New NASA Spectrometer Locates Planetary Methane \"Super Emitter\" Sources

Schematic of the Earth Surface Mineral Dust Source Investigation (EMIT) spectrophotometer installed on the International Space Station on July 24, 2022. Photo: NASA/Jet Propulsion Laboratory/CalTech

Methane is an especially important gas to locate and minimize, as it is one of the most dangerous of greenhouse gases by volume, with the ability to trap as much as 30 times more solar energy than an equivalent volume of carbon dioxide over a hundred years. Methane can trap as much as 80 times the solar energy of carbon dioxide during the first ten years it is present in the atmosphere, before it begins to break down.

The tool which is making this possible is a new specialized spectrophotometer system which was installed on the International Space Station in July 2022.

The solution begins with what scientists refer to as a “spectral fingerprint” for methane. That is a map of the relative intensity of various frequencies of light emitted as plumes of the gas are released into the air.

That spectral map is then compared to the light spectra sensors in the space-based Earth Surface Mineral Dust Source Investigation (EMIT) detect when they are looking down on the Earth. If the light spectrum detected through EMIT is sufficiently close to methane spectrum, after subtracting background wavelengths such as are radiated and re-radiated from blocks, rocks, and soil, for example, then the system flags that it has detected methane.

The cube (left) shows methane plumes (purple, orange, yellow) over Turkmenistan. The rainbow colors are the spectral fingerprints from corresponding spots in the front image. The blue line in the graph (right) shows the methane fingerprint EMIT detected; the red line is the expected fingerprint based on an atmospheric simulation. Photo: NASA/Jet Propulsion Lab/Caltech

Because of the precision imaging nature of the EMIT device, it can scan wide areas up to 50 miles and more, while providing resolution elements the size of a football field.

EMIT was originally designed with another important mission in mind: scanning for and mapping the presence of minerals and dust particulates on our planet’s deserts. That data will be used help scientists understand how airborne dust propagates and its impacts on climate events, including heat trapping, rainfall, and extreme weather.

High-level system diagram for how the Earth Surface Mineral Dust Source Investigation (EMIT) system will be utilized to track the movement of dust particles and their impact on climate. Photo: NASA/Jet Propulsion Laboratory/CalTech

In its alternate role as a mapper of greenhouse gas emissions including methane and carbon dioxide, however, EMIT has already demonstrated surprising success. Since it went “live” just a few months ago, the system has helped identify and quantify over 50 sites known as “super-emitters” in regions such as the Southwestern United States where drought is also producing high concentrations of dust, the Middle East, and Central Asia. The “super emitter” designation is used to describe areas of high methane output normally associated with fossil fuel harvesting and distribution, waste and agricultural sectors, and the equipment, plants, and other infrastructure associated with them.

One of the bigger areas discovered was in Iran in an area just south of the nation’s capital of Iran. The EMIT system was able to discover a methane plume a minimum of 3 miles (4.8 kilometers) long, all coming from an enormous landfill there. The methane produced at this site comes primarily from decomposition.

A methane plume at least 3 miles (4.8 kilometers) long billows into the atmosphere south of Tehran, Iran. The plume, detected by NASA’s Earth Surface Mineral Dust Source Investigation mission, comes from a major landfill, where methane is a byproduct of decomposition. Photo: NASA/Jet Propulsion Lab/Caltech

Another example came in a scan near the port city of Hazar, Turkmenistan, located on the Caspian Sea. This revealed a total of 12 separate methane plumes which extended outwards some 20 kilometers.

East of Hazar, Turkmenistan, a port city on the Caspian Sea, 12 plumes of methane stream westward. The plumes were detected by NASA’s Earth Surface Mineral Dust Source Investigation mission and some of them stretch for more than 20 miles (32 kilometers). Photo: NASA/Jet Propulsioin Laboratory/CalTech

The total methane output flow from the plumes detected in Turkmenistan have been determined to be as large as what the Aliso Canyon gas leak in 2015 produced, during a major rupture in the pipeline there. That accident, located just outside Los Angeles, at times spewed 110,000 pounds (50,000 kilograms) of methane into the air per hour. That accident was one of the worst ever recorded in the United States, which says much about what it would mean to be about to cap the Turkmenistan plumes.

A third example came when the EMIT spectrophotometer was able to detect a 2 miles (3.3 kilometers) long methane plume located in the Permian Basin fossil fuel prospecting region, southeast of Carlsbad, New Mexico. Based on data gathered, scientists estimate that location was blowing 40,300 pounds (18,300 kilograms) per hour of methane into the atmosphere above and nearby. That puts its output close to as bad as what the Aliso Canyon accident released.

Scientists at NASA associated with the project are excited by what they have already discovered and what it could mean to minimize methane emissions for the future.

“These results are exceptional, and they demonstrate the value of pairing global-scale perspective with the resolution required to identify methane point sources, down to the facility scale,” said David Thompson, EMIT’s instrument scientist and a senior research scientist at NASA’s Jet Propulsion Laboratory, located near California Institute of Technology in Southern California. “It’s a unique capability that will raise the bar on efforts to attribute methane sources and mitigate emissions from human activities.”

Plans now are for EMIT to continue its mapping over as much of the world as possible. Special focus areas will be some of the driest regions of the Earth, Asia, Australia, North and South America, and Africa.