Why are there so many methane satellites?

From the article:

In the years since GOSAT launched, the field of methane monitoring has exploded. Today, there are two broad categories of methane instruments in space. Area flux mappers, like GOSAT, take global snapshots. They can show where methane concentrations are generally higher, and even identify exceptionally large leaks — so-called “ultra-emitters.” But the vast majority of leaks, big and small, are invisible to these instruments. Each pixel in a GOSAT image is 10 kilometers wide. Most of the time, there’s no way to zoom into the picture and see which facilities are responsible.

Point source imagers, on the other hand, take much smaller photos that have much finer resolution, with pixel sizes down to just a few meters wide. That means they provide geographically limited data — they have to be programmed to aim their lenses at very specific targets. But within each image is much more actionable data.

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The reason why we don’t have enough coverage has to do with the size of the existing images, their resolution, and the amount of time it takes to get them. One of the challenges, Thorpe said, is that it’s very hard to get a continuous picture of any given leak. Oil and gas equipment can spring leaks at random. They can leak continuously or intermittently. If you’re just getting a snapshot every few weeks, you may not be able to tell how long a leak lasted, or you might miss a short but significant plume. Meanwhile, oil and gas fields are also changing on a weekly basis, Joost de Gouw, an atmospheric chemist at the University of Colorado, Boulder, told me. New wells are being drilled in new places — places those point-source imagers may not be looking at.

“There’s a lot of potential to miss emissions because we’re not looking,” he said. “If you combine that with clouds — clouds can obscure a lot of our observations — there are still going to be a lot of times when we’re not actually seeing the methane emissions.”

De Gouw hopes MethaneSAT will help resolve one of the big debates about methane leaks. Between the millions of sites that release small amounts of methane all the time, and the handful of sites that exhale massive plumes infrequently, which is worse? What fraction of the total do those bigger emitters represent?

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MethaneSAT sits somewhere between the global mappers and point source imagers. It will take larger images than GHGSat, each one 200 kilometers wide, which means it will be able to cover more ground in a single day. Those images will also contain finer detail about leaks than GOSAT, but they won’t necessarily be able to identify exactly which facilities the smaller leaks are coming from. Also, unlike with GHGSat, MethaneSAT’s data will be freely available to the public.

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MethaneSAT won’t be able to look at every source of methane emissions around the world. The project is limited by how much data it can send back to Earth, so it has to be strategic. Sargent said they are limiting data collection to 30 targets per day, and in the near term, those will mostly be oil and gas producing regions. They aim to map emissions from 80% of global oil and gas production in the first year. The outcome could be revolutionary.