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.