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Why are there so many methane satellites?

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Re: Why are there so many methane satellites?

#21

Post by photochemsyn »

How these satellites work (full text):

"Mapping methane point emissions with the PRISMA spaceborne imaging spectrometer" (2021)

https://www.sciencedirect.com/science/article/abs/pii/S00344...

> "The retrieval of methane from space measurements typically relies on spectrally-resolved measurements of solar radiation reflected by the Earth's surface in the shortwave infrared (SWIR) part of the spectrum (~1600–2500 nm). Methane presents two absorption bands in this region, a weaker one around 1700 nm and a stronger one around 2300 nm. Carbon dioxide, nitrous oxide and especially water vapor also present optical activity in the SWIR (see Fig. 1)"

Re: Why are there so many methane satellites?

#22

Post by dannyz »

jessriedel wrote: post #16

Putting aside the climate aspects and just concentrating on companies that are trying to identify methane leaks: If I have a device that can accurately see methane leaks, I am very surprised it's really more economical to put them on satellites than to operate them locally. Yes, I get that you can have one device in orbit that can do the job for multiple companies, but satellites are just fantastically expensive. Unl…

The short answer is to measure methane you rely on methane absorption features. To do that you need to be looking at a source through the methane plume, from a satellite this source is the ground. From a ground instrument you can use the sun as a source, but it limits the times of day/direction/location you can measure from.

Re: Why are there so many methane satellites?

#23

Post by cmyr »

cabirum wrote: post #9

Because these are either spy sats or even weapons in space disguised as "methane detectors".

If you're going to post quite sensationalist speculation please at least provide some attempt at a source or rationale. It doesn't really pass the sniff test that any goverment would bother with this banal subterfuge when they are more than capable of putting secret payloads into orbit, and have done so many times[1].

e.g. this, just the first relevant thing I could find https://spaceflightnow.com/2021/04/26/spy-satellite-successf...

Re: Why are there so many methane satellites?

#24

Post by staunton »

codeflo wrote: post #17
trompetenaccoun wrote: post #7

Earlier quoted context omitted.

That's a misunderstanding. The methane stays in the atmosphere a few years until it reacts with oxygen to CO2. So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas. You're left with CO2 either way, even when you burn the methane. That's why it's so bad. And that's why actually when companies or politicians tell you about "clean" gas, it's very mislead…

Sure, but the question is still whether that carbon came from a fossil source or was part of the cycle to begin with. Let's say a cow eats grass, produces methane, the methane gets converted into CO2, the grass grows back. No net increase in CO2. If, on the other hand, the methane came from natural gas, you have permanently added carbon to the cycle.

The "short-term" effect on warming is quite severe and very relevant. Also, while carbon atoms are conserved, methane is not. You can make a lot of methane from biomass without needing to absorb methane to produce the biomass.

Re: Why are there so many methane satellites?

#25

Post by llbeansandrice »

alwa wrote: post #13
cabirum wrote: post #9

Because these are either spy sats or even weapons in space disguised as "methane detectors".

“Many” seems to mean only a dozen-odd. Which seems like an awfully small number to image the entire earth at meaningful levels of resolution or frequency. Which also seems to be the article’s lesson. FWIW, it looks like Starlink alone is up to 5,942 satellites in orbit [0] these days [0] https://planet4589.org/space/con/star/stats.html

> it looks like Starlink alone is up to 5,942 satellites in orbit [0] these days

Starlink operates by far the largest constellation of satellites. Definitely the largest commercial constellation. That's like saying Google "just" serves ~8.5bn search queries/day. I might be mistaking your implication tho.

Re: Why are there so many methane satellites?

#26

Post by iraqmtpizza »

cmyr wrote: post #23
cabirum wrote: post #9

Because these are either spy sats or even weapons in space disguised as "methane detectors".

If you're going to post quite sensationalist speculation please at least provide some attempt at a source or rationale. It doesn't really pass the sniff test that any goverment would bother with this banal subterfuge when they are more than capable of putting secret payloads into orbit, and have done so many times[1]. e.g. this, just the first relevant thing I could find https://spaceflightnow.com/2021/04/26/spy-sate…

Secret payloads which are impossible to track via radar or optically either from the ground or via other satellites? Really? Tell me more.

Re: Why are there so many methane satellites?

#27

Post by photochemsyn »

jessriedel wrote: post #16

Putting aside the climate aspects and just concentrating on companies that are trying to identify methane leaks: If I have a device that can accurately see methane leaks, I am very surprised it's really more economical to put them on satellites than to operate them locally. Yes, I get that you can have one device in orbit that can do the job for multiple companies, but satellites are just fantastically expensive. Unl…

Ground-based sampling has different capabilities, e.g. these days you can mount a small mass spectrometer (see the ones going to Mars, the Moon) or related devices on a drone and get data about a much wider range of particulates and compounds. e.g.

"VOC Sampler on a Drone Assisting in Tracing the Potential Sources by a Dispersion Model - Case Study of Industrial Emissions" (2023)

https://aaqr.org/articles/aaqr-23-07-tn-0169

> "Two plants which manufacture petrochemical products at an industrial complex in Kaohsiung City, southern Taiwan, were applied as the targets for VOCs sampling and further qualitative and quantitative analysis in the laboratory. Aromatic hydrocarbons, including toluene of 433 ppb, ethylbenzene and xylenes of 100–200 ppb and phenol of 111 ppb were identified."

US EPA also has a similar program.

Re: Why are there so many methane satellites?

#28

Post by metaphor »

trompetenaccoun wrote: post #7
codeflo wrote: post #3

I get that methane has a strong greenhouse effect, and that climate models need to account for its concentration to make accurate predictions. But in terms of climate activism, isn't worrying about methane mostly a red herring? My understanding is that it only stays in the atmosphere for 12 years or so. It doesn't accumulate over centuries the way CO2 does. This means even if we manage to permanently reduce the amoun…

That's a misunderstanding. The methane stays in the atmosphere a few years until it reacts with oxygen to CO2. So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas. You're left with CO2 either way, even when you burn the methane. That's why it's so bad. And that's why actually when companies or politicians tell you about "clean" gas, it's very mislead…

> So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas.

In case anyone else was wondering, the EPA[1] puts a layman figure on that notional multiple:

>> Methane's lifetime in the atmosphere is much shorter than carbon dioxide (CO2), but CH4 is more efficient at trapping radiation than CO2. Pound for pound, the comparative impact of CH4 is 28 times greater than CO2 over a 100-year period.

[1] https://www.epa.gov/ghgemissions/overview-greenhouse-gases#m...

Re: Why are there so many methane satellites?

#29

Post by Scarblac »

codeflo wrote: post #3

I get that methane has a strong greenhouse effect, and that climate models need to account for its concentration to make accurate predictions. But in terms of climate activism, isn't worrying about methane mostly a red herring? My understanding is that it only stays in the atmosphere for 12 years or so. It doesn't accumulate over centuries the way CO2 does. This means even if we manage to permanently reduce the amoun…

The half life is 12 years.

So after 24 there's still a quarter, after 36 still an eighth, etc. It's worse than CO2 for a very long time, and then it is CO2.

Re: Why are there so many methane satellites?

#30

Post by dylan604 »

alwa wrote: post #13
cabirum wrote: post #9

Because these are either spy sats or even weapons in space disguised as "methane detectors".

“Many” seems to mean only a dozen-odd. Which seems like an awfully small number to image the entire earth at meaningful levels of resolution or frequency. Which also seems to be the article’s lesson. FWIW, it looks like Starlink alone is up to 5,942 satellites in orbit [0] these days [0] https://planet4589.org/space/con/star/stats.html

the field of view from LEO (for Starlink) is so much smaller than from GEO. I'm not sure what the orbit is for the methane satellites, but the number of satellites alone isn't the only factor.
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