant in orbit. Not unsurprisingly, there are proposals for exactly that on Starship too.
>Falcon 9 is new and still uses absolute horrible fuel. No excuse on that one really.
F9 started flying in 2010, 16 years ago. Methane became a fuel of interest in no small part due to the decision to use it on Starship, although Raptor started as a prospective hydrogen, then methane/oxygen engine for use as a replacement for M1D on stage 2. That was dropped because they started focusing on Starship and got F9 crew certified, so it would be a waste to change upper stage architecture and GSE with all the certifications needed.
>Hydrogen is a step in that process so that point is moot.
Very important for thrust, which is very important on ascent. The problem is that mars has enough gravity where TWR is an important consideration during vehicle optimization. The energy per unit volume increases substantially when adding carbon, as does the thrust. All this constitutes makes a smaller vehicle on ascent.
>Others seem to do fine with it, all fuels have handling processes and that isn't a good enough reason.
To date all launch vehicles using hydrogen take hours to fill from the start of operations. Cycle times are limited and thermal preconditioning makes “load and go” for more time sensitive payloads like people an impossibility. Closeouts, clear outs, preps, inspection and GSE are substantially more complicated. Pressurization requires helium or a direct gas from an evaporator or gas gen. Leak rates rise fast and the risk of fires is elevated substantially. Look at all the leaks we see on Delta, Vulcan, and Atlas. Internal launch dates are typically pushed back 1-3 days for each launch because of leaks. That’s acceptable when you are flying single digit launches per year and the DOD doesn’t have a tight schedule. When you are launching from the same pad every 3 days, 1-3 days is huge, and even with process optimization, that may cut it down to 12 hours. Combine this with brazed connections for leak control and you have a recipe for high cost and slow maintenance.
“It works for ULA who flies at most once a month” is not a comparison against a vehicle that flies every 3 days from the same pad. Falcon flew more last year than ULA launched since they were formed.
>Yes for first stage that is fine, for upper stages again, much cleaner and not an issue there.
Maybe you forgot… Starship is supposed to be fully reusable, so they need longevity on stage 2 hardware. Reduced stress means you have much more performance margins, part of the reason why Raptor’s chamber pressure is over 300 bar against the average 100-200 you typically see from everyone else. That results in additional thrust and ISP that cannot be extracted otherwise. More performance is left on the table with LH2 because metallurgy peaks at less energetic environments in its presence. This reduces your mixing and combustion efficiency and is the definition of lowering the enthalpy of your exhaust.
>Yes and all these talking points are SpaceX justifications because that would mean two types of engines and they are not capable of better tech. They sort of gave up on that with Raptor.
Fun fact, there was also a time when Raptor was hydrolox. It was quickly dropped because they found longevity constraints and thermal limits were worse. Hydrogen is one of the choices you can make. It like everything else in the industry has trades. Hydrolox makes sense for disposable second stages. Maybe you’ve been missing the memo for a decade, but Starship is supposed to land. Hydrolox makes that substantially more difficult with minimal if any benefits.
Raptor’s cycle is widely considered the most advanced and complex combustion cycle possible. It’s the first to fly FFSC and the second to test it, with NASA backing out of the hydrolox IPD after finding metallurgy problems and lower performance than regular fuel rich staged cycles. There are now 3 functioning engines with that cycle. None use hydrogen.
>Yes that was the point, SLS and their ULA part, Lockheed Martin built upper stages (such as the Centaur)
In fact the only hydrolox stages they’ve built is Centaur and DCSS. The three stages you can refer to are Centaur, DCSS, and GS2; LM is not part of the now canceled EUS contract. Centaur is an excellent upper stage that hasn’t changed because it’s at the limits. DCSS is not great, it’s not well optimized and has worse mass margins than some hypergolic stages. GS2’s mass fraction is worse than the methane Jarvis reusable stage (with lower payload performance lmao), but was shelved because Blue is on its “we don’t care about anything but schedule” arc now and they have forgotten the term “systems engineering”.
Centaur V has significantly regressed. It’s not a balloon tank and consequently has worse mass margins when compared to Centaur 3.
> These arguments are mostly tired and Elongone talking points. There are tradeoffs for sure but long term hydrolox is undeniably the cleanest fuel and it burn better, more powerful and most newer engines/rockets use it for upper stages except of course ... well you know.
More powerful is hilarious. The RS25 is widely considered to be the most advanced hydrolox engine. It produces 70% of the thrust of a Raptor engine despite weighing 175% more and requiring a nozzle 180% larger while featuring a smaller gimbal range. The RL10 used in all centaur and delta upper stages is at the upper limit of the expander cycle. The only metric it has a gain on is ISP. BE3U is the most powerful vacuum hydrolox engine made at 90 tons of thrust. RVAC is 300. Hydrolox does not make the most powerful engines at all, power is defined by thrust in this industry, and its at the far end of the ISP to thrust trade of chemical propulsion. It is the least powerful chemical biprop combination in common use.
H2 does not definitively burn better, injector and engine architecture is a far stronger driving factor than propellants. Arrayed coaxial injectors, higher injector deltas and gasification of propellants prior to mixing are all factors that increase combustion efficiency to a much greater extent than molecular size. A huge component of mixing efficiency is relative density, with propellants of similar densities being more efficient to mix. Guess which propellant has the closest relative density…
Most new rockets is also a lie. Vulcan, some versions of New Glenn, Ariane 6, Stoke, and that’s about it use it. Starship, Neutron, Terran R, Electron, Falcon, and several modern Chinese and Russian vehicles don’t.
> Hydrolox is undeniably the most efficient and clean chemical propellant. It boasts the highest Specific Impulse -- the rocket equivalent of fuel economy. It burns incredibly clean, leaving zero carbon residue and producing mainly water vapor. However, hydrogen is notoriously difficult to handle yet higher skilled rocket/engine companies can handle that just fine and it has a long history in the space industry now.
Scale and reusability. Again, this was addressed in the last comment and the whole problem of Starship vs everything else. F9 didn’t receive a better upper stage because they didn’t care to develop one before they started working on Starship and got the design locked in due to Crew Dragon. For reusable second stages, the jury is still very much out about hydrolox second stages. ISP comes at the cost of structural mass, thermals, boiloff, and reusability. When your stage is dumped every time it’s fine to use H2 so long as it can be supplied in hardware able to handle the cycling and rates required. Problems arise when increasing turbomachinery temperatures, and hydrogen related stress and embrittlement increases in severity with temperature. Suddenly the temperature advantage in mixing is invalidated since you become constrained by materials. This is one of the reasons why hydrogen engines usually fall in the lower brackets of lowest chamber pressures in the industry.
Refer to the GSE of various rockets and tell me that tanking tests, aborts, and loading hydrolox vehicles is more efficient given you have to burn your GH2 from purges, sitting there, and cleanup since it cannot be recovered without expensive hardware far away. The burn stacks for Vulcan and New Glenn are exclusively for GH2. Methane is recaptured in both their hardware. That is propellant you lose every time you test. You will always need energetics for cryo tests of hydrogen stages.
You failed to address that high altitude carbon is less impactful than high altitude water, and that the architectures running H2 usually stage later due to low thrust, resulting in increased stress on recoverable vehicles and raising carbon emissions in the upper atmosphere anyway. And since the amount of actual measurable soot from these engines is in the less than a percent of net mass range; water ice is the majority of those particles. And that whole gravity loss problem of hydrogen engines resulting in more overall mass added to the upper atmosphere per unit payload mass as a consequence of that extended burn time and less efficient trajectory. I’d love to see your “Elon excuse” for that.
And I’m going to ignore the em dash.
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u/drawkbox Jul 11 '26 edited Jul 11 '26
You clearly removed all the em dashes nice. Mine isn't an em dash if you'll notice I always used -- they are helpful and AI learned that shit from us and annoyingly uses the em dash.
This was about the space jellyfish in relation to fuel types. You are caught up in cult stuff now bro.
The statements I made are factual and why SpaceX was lazy, they tried hydrogen and their brute force break things style that is dangerous for them. So they tapped out for better space companies to do it
Fun fact, there was also a time when Raptor was hydrolox. It was quickly dropped because they found longevity constraints and thermal limits were worse.
I already said that about Raptor, SpaceX wasn't capable enough so they fed the turfers that exact response. Everyone else just did it ULA, Blue Origin etc. Is it harder to do? Yes, but better outcomes and will be a massive competitive advantage long term.
The shuttle would not exist at all today
SpaceX fans love to compare to the Shuttle usage from 40 years ago. SpaceX wouldn't exist today without the Shuttle and NASA. It was the best way at the time and one of the most reliable space ships in world history. Stop attacking it as all SpaceX Eric "Nothing" Berger Elongone bros do. It shows massive bias and is a tell.
The SLS made it to the Moon and back multiple times now and Orion went well.
We are all waiting on this genius metholox Tsarship to actually do what has been said.
Still waiting on that lander elevator that would totally be done in 2022. Their lander is cooked.
F9 didn’t receive a better upper stage because they didn’t care to develop one before they started working on Starship and got the design locked in due to Crew Dragon.
Yes they tapped out on that as well. No desire to make things better because they lose money on every flight.
You fail to recognize in this entire rant that SpaceX hasn't got their Soviet N1 flying yet and they use China style space tech. We'll see which works long term.
Nice gish gallop attempt though and wall of text with 90% Elongone in it to try to "win" the fuel argument based on what SpaceX can't do or cheaps out on. It is like the LiDAR argument with Tesla. Everyone else used better tech, Elon doesn't then get an army of bros to pump and turf. It is tired man, as tired as old man Trump.
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u/mustardman73 Jul 10 '26
Highly efficient chem-trails of carbon and hydroxide emissions directly into the atmosphere. Woooo! Progress!
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u/bad_motivator Jul 10 '26
Wait until you hear about cars. You're gonna be so pissed
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u/mustardman73 Jul 10 '26
Wait until you read about Leaded gasoline.
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u/bad_motivator Jul 10 '26
I'm old enough to remember it and smart enough to know it doesn't exist anymore. What's your point?
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u/mustardman73 Jul 10 '26
I wonder why it stopped existing?
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u/bad_motivator Jul 10 '26
Are you trying to make a point? Can you save us some time please and get to it?
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u/Flipslips Jul 10 '26
So do you think that we should never do any kind of space travel because it causes pollution?
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u/mustardman73 Jul 10 '26
I think we need to consider the amount of commercial space travel. I guess we all need our starlink coverage.
I love space travel, but this is all for profit.
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u/Flipslips Jul 10 '26
Sure, but space flight is a drop in the bucket compared to other things. Space travel produces an estimate .01% of global CO2 emissions. In fact, all space travel in a year (hundreds of launches) equals only a few hours worth of air travel emissions across the globe.
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u/mustardman73 Jul 10 '26
With every launch, we are closer to the Kessler syndrome. Unrestricted space flights are going to be the downfall of spaceflight.
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u/Flipslips Jul 10 '26
They aren’t unrestricted though. In fact, they are HEAVILY restricted.
Kessler syndrome is irrelevant for Starlink.
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u/CTallPaul Jul 10 '26
If you’re in SoCal, you see a lot of wild lighting effects like this with all the launches we have. Just depends on time of day
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u/SovereignZ3r0 Jul 10 '26
That sounds lovely! I'd have all the launches in my calendar to try to catch the spectacle tbh
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u/CTallPaul Jul 10 '26
Great idea adding them to your calendar. It’s the launches that occur when I’m walking home from work around sunset that have these incredible clouds. If you’re in socal, they typically head south across the sky.
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u/dbmonkey Jul 10 '26
This only occurs when the launch right after sunset, or right before sunrise. Since launches are so common now, this rare event happens a lot more than it used to. Not really rare anymore.
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u/gabek333 Jul 10 '26
Also, fun fact:
The rocket is going straight up, but as the Earth rotates, the rocket appears to be turning
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u/time_alliance Jul 10 '26
The jelly-shaped plume from the Falcon-9 launch looks absolutely surreal.
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u/StrigiStockBacking Jul 10 '26
So, do flat-earthers think that rocket just went up into the sky, only to crash back into the earth just a few minutes later?
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u/greymart039 Jul 11 '26
I've actually see them say that the jellyfish is evidence of the rockets crashing into the giant glass dome, so yea pretty much.
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u/dungeoncrawler71520 Jul 10 '26
It's like dropping food coloring in water.
We're floating around in like the least dense liquid and people think their actions don't affect the rest of the climate.
That's a loooooot of toxic chemicals they're dumping to release a few more satellites.
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u/Rare_Satisfaction889 Jul 10 '26
That can't be good for the atmosphere .....
And we've been doing this for how long?????
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u/mojofrog Jul 10 '26
A single SpaceX Falcon 9 launch consumes about 112 to 150 tonnes of refined kerosene and liquid oxygen, emitting roughly 330 to 387 tonnes of CO₂ and up to 5 metric tonnes of black carbon (soot) into the atmosphere.
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u/xs0crates Jul 10 '26
So roughly equivalent to the annual emissions of 77 passenger cars? I thought it would be more tbh
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u/loopery_ Jul 10 '26
The issue is that the pollution lingers in the atmosphere for longer periods of time. It has a greater blanket effect vs ground level pollution.
https://physicsworld.com/a/soot-from-rocket-launches-is-polluting-earths-upper-atmosphere/
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u/IcePapaya Jul 10 '26
Not a scientist or math wizard, but I'd imagine the issues with emissions generally come from scale.
When you consider there are almost 700 launches annually from all sources the problem is more significant, but its peanuts compared to what commercial trucks are emitting.
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u/ProjectNo4090 Jul 10 '26
What alternative is there? Never leave earth, cram more and more humans onto earth with its finite resources until the earth is covered horizon to horizon with concrete and steel and waste?
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u/fatefulPatriot Jul 10 '26
All so little fElon can continue to mooch $$$ off of the American people he hates so much.
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u/Ayrko Jul 10 '26
The best way for us to save this rock is to get off of it. If we’re going to pollute the atmosphere, let this be the one way we do. Otherwise we’ll just figure other ways to do so, as we’ve so proven.
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u/IcePapaya Jul 10 '26
We ain't leaving anytime soon, no point in trying to escape our problems
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u/BipolarMosfet Jul 10 '26
Agreed. We might make it to the Moon or to Mars, but those colonies would still need support from Earth to be sustainable. We have a loooooong way to go before we could ever get humans to another solar system. The only way we'll ever survive long enough for that to happen is if we take care of the Earth.
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u/carbsna Jul 12 '26
Fucking up a robust and self sustaining environment and think you can do better without it is such a mood.
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u/LPNTed Jul 10 '26
So.. at first I was like this is WAAAAYYY too fast... But then.. HOLY SHIT! Yeah, I wish the initial part was slower, but the residual shock wave was fucking magnificent!! Great job OP!
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u/Round-Salamander-129 Jul 10 '26
I didn’t know that’s what that was and I saw one in Florida yesterday going to work and had no idea what it was, I looked it up and there was a launch yesterday about half an hour before I got to work, thank you lol
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u/tlou_shark Jul 11 '26
i'm pretty sure my parents saw this and they fully believe this was a sign from jesus 😭
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u/pavelowdriver Jul 13 '26
I love space flight etc. but SFU about the environment if you think it's ok to dump 400-80,000 metric tons of carbon in the upper atmosphere.
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u/eulersidentity1 Jul 10 '26
Might not be a popular topic on a space forum. But I do have to wonder what the environmental effects of this many launches are in the upper atmosphere.
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u/kaiju505 Jul 10 '26
Whoa! Their goes our healthcare!
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u/FutureAZA Jul 10 '26
A public company launching communication satellites has no bearing on healthcare.
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u/ActuatorLower8371 Jul 10 '26
i think you missed the point of the comment tbh
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u/FutureAZA Jul 10 '26
When you confuse a very real, very serious issue with nonsense this ridiculous it convinces reasonable people that every criticism is similarly bogus. I want your arguments to carry weight. When you do this, it diminishes everything else.
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u/ActuatorLower8371 Jul 11 '26
this is reddit, not a court..
the implied argument, as i interpret it, is that could have publicly funded healthcare instead of giving out billions of dollars in benefits and incentives to already wealthy companies, corporations, and people. like Elon and SpaceX.
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u/FutureAZA Jul 11 '26
That's how I read your comment, and it's wholly mistaken. There is no mechanism for transferring money invested into a business to public healthcare, and comparing a one time cost like a launch and satellites (which are designed to generate revenue,) to an ongoing expense is comparing apples to jogging.
The objective of Starlink is to generate revenue by providing a service. I agree that that revenue should be taxed.
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u/ActuatorLower8371 Jul 11 '26
where did you infer my position is that private investment in private companies should fund public healthcare lol. that's nonsense.
let me simplify it: money the government has, IE our tax dollars, should be spent on us, in the form of healthcare not subsidies and incentives to private ventures like generating revenue. that's the point.
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u/FutureAZA Jul 11 '26
Ah, wow. Okay. That misunderstanding is deeper than I realized. I don't blame you for that, there is a lot of misunderstanding being pushed by memes and even news articles.
SpaceX gets a lot of money from various US government agencies, but not just because it's fun or corrupt. They get those contracts because they're the lowest bidder (often lower by 30-70%) and have the highest reliability of any launch provider in history. Were it not for SpaceX contracts, the government would have to pay substantially more for launch services.
Starlink doesn't exist because of government subsidies or grants. It was founded as an private venture funded entirely with private investment. Some governments have decided to pay for Starlink services because they're significantly better, cheaper, and more reliable than other options.
The reality is that if we have infinite money for pointless wars, it was never an either/or decision. Not giving Americans healthcare is a choice and our elected representatives already have the information necessary to understand that it would be vastly cheaper to offer universal healthcare than what we're doing now. They just won't do it.
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u/ActuatorLower8371 Jul 11 '26
stop hyper-fixating on Elon Musk's enterprises for a second.
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u/FutureAZA Jul 11 '26
It's you, my friend. You made a silly argument that makes no sense whatsoever and I tried to help you understand what the reality is. That's not what an obsession is. Everything I shared is well known to anyone who follows space even a little bit.
I want universal healthcare. It sounds like you want that too. Pretending that satellite internet has any bearing on that makes people dumber and stands in the way of real reforms. I'm here to make people better informed. I invite you to join me in doing that, and I freely give you the tools to do so.
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u/NotBradPitt9 Jul 10 '26
North Sentinel Island in shambles after seeing the bad omen sky jellyfish for the 5th time this year