“Safety tends to not be on the front burner until it really needs to be on the front burner.”
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Maybe it’s time to reassess the risk of space junk falling to Earth
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Print article with illustrations showing the difference between rocket/satellites and meteorites.
The incorporation of metals from reentry into stratospheric particles.
The incorporation of metals from reentry into stratospheric particles.
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No, I'm not going to watch a video which is likely just a rehash of papers which have already been posted and discussed in this thread multiple times.
If you're not "confused" - please provide a summary of the high points, along with references backing up claims.
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Oh, excellent. Maybe there will be something new.
(reads)
Nope. Rehash of what we already discussed. Oh, well.
"This study only calculates the amount of aluminum oxide particles. We did not calculate exactly how much ozone will be depleted."
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also meteorites deposit WAY WAY more metals into the atmosphere than even the largest proposed Starlink configuration would. you could likely have a few duplicates of said configuration and still be orders of magnitude short. honestly I'd focus more on the mining and refining side, but for a lot of the regions Starlink addresses, the alternative would be worse there, if the alternative exists - which isn't always the case.
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Everything breaks down eventually, and parts of the ISS ARE breaking down, maybe future stations with better interchangeability and with the development of space cutting tools (to deal with vacuum welding- likely needs an EM spall collection system) but the ISS isn't that, and it would cost more energy to raise to TLI than GTO which is already too much
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Last year my time-lapse camera caught re-entry debris from the Dragon Endurance 2 passing over Colorado (the Great Sand Dunes National Park is lower right). A SpaceX engineer contacted me for GPS coords and position of my camera as they wanted to recover the debris, which they figured was somewhere near Limon Colorado.
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thinking about it, for constellations, because you are dealing with mass produced satellites, going to cf structure (with dense electronics and propulsion systems to avoid the dragon trunk problem) being black will also help with both light pollution and heat radiation. A significant part of the problem with CF is the tooling, mass production however will average much of those costs out. saving structural mass is good all around, may reduce the amount of reaction mass you need for your target sat life + margin which may allow you to launch more sats at once.
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Your runon paragraph addressed precisely zero new items and precisely zero of the points brought up in response to earlier posts about this research.
Wake me up when you can address either.
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biggest thing IMO is the assumption that they are mostly aluminum or will continue to be so. most satellites traditionally are made from aluminum, because its light and easy to work with and with satellites traditionally being fairly custom and made in small numbers, "easy to work with" it a pretty critical detail, when you start talking about hundreds or thousands of identical units with minor modifications between- even with some semi custom variants for other users, materials that are lighter but need more custom tooling to work with, such as carbon fiber, start making more sense
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Unless it manages to stabilize edge on. If it can stick in the ground, it can stick in a person.
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The scientific paper didn’t have the info, so link to a video? Always the most reliable and utilitarian of sources.
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Since you’re not big on reading-
The researchers were surprised to find a variety of vapourized metals in the stratosphere that they linked to satellites and spent rocket boosters.
I started seeing not just the metals you expect from meteors, which are things like iron and magnesium, but also weird metals."
The first of those was lithium, there's almost no lithium in meteors that burn up in the atmosphere. But then more and more started popping out — in all, 20 different metals — including an excess of aluminum, as well as niobium and hafnium.
Most rockets are have large quantities of aluminum, while the cones around rocket engines contain niobium and hafnium, along with zirconium. “
So my point and the scientists who seem to know a thing or two about it. Suggest that there IS a difference between meteor fallout and satellite fallout. Another study - ‘we show that N2O emission currently is the single most important ozone-depleting emission’
Sure they might start making satellites and associated solar panels computer chips etc. out of not harmful substances.
The Montreal Protocol didn’t consider this new source of ozone depletion. It might be a good idea to address the problem sooner than later.
I believe Mr. Tom that was your concern?
“As I commented in the other thread, this paper is looking too narrowly at the problem. Iron oxide also depletes the ozone layer, and there's a hell of a lot more iron in meteorites than there is aluminum. Plus all the nickel, silica, etc.
The real question is how much satellite debris affects ozone compared to meteorite debris, and whether this will have a meaningful effect on net ozone concentrations.”
No2 which is created by melting satellites is the biggest ozone depleting substance and is put there by humans/ ie we can do something about it. Perhaps you are too young to remember the first ‘holes in the ozone’ from cfc’s and their impact.
The researchers were surprised to find a variety of vapourized metals in the stratosphere that they linked to satellites and spent rocket boosters.
I started seeing not just the metals you expect from meteors, which are things like iron and magnesium, but also weird metals."
The first of those was lithium, there's almost no lithium in meteors that burn up in the atmosphere. But then more and more started popping out — in all, 20 different metals — including an excess of aluminum, as well as niobium and hafnium.
Most rockets are have large quantities of aluminum, while the cones around rocket engines contain niobium and hafnium, along with zirconium. “
So my point and the scientists who seem to know a thing or two about it. Suggest that there IS a difference between meteor fallout and satellite fallout. Another study - ‘we show that N2O emission currently is the single most important ozone-depleting emission’
Sure they might start making satellites and associated solar panels computer chips etc. out of not harmful substances.
The Montreal Protocol didn’t consider this new source of ozone depletion. It might be a good idea to address the problem sooner than later.
I believe Mr. Tom that was your concern?
“As I commented in the other thread, this paper is looking too narrowly at the problem. Iron oxide also depletes the ozone layer, and there's a hell of a lot more iron in meteorites than there is aluminum. Plus all the nickel, silica, etc.
The real question is how much satellite debris affects ozone compared to meteorite debris, and whether this will have a meaningful effect on net ozone concentrations.”
No2 which is created by melting satellites is the biggest ozone depleting substance and is put there by humans/ ie we can do something about it. Perhaps you are too young to remember the first ‘holes in the ozone’ from cfc’s and their impact.
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It’s my understanding that both on volume and energy, all hypersonic wind tunnels fall far, far short of simulating re-entry.
To do so at significant scale would require a significant fraction of the entire electrical generating capacity of the US, IIRC.
This is one of the reasons that testing actual re-entries is being done for Starship. You can make some educated guesses based on modelling, but you can’t prove a design on the ground.
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Doesn’t actually work that way. SpaceX painted their satellites black, and it didn’t help that much in terms of brightness, less than an order of magnitude. White paint radiates heat almost as well as black paint, and doesn’t absorb most of the light from the Sun. This is the whole nonsense “black clothes in the desert” argument, but in space.
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Thoroughly off topic now, but I feel way hotter in the sun in a black T-shirt vs a light color one
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My new concerns are your incoherent paragraphs, and that you seem to be confusing "We don't want to watch your video" as "We don't want to read"
Throwing a remix of the same stuff at the wall a 4th time doesn't improve your position.
Try to come up with some clear answers, or new and clear points.
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Klive Aleksaander
Ars Praetorian
How about you link to some actual, real studies that support your ozone assumptions?
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They can't. The study literally said the researchers didn't do any calculations about effects on ozone.
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Klive Aleksaander
Ars Praetorian
Yeah, I saw your comment on that.
Basically, my response was more of a challenge for them to find some genuine support for their POV.
Edit: spellinge
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Yes, we’ve all read the Murphy paper. The fact that they can pinpoint different elements in tiny droplets is different than the question of how they affect the stratosphere.
You know what else catalyzes the photochemical activation of chlorine? The literal tons of iron oxide a day contributed to the atmosphere by micrometeorites.
EDIT: As we’ve known for a long time, the best way to protect the ozone layer will be to keep long-lived chlorine products out of the atmosphere. How chlorine is activated from reservoir species in the stratosphere is just one element in the complex cycle of ozone depletion, which ultimately lead back to long-lived chlorine compounds making their way into the stratosphere.
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It is full of rocket fuel, it is rigged to blow. The whole probem of rocketry is blowing up the fuel correctly
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That bit is fine, but it does NOT say anything about ozone.
Again, yes N2O is a concern with ozone depletion, but the biggest source of that we can do something about is terrestial human activity (burning fossil fuels being a big one). Where's the published link between stratospheric N2O and the presence of metal oxides?
Well is it NO2 or N2O? Those are not the same thing at all, and are going to have different reaction pathways. And again, where is the citation for all these connections that were not in the article you linked to, which the media coverage was based off? I'm not saying it can't have an effect, but you seem to be adding a lot of conjecture to what the scientists actually said, which was basically "We don't know (yet)".
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Here’s the paper everyone points to about aluminum oxides catalyzing the photochemical activation of chlorine:
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Interesting paper. "The chlorine activation reaction ClONO2+ HCl -> HNO3 + Cl2..." The one thing I don't see mentioned in there is why they start with ClONO2 in the first place. There must be a reason for it, which presumably other experts in the field would be aware of (and possibly why it isn't mentioned). I will have to do some digging...
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Those are the two dominant reservoir gasses for chlorine in the stratosphere.
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I've no doubt you're right here, but it also seems a stretch from going to SRBs in the stratosphere to satellites re-entering the atmosphere. SRBs are typically full of aluminum powder and perchlorates, creating finely dispersed, relatively pure alumina powder. Such boosters typically dump many tons of aluminum in huge bursts (the multi-ton grains are typically about 15% percent aluminum powder). Satellite decomposition, conversely, occurs at much higher altitudes, involves considerably less aluminum, and undoubtedly creates it in much different and probably much more varied particle sizes.
I also, as a nit, found it interesting that the videos referred to Starlink satellites as 'about the size of a pickup', which is likely true, but their mass, at least for now, is considerably less: typically a few hundred kilograms, rather than 1,000 or so.
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True. I also hadn't appreciated that most of the big chunks also appear to have large metallic components embedded in them, which would increase their lethality quite a bit: they add both mass and rigidity to the shards.
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The ODARs are published, so if you think FCC isn’t doing a good job, you could have someone else take a look.
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That substantially antedates Rush. Dixie Lee Ray (onetime head of AEC) used to claim that volcanos put more pollutants (and radioactive materials) into the atmosphere than human activities.
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alisonken1
Ars Centurion
Interestingly enough - "Cost Prohibitive" is also used when talking about space/weight budgets, not just cash. It's easier to say than getting into specifics of why until it's time to actually talk about getting into the weeds about why it's cost prohibitive.
EDIT: In my thoughts example,
Example 1: "... Cost Prohibitive ..."
Example 2: "... it would take too much extra propellant (which gets into the Rocket Equation) to do what you want ..."
See the difference between the two?
EDIT2: Don't know if the original quote was actually about cash v. others. Just noting that the phrase has multiple meanings that require context to be accurate.
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But keep in mind the buried lede on that alumina paper:
The implication of that is that It might be the case that pretty much any oxide particle will have the same result, and all that matters is the total surface area of all such particles in a given volume.
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Yeah and anything beyond LEO is going to take a lot of delta V to de orbit it. Even the higher end of LEO is going to take a fair amount of fuel to de-orbit. MEO and GEO are just completely impractical. You'd need huge fuel reserves and you'd still have the risk associated with months or years of the orbit crossing lower orbits before it actually de-orbit. Quickly de-orbiting a GEO sat would take a lot more thrust than the station keeping engines can provide.
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This is a Dragon 2 issue so Cargo Dragon doesn't count. Cargo Dragon deorbited with its trunk, Dragon 2 doesn't. The reason Dragon 2 discards the trunk in orbit before deorbiting is that if the trunk fails to detach it is likely a complete loss of vehicle and crew.
NASA has already lost 22 astronauts and they are a bit sensitive to the risk of losing more.
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I'm a day behind, so maybe this was addressed earlier, but something in your gutter being magnetic does not mean it's a meteorite.
I guess the thought process is magnets are mysterious and meteorites are mysterious so magnets must be meteorites, but that's simply not correct.
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A few of what I think are relevant sections from the newer paper that was linked to above:
In 2022, the total mass of reentering objects was estimated to be 332.5 metric tons (ESA, 2023), a 21% increase from the previous year, with 93% of that mass originated from LEO. More than one million radio-frequency spectrum allocation requests were made for planned satellites over the last 5 years (Falle et al., 2023). Forecasts point to future reentry rates of 800–3,200 metric tons per year for satellites, and up to 1,000 metric tons per year for launch vehicles (Organski et al., 2020). The engineering approach of design-for-demise (Kärräng et al., 2019; Waswa & Hoffman, 2012) and the deployment of active debris removal solutions may further exacerbate the aforementioned trend. As for natural sources, meteoroids enter the atmosphere at an average rate of over 11,750 metric tons per year (Drolshagen et al., 2017).
The differential equation is iteratively solved for a null initial velocity at a geometric altitude of 86 km. The settling time is computed for clusters such as the ones presented in Figure 1c, with aerodynamic diameter ranging within 0.4–4.2 nm. At macro scale, the expected value for the aerodynamic diameter is estimated to be 4.1 nm (Ferreira et al., 2023b), taking up to 30 years to reach the altitude of 40 km.
It is then possible to infer that a single reentry event of a 250-kg satellite with a 30% aluminum mass fraction yields approximately 29.8 kg worth of AlO particles and 51.0 kg of Al after thermal ablation, in the higher mesosphere.
Studies have shown that the meteoroid flux averages at 32.2 metric tons/day considering the largest object statistically expected to hit the Earth every day has a diameter of 0.5 m (Drolshagen et al., 2017). However, objects of such size in a hypervelocity entry (Hunt et al., 2004) and excitation temperatures around 4,400 K (Jenniskens, 2004) are expected to fully demise (Guttormsen et al., 2020). Further, a comprehensive analysis of historic meteorite surveys as to chemical composition points to a mean aluminum mass fraction of 1.2% (Schulz & Glassmeier, 2021). The TOA aluminum injection from micrometeoroids is 141.1 metric tons/year, and it is taken to be time-invariant. As for anthropogenic contributions, satellite-related objects reentering from LEO totaled 121.8 metric tons in 2016 (ESA, 2017) and 308.9 metric tons in 2022 (ESA, 2023). Concerning the future mega-constellations scenario, the worst-case estimation of Organski et al. (2020) is taken, with up to 3,200 metric tons of satellites reentering each year.
We then estimate an increase in TOA aluminum compounds (and excess ratio) originated from satellites, from 5.36 metric tons in 2016 (3.8% in excess of natural sources) to 41.7 metric tons in 2022 (excess of 29.5%). The future mega-constellations scenario of increased reentry rates would lead to 912.0 metric tons per year of TOA aluminum from satellites only (excess of 646%).
Potential Ozone Depletion From Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations
Spacecraft burn up during atmospheric reentry, loosing an average of 51%–95% of their mass in the process (Anselmo & Pardini, 2005; Pardini & Anselmo, 2019).In 2022, the total mass of reentering objects was estimated to be 332.5 metric tons (ESA, 2023), a 21% increase from the previous year, with 93% of that mass originated from LEO. More than one million radio-frequency spectrum allocation requests were made for planned satellites over the last 5 years (Falle et al., 2023). Forecasts point to future reentry rates of 800–3,200 metric tons per year for satellites, and up to 1,000 metric tons per year for launch vehicles (Organski et al., 2020). The engineering approach of design-for-demise (Kärräng et al., 2019; Waswa & Hoffman, 2012) and the deployment of active debris removal solutions may further exacerbate the aforementioned trend. As for natural sources, meteoroids enter the atmosphere at an average rate of over 11,750 metric tons per year (Drolshagen et al., 2017).
The differential equation is iteratively solved for a null initial velocity at a geometric altitude of 86 km. The settling time is computed for clusters such as the ones presented in Figure 1c, with aerodynamic diameter ranging within 0.4–4.2 nm. At macro scale, the expected value for the aerodynamic diameter is estimated to be 4.1 nm (Ferreira et al., 2023b), taking up to 30 years to reach the altitude of 40 km.
It is then possible to infer that a single reentry event of a 250-kg satellite with a 30% aluminum mass fraction yields approximately 29.8 kg worth of AlO particles and 51.0 kg of Al after thermal ablation, in the higher mesosphere.
Studies have shown that the meteoroid flux averages at 32.2 metric tons/day considering the largest object statistically expected to hit the Earth every day has a diameter of 0.5 m (Drolshagen et al., 2017). However, objects of such size in a hypervelocity entry (Hunt et al., 2004) and excitation temperatures around 4,400 K (Jenniskens, 2004) are expected to fully demise (Guttormsen et al., 2020). Further, a comprehensive analysis of historic meteorite surveys as to chemical composition points to a mean aluminum mass fraction of 1.2% (Schulz & Glassmeier, 2021). The TOA aluminum injection from micrometeoroids is 141.1 metric tons/year, and it is taken to be time-invariant. As for anthropogenic contributions, satellite-related objects reentering from LEO totaled 121.8 metric tons in 2016 (ESA, 2017) and 308.9 metric tons in 2022 (ESA, 2023). Concerning the future mega-constellations scenario, the worst-case estimation of Organski et al. (2020) is taken, with up to 3,200 metric tons of satellites reentering each year.
We then estimate an increase in TOA aluminum compounds (and excess ratio) originated from satellites, from 5.36 metric tons in 2016 (3.8% in excess of natural sources) to 41.7 metric tons in 2022 (excess of 29.5%). The future mega-constellations scenario of increased reentry rates would lead to 912.0 metric tons per year of TOA aluminum from satellites only (excess of 646%).
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