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> SpaceX is deorbiting about one or two satellites daily, and that number is only going to grow. > What that means for our planet isn't entirely clear 100 ton

> SpaceX is deorbiting about one or two satellites daily, and that number is only going to grow. > What that means for our planet isn't entirely clear 100 tons of meteors hit Earth every day[1], so it seems fairly clear the 800kg Starlink v2 mini satellites[2] don't amount to much. Maybe once a dozen providers are deorbiting a similar amount of mass daily, we might notice. But even then I'm not sure there would be any negative effects. This seems like clickbait scare mongering at the moment. 1: https://pressbooks.online.ucf.edu/astronomybc/chapter/14-1-meteors/ https://pressbooks.online.ucf.edu/astronomybc/chapter/14-1-m... 2: https://dishycentral.com/how-big-are-starlink-satellites https://dishycentral.com/how-big-are-starlink-satellites

goopypoop 1y ago
> The typical meteor is produced by a particle with a mass of less than 1 gram—no larger than a pea > The total mass of meteoric material entering Earth’s atmosphere is estimated to be about 100 tons per day
- timschmidt 1y ago
  ... yes? Does the mass of individual meteors or satellites matter if they both burn up on [re]entry? On average, something like 17 meteors large enough to strike the ground hit earth daily.
thayne 1y ago
The composition is different though. In particular, these satellites probably have more heavy elements for things like batteries and electronics
- andsoitis 1y ago
  Meteors contain various heavy metals, primarily iron and nickel, which form metallic cores of asteroids and make up the bulk of many meteorites. They also contain other siderophilic metals, including cobalt, chromium, gold, platinum, iridium, and tungsten. The high concentration of these metals, especially precious metals like gold and platinum, is due to their affinity for sinking to the core of early planets and asteroids, which are remnants of the primordial solar system.
  - timschmidt 1y ago
    Further, satellites like Starlink's are engineered to burn up on re-entry. Meaning that they are manufactured of materials known to combust at re-entry velocities in thicknesses and shapes appropriate to that end.
- eesmith 1y ago
  One key difference is the satellites have a lot of aluminum - a light element - while meteors do not. Estimates I've seen are that the amount of Al in the upper atmosphere will be dominated by satellite demise. And we don't know how that will affect things. The history of CFC and the ozone layer suggests caution.
fumblertzu 1y ago
but those 100 tons do not contain that much aluminum. I remember a story where the aluminum aerosols may have a strong effect https://cires.colorado.edu/news/within-15-years-plummeting-satellites-could-release-enough-aluminum-alter-winds-temp https://cires.colorado.edu/news/within-15-years-plummeting-s...
- timschmidt 1y ago
  At least 1.4% of Earth is aluminum. Meteors will have similar composition on average. Aluminum smelting likely vaporizes a much larger volume of material.
  - eesmith 1y ago
    That aluminum is not in the upper atmosphere. Quoting https://www.nature.com/articles/s41598-021-89909-7.pdf https://www.nature.com/articles/s41598-021-89909-7.pdf > ... the satellites are mostly aluminum; most meteoroids, in contrast, contain less than 1% Al by mass 25 . Thus, depending on the atmospheric residence time of material from reentered satellites, each mega-constellation will produce fine particulates that could greatly exceed natural forms of high-altitude atmospheric aluminum deposition, particularly if the full numbers of envisaged satellites are launched. Anthropogenic deposition of aluminum in the atmosphere has long been proposed in the context of geoengineering as a way to alter Earth’s albedo 26 . These proposals have been scientifically controversial and controlled experiments encountered substantial opposition 27 . Mega-constellations will begin this process as an uncontrolled experiment 28 . Or from https://www.science.org/doi/pdf/10.1126/science.adr9689 https://www.science.org/doi/pdf/10.1126/science.adr9689 > Concerns are mostly focused on aluminum, the most common component in satellites. If the disintegrated metal ends up as aluminum oxide or hydroxide, it can react with hydrogen chloride — the main reservoir of chlorine in the stratosphere, a hangover from the days of chlorofluorocarbons — to produce aluminum chloride. Hydrogen chloride is a relatively safe repository for chlorine, but aluminum chloride is easily split apart by light, freeing the chlorine to destroy ozone. Metal aerosols could also seed the creation of more polar stratospheric clouds, which catalyze reactions that liberate destructive forms of chlorine. “One can speculate, but without critical laboratory measurements of the chemistry, it’s very hard to know [the effects],” says John Plane, an atmospheric chemist at the University of Leeds. ... “You have to wonder whether [SpaceX] is creating a major problem 30 years from now,” Lionnet says.
SeanAnderson 1y ago
I had no idea 100 tons of external material was entering our atmosphere each day. Fascinating.
- timschmidt 1y ago
  An additional tidbit: this is not enough mass to offset the amount of helium and hydrogen which escapes Earth's atmosphere daily. Earth is on net losing mass. Eventually, Earth will lose all the hydrogen locked in it's oceans via this process. Not sure if that's destined to happen before or after we're engulfed by the expanding sun though.
  - khuey 1y ago
    At the current rate of loss Earth has 150 billion years worth of hydrogen.
    - rkomorn 1y ago
      Well that's bad news for all the infrastructure projects in my current city and country. They're gonna run out of hydrogen before our subway extension is finished.
deleted 1y ago
[deleted]
throwup238 1y ago
It’s closer to 43+-14 tons and most of that is cosmic dust [1] and most of that is under a millimeter in size [2]. [1] https://en.wikipedia.org/wiki/Cosmic_dust https://en.wikipedia.org/wiki/Cosmic_dust [2] https://www.sciencedirect.com/science/article/pii/S0012821X21000534 https://www.sciencedirect.com/science/article/pii/S0012821X2...
mrtksn 1y ago
I think probably means SpaceX will need to keep sending rockets at rate of 1 or 2 satellites per day to replenish the infra. How much impact sending 800kg satellite into low orbit has? (in batches, obviously)

goopypoop 1y ago

> The typical meteor is produced by a particle with a mass of less than 1 gram—no larger than a pea > The total mass of meteoric material entering Earth’s atmosphere is estimated to be about 100 tons per day

timschmidt 1y ago
... yes? Does the mass of individual meteors or satellites matter if they both burn up on [re]entry? On average, something like 17 meteors large enough to strike the ground hit earth daily.

thayne 1y ago

The composition is different though. In particular, these satellites probably have more heavy elements for things like batteries and electronics

andsoitis 1y ago
Meteors contain various heavy metals, primarily iron and nickel, which form metallic cores of asteroids and make up the bulk of many meteorites. They also contain other siderophilic metals, including cobalt, chromium, gold, platinum, iridium, and tungsten. The high concentration of these metals, especially precious metals like gold and platinum, is due to their affinity for sinking to the core of early planets and asteroids, which are remnants of the primordial solar system.
- timschmidt 1y ago
  Further, satellites like Starlink's are engineered to burn up on re-entry. Meaning that they are manufactured of materials known to combust at re-entry velocities in thicknesses and shapes appropriate to that end.
eesmith 1y ago
One key difference is the satellites have a lot of aluminum - a light element - while meteors do not. Estimates I've seen are that the amount of Al in the upper atmosphere will be dominated by satellite demise. And we don't know how that will affect things. The history of CFC and the ozone layer suggests caution.

fumblertzu 1y ago

but those 100 tons do not contain that much aluminum. I remember a story where the aluminum aerosols may have a strong effect https://cires.colorado.edu/news/within-15-years-plummeting-satellites-could-release-enough-aluminum-alter-winds-temp https://cires.colorado.edu/news/within-15-years-plummeting-s...

timschmidt 1y ago
At least 1.4% of Earth is aluminum. Meteors will have similar composition on average. Aluminum smelting likely vaporizes a much larger volume of material.
- eesmith 1y ago
  That aluminum is not in the upper atmosphere. Quoting https://www.nature.com/articles/s41598-021-89909-7.pdf https://www.nature.com/articles/s41598-021-89909-7.pdf > ... the satellites are mostly aluminum; most meteoroids, in contrast, contain less than 1% Al by mass 25 . Thus, depending on the atmospheric residence time of material from reentered satellites, each mega-constellation will produce fine particulates that could greatly exceed natural forms of high-altitude atmospheric aluminum deposition, particularly if the full numbers of envisaged satellites are launched. Anthropogenic deposition of aluminum in the atmosphere has long been proposed in the context of geoengineering as a way to alter Earth’s albedo 26 . These proposals have been scientifically controversial and controlled experiments encountered substantial opposition 27 . Mega-constellations will begin this process as an uncontrolled experiment 28 . Or from https://www.science.org/doi/pdf/10.1126/science.adr9689 https://www.science.org/doi/pdf/10.1126/science.adr9689 > Concerns are mostly focused on aluminum, the most common component in satellites. If the disintegrated metal ends up as aluminum oxide or hydroxide, it can react with hydrogen chloride — the main reservoir of chlorine in the stratosphere, a hangover from the days of chlorofluorocarbons — to produce aluminum chloride. Hydrogen chloride is a relatively safe repository for chlorine, but aluminum chloride is easily split apart by light, freeing the chlorine to destroy ozone. Metal aerosols could also seed the creation of more polar stratospheric clouds, which catalyze reactions that liberate destructive forms of chlorine. “One can speculate, but without critical laboratory measurements of the chemistry, it’s very hard to know [the effects],” says John Plane, an atmospheric chemist at the University of Leeds. ... “You have to wonder whether [SpaceX] is creating a major problem 30 years from now,” Lionnet says.

SeanAnderson 1y ago

I had no idea 100 tons of external material was entering our atmosphere each day. Fascinating.

timschmidt 1y ago
An additional tidbit: this is not enough mass to offset the amount of helium and hydrogen which escapes Earth's atmosphere daily. Earth is on net losing mass. Eventually, Earth will lose all the hydrogen locked in it's oceans via this process. Not sure if that's destined to happen before or after we're engulfed by the expanding sun though.
- khuey 1y ago
  At the current rate of loss Earth has 150 billion years worth of hydrogen.
  - rkomorn 1y ago
    Well that's bad news for all the infrastructure projects in my current city and country. They're gonna run out of hydrogen before our subway extension is finished.

deleted 1y ago

[deleted]

throwup238 1y ago

It’s closer to 43+-14 tons and most of that is cosmic dust [1] and most of that is under a millimeter in size [2]. [1] https://en.wikipedia.org/wiki/Cosmic_dust https://en.wikipedia.org/wiki/Cosmic_dust [2] https://www.sciencedirect.com/science/article/pii/S0012821X21000534 https://www.sciencedirect.com/science/article/pii/S0012821X2...

mrtksn 1y ago

I think probably means SpaceX will need to keep sending rockets at rate of 1 or 2 satellites per day to replenish the infra. How much impact sending 800kg satellite into low orbit has? (in batches, obviously)