Rocket Engine Exhaust Pollution Extends High Into Earth's Atmosphere 62
The American Institute of Physics reports via Phys.Org: In Physics of Fluids, researchers from the University of Nicosia in Cyprus assessed the potential impact of a rocket launch on atmospheric pollution by investigating the heat and mass transfer and rapid mixing of the combustion byproducts for altitudes up to 67 kilometers into the atmosphere. The team modeled the exhaust gases and developing plume at several altitudes along a typical trajectory of a standard present-day rocket. They did this as a prototypical example of a two-stage rocket to transport people and payloads into Earth's orbit and beyond.
The researchers found the production of thermal nitrogen oxides (NOx), components of the combustion exhaust, can remain high up to altitudes with an ambient atmospheric pressure above or even slightly below the nozzles' exit pressure, i.e., below an altitude of approximately 10 km. At the same time, the emitted mass of carbon dioxide as the rocket climbs 1 kilometer in altitude in the mesosphere is equivalent to that contained in 26 cubic kilometers of atmospheric air at the same altitude. They found the impact on the atmosphere locally and momentarily in the mesosphere can be significant. While air currents will gradually transport and mix the exhaust CO2 throughout the atmosphere, eventually bringing the CO2 back down to its naturally occurring levels, the time scale over which this happens is not clear.
The scientists believe a certain number of rocket launches might still exist above which mesospheric carbon dioxide could accumulate over time, thus increasing the naturally occurring levels and affecting our climate. Their results suggest that in the worst-case scenario, sufficient NOx could be produced over the time it takes the rocket to reach an altitude of 10 kilometers to pollute over 2 cubic kilometers of atmospheric air with a NOx concentration that, according to the World Health Organization, would be at a level hazardous to human health.
The researchers found the production of thermal nitrogen oxides (NOx), components of the combustion exhaust, can remain high up to altitudes with an ambient atmospheric pressure above or even slightly below the nozzles' exit pressure, i.e., below an altitude of approximately 10 km. At the same time, the emitted mass of carbon dioxide as the rocket climbs 1 kilometer in altitude in the mesosphere is equivalent to that contained in 26 cubic kilometers of atmospheric air at the same altitude. They found the impact on the atmosphere locally and momentarily in the mesosphere can be significant. While air currents will gradually transport and mix the exhaust CO2 throughout the atmosphere, eventually bringing the CO2 back down to its naturally occurring levels, the time scale over which this happens is not clear.
The scientists believe a certain number of rocket launches might still exist above which mesospheric carbon dioxide could accumulate over time, thus increasing the naturally occurring levels and affecting our climate. Their results suggest that in the worst-case scenario, sufficient NOx could be produced over the time it takes the rocket to reach an altitude of 10 kilometers to pollute over 2 cubic kilometers of atmospheric air with a NOx concentration that, according to the World Health Organization, would be at a level hazardous to human health.
What's next? (Score:3)
What's next from In Physics of Fluids? Water is wet?
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So, if the rocket carries LOX and CH4 , and they are in the upper atmosphere (which is very thin) where does all the Nitrogen come from?
Just wonderin
Geez (Score:2, Insightful)
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Of all the things causing pollution and climate change this is such a stupid issue to get bent out of shape over.
Why? Please explain using science while arguing your case for the benefits of ignoring this research.
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Of all the things causing pollution and climate change this is such a stupid issue to get bent out of shape over.
Why? Please explain using science
Polluting "two cubic kilometers of air" with NOx sounds ominous, but it's over a column ten kilometers high. That means a footprint of 0.2 cubic square kilometers at the ground (the place people breathe). So it would be potentially expose people to pollution if they are within .25 km of the pad, for a period possibly as long as one or even two minutes.
I suggest people should not be within .25 km of the pad when a Starship lifts off.
As for the total: it's trivial compared to cars. By quoting NOx in cubic
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Of all the things causing pollution and climate change this is such a stupid issue to get bent out of shape over.
Why? Please explain using science while arguing your case for the benefits of ignoring this research.
Because it is the equivalent of complaining about the guy pissing over the railing of the Deepwater Horizon oil platform. He is technically polluting, but the oil spill is what is killing everything...
Re:Geez (Score:4, Insightful)
If Musk and Bezos have their way then rocket launches will become a lot more frequent. Starlink requires regular launches, with thousands of satellites being replaced every year as old ones de-orbit. It's something worth considering.
Combined with the pollution from thousands of de-orbiting defunct satellites every year, it looks like we are once again going to ignore the environmental cost.
Re:Geez (Score:5, Informative)
Excellent points, which would require either much more efficient launch systems (Starlink ought to be able to use the Space Gun approach or the hybrid Advanced Rocket Launch Assist method) or much more efficient approaches to resolve.
ObNote - for those not familiar, the Space Gun uses a chain of charges that are detonated with very precise timing within a barrel such that the exit velocity of a mini satellite would be sufficient to put it in Low Earth Orbit whilst keeping each individual shock sufficiently low that the insides of the satellite aren't damaged. This obviates the need for any rocket at all for very small payloads.
The problem with the Space Gun is that the designer was rebuffed by people paid by rocket manufacturers, so turned to - let's call him an Unpopular, Unorthodox Source, who wanted to use the Space Gun to launch things that weren't satellites. Unfortunately, said UUS was also very skilled at causing trouble with his neighbours, with the result that the designer died of lead poisoning.
The ARLA method is to start with something similar to a Space Gun, but reduced in power, keeping the stresses down. The idea of ARLA is not to replace the entire rocket but only the first stage.
The same guy was actually involved in building the initial version of ARLA, back in the 1960s, as part of the High Altitude Research Project (HARP). He could replace the first 1.5 stages of any conventional rocket of the time. That's quite significant.
https://space.stackexchange.co... [stackexchange.com]
Fuel efficiency hasn't improved much since 1967, but it has improved. This means you can dispense with a reusable first stage because you don't have the first stage of the rocket. The gains don't reduce the savings to below 1 stage. It may reduce the second stage a bit but not by half.
https://www.bbc.com/future/art... [bbc.com]
So we know the HARP/ARLA launch system actually works because it actually worked. Yes, you'll still create pollution, but it'll be a great deal less and it'll be within a relatively small hemisphere around the gun barrel rather than a column.
NASA has also looked into turbine-assisted ramjets (TAR) that would basically accelerate the launch vehicle from stationary (a speed ramjets really don't like) to Mach 6, then scramjets up to hypersonic velocities (Mach 20 being achievable) and aircraft-assisted ramjets (so you basically carry the ramjet-equipt rocket on a plane and drop it at around Mach 1, so that the ramjet can operate efficiently).
A hydrogen-powered scramjet can, in principle, operate in the atmosphere at speeds of around Mach 20, although experiments by Australia and the US on hypersonic scramjet vehicles tended to end in absolute disaster.
Ramjet/scramjet hybrids are theoretically possible. Scramjets won't work well below Mach 6, so you'd either need to launch from an X-15 or something similar, or you'd need a ramjet mode to get up to a high enough velocity.
Given you can also make turbine/ramjet hybrids, it's possible to imagine a single engine that can operate in all three modes.
I am unsure on this, but I think HOTOL was supposed to have one set of engines that worked from stationary to suborbital flight. If that's correct, then it would presumably be using such a three-way hybrid engine.
If you could get a vehicle that didn't disintegrate, though, then you could (again) replace the whole of the first stage with one of these ramjet ideas. The TAR engine has, thus far, been too heavy to work and the scramjet alone has had a nasty habit of melting and/or exploding.
It's unclear how much ramjets and scramjets would improve the environmental impact, let alone a three-way hybrid engine. Clearly, nowhere near as much as a Space Gun or ARLA system.
You can't go by the fuel effic
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I'm not convinced by space launch guns, or for that matter spinning or track based accelerators. When the launch vehicle emerges it's travelling through the low atmosphere which is pretty thick, i.e. a lot of drag and heating. With explosions you are applying very big forces to the launch vehicle, where as with a rocket engine the same total amount of force is spread over time so the maximum force experienced is a small fraction.
Ramjets and scramjets seem more feasible. Even then though you need rocket engi
Re: Geez (Score:3)
Revenue from joyrides subsidizes the tech needed to cheaply launch the satellite constellations necessary for people to affordably watch 2160p120 cat videos in the middle of nowhere & eventually get us to Mars. Raising taxes on joyrides thus reduces the affordability and usability of satellite internet & delays our arrival on Mars, just so environmentalists can circle-jerk about "true costs" and feel smug about their relationship with their imaginary Earth-mother.
Re: Geez (Score:2)
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If Musk and Bezos have their way then rocket launches will become a lot more frequent. Starlink requires regular launches, with thousands of satellites being replaced every year as old ones de-orbit. It's something worth considering.
Yes, and pricing airline travel to be cost-prohibitive as a considerably larger benefit to the environment would help too, along with telling Greed in commercial real estate to Fuck Off when demanding to create massive pollution again by forcing workers back into a worthless building they haven't been in for years now, to do the same job they've been doing.
I can think of a few billion more reasons that are a lot more impactful than rocket launches.
Combined with the pollution from thousands of de-orbiting defunct satellites every year, it looks like we are once again going to ignore the environmental cost.
Depends on how you look at it. Unless someone stands up and
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Depends on how you look at it. Unless someone stands up and gets humanity off this dying rock, we're destined to extinct ourselves right here, forever addicted to the Disease of Greed.
There is essentially zero chance that at current rates of change we can establish even the smallest of sustainable colonies on another planet before we autoeuthanize as a species. There is no planet B. We should certainly be pursuing space colonization, but not at the expense of the biosphere that has to support the human race for the foreseeable future.
Re: Geez (Score:2)
In theory, Starship could have a positive impact on the atmosphere. It burns methane and produces only CO2, which means no nitrous oxide, and it turns a horrific greenhouse gas into a not so bad but still pretty bad one. The problem is that to do that you would have to fuel it entirely with methane that would otherwise have been released into the atmosphere. Collecting cow burps needs to be on Elon Muskâ(TM)s radar.
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In theory, Starship could have a positive impact on the atmosphere. It burns methane and produces only CO2, which means no nitrous oxide, and it turns a horrific greenhouse gas into a not so bad but still pretty bad one. The problem is that to do that you would have to fuel it entirely with methane that would otherwise have been released into the atmosphere.
SpaceX's plan for Starship is to eventually switch to burning manufactured methane, made from CO2 extracted from the atmosphere, so that Starship's fuel will be carbon neutral.
I'm not clear from the summary, but it seems like this research might be implying that CO2 injected high into the atmosphere is somehow worse than the same amount of CO2 at lower altitudes, though.
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Won't burning methane also produce water vapor, a much worse greenhouse gas, in a part of the atmosphere that currently has zero water vapor?
While water vapor disassociates at those altitudes, I don't know how quick and whether it may be a problem if plans to have thousands of launches a year go forward.
BTW, the nitrous oxide can be formed from atmospheric nitrogen being exposed to high heat so burning methane can produce it.
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Combined with the pollution from thousands of de-orbiting defunct satellites every year, it looks like we are once again going to ignore the environmental cost.
SpaceX's long-term plan is to manufacture [wikipedia.org] CH4, on both Earth and Mars, from atmospheric CO2 and water. On Mars this is necessary because there's no convenient source of methane available. On Earth it allows the fuel to be carbon neutral. Though this research seems to imply that injecting CO2 high in the atmosphere is somehow worse than the same amount of CO2 lower altitudes. If that's true, then more thinking will be necessary.
But SpaceX, at least, is thinking about the environmental cost.
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I hope they manage to do it, but given Musk's hit/miss ratio I'm not going to hold out too much hope.
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That assumes you think he will ever get there on some of these ideas.
If they ever make full self driving work it will be a huge liability for Tesla as they will have to upgrade millions of vehicles for free.
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I hope they manage to do it, but given Musk's hit/miss ratio I'm not going to hold out too much hope.
I think its safe to trust Musk's far more than it is to trust government and other billionaires. He seems to turn his plans in to actions more often than not. If he thinks something is good idea he goes out and does it no matter what anyone else seems to think.
I still believe his goal is to make himself king of Mars but if it gets us to Mars, I'm okay with that.
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SpaceX's long-term plan is to manufacture CH4, on both Earth and Mars, from atmospheric CO2 and water. On Mars this is necessary because there's no convenient source of methane available. On Earth it allows the fuel to be carbon neutral. Though this research seems to imply that injecting CO2 high in the atmosphere is somehow worse than the same amount of CO2 lower altitudes.
It's also NOx and not just CO2. When NO reacts with O3 it produces NO2, and NO2 reacts with O3 to make NO3. So NOx emissions deplete ozone. It actually seems like upper atmosphere CO2's effects are not well understood [phys.org].
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Of all the things causing pollution and climate change this is such a stupid issue to get bent out of shape over.
The whole point is that we don't really understand what the impact of rocket engine exhaust is on the atmosphere.
It's quite possible that it will be fairly trivial compared to other sources of pollution, but it would be nice to have some solid evidence behind that answer.
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Of all the things causing pollution and climate change this is such a stupid issue to get bent out of shape over.
Who is getting bent out of shape over this? From what I've seen on slashdot so far:
0 -- the number of people getting bent out of shape over this
1 -- the number of people getting bent out of shape because they imagine other people are getting bent out of shape over this
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Re: Geez (Score:1)
Channeling Trump's Last Words (Score:3, Funny)
We can make more ozone holes to let that crap out.
Significative? (Score:3, Interesting)
At an altitude of 70km, the equivalent CO2 mass emitted has climbed to an equivalent 26 km3 of local ambient atmospheric air, a significant value.
How significative is that? The volume of the atmostphere between 70 and 71 km is about 521,415,439 km3. That is more than half a Billion cubic kilometers. 26 km3 is a 1 in 20,000,000 (one in twenty million) part.
What this means is that we would need 20 million rocket launches to double the amount of CO2 at this altitude. At a rate of 200 launches per year (that would be a 50% increase from current rate) it would take 100,000 years to reach that figure. That is, assuming that the CO2 would have stayed in this band, instead of falling or disipating into space.
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It's highly significative. This issue is super serial.
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It's highly significative. This issue is super serial.
You are wrong.
My Apple 2e has a super serial card. I don't think the Voyager has a super serial card. The RS232 lead wouldn't reach back to Earth.
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I doubt that. More likely is that SpaceX started using a lot of launches with a lot more planned. It is an obvious new research area and has nothing to do with Elon's buyout news.
1990 Called, Civilisation already knew that (Score:2)
Too many rocket launches added to pollution and subsequent global warming
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Spaceflight becoming common (Score:2)
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Even worse with Virgin Galactic (Score:2)
They use an absolutely filthy solid rocket which farts out tons of black shit (watch any of their launches). But hey, as long as some rich bros can spend a few seconds weightless for bragging rights on Instagram I'm sure its worth it.
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Solution already found (Score:2)
Right on cue... (Score:2)
...here come the first waves of the "we have to stop SpaceX" coordinated media propaganda campaign.
This research is probably valid, but the media journalist reporting it is presenting it in certain ways for certain goals. And those goals don't have much to do with the research. Just look at most of the comments in this thread by people who didn't stop to break down the math in the research. The spatial footprint and accumulation rates they're talking about are miniscule, in context. But they are reporte
This study assumes RP-1 propellant (Score:2)
This study considers a typical present-day rocket using RP-1 as the propellant that can generate 6806kN of thrust via a total of nine nozzles.
Some propellants release scarily toxic combustion products, and others are pretty much benign (eg: just water vapour). Feels a bit disingenuous to generalize and group all launches in that way. This seems more like a cry for attention and funding than a carefully r
NOx? Really? (Score:2)
However, rockets don't use air as an oxidizer. Modern rockets typically use purified liquid oxygen. Therefore, there is no nitrogen to create NOx in the combustion process. So where is this NOx coming from? From TFA:
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Just because nitrogen is heated to NOx forming temperatures, does not mean NOx will be formed. Oxygen needs to be present as well, and there should be a negligible amount in the exhaust plume, as most rockets run fuel rich to avoid oxidizing hardware.
Turbulence at the boundary layer between the exhaust and atmosphere causes mixing, so the question is then really do the temps stay high enough while the mixing occurs... Hmm, and also, are there any points at which the mixture is lean, and will any NOx produced there make it out of the engine or will it react with something else first? I know rocket engines are run rich to avoid burning the engine instead of the fuel, but I also know some engines have lean conditions in some of their parts (like a preburne
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Turbulence at the boundary layer between the exhaust and atmosphere causes mixing, so the question is then really do the temps stay high enough while the mixing occurs...
Exactly. The mechanism they are proposing is very complex. Which is why I want to see more research. Preferably empirical.
Hmm, and also, are there any points at which the mixture is lean, and will any NOx produced there make it out of the engine or will it react with something else first? I know rocket engines are run rich to avoid burning the engine instead of the fuel, but I also know some engines have lean conditions in some of their parts (like a preburner.)
Remember, it's impossible (and I don't use that term often) for NOx to be made in a rocket engine that uses typical hydrocarbons as fuel and LOX as an oxidizer, because there is no nitrogen present in the engine. It doesn't matter if the mixture is rich or lean.
A lean engine might produce some/more NOx in the plume because super-heated oxygen would be coming in contact with the nit
Shit (Score:2)
Really? (Score:1)
smoke cigarettes, (Score:1)
When someone says that smoking is harmful I always want to say that our water is so polluted that smoking has almost no negative impact on our health compared to air pollution. Especially considering the fact that I don't smoke cigarettes, I smoke bongs [everythingfor420.com] . It doesn't affect the people around me at all.
considering the fact (Score:1)
When someone says that smoking is harmful I always want to say that our water is so polluted that smoking has almost no negative impact on our health compared to air pollution. Especially considering the fact that I don't smoke cigarettes, I smoke bongs [everythingfor420.com] . It doesn't affect the people around me at all.
Cbd products (Score:1)