Starlink generated pollution

[Jim]

Not a snarky post, but legitimate question.  What are the compounds that are vaporized when a Starlink satellite reenters?  The equivalent of the total payload mass of one launch will be vaporized every X.Y years.

[DigitalMan]

I think the FCC documents discussed this, but I don't recall the details.

edit: so far I found:

From June 2021: (if all satellites reenter at once)

“SpaceX would still create about 0.5% the amount
of alumina as the metals generated by meteorites entering the Earth’s
atmosphere in a given year.”

[DanClemmensen]

Not a snarky post, but legitimate question.  What are the compounds that are vaporized when a Starlink satellite reenters?  The equivalent of the total payload mass of one launch will be vaporized every X.Y years.

I think this is a legitimate question, of course, and is well worth a standalone analysis.

It might be a bit more comprehensive if we also knew the compounds emitted during launch and recovery of the booster, including the catcher ship operation, the vaporized F9 second stage, and pollution associated with manufacture and delivery of the satellites and the launcher. Also the pollution associated with manufacture and delivery of the terminals and the electricity to run them. This is also not snarky.

The other side of the balance sheet is also worth looking at. Is there a benefit to society (measured in this case in pollution avoided) to providing Internet service? Internet cat memes and porn may not be a positive benefit, but avoided travel and improved education can both cut down on pollution, and satellite internet replaces land lines which can make a horrific polluting mess in some locations.

These additional questions should not be used to interfere with the analysis you asked for. They can be investigated later.

[daedalus1]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

[DanClemmensen]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

[daedalus1]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

I didn't say it wasn't a legitimate question. I said it was unfair to take a narrow view of polution. Rocket propellants are by far the biggest contribution to the atmosphere and some are highly toxic. One rocket launch will probably equal a decades worth of Starlink deorbited mass into the atmosphere.

[steveleach]

To give us a starting point that we can iterate on, I found the mineral composition of a 129g iPhone at

https://www.engineering.com/story/what-raw-materials-are-used-to-make-hardware-in-computing-devices

31g aluminium (24%)
20g carbon
19g oxygen
18g iron (14%)
8g silicon
8g copper
6g cobalt (5%)
5g hydrogen
5g chrome

Starlink satellites are 227kg according to
https://en.wikipedia.org/wiki/Starlink#Satellite_hardware

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Using the iPhone mineral percentages that gives...
326t aluminium
190t iron
68t cobalt

For context, "Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons."
 
http://curious.astro.cornell.edu/about-us/75-our-solar-system/comets-meteors-and-asteroids/meteorites/313-how-many-meteorites-hit-earth-each-year-intermediate

[jimvela]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

I didn't say it wasn't a legitimate question. I said it was unfair to take a narrow view of polution. Rocket propellants are by far the biggest contribution to the atmosphere and some are highly toxic. One rocket launch will probably equal a decades worth of Starlink deorbited mass into the atmosphere.

Doubtful. Show your numbers.

[Zed_Noir]

Think it is not what compounds are generated when Starlink comsats and other satellite reenters the atmosphere that is the most important issue. After vaporization mostly some sort of metallic aerosol is all that remains, AIUI. Said aerosol is not well understood in how it affects the atmospheric column and weather patterns if it is present over a wide area.

[DanClemmensen]

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Using the iPhone mineral percentages that gives...
326t aluminium
190t iron
68t cobalt

For context, "Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons."
 
http://curious.astro.cornell.edu/about-us/75-our-solar-system/comets-meteors-and-asteroids/meteorites/313-how-many-meteorites-hit-earth-each-year-intermediate

So to a crude first-order approximation  based on 5 minutes of armchair analysis (excellent and thanks, btw), de-orbiting of Starlink (and the rest of the satellites, since they are a small proportion) will increase the natural impingement on the atmosphere by 0.5% to 1%.

At a speculative wild guess, a deeper analysis, costing maybe $1 million, will change this by less than a factor of two. A much deeper analysis, costing maybe $10 million, taking three years, and resulting in three or more PhD theses, will refine this from "crude" to within a factor of two".

I speculate based on no input whatsoever that the rest of the launch effects will overwhelm the de-orbiting effects by a factor of at least ten. This will depend critically on how these effects are weighted in the evaluation. Global warming? Global warming timescale? heavy-metal effects in the ocean? heavy-metal effect in the atmosphere?

I further speculate that various interests will seize on these results to support various positions, including contradictory positions.

[Robotbeat]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

Indeed, quagmires. That’s not reasonable unless you think every aircraft flight should also have a full life-cycle pollution analysis.

It’s good to study this stuff and find ways to improve over time if necessary. Insisting on insane cost burdens like a lengthy pollution life cycle analysis for every flight is not.

Red tape as a time tax on such things is incredibly bad. A straight pollution tax (if necessary) without red tape would be FAR more efficient and better.

Red tape often ends up delaying, not improving outcomes. “We checked all the boxes and studied it, now we’ll go ahead and do the thing anyway.” Red tape time tax is essentially like a pollution tax but instead of money being put in the public coffer, it’s just lit on fire.

[Robotbeat]

BTW, it’s not a problem now or even at the Megatonne to LEO annually range, but at 100 annual Megatonnes per year, the nitrogen oxides produced by high speed reentry, even with reusable heatshields like Shuttle’s, starts causing problems. The solution is rotating tethers to remove even a little bit of the entry velocity (as the production of nitrogen oxides is proportional to the velocity to some power at least 2, could be much higher).

Same would be true for reentering expendable spacecraft or extraterrestrial resources.

[DanClemmensen]

BTW, it’s not a problem now or even at the Megatonne to LEO annually range, but at 100 annual Megatonnes per year, the nitrogen oxides produced by high speed reentry, even with reusable heatshields like Shuttle’s, starts causing problems. The solution is rotating tethers to remove even a little bit of the entry velocity (as the production of nitrogen oxides is proportional to the velocity to some power at least 2, could be much higher).

Same would be true for reentering expendable spacecraft or extraterrestrial resources.

What is the effect of reentering non-expendable spacecraft? does the production of nitrogen oxides depend on the nature of the TPS? Is a reusable junk collection mission counterproductive?

[Robotbeat]

It’s based just on the reentering mass and velocity. It might depend on the shape a little bit.

But it doesn’t really depend on what the thing is made of, unlike, say, high altitude dust from expended stages and Starlinks.

If Starlink reentries become a problem, just will have to dispose of them via Starship Chomper. Maybe end of life, they group together and then Chomper brings them down.

[Robotbeat]

Oh, and high altitude solid rocket motor exhaust can cause a similar dust problem as reentering satellites. Back when Shuttle was projected to do a lot of flights, that was a real concern. Lots of aluminum in that exhaust. Between the SRBs and the solids, maybe 100 tons of dust up there per launch. 40 launches per year, that’s more than Starlink’s wildest projections.

[su27k]

There were some papers about the effect of burning up satellites in the atmosphere, but I believe the TL;DR is that nobody knows what exactly is the effect yet, it's even possible that the particulates spread in the upper atmosphere could have a cooling effect.

The concern here is that materials fall to Earth naturally don't have a lot of aluminium in it, while satellite has a lot of aluminium in it. But IIRC the papers usually just assume the entire satellite is solid block of aluminium, which is also inaccurate.

[daedalus1]

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

I didn't say it wasn't a legitimate question. I said it was unfair to take a narrow view of polution. Rocket propellants are by far the biggest contribution to the atmosphere and some are highly toxic. One rocket launch will probably equal a decades worth of Starlink deorbited mass into the atmosphere.

Doubtful. Show your numbers.

I said 'probably' as an educated guess to make a point. If you want numbers feel free to produce them.
Roughly 1% of 4000 starlink deorbits in a year times ten years equals 400. Times 225kg = less than 100 tonnes.

[jak Kennedy]

Think it is not what compounds are generated when Starlink comsats and other satellite reenters the atmosphere that is the most important issue. After vaporization mostly some sort of metallic aerosol is all that remains, AIUI. Said aerosol is not well understood in how it affects the atmospheric column and weather patterns if it is present over a wide area.

There must have been some studies on how meteorites affect the atmosphere?

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

I didn't say it wasn't a legitimate question. I said it was unfair to take a narrow view of polution. Rocket propellants are by far the biggest contribution to the atmosphere and some are highly toxic. One rocket launch will probably equal a decades worth of Starlink deorbited mass into the atmosphere.

Doubtful. Show your numbers.

I said 'probably' as an educated guess to make a point. If you want numbers feel free to produce them.
Roughly 1% of 4000 starlink deorbits in a year times ten years equals 400. Times 225kg = less than 100 tonnes.

 If less then 100 tonnes per year then about the same as meteorites per day.

https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html

NASA page in tons    I'm surprised they don't write at in least both units coming from NASA if they are not going to embrace metric.

[daedalus1]

Think it is not what compounds are generated when Starlink comsats and other satellite reenters the atmosphere that is the most important issue. After vaporization mostly some sort of metallic aerosol is all that remains, AIUI. Said aerosol is not well understood in how it affects the atmospheric column and weather patterns if it is present over a wide area.

There must have been some studies on how meteorites affect the atmosphere?

If you want to quantify polution from satellites, to be fair it's best to take a holistic approach from all governments and agencies. And also oceanic polution as well as atmospheric.
It is unfair to keep focusing on SpaceX.
All other agencies/governments drop most of their launch vehicles into the ocean. Virgin Orbit did it a few hours ago.

It's a legitimate question, not unfair. Starlink is by far the largest constellation and will get larger. Even if it is ten time "less polluting" per satellite than average, it's still important. Among other things, the answer would help inform a decision to clean up space junk, both Starlink and non-Starlink. I think it would be be a good idea to require a life-cycle pollution analysis for any launch, where life-cycle includes deorbiting. The main problem is that such mandates tend to become bureaucratic quagmires.

I didn't say it wasn't a legitimate question. I said it was unfair to take a narrow view of polution. Rocket propellants are by far the biggest contribution to the atmosphere and some are highly toxic. One rocket launch will probably equal a decades worth of Starlink deorbited mass into the atmosphere.

Doubtful. Show your numbers.

I said 'probably' as an educated guess to make a point. If you want numbers feel free to produce them.
Roughly 1% of 4000 starlink deorbits in a year times ten years equals 400. Times 225kg = less than 100 tonnes.

 If less then 100 tonnes per year then about the same as meteorites per day.

https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html

NASA page in tons    I'm surprised they don't write at in least both units coming from NASA if they are not going to embrace metric.

Read it again.
100 tonnes in a decade.

[niwax]

To give us a starting point that we can iterate on, I found the mineral composition of a 129g iPhone at

https://www.engineering.com/story/what-raw-materials-are-used-to-make-hardware-in-computing-devices

31g aluminium (24%)
20g carbon
19g oxygen
18g iron (14%)
8g silicon
8g copper
6g cobalt (5%)
5g hydrogen
5g chrome

Starlink satellites are 227kg according to
https://en.wikipedia.org/wiki/Starlink#Satellite_hardware

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Using the iPhone mineral percentages that gives...
326t aluminium
190t iron
68t cobalt

For context, "Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons."
 
http://curious.astro.cornell.edu/about-us/75-our-solar-system/comets-meteors-and-asteroids/meteorites/313-how-many-meteorites-hit-earth-each-year-intermediate

For comparison, each Ariane 5 solid booster burns 277t of 18% aluminium, 68% ammonium perchlorate and 14% rubber binder. SLS burns about 800t of rubber per side (Improvement over Shuttle: Now without the asbestos lining!).

I think it's certainly a valid question to ask about Starlink, as it will be the biggest concentration of LEO reentries for the time being. At the same time, I don't expect any showstoppers here.

[dondar]

Current launch cycles include second stage burnouts. So you can include those as well.

The numbers and effects still stay irrelevant.

To those wanting to make models, "warn about dangers" and do other "socially engaging stuff" a small word of warning: there will be discussion which would (and will) end with much father consequences than you want/expect or even think about. The already existing baggage of sudoscience is enormous. You do want to science sh^t out before even beginning.

 Musk accepts modern discourse, but others won't in this case. Just saying.

[Jim]

I was thinking more about elements such as cobalt and chrome which are not commonly airborne

[meekGee]

This is not a real concern, since it's small in mass and globally distributed.

Compare this to something localized like STS SB exhaust or any smokestack in a factory or refinery and not only is the tonnage higher in the latter examples, but also the concentration gradient is centered right smack on top of population centers and local watersheds.

As folks pointed out, even on a similar track, incoming meteors (and volcanoes) also introduce larger quantities of solid particulates at a global scale.

If you want to crusade for the environment, which is a noble cause, there are much better starting points.

[Jim]

Then the same applies to non reusable vehicles.

[Robotbeat]

I was thinking more about elements such as cobalt and chrome which are not commonly airborne

Huh. I sort of doubt there’s much of those elements in Starlink as they’re kind of expensive, but it gave me an idea:

If non-organic materials in reentry are a problem (and I don’t think they are, to be honest), you could make satellites largely of organic materials. I.e, plastic satellites (think composites).

Wooden satellites make more sense than one might think as well. Would get a much stronger in absence of water in a vacuum (strength to weight comparable to aluminum, maybe better in certain circumstances), although they’d have to be protected from atomic oxygen, which attacks wood very successfully.

[Robotbeat]

I think there’s plenty of room for adjusting the design of demiseable spacecraft if a significant environmental problem is found.  Such efforts at studying issues should therefore be solutions-oriented.

[DigitalMan]

I think the most current information is the one I quoted from, the FCC response to the ViaSat allegations that NEPA should be involved and that Starlink was not good.

[steveleach]

I was thinking more about elements such as cobalt and chrome which are not commonly airborne

So about 70t of cobolt and 50t of chrome a year, using the "oversized iphone" model.

According to https://www.permanent.com/meteorite-compositions.html a meterorite might be 0.5% cobolt, so that's 250t for a middle-ish estimate of 50,000t per year.

So using those numbers, starlinks deorbiting would make a measurable difference (+20%) to the amount of cobolt entering the atmosphere from space.

For comparison, though, for CO2 where we are worried about an extra hundred parts per million, the problem is measured in gigatons.

Even if harmful cobolt levels were measured in parts per billion, 70t would be a few orders of magnitude below 1 ppb.

According to https://en.wikipedia.org/wiki/Cobalt_poisoning it would take 20g of cobolt to give a 100kg person a 50% chance of death from cobolt.

[IRobot]

I was thinking more about elements such as cobalt and chrome which are not commonly airborne

Huh. I sort of doubt there’s much of those elements in Starlink as they’re kind of expensive,

Cobalt would mostly be used on a battery. Even Tesla batteries are moving away from Cobalt and most use zero.
Even so, older batteries use around 4kg of Cobalt for a ~480kg battery, i.e. <1%. Compared to the mass of the car, it's 0,2%.
The iPhone analogy shows 5%, which I think it's too much.

[Michael S]

Would it be more appropriate to ask how the dust of the burned up satellites will affect the upper atmosphere?
I recall statements about vapor being increased at higher altitudes due to aircraft and how that was creating a very small but noticeable difference in reflectivity.

Honestly, considering that there are tons of asteroid and cometary debris burning up in the atmosphere every year, I would think that as long as we are not introducing elements like lead and arsenic, other highly toxic elements, life at the surface might be ok.

However, I found this forum because I wanted to ask Jim if he thought that a satellite burning up completely in the atmosphere was better than some of it making to the ocean.  If Jim is the one now ask this question….
Should we be concerned?

[guckyfan]

100% demisable was a FCC requirement for granting the Starlink license. With the number of satellites deorbiting there would be a non zero risk of some debris hitting humans on the ground.

SpaceX had to redesign the Hall thrusters, the laser mirrors and the reaction wheels to meet this requirement.

[su27k]

This is a relevant article, it looks like it's mainly an Aerospace Corp team studying this: Aerospace Corp. raises questions about pollutants produced during satellite and rocket reentry

Martin Ross talked about this in a Space Show episode: https://thespaceshow.com/show/08-jun-2021/broadcast-3702-dr.-martin-ross

[steveleach]

This is a relevant article, it looks like it's mainly an Aerospace Corp team studying this: Aerospace Corp. raises questions about pollutants produced during satellite and rocket reentry

Martin Ross talked about this in a Space Show episode: https://thespaceshow.com/show/08-jun-2021/broadcast-3702-dr.-martin-ross

I was hoping to see some actual information in that SpaceNews article, but it did at least lead me to this paper (abstract)...

https://ui.adsabs.harvard.edu/abs/2020AGUFMGC0420004H/abstract

Does anyone have access to the paper itself?

[cdebuhr]

This is a relevant article, it looks like it's mainly an Aerospace Corp team studying this: Aerospace Corp. raises questions about pollutants produced during satellite and rocket reentry

Martin Ross talked about this in a Space Show episode: https://thespaceshow.com/show/08-jun-2021/broadcast-3702-dr.-martin-ross

I was hoping to see some actual information in that SpaceNews article, but it did at least lead me to this paper (abstract)...

https://ui.adsabs.harvard.edu/abs/2020AGUFMGC0420004H/abstract

Does anyone have access to the paper itself?

That looks like a conference abstract so that may be all there is (unless you happened to go the the Fall 2020 AGU meeting and see the associated talk).  That said, if the research was something one or more of these authors is was actually pursuing, and not just a sideshow/distraction for them, they may have published a real, peer-reviewed paper on the topic.  If you can find a webpage for one or more of the authors, they'll likely include a list of significant contributions.

[vsatman]

it is strange that everyone forgot about the F9 second stage, which weighs 4 tons, that is, like 15 satellites

[matthewkantar]

it is strange that everyone forgot about the F9 second stage, which weighs 4 tons, that is, like 15 satellites

Second stages are not relevant because all lunch vehicles burn them up in the atmosphere. Only SpaceX specific concerns shall be raised.

[steveleach]

it is strange that everyone forgot about the F9 second stage, which weighs 4 tons, that is, like 15 satellites

Second stages are not relevant because all lunch vehicles burn them up in the atmosphere. Only SpaceX specific concerns shall be raised.

Not for much longer 

[su27k]

it is strange that everyone forgot about the F9 second stage, which weighs 4 tons, that is, like 15 satellites

Some of the models do include launch vehicle re-entry, it's mentioned in the SpaceNews article (although there may be a typo here): "If all those constellations materialize, the annual mass of satellites reentering Earth’s atmosphere eventually could rise from a current level of roughly 100 metric tons to between 800 and 3,200 metric tons. Launch vehicles reentries could account for another metric ton per year."

But this is not a concern for Starlink since they'll be using Starship.

[su27k]

In the latest response to Viasat, SpaceX quoted 3 studies to show satellite reentry has negligible effect on the environment:

Similarly, two independent studies that the European Space Agency (“ESA”) commissioned in 2019—the ATISPADE and ARA studies—show that satellite reentry has a “negligible” effect on the environment.¹⁸

The ATISPADE study looked at the effect of reentering satellites on the ozone layer. It found that, in the worst case analyzed, the additional yearly ozone reduction was “negligible when compared to the impact of anthropogenic activities,” only between 0.0006% and 0.0008% of global annual ozone loss.¹⁹ While the worst case used in the study assumed an average of 450 tons worth of satellites reentering every year and a peak of 650 tons per year,²⁰ the fundamental conclusion—that the impact to the ozone is “negligible” compared to other sources—remains valid even when extrapolating to one order of magnitude more mass per year, as Viasat aggressively assumes would occur.²¹

But Viasat presents no justification for its allegations that these extremely aggressive scenarios will come to pass. Indeed, one leading study raises questions about Viasat’s fundamental premise, finding that the chemical reactions that take place during meteorite reentry do not create alumina at all, even though meteorites contain aluminum.²² In fact, no alumina has ever been detected using rocket-borne spectrometry specifically looking for all aluminum species precipitated by reentering meteorites.

The ESA-commissioned ARA study undercuts Viasat’s overblown claims—parroted by NRDC/IDA and others—about the climate effects of the Gen2 satellites. The study found the climate effects of satellite reentry to be minute compared to other man-made sources. For instance, in the worst-case scenario, the annual impact of satellite reentry was 290,000 times less than the annual impact of the aviation sector and 650,000 times less than the annual impact of the road transportation sector.²³ Again, even when extrapolated to an order of magnitude greater than the worst case evaluated in the ARA study, the effect would remain negligible relative to other man-made sources. Similarly, assuming the extremely aggressive reentry figures that Viasat touts, the annual impact of reentering Gen2 satellites on Earth’s albedo—the fraction of solar radiation that is reflected away from Earth—will be negligible compared to natural sources (i.e., just 0.005% of the amount of mineral dust created annually through naturally occurring dust storms from the Sahara Desert alone).²⁴

FCC filing: https://licensing.fcc.gov/myibfs/download.do?attachment_key=17743215

Reference #22 is the paper Meteor-Ablated Aluminum in the Mesosphere-Lower Thermosphere

[su27k]

Studies flag environmental impact of reentry

Space hardware tumbling out of orbit may lead to unforeseen environmental and climate impacts. Due to the growing scale and pace of launch activities, what is needed is better monitoring of the situation, as well as regulation to create an environmentally sustainable space industry.

Making that case is Jamie Shutler, associate professor of Earth observation at the University of Exeter, Cornwall.

Shutler and colleagues authored the research paper “Atmospheric impacts of the space industry require oversight” in the August issue of the journal Nature Geoscience.

[freddo411]

Studies flag environmental impact of reentry

Space hardware tumbling out of orbit may lead to unforeseen environmental and climate impacts. Due to the growing scale and pace of launch activities, what is needed is better monitoring of the situation, as well as regulation to create an environmentally sustainable space industry.

Making that case is Jamie Shutler, associate professor of Earth observation at the University of Exeter, Cornwall.

Shutler and colleagues authored the research paper “Atmospheric impacts of the space industry require oversight” in the August issue of the journal Nature Geoscience.

This isn't about the environment.   It seems to be, like a lot "regulation", about controlling other people.   

[TheRadicalModerate]

To give us a starting point that we can iterate on, I found the mineral composition of a 129g iPhone at

https://www.engineering.com/story/what-raw-materials-are-used-to-make-hardware-in-computing-devices

31g aluminium (24%)
20g carbon
19g oxygen
18g iron (14%)
8g silicon
8g copper
6g cobalt (5%)
5g hydrogen
5g chrome

Starlink satellites are 227kg according to
https://en.wikipedia.org/wiki/Starlink#Satellite_hardware

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Within 5 years, most Starlinks will be v2, which weigh 2t apiece.  So, using your cited percentages, you'll be looking at 2880t of aluminum (really aluminum oxide) aerosols per year.  However, a lot depends on the size of particles formed during reentry.  Orbital decay is a lot slower than interplanetary meteor and dust strikes, and presumably would make larger droplets, some of which won't make very good aerosols.

I found this PhD dissertation on how alumina aerosols help to catalyze the creation of free chlorine that can destroy ozone.  Can't say I've more than skimmed it, but it's on point for this discussion.  Pay special attention to Chapter IV.

Here's another reference that seems to be on point.

Seems to me that this needs investigating, but it's not time for people to get their knickers in a twist yet.  I think the basic thesis that satellites in general and Starlinks in particular will significantly increase metallic aerosols is valid.  After that, you need to do a whole bunch of research to figure out the size distribution of aerosols and their corresponding half-lives in the atmosphere.

[Nomadd]

To give us a starting point that we can iterate on, I found the mineral composition of a 129g iPhone at

https://www.engineering.com/story/what-raw-materials-are-used-to-make-hardware-in-computing-devices

31g aluminium (24%)
20g carbon
19g oxygen
18g iron (14%)
8g silicon
8g copper
6g cobalt (5%)
5g hydrogen
5g chrome

Starlink satellites are 227kg according to
https://en.wikipedia.org/wiki/Starlink#Satellite_hardware

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Within 5 years, most Starlinks will be v2, which weigh 2t apiece.  So, using your cited percentages, you'll be looking at 2880t of aluminum (really aluminum oxide) aerosols per year.  However, a lot depends on the size of particles formed during reentry.  Orbital decay is a lot slower than interplanetary meteor and dust strikes, and presumably would make larger droplets, some of which won't make very good aerosols.

I found this PhD dissertation on how alumina aerosols help to catalyze the creation of free chlorine that can destroy ozone.  Can't say I've more than skimmed it, but it's on point for this discussion.  Pay special attention to Chapter IV.

Here's another reference that seems to be on point.

Seems to me that this needs investigating, but it's not time for people to get their knickers in a twist yet.  I think the basic thesis that satellites in general and Starlinks in particular will significantly increase metallic aerosols is valid.  After that, you need to do a whole bunch of research to figure out the size distribution of aerosols and their corresponding half-lives in the atmosphere.

I'm not that confident in my 2 minutes of Google research, but I'm getting somewhere around 1,000 tons of aluminum in mostly oxide form from meteors each year.

[DanClemmensen]

To give us a starting point that we can iterate on, I found the mineral composition of a 129g iPhone at

https://www.engineering.com/story/what-raw-materials-are-used-to-make-hardware-in-computing-devices

31g aluminium (24%)
20g carbon
19g oxygen
18g iron (14%)
8g silicon
8g copper
6g cobalt (5%)
5g hydrogen
5g chrome

Starlink satellites are 227kg according to
https://en.wikipedia.org/wiki/Starlink#Satellite_hardware

If we assume 30,000 satellites with a life of 5 years, that's 6000 de-orbiting a year.

6,000 * 227 kg = 1,362,000kg = 1362 tonnes

Within 5 years, most Starlinks will be v2, which weigh 2t apiece.  So, using your cited percentages, you'll be looking at 2880t of aluminum (really aluminum oxide) aerosols per year.  However, a lot depends on the size of particles formed during reentry.  Orbital decay is a lot slower than interplanetary meteor and dust strikes, and presumably would make larger droplets, some of which won't make very good aerosols.

I found this PhD dissertation on how alumina aerosols help to catalyze the creation of free chlorine that can destroy ozone.  Can't say I've more than skimmed it, but it's on point for this discussion.  Pay special attention to Chapter IV.

Here's another reference that seems to be on point.

Seems to me that this needs investigating, but it's not time for people to get their knickers in a twist yet.  I think the basic thesis that satellites in general and Starlinks in particular will significantly increase metallic aerosols is valid.  After that, you need to do a whole bunch of research to figure out the size distribution of aerosols and their corresponding half-lives in the atmosphere.

I'm not that confident in my 2 minutes of Google research, but I'm getting somewhere around 1,000 tons of aluminum in mostly oxide form from meteors each year.

By comparison, each SLS SRB masses 730 t, so 1460t per launch, and 16% of the fuel mass is aluminum, so maybe 146 t per launch, which combines with oxygen from the oxidizer to form Al₂O₃ with a mass of about 280 t.

[dchill]

As another regulatory example, the US still allows lead in AVGAS, which is the fuel used by propeller airplanes.

According to this article:
https://ceh.org/air-and-water/avgas-map-californians-affected-by-lead-from-aviation-fuel

"Currently, leaded avgas is the largest source of lead air pollution in the US, responsible for over 500 tons of lead emissions per year."

I'd say lead is a much more dangerous element to have raining down on our heads than aluminum or most of the other material that's in reentering space hardware.  Of course most of that lead is coming down in populated urban areas versus over the ocean or remote areas.

Personally I'd rather see the government deal with that old technology first before they regulate an industry that's still changing and finding its legs.

Given that, however, I'd say that if the toxicity of all the elements reentering from space is less than the equivalent of 250 tons of lead per year than that's perhaps a fair cross-industry level of regulation.

[shark0302]

As another regulatory example, the US still allows lead in AVGAS, which is the fuel used by propeller airplanes.

According to this article:
https://ceh.org/air-and-water/avgas-map-californians-affected-by-lead-from-aviation-fuel

"Currently, leaded avgas is the largest source of lead air pollution in the US, responsible for over 500 tons of lead emissions per year."

I'd say lead is a much more dangerous element to have raining down on our heads than aluminum or most of the other material that's in reentering space hardware.  Of course most of that lead is coming down in populated urban areas versus over the ocean or remote areas.

Personally I'd rather see the government deal with that old technology first before they regulate an industry that's still changing and finding its legs.

Given that, however, I'd say that if the toxicity of all the elements reentering from space is less than the equivalent of 250 tons of lead per year than that's perhaps a fair cross-industry level of regulation.

Yep, and g100ul was recently certified for all  prop plane'sin the US. It's now the problem of getting it in mass production.
https://generalaviationnews.com/2022/09/03/gami-unleaded-fuel-approved-for-all-general-aviation-aircraft/#:~:text=(GAMI)%20to%20be%20used%20by,and%20IO%2D360%20piston%20engines.

But this is an example of still using 70 year old technology cause it is certified.

[TheRadicalModerate]

Given that, however, I'd say that if the toxicity of all the elements reentering from space is less than the equivalent of 250 tons of lead per year than that's perhaps a fair cross-industry level of regulation.

The issue isn't direct toxicity to humans; it's that alumina can catalyze the creation of free chlorine, which can deplete ozone.  Lead doesn't do that.

[oldAtlas_Eguy]

Given that, however, I'd say that if the toxicity of all the elements reentering from space is less than the equivalent of 250 tons of lead per year than that's perhaps a fair cross-industry level of regulation.

The issue isn't direct toxicity to humans; it's that alumina can catalyze the creation of free chlorine, which can deplete ozone.  Lead doesn't do that.

Which all the alumina in the 365,000t of meteorite material does really well every year. Of which the amounts of the alumina in the sats would be lost in the error margins due to the constant and widely varying atomic makeup of the meteorites every year. The meteorites are mostly oxygen, silicon, alumina, and titanium.

It is not a problem and will not be for a long time. Such that in not that far into the future companies will make fortunes on gathering up old sats and pieces to then 'melt down' and feed back into the on-orbit manufacturing market. They would also likely collect quite a bit of meteorite material as well.

Do not make it into one. Pollution is a matter of significant percentage. Even at 2,000t of sats returning in a year. It is in the margin of error of variation for the meteorite material which can vary each year by +-20%. NOTE 20%of 365,000t is 73,000t.

[TheRadicalModerate]

Given that, however, I'd say that if the toxicity of all the elements reentering from space is less than the equivalent of 250 tons of lead per year than that's perhaps a fair cross-industry level of regulation.

The issue isn't direct toxicity to humans; it's that alumina can catalyze the creation of free chlorine, which can deplete ozone.  Lead doesn't do that.

Which all the alumina in the 365,000t of meteorite material does really well every year. Of which the amounts of the alumina in the sats would be lost in the error margins due to the constant and widely varying atomic makeup of the meteorites every year. The meteorites are mostly oxygen, silicon, alumina, and titanium.

It is not a problem and will not be for a long time. Such that in not that far into the future companies will make fortunes on gathering up old sats and pieces to then 'melt down' and feed back into the on-orbit manufacturing market. They would also likely collect quite a bit of meteorite material as well.

Do not make it into one. Pollution is a matter of significant percentage. Even at 2,000t of sats returning in a year. It is in the margin of error of variation for the meteorite material which can vary each year by +-20%. NOTE 20%of 365,000t is 73,000t.

I've got a reference that says 30t of cosmic dust per day, 1.4% of which is elemental aluminum.  So that's about 11,000t of meteors/meteorites/dust per year, with 153t of it being aluminum.  6000 Starlinks/year, each 2t, with maybe 25% being aluminum, would be 3000t/year.

However, it's really the surface area of the Al₂O₃ that's the issue.  I'd expect most meteors to completely vaporize, then re-condense as extremely fine particles, therefore with very high surface/volume ratio.  On the other hand, reentering satellites will likely produce droplets with considerably lower surface/volume ratios. 

Given what the actual ratios for both cosmic and satellite aluminum are, this could be anything from a nothingburger to a big problem.  Not a slam-dunk answer either way.  Sounds to me like something that needs some investigation.

I do think that the Nature piece's title, “Atmospheric impacts of the space industry require oversight”, is inflammatory.  I'm not sure if that's the author's title or whether the editors juiced it up for controversy.  "Oversight" with our current state of knowledge isn't warranted.  But improving the current state of knowledge is warranted.

[steveleach]

I do think that the Nature piece's title, “Atmospheric impacts of the space industry require oversight”, is inflammatory.  I'm not sure if that's the author's title or whether the editors juiced it up for controversy.  "Oversight" with our current state of knowledge isn't warranted.  But improving the current state of knowledge is warranted.

I don't think it would be particularly unreasonable for mega-constellation operators to be required to do an environmental assessment in this area as part of the overall licensing process.

It is probably a non-issue, but let's have the operators prove that it is,

[TheRadicalModerate]

I do think that the Nature piece's title, “Atmospheric impacts of the space industry require oversight”, is inflammatory.  I'm not sure if that's the author's title or whether the editors juiced it up for controversy.  "Oversight" with our current state of knowledge isn't warranted.  But improving the current state of knowledge is warranted.

I don't think it would be particularly unreasonable for mega-constellation operators to be required to do an environmental assessment in this area as part of the overall licensing process.

It is probably a non-issue, but let's have the operators prove that it is,

This gets back to the whole question of whether the FCC or some other agency can force an Environmental Impact Statement for space operations.  Several of SpaceX's competitors tried to force this on them, unsuccessfully.  I can't remember the entire set of bureaucratic mumbo-jumbo involved, but it basically boiled down to on-orbit satellite operations having a class exemption from EIS requirements.

Beyond that, it would be incredibly difficult for an operator to prove that its operations were not harmful.  I think the burden is on the government to set regulations for the amount of various materials, of various sizes, that get left in the atmosphere as aerosols, and cite the research.

This isn't going to be a problem that destroys the ozone layer next year, or even next decade.  If the international community is worried about this, then they should fund the research, and then we can do something like modify the Montreal Protocol if it turns out to be an issue.

[Robotbeat]

“Environmental assessment” is just the same thing as a time tax. It doesn’t change the out outcome, just makes it take years longer. We’d be better off just charging them a fee.

I think an EA is an absolutely terrible idea.

[RedLineTrain]

It is probably a non-issue, but let's have the operators prove that it is,

I don't think any of our environmental laws are based on the precautionary principle.  If they were, nothing would get done or built.

[Robotbeat]

It is probably a non-issue, but let's have the operators prove that it is,

I don't think any of our environmental laws are based on the precautionary principle.  If they were, nothing would get done or built.

Well…

[steveleach]

It is probably a non-issue, but let's have the operators prove that it is,

I don't think any of our environmental laws are based on the precautionary principle.  If they were, nothing would get done or built.

Straying off topic and into politics here, but maybe environmental laws could stand being a little more precautionary. 

I'd personally like to see all (public) businesses be required to publicly report the environmental impact of their operations and products, the same way they have to report their finances, so for me the impact of deorbiting satellites is just one aspect of that.

[su27k]

This gets back to the whole question of whether the FCC or some other agency can force an Environmental Impact Statement for space operations.  Several of SpaceX's competitors tried to force this on them, unsuccessfully.  I can't remember the entire set of bureaucratic mumbo-jumbo involved, but it basically boiled down to on-orbit satellite operations having a class exemption from EIS requirements.

Worth pointing out that just because something falls under NEPA categorical exclusion does not mean there's no environmental review for it, per 47 CFR § 1.1307 (c):

(c) If an interested person alleges that a particular action, otherwise categorically excluded, will have a significant environmental effect, the person shall electronically submit to the Bureau responsible for processing that action a written petition setting forth in detail the reasons justifying or circumstances necessitating environmental consideration in the decision-making process. ... The Bureau shall review the petition and consider the environmental concerns that have been raised. If the Bureau determines that the action may have a significant environmental impact, the Bureau will require the applicant to prepare an EA (see §§ 1.1308 and 1.1311), which will serve as the basis for the determination to proceed with or terminate environmental processing.

In case of Starlink, interested persons did raise allegation that Gen2 has significant environmental effect, including the environmental impact of the re-entry. And FCC did perform a review of the petition and considered environmental concerns raised, so an environmental review is indeed performed, and FCC's conclusion regarding satellite reentry is that:

Based on the record, we are not convinced that reentering SpaceX Gen2 Starlink satellites may have a significant environmental impact necessitating an EA. As SpaceX states, the European Space Agency (ESA) initiated two studies, looking into specifically the atmospheric impact of spacecraft demise upon reentry and concluding that the impact was negligible compared to other anthropogenic activities.451

[steveleach]

This gets back to the whole question of whether the FCC or some other agency can force an Environmental Impact Statement for space operations.  Several of SpaceX's competitors tried to force this on them, unsuccessfully.  I can't remember the entire set of bureaucratic mumbo-jumbo involved, but it basically boiled down to on-orbit satellite operations having a class exemption from EIS requirements.

Worth pointing out that just because something falls under NEPA categorical exclusion does not mean there's no environmental review for it, per 47 CFR § 1.1307 (c):

(c) If an interested person alleges that a particular action, otherwise categorically excluded, will have a significant environmental effect, the person shall electronically submit to the Bureau responsible for processing that action a written petition setting forth in detail the reasons justifying or circumstances necessitating environmental consideration in the decision-making process. ... The Bureau shall review the petition and consider the environmental concerns that have been raised. If the Bureau determines that the action may have a significant environmental impact, the Bureau will require the applicant to prepare an EA (see §§ 1.1308 and 1.1311), which will serve as the basis for the determination to proceed with or terminate environmental processing.

In case of Starlink, interested persons did raise allegation that Gen2 has significant environmental effect, including the environmental impact of the re-entry. And FCC did perform a review of the petition and considered environmental concerns raised, so an environmental review is indeed performed, and FCC's conclusion regarding satellite reentry is that:

Based on the record, we are not convinced that reentering SpaceX Gen2 Starlink satellites may have a significant environmental impact necessitating an EA. As SpaceX states, the European Space Agency (ESA) initiated two studies, looking into specifically the atmospheric impact of spacecraft demise upon reentry and concluding that the impact was negligible compared to other anthropogenic activities.451

Ah, that's good info there, thanks. Sounds like the process I was hoping for already exists, and was already followed.

[RedLineTrain]

It is probably a non-issue, but let's have the operators prove that it is,

I don't think any of our environmental laws are based on the precautionary principle.  If they were, nothing would get done or built.

Straying off topic and into politics here, but maybe environmental laws could stand being a little more precautionary. 

I'd personally like to see all (public) businesses be required to publicly report the environmental impact of their operations and products, the same way they have to report their finances, so for me the impact of deorbiting satellites is just one aspect of that.

SpaceX is not a public business.

[meekGee]

This entire notion started circulating the web a couple years ago. It's akin to "Electric cars are dirty since they actually burn coal" - an obviously preposterous proposition that is just put out there to see if it will stick.

The basic numbers don't hold up even on first scrutiny, and in this case I'm glad they got debunked quickly and clearly.

Sadly, give it another year, and there will be a new one.

[TheRadicalModerate]

The basic numbers don't hold up even on first scrutiny, and in this case I'm glad they got debunked quickly and clearly.

Please provide said numbers that don't hold up to scrutiny.

[meekGee]

The basic numbers don't hold up even on first scrutiny, and in this case I'm glad they got debunked quickly and clearly.

Please provide said numbers that don't hold up to scrutiny.

How do you even start to compare 1000 tons per year, most of which is battery and structure and solar panels, and is largely vaporized in the upper atmosphere and over oceans, to the impact of global industrial pollution?  It's orders of magnitude off....

And how come nobody thought of this before SpaceX?  Starlink may equal all of the other satellites combined, but that's still ballpark the same thing....

Which is what ESA found out:

Based on the record, we are not convinced that reentering SpaceX Gen2 Starlink satellites may have a significant environmental impact necessitating an EA. As SpaceX states, the European Space Agency (ESA) initiated two studies, looking into specifically the atmospheric impact of spacecraft demise upon reentry and concluding that the impact was negligible compared to other anthropogenic activities.

I think the burden is on whoever initiated or is propagating these concerns to actually show a number.

What material is of concern? How much do they think is being dumped?  How does it compare to other sources?

If they don't, then what they're doing is just starting a rumor and demanding that the target of the rumor prove that it's wrong.  It's called FUD.

[Robotbeat]

The basic numbers don't hold up even on first scrutiny, and in this case I'm glad they got debunked quickly and clearly.

Please provide said numbers that don't hold up to scrutiny.

The "numbers" (it's not even numbers, just assertions) that claim this is a significant environmental problem. (FCC/SpaceX show they aren't by referencing a European study, see up-thread: https://forum.nasaspaceflight.com/index.php?topic=55599.msg2444437#msg2444437.)

As far as EVs, just about any modern study that isn't essentially funded by fossil fuel interests (or traditional automakers) shows that even with presumably increased manufacturing emissions, the per-mile of emissions of EVs in a place like the US is less than half of conventional cars (less than a third if you don't count manufacturing emissions).
https://www.epa.gov/greenvehicles/electric-vehicle-myths#Myth2

[TheRadicalModerate]

How do you even start to compare 1000 tons per year, most of which is battery and structure and solar panels, and is largely vaporized in the upper atmosphere and over oceans, to the impact of global industrial pollution?  It's orders of magnitude off....

This has nothing to do with terrestrial pollution.  It has to do with ozone depleting substances.  Alumina is a catalyst that's good at cleaving chlorine ions off of chlorine reservoir compounds, mostly chlorine nitrates and hydrochloric acid.  Chlorine ions are themselves a catalyst for destroying ozone, with one chlorine ion cycling over and over between Cl^- and ClO^- forms.  Wikipedia says one Cl atom is good for converting 100,000 ozone molecules to O₂, before it's bonded back into one of the reservoir compounds.

And how come nobody thought of this before SpaceX?  Starlink may equal all of the other satellites combined, but that's still ballpark the same thing....

The non-paranoid, non-conspiracy-theory explanation is simply that nobody imagined constellations of 30,000 satellites in orbits that could decay in 5 years.  When they could imagine them, they started thinking about the implications.

Which is what ESA found out:

Based on the record, we are not convinced that reentering SpaceX Gen2 Starlink satellites may have a significant environmental impact necessitating an EA. As SpaceX states, the European Space Agency (ESA) initiated two studies, looking into specifically the atmospheric impact of spacecraft demise upon reentry and concluding that the impact was negligible compared to other anthropogenic activities.

I think the burden is on whoever initiated or is propagating these concerns to actually show a number.

On this, we agree.  There is no consensus, let alone proof, that this is actually a problem, which is exactly why the regulators left it alone.  They were right to do so.

But that's not the same as denying the existence of a problem.  The gap between those two states is an indication that research is required.

If they don't, then what they're doing is just starting a rumor and demanding that the target of the rumor prove that it's wrong.  It's called FUD.

They certainly aren't demanding that SpaceX and other megaconstellation operators prove them wrong.  Seems to me that they'd like for people to think about the problem.

I have no idea if the authors of the paper have a political axe to grind--and neither do you.  But that doesn't really matter if the problem they've surfaced has a substantial enough analysis behind it to warrant additional research.

I'm far from an expert on atmospheric chemistry, but I can do order-of-magnitude estimates as well as the next person, and to me it looks like the amount of alumina injected into the stratosphere by a Starlink-scale constellation is a substantial chunk of the natural injection of the same compound via meteors and cosmic dust.  I encourage you to do your own estimates, instead of just waving your arms around.

Seems to me that you're advocating for a specific scientific investigation not to be done, simply because you don't like the implications.  I don't like the implications either, but I'm still willing to let the scientific method take its course.  You should be, too.

[Robotbeat]

There’s a point where we can start talking about recovering the hardware or upgrading it in situ instead of just burning it up. But we’re not near that point. To imply otherwise right now, without hard data, just vague concerns without numbers and ignoring FCC/ESA studies, is concern-trolling. Bring actual data so concerns can be examined in a falsifiable way.

Shuttle launched up to 9 times per year, burning 1000 tons of aluminum-heavy SRB propellant each time. That’s much greater mass than the Starlink satellites per year that have been approved.

[steveleach]

There’s a point where we can start talking about recovering the hardware or upgrading it in situ instead of just burning it up. But we’re not near that point. To imply otherwise right now, without hard data, just vague concerns without numbers and ignoring FCC/ESA studies, is concern-trolling. Bring actual data so concerns can be examined in a falsifiable way.

Shuttle launched up to 9 times per year, burning 1000 tons of aluminum-heavy SRB propellant each time. That’s much greater mass than the Starlink satellites per year that have been approved.

The fact that someone else is/was polluting more than you doesn't absolve you from responsibility. And as a species we've made enough mistakes that we should know by now to stop these things before they become a problem.

I can't speak for TheRadicalModerate, but my own concerns here are generic, rather than specific to Starlink, in case anyone thinks this is me hating on SpaceX. Anyone who launches something into orbit should, imho, should be required to assess the impact of it being in orbit, and the impact of it burning up in the atmosphere (if that is what will happen to it at the end of its life).

To me it sounds like SpaceX have already done that, at least to the FCC's satisfaction, with Starlink.

And let's dispense with the "concern trolling" allegations please.

[Robotbeat]

Yes. The question has already been answered by the FCC, and additional concerns brought up should be quantitative, not vague.

[DanClemmensen]

The fact that someone else is/was polluting more than you doesn't absolve you from responsibility. And as a species we've made enough mistakes that we should know by now to stop these things before they become a problem.

I can't speak for TheRadicalModerate, but my own concerns here are generic, rather than specific to Starlink, in case anyone thinks this is me hating on SpaceX. Anyone who launches something into orbit should, imho, should be required to assess the impact of it being in orbit, and the impact of it burning up in the atmosphere (if that is what will happen to it at the end of its life).

A big problem with generic environmental reviews is they assume that the status quo is acceptable. This ignores any potential benefit the project has for the environment. For example, a satellite constellation might reduce the need to install fiber, and the total environmental cost of the fiber network install may be high.

The extreme example of this is ignoring climate change when delaying the use of nuclear power generation, starting in about 1970. Yes, almost every environmental and safety objection to nuclear power is valid, but climate change is likely to be far worse. Today, renewables are a better choice, but we now have a 50-year accumulation of CO₂ to deal with.

[Barley]

Shuttle launched up to 9 times per year, burning 1000 tons of aluminum-heavy SRB propellant each time. That’s much greater mass than the Starlink satellites per year that have been approved.

Addressing just a narrow issue.

Does it matter how high the alumina is released?  I'd guess that lower down it rains out quickly and you'd have to inject it higher in the stratosphere to have much effect on the ozone layer.   Eyeballing the booster thrust curves over half the burn is before max-Q at 11km and more than 3/4 below 16km, perhaps much more that 3/4 it's not a well calibrated eyeball.

In contrast everything injected from above will eventually reach the ozone layer.

[TheRadicalModerate]

I can't speak for TheRadicalModerate, but my own concerns here are generic, rather than specific to Starlink, in case anyone thinks this is me hating on SpaceX. Anyone who launches something into orbit should, imho, should be required to assess the impact of it being in orbit, and the impact of it burning up in the atmosphere (if that is what will happen to it at the end of its life).

To me it sounds like SpaceX have already done that, at least to the FCC's satisfaction, with Starlink.

My concern is specific to what the scientific community is hypothesizing, i.e., that certain types of rocket debris and exhaust are ozone-depleting substances.  At this point, that hypothesis is yet to be disproved, and there is some evidence that it may be correct.  Apparently, neither the FCC nor ESA thinks that there's enough evidence to take regulatory action at this time.  That sounds like a correct assessment.

Note that the amount of time from when Rowland and Molina came up with the CFC hypothesis, which was immediately dismissed as crackpottery, both by large swathes of the scientific in general and by the CFC manufacturers in great detail, to when the Montreal Protocol was ratified, was about 13 years.  That's the blink of an eye in diplomatic terms.  So I'd expect that if any experimental evidence comes to light  that shows a steep ozone depletion curve, either as a result of alumina reentry debris or from SRBs spewing out not only alumina but also a wide variety of chlorinated chemicals and nitrous oxide, international action will be swift.

Again, there's little evidence to back up the debris hypothesis at this time, and regulation is unlikely until evidence exists--if it ever does.  But this bears watching.

[TheRadicalModerate]

Shuttle launched up to 9 times per year, burning 1000 tons of aluminum-heavy SRB propellant each time. That’s much greater mass than the Starlink satellites per year that have been approved.

Addressing just a narrow issue.

Does it matter how high the alumina is released?  I'd guess that lower down it rains out quickly and you'd have to inject it higher in the stratosphere to have much effect on the ozone layer.   Eyeballing the booster thrust curves over half the burn is before max-Q at 11km and more than 3/4 below 16km, perhaps much more that 3/4 it's not a well calibrated eyeball.

In contrast everything injected from above will eventually reach the ozone layer.

Alumina particles from SRBs are pretty big, which does help them precipitate out fairly quickly.  Alumina from meteoroids and dust are extremely small, which makes them more effective aerosols, with high surface/volume ratios.  But I don't think we have a huge amount of data about the distribution of particle sizes that come from an orbital reentry.

My guess is that the lower speed of entry (as opposed to interplanetary entry speeds for meteoroids) implies bigger droplets of alumina, which would reduce the area/volume ratio and also precipitate out quicker.  So there are lots of unknowns that need to be carefully characterized before anybody gets their knickers in a twist about this.

[Robotbeat]

Still waiting for these concern arguments to either link to studies or provide falsifiable, quantifiable (ie number-containing) statements.

…rather than handwaving and rhetoric.

[TheRadicalModerate]

Still waiting for these concern arguments to either link to studies or provide falsifiable, quantifiable (ie number-containing) statements.

…rather than handwaving and rhetoric.

The paper that's been reported on in SpaceNews and other outlets is behind a paywall, but here's the link if you want to spend $32 on it.

In addition I linked a PhD dissertation on alumina catalysts up-thread.  This paper is oriented more around making Space Shuttle ozone depletion models more accurate, and comes to the conclusion that the alumina is a significant activator of ODSes, and needs to be included in the modeling--as does what little I can read of the Shutler paper.

The only numbers I'm fooling with are the ones comparing aluminum entering the atmosphere from orbital debris with the natural rate of aluminum from meteoroids/cosmic dust, and noting that, if Starlink really winds up with 30,000 birds, then the reentry aluminum mass is likely at least as large as the natural mass.  Contrary to what you're insinuating here, those numbers are up-thread.

My position is that this doesn't require regulation right now, and may never require regulation, but that we ought to be really sure that we haven't created yet another significant ozone depletion pathway.  If you'd like to characterize that as concern-trolling, go right ahead.

[Robotbeat]

Thanks, that’s exactly what I wanted.

[meekGee]

Still waiting for these concern arguments to either link to studies or provide falsifiable, quantifiable (ie number-containing) statements.

…rather than handwaving and rhetoric.

The paper that's been reported on in SpaceNews and other outlets is behind a paywall, but here's the link if you want to spend $32 on it.

In addition I linked a PhD dissertation on alumina catalysts up-thread.  This paper is oriented more around making Space Shuttle ozone depletion models more accurate, and comes to the conclusion that the alumina is a significant activator of ODSes, and needs to be included in the modeling--as does what little I can read of the Shutler paper.

The only numbers I'm fooling with are the ones comparing aluminum entering the atmosphere from orbital debris with the natural rate of aluminum from meteoroids/cosmic dust, and noting that, if Starlink really winds up with 30,000 birds, then the reentry aluminum mass is likely at least as large as the natural mass.  Contrary to what you're insinuating here, those numbers are up-thread.

My position is that this doesn't require regulation right now, and may never require regulation, but that we ought to be really sure that we haven't created yet another significant ozone depletion pathway.  If you'd like to characterize that as concern-trolling, go right ahead.

Yup interestingly 30,000 satellite, 3 year life span, and 2 tons per satellite, you arrive at about 50 tons/day which is the same as the estimated meteor mass input.  Coincidence?  I smell a rat.  Clearly Musk wants to replace meteors.

However, my "orders of magnitude" comment was about industry and volcanoes (millions or billions of tons) compared with the aforementioned 20,000 tons.  Sure they're emitted at lower altitudes, but so were CFCs and we know how that went.

And I'd mention the Space Shuttle not because it created more pollution, but because the same characters that propagate the "Starlink Pollution" meme were not concerned one bit about Shuttle pollution.  Just like "Electric cars use Coal" and "immensely complex and high risk", you sometimes just need to look where the memes are coming from.

[TheRadicalModerate]

Still waiting for these concern arguments to either link to studies or provide falsifiable, quantifiable (ie number-containing) statements.

…rather than handwaving and rhetoric.

The paper that's been reported on in SpaceNews and other outlets is behind a paywall, but here's the link if you want to spend $32 on it.

In addition I linked a PhD dissertation on alumina catalysts up-thread.  This paper is oriented more around making Space Shuttle ozone depletion models more accurate, and comes to the conclusion that the alumina is a significant activator of ODSes, and needs to be included in the modeling--as does what little I can read of the Shutler paper.

The only numbers I'm fooling with are the ones comparing aluminum entering the atmosphere from orbital debris with the natural rate of aluminum from meteoroids/cosmic dust, and noting that, if Starlink really winds up with 30,000 birds, then the reentry aluminum mass is likely at least as large as the natural mass.  Contrary to what you're insinuating here, those numbers are up-thread.

My position is that this doesn't require regulation right now, and may never require regulation, but that we ought to be really sure that we haven't created yet another significant ozone depletion pathway.  If you'd like to characterize that as concern-trolling, go right ahead.

Yup interestingly 30,000 satellite, 3 year life span, and 2 tons per satellite, you arrive at about 50 tons/day which is the same as the estimated meteor mass input.  Coincidence?  I smell a rat.  Clearly Musk wants to replace meteors.

30,000 birds, 5 year lifetime.  33t/day.  Pick some percentage that you think will be aluminum.  25%?  1500t/year.

The Spencer dissertation used 1.6E4t of meteoroid dust, and didn't distinguish between silicates, Fe, Ni, Al, Mg, and Ti oxides.¹  That would make the new stuff a 9.4% increase.  If you do an apples-to-apples comparison with just Al, which is, according to another reference, 1.4% of the meteoroid mass,  the Starlink aluminum would be 670% more.

However, my "orders of magnitude" comment was about industry and volcanoes (millions or billions of tons) compared with the aforementioned 20,000 tons.  Sure they're emitted at lower altitudes, but so were CFCs and we know how that went.

So your argument is that, because we emitted lots of CFCs and then took action to drastically reduce their emission, that we shouldn't worry about adding new sources that can enhance the conversion of chlorine from its reservoirs?

And yes, there are natural sources of ozone depleting substances.  But those natural sources are why the ozone layer has roughly the concentration that it has.  The question is whether we're going to add substances that force it away from that equilibrium.

And I'd mention the Space Shuttle not because it created more pollution, but because the same characters that propagate the "Starlink Pollution" meme were not concerned one bit about Shuttle pollution.  Just like "Electric cars use Coal" and "immensely complex and high risk", you sometimes just need to look where the memes are coming from.

The "same characters" did a fair amount of work looking a Space Shuttle SRBs and concluded that the effect was significant but nothing like the effects of CFCs.  I suspect that this will be the ultimate answer to the orbital debris question.  But at this point, we don't know. 

Are your suspicions that some secret cabal of scientists is out to get us so great that you'd actively suppress their work?  And if you're not that paranoid, then isn't this just a perfectly legitimate piece of atmospheric science that you can expect to turn out to be nothing?

__________________
¹Spencer also asserts that there are other substrates beside alumina that can catalyze free chlorine production, which I assume is his rationale for comparing things to all meteoroid dust, not just the aluminum in the dust.  However, he only measured the reactivity of alumina and silicate glasses.

[Robotbeat]

I honestly don’t think the exact metal oxide chosen necessarily makes a huge difference. All would likely have similar catalytic effects (or not).

[TheRadicalModerate]

I honestly don’t think the exact metal oxide chosen necessarily makes a huge difference. All would likely have similar catalytic effects (or not).

If I'm reading the dissertation right, the issue is that HCl adsorbs quite readily to certain substrates but not others, and the presence of HCl, when bound to the substrates, allowed chlorine to cleave off of chlorine nitrates.  They tested alumina, sliica-based glasses, and then used teflon and sulfuric acid droplets as controls.  Alumina and glass had roughly the same reactivity, so it's not a terrible assumption that other oxide-based substrates might as well.  But this vastly exceeds my meager chemistry knowledge.

A 9% reactivity increase would obviously be much more benign than a 670% increase.  If this becomes a hot topic, I'd expect that there are plenty of grad students who can characterize this much more precisely.

Remember, small changes in free chlorine concentrations cause large changes in ozone depletion.  Knowing that number is fairly important.

[Robotbeat]

Just saying that if you're comparing meteorites to Starlink and you cherrypick alumina for no particular reason except that it artificially amplifies the comparison by an order of magnitude… …that is not exactly a neutral decision.

[TheRadicalModerate]

Just saying that if you're comparing meteorites to Starlink and you cherrypick alumina for no particular reason except that it artificially amplifies the comparison by an order of magnitude… …that is not exactly a neutral decision.

I'm cherrypicking alumina because that's what the research is cherrypicking.  Now, there's a reason for that:  a lot of the research was into SRB pollution.  I'd expect similar measurements for all of the other likely metallic oxides to be coming soon.  If it turns out that the same chemistry occurs with most metallic oxides, then it's likely a non-problem.  But if not, then we need to keep an eye on this.

[Robotbeat]

Except the most likely result is the effects of metal oxides are similar. The opposite assumption, that other metal oxides have negligible effect, is exceedingly unlikely, and yet that’s the one you implicitly chose… yeah, this is cherrypicking.

[Robotbeat]

Current Gen Starlink has a lifetime of around 5-7 years. If we assume the larger satellites last a little longer, say 10 years, then that puts the amount of alumina generated per year for the full 30,000 constellation as similar to Shuttle’s peak year of 1985, including the LWT burned up mass. (Not counting shuttle’s payloads burning up.)

That’s assuming SpaceX doesn’t implement servicing or active capture.

[meekGee]

Still waiting for these concern arguments to either link to studies or provide falsifiable, quantifiable (ie number-containing) statements.

…rather than handwaving and rhetoric.

The paper that's been reported on in SpaceNews and other outlets is behind a paywall, but here's the link if you want to spend $32 on it.

In addition I linked a PhD dissertation on alumina catalysts up-thread.  This paper is oriented more around making Space Shuttle ozone depletion models more accurate, and comes to the conclusion that the alumina is a significant activator of ODSes, and needs to be included in the modeling--as does what little I can read of the Shutler paper.

The only numbers I'm fooling with are the ones comparing aluminum entering the atmosphere from orbital debris with the natural rate of aluminum from meteoroids/cosmic dust, and noting that, if Starlink really winds up with 30,000 birds, then the reentry aluminum mass is likely at least as large as the natural mass.  Contrary to what you're insinuating here, those numbers are up-thread.

My position is that this doesn't require regulation right now, and may never require regulation, but that we ought to be really sure that we haven't created yet another significant ozone depletion pathway.  If you'd like to characterize that as concern-trolling, go right ahead.

Yup interestingly 30,000 satellite, 3 year life span, and 2 tons per satellite, you arrive at about 50 tons/day which is the same as the estimated meteor mass input.  Coincidence?  I smell a rat.  Clearly Musk wants to replace meteors.

30,000 birds, 5 year lifetime.  33t/day.  Pick some percentage that you think will be aluminum.  25%?  1500t/year.

The Spencer dissertation used 1.6E4t of meteoroid dust, and didn't distinguish between silicates, Fe, Ni, Al, Mg, and Ti oxides.¹  That would make the new stuff a 9.4% increase.  If you do an apples-to-apples comparison with just Al, which is, according to another reference, 1.4% of the meteoroid mass,  the Starlink aluminum would be 670% more.

However, my "orders of magnitude" comment was about industry and volcanoes (millions or billions of tons) compared with the aforementioned 20,000 tons.  Sure they're emitted at lower altitudes, but so were CFCs and we know how that went.

So your argument is that, because we emitted lots of CFCs and then took action to drastically reduce their emission, that we shouldn't worry about adding new sources that can enhance the conversion of chlorine from its reservoirs?

And yes, there are natural sources of ozone depleting substances.  But those natural sources are why the ozone layer has roughly the concentration that it has.  The question is whether we're going to add substances that force it away from that equilibrium.

And I'd mention the Space Shuttle not because it created more pollution, but because the same characters that propagate the "Starlink Pollution" meme were not concerned one bit about Shuttle pollution.  Just like "Electric cars use Coal" and "immensely complex and high risk", you sometimes just need to look where the memes are coming from.

The "same characters" did a fair amount of work looking a Space Shuttle SRBs and concluded that the effect was significant but nothing like the effects of CFCs.  I suspect that this will be the ultimate answer to the orbital debris question.  But at this point, we don't know. 

Are your suspicions that some secret cabal of scientists is out to get us so great that you'd actively suppress their work?  And if you're not that paranoid, then isn't this just a perfectly legitimate piece of atmospheric science that you can expect to turn out to be nothing?

__________________
¹Spencer also asserts that there are other substrates beside alumina that can catalyze free chlorine production, which I assume is his rationale for comparing things to all meteoroid dust, not just the aluminum in the dust.  However, he only measured the reactivity of alumina and silicate glasses.

Nope, that was not my argument at all...

I said industrial sources of Alumina and other contaminants are many orders of magnitude higher, and you can't wave that off as "itst only low altitude pollution" because for example CFCs did a lot of damage from that low altitude.

As for numbers  30,000 sats are mostly VLEO, so 3 years.  10,000 reentries per year  times 2 tons, divided by 365, gets you 55 tons of stuff per day.

Some fraction of which is Alumina

[TheRadicalModerate]

Nope, that was not my argument at all...

I said industrial sources of Alumina and other contaminants are many orders of magnitude higher, and you can't wave that off as "itst only low altitude pollution" because for example CFCs did a lot of damage from that low altitude.

As for numbers  30,000 sats are mostly VLEO, so 3 years.  10,000 reentries per year  times 2 tons, divided by 365, gets you 55 tons of stuff per day.

Some fraction of which is Alumina

[Edit:  Most] CFC's are gases at STP, and don't condense as they get higher in the atmosphere.  They're not water-soluble, and they can't nucleate water droplets.  So as winds loft them through the troposphere, there are very few mechanisms to remove them.  And once they reach the stratosphere, they photo-dissociate into free chlorine, which is what causes all the problems.

Alumina is a particulate.  It will nucleate water droplets, which precipitate the particles back to the ground.

Alumina from space will also eventually fall through the topopause and get carried down to Earth by water.  But it's falling through the stratosphere from the top, where it persists as an aerosol for quite awhile.

This is another area where I'd like to know the size distribution of various alumina particles.  I would expect industrial alumina to be fairly coarse-grained.  I would expect meteoroid alumina to be fine-grained.  And I'd expect orbital debris to be somewhere in between.  The size of the particles will be critically important in estimating the lifetime in the stratosphere, and therefore how many chlorine-freeing reactions they can enable.

BTW:  CFCs don't do damage at low altitude.  They have to be lofted into the stratosphere before the mischief starts.  But that's a pure atmospheric mixing problem.  The tropopause isn't a hard boundary.

[meekGee]

Nope, that was not my argument at all...

I said industrial sources of Alumina and other contaminants are many orders of magnitude higher, and you can't wave that off as "itst only low altitude pollution" because for example CFCs did a lot of damage from that low altitude.

As for numbers  30,000 sats are mostly VLEO, so 3 years.  10,000 reentries per year  times 2 tons, divided by 365, gets you 55 tons of stuff per day.

Some fraction of which is Alumina

[Edit:  Most] CFC's are gases at STP, and don't condense as they get higher in the atmosphere.  They're not water-soluble, and they can't nucleate water droplets.  So as winds loft them through the troposphere, there are very few mechanisms to remove them.  And once they reach the stratosphere, they photo-dissociate into free chlorine, which is what causes all the problems.

Alumina is a particulate.  It will nucleate water droplets, which precipitate the particles back to the ground.

Alumina from space will also eventually fall through the topopause and get carried down to Earth by water.  But it's falling through the stratosphere from the top, where it persists as an aerosol for quite awhile.

This is another area where I'd like to know the size distribution of various alumina particles.  I would expect industrial alumina to be fairly coarse-grained.  I would expect meteoroid alumina to be fine-grained.  And I'd expect orbital debris to be somewhere in between.  The size of the particles will be critically important in estimating the lifetime in the stratosphere, and therefore how many chlorine-freeing reactions they can enable.

BTW:  CFCs don't do damage at low altitude.  They have to be lofted into the stratosphere before the mischief starts.  But that's a pure atmospheric mixing problem.  The tropopause isn't a hard boundary.

This exchange shows how impossible it is to argue against vague assertions.

You're saying:  Starlink satellites can harm the ozone via production of Alumina particles.

I'm saying:  There's 50 tons per day (under worst case assumption), some fraction of which is Aluminum, some fraction of which becomes Alumina, some of which may linger in the upper atmosphere.  That's all we know. There's nothing else I can directly counter, except provide context.

For example, other pollution mechanisms that are vastly larger.  Except for each one, you'll find differences, and the conversation now shifts to whether I've proven beyond a shadow of a doubt that your assertion is wrong.  Which I can't, since it's too vague.

So I give up.

Apparently other agencies looked at this and arrived at the same conclusion I did, for pretty much the same reasons.

You can argue with them.

I'm going to go party today as if I still have a job

[LouScheffer]

This could be studied, if required.  Build a test satellite enriched in ²⁶Al, an aluminum isotope uncommon in nature.  Have it re-enter at a known time and place, then sample the upper-atmosphere plume using NASA's U2s, weather balloons, and sounding rockets.  From these samples, deduce the size distribution of the aluminum (and other) particles, and what fraction of the particles come from the satellite.  From this the impact of the satellite entry on the ozone layer can be estimated.

[novo2044]

This could be studied, if required.  Build a test satellite enriched in ²⁶Al, an aluminum isotope uncommon in nature.  Have it re-enter at a known time and place, then sample the upper-atmosphere plume using NASA's U2s, weather balloons, and sounding rockets.  From these samples, deduce the size distribution of the aluminum (and other) particles, and what fraction of the particles come from the satellite.  From this the impact of the satellite entry on the ozone layer can be estimated.

Well the missing element is to what extent do such alumina particles actually degrade the ozone layer?  There's some literature here but it mostly seems to be studying the alumina that's ejected by SRB's, which is tricky because the same boosters also apparently release Hcl at the same time.  That said, what little I could glean suggests attempts at observing any measurable change in the ozone layer caused by boosters ejecting a nontrivial amount of alumina and chlorine at high altitudes found little or no observable effect.  Most of these studies seemed quite old, perhaps with modern imaging more subtle effects might be detectable.

[whitelancer64]

Full PDF (80 pages) attached:

Large Constellations of Satellites:
Mitigating Environmental and Other Effects

GAO-22-105166
Published: Sep 29, 2022. Publicly Released: Sep 29, 2022.

https://www.gao.gov/products/gao-22-105166

"Enabled by declines in the costs of satellites and rocket launches, commercial enterprises are deploying large constellations of satellites into low Earth orbit. Satellites provide important data and services, such as communications, internet access, Earth observation, and technologies like GPS that provide positioning, navigation, and timing. However, the launch, operation, and disposal of an increasing number of satellites could cause or increase several potential effects.

This report discusses (1) the potential environmental or other effects of large constellations of satellites; (2) the current or emerging technologies and approaches to evaluate or mitigate these effects, along with challenges to developing or implementing these technologies and approaches; and (3) policy options that might help address these challenges.

To conduct this technology assessment, GAO reviewed technical studies, agency documents, and other key reports; interviewed government officials, industry representatives, and researchers; and convened a 2-day meeting of 15 experts from government, industry, academia, and a federally funded research and development center. GAO is identifying policy options in this report."