6 ms·

I was under the impression that regular use of rocket fuel made a lot of land extremely toxic.

by gleenn 3y ago

nickff 3y ago
It depends on the fuel, and the number of leaks (the latter usually being relatively high). Some fuels such as hydrazine and red fuming nitric acid are indeed quite dangerous, but Starship mostly uses methane and oxygen.
cdchn 3y ago
I figure it would depend on the rocket fuel. LOX and Liquid Hydrogen/Methane probably isn't so bad, stuff like hydrazine I could imagine wouldn't be great.
- dylan604 3y ago
  But hydrazine makes for a great ingredient in bottled water! https://www.usatoday.com/story/news/nation/2023/10/05/real-water-contamination-case-liver-illnesses/71077761007/ https://www.usatoday.com/story/news/nation/2023/10/05/real-w...
oittaa 3y ago
Why would you think that methane is toxic? I know the average american knows nothing about even 6th grade chemistry but these kind of comment pop up on every thread about rockets.
- elteto 3y ago
  > The average american... Ah, yes, as we all know, Americans are unique in the entire world for their lack of knowledge of chemistry.
  - oittaa 3y ago
    https://www.google.com/search?q=is+methane+toxic https://www.google.com/search?q=is+methane+toxic
  - mensetmanusman 3y ago
    We are unique in that we pay 10x as much to know as little as we do.
- wil421 3y ago
  >Two of six mice exposed to 70% methane in air died in 18 min, whereas mice exposed to 70% nitrogen in air developed only ataxia. Animals exposed to 50-90% methane in oxygen showed mild depression and a marked decrease in locomotion, but no ataxia. Thus, the toxic effect of methane is much greater than that of nitrogen when available oxygen is low, but methane has little effect when oxygen is readily available. It seems that the toxicity of methane should be discussed not alone, but rather with respect to the partial pressure of oxygen in the atmosphere in question. https://www.ncbi.nlm.nih.gov/books/NBK208285/#:~:text=Thus%2C%20the%20toxic%20effect%20of,when%20oxygen%20is%20readily%20available https://www.ncbi.nlm.nih.gov/books/NBK208285/#:~:text=Thus%2....
  - MikusR 3y ago
    https://twitter.com/justsaysinmice https://twitter.com/justsaysinmice
  - Someone 3y ago
    What is “70% nitrogen in air”? https://en.wikipedia.org/wiki/Atmosphere_of_Earth https://en.wikipedia.org/wiki/Atmosphere_of_Earth: “As of 2023, by mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.” Did they take out nitrogen, added 7 parts nitrogen to 10 parts of air, use something else than mole fraction, …?
  - Dylan16807 3y ago
    I guess by that measure sandwiches are toxic because if you replace someone's water intake with sandwiches they'll die.
elteto 3y ago
Which rocket fuel? There's so many different ones. Methalox engines produce water vapor. Kerolox engines use refined kerosene, so lots of soot and your regular fossil fuel combustion byproducts. And then there's the hypergols, which are indeed, incredibly toxic.
bryanlarsen 3y ago
That'd require: 1) regular spills of fuel, that 2) aren't burnt up in the air before they hit the ground and 3) are liquid, not gaseous, and 4) are hypergolic. Boca Chica doesn't have any of those 4 requirements.
- jjk166 3y ago
  1) Fuel spills happen as a regular part of working with fuels (leaking pipes, loose fittings, safety purges, general clumsiness, etc) not just rocket explosions. 2) Even if a rocket explodes in the air it is unlikely all of its propellant will completely burn up (fuels aren't mixed, the ratios are optimized for a specific combustion conditions, and there are multiple tanks, etc), and there are many failure modes besides "massive explosion" 3) Just because the main component of a fuel will boil off eventually doesn't mean chemicals added to the propellant or produced in side reactions will 4) Hypergolic just means chemicals spontaneously combust on contact with one another; it has nothing to do with environmental risk.
  - Dylan16807 3y ago
    > 3) Just because the main component of a fuel will boil off eventually doesn't mean chemicals added to the propellant or produced in side reactions will What do you have in mind that exists in quantities large enough to make things "extremely toxic"? > 4) Hypergolic just means chemicals spontaneously combust on contact with one another; it has nothing to do with environmental risk. Nothing except if you look at the actual list of rocket fuels that get used.
    - jjk166 3y ago
      > What do you have in mind that exists in quantities large enough to make things "extremely toxic"? I don't know where you are quoting "extremely toxic" from but even small quantities of toxic chemicals can be cause for concern. > Nothing except if you look at the actual list of rocket fuels that get used. Just because a square's a rectangle doesn't make a rectangle a square. Hypergolics are toxic does not equal non-hypergolics are non-toxic. For example, hydrazine monopropellant.
avmich 3y ago
Methane is gas, liquified methane spills evaporate and go to atmosphere. Not perfect, but no land poisoning either. SpaceX does use hydrazine-related components in Dragon and Crew Dragon, but they don't launch from Boca Chica (and rather small by mass) - AFAIK Starship is planned to be 100% methane-oxygen vehicle, justification for Mars flight.
dotnet00 3y ago
That's mainly a hypergolic fuel thing. The goal with Starship is to try to use Methalox everywhere so that's the only thing that needs to be resupplied. Long term this would be meaningful for ISRU, but short term this would be meaningful for in-space refueling and propellant depots. A more typical approach of using different fuel types for different things would create all sorts of restrictions on capabilities and would make in-space refueling more complicated.
nwallin 3y ago
Depends on the rocket fuel. Oxygen, methane, hydrogen are basically completely non-toxic. RP-1 is a pure form of kerosene and is non-toxic enough that it doesn't need special handling. Hydrazine, fuming nitric acid, nitrogen tetroxide... basically all hypergolic propellants are absurdly toxic. The SpaceX tests at Boca Chica have been almost entirely oxygen, methane, and RP-1.

I was under the impression that regular use of rocket fuel made a lot of land extremely toxic.

by gleenn 3y ago

I was under the impression that regular use of rocket fuel made a lot of land extremely toxic.

It depends on the fuel, and the number of leaks (the latter usually being relatively high). Some fuels such as hydrazine and red fuming nitric acid are indeed quite dangerous, but Starship mostly uses methane and oxygen.

cdchn 3y ago

I figure it would depend on the rocket fuel. LOX and Liquid Hydrogen/Methane probably isn't so bad, stuff like hydrazine I could imagine wouldn't be great.

dylan604 3y ago
But hydrazine makes for a great ingredient in bottled water! https://www.usatoday.com/story/news/nation/2023/10/05/real-water-contamination-case-liver-illnesses/71077761007/ https://www.usatoday.com/story/news/nation/2023/10/05/real-w...

oittaa 3y ago

Why would you think that methane is toxic? I know the average american knows nothing about even 6th grade chemistry but these kind of comment pop up on every thread about rockets.

elteto 3y ago
> The average american... Ah, yes, as we all know, Americans are unique in the entire world for their lack of knowledge of chemistry.
- oittaa 3y ago
  https://www.google.com/search?q=is+methane+toxic https://www.google.com/search?q=is+methane+toxic
- mensetmanusman 3y ago
  We are unique in that we pay 10x as much to know as little as we do.
wil421 3y ago
>Two of six mice exposed to 70% methane in air died in 18 min, whereas mice exposed to 70% nitrogen in air developed only ataxia. Animals exposed to 50-90% methane in oxygen showed mild depression and a marked decrease in locomotion, but no ataxia. Thus, the toxic effect of methane is much greater than that of nitrogen when available oxygen is low, but methane has little effect when oxygen is readily available. It seems that the toxicity of methane should be discussed not alone, but rather with respect to the partial pressure of oxygen in the atmosphere in question. https://www.ncbi.nlm.nih.gov/books/NBK208285/#:~:text=Thus%2C%20the%20toxic%20effect%20of,when%20oxygen%20is%20readily%20available https://www.ncbi.nlm.nih.gov/books/NBK208285/#:~:text=Thus%2....
- MikusR 3y ago
  https://twitter.com/justsaysinmice https://twitter.com/justsaysinmice
- Someone 3y ago
  What is “70% nitrogen in air”? https://en.wikipedia.org/wiki/Atmosphere_of_Earth https://en.wikipedia.org/wiki/Atmosphere_of_Earth: “As of 2023, by mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.” Did they take out nitrogen, added 7 parts nitrogen to 10 parts of air, use something else than mole fraction, …?
- Dylan16807 3y ago
  I guess by that measure sandwiches are toxic because if you replace someone's water intake with sandwiches they'll die.

elteto 3y ago

Which rocket fuel? There's so many different ones. Methalox engines produce water vapor. Kerolox engines use refined kerosene, so lots of soot and your regular fossil fuel combustion byproducts. And then there's the hypergols, which are indeed, incredibly toxic.

bryanlarsen 3y ago

That'd require: 1) regular spills of fuel, that 2) aren't burnt up in the air before they hit the ground and 3) are liquid, not gaseous, and 4) are hypergolic. Boca Chica doesn't have any of those 4 requirements.

jjk166 3y ago
1) Fuel spills happen as a regular part of working with fuels (leaking pipes, loose fittings, safety purges, general clumsiness, etc) not just rocket explosions. 2) Even if a rocket explodes in the air it is unlikely all of its propellant will completely burn up (fuels aren't mixed, the ratios are optimized for a specific combustion conditions, and there are multiple tanks, etc), and there are many failure modes besides "massive explosion" 3) Just because the main component of a fuel will boil off eventually doesn't mean chemicals added to the propellant or produced in side reactions will 4) Hypergolic just means chemicals spontaneously combust on contact with one another; it has nothing to do with environmental risk.
- Dylan16807 3y ago
  > 3) Just because the main component of a fuel will boil off eventually doesn't mean chemicals added to the propellant or produced in side reactions will What do you have in mind that exists in quantities large enough to make things "extremely toxic"? > 4) Hypergolic just means chemicals spontaneously combust on contact with one another; it has nothing to do with environmental risk. Nothing except if you look at the actual list of rocket fuels that get used.
  - jjk166 3y ago
    > What do you have in mind that exists in quantities large enough to make things "extremely toxic"? I don't know where you are quoting "extremely toxic" from but even small quantities of toxic chemicals can be cause for concern. > Nothing except if you look at the actual list of rocket fuels that get used. Just because a square's a rectangle doesn't make a rectangle a square. Hypergolics are toxic does not equal non-hypergolics are non-toxic. For example, hydrazine monopropellant.

avmich 3y ago

Methane is gas, liquified methane spills evaporate and go to atmosphere. Not perfect, but no land poisoning either. SpaceX does use hydrazine-related components in Dragon and Crew Dragon, but they don't launch from Boca Chica (and rather small by mass) - AFAIK Starship is planned to be 100% methane-oxygen vehicle, justification for Mars flight.

dotnet00 3y ago

That's mainly a hypergolic fuel thing. The goal with Starship is to try to use Methalox everywhere so that's the only thing that needs to be resupplied. Long term this would be meaningful for ISRU, but short term this would be meaningful for in-space refueling and propellant depots. A more typical approach of using different fuel types for different things would create all sorts of restrictions on capabilities and would make in-space refueling more complicated.

nwallin 3y ago

Depends on the rocket fuel. Oxygen, methane, hydrogen are basically completely non-toxic. RP-1 is a pure form of kerosene and is non-toxic enough that it doesn't need special handling. Hydrazine, fuming nitric acid, nitrogen tetroxide... basically all hypergolic propellants are absurdly toxic. The SpaceX tests at Boca Chica have been almost entirely oxygen, methane, and RP-1.