Methane mapping over Saudi Arabia.
Credit: Thorpe et al, Science Advances/10.1126/sciadv.adh2391
NASA didn’t plan for its Earth Surface Mineral Dust Source Investigation (EMIT) instrument to do much about climate change when the device first hitched a ride to space. But roughly a year and a half after being attached to the International Space Station (ISS), EMIT has become an unlikely—yet impressively accurate—emissions-tracking tool.
EMIT was born from a desire to track Earth’s mineral dust cycle. As winds circulate throughout our atmosphere, they kick up dust from arid regions and carry the particles elsewhere. Depending on the type of dust being carried, this can produce a cooling or warming effect, ultimately affecting the weather—and long-term climate patterns—we experience on the ground. While we can’t prevent wind from moving dust around, EMIT can help scientists understand this ever-present cause-and-effect via imaging spectroscopy, which reveals dusty minerals’ unique fingerprints.
But imaging spectroscopy is good for more than just tracking dust. While the scientists behind EMIT knew the instrument would be able to capture methane emissions, they didn’t know exactly how adept it would be at doing so. In a paper for Science Advances, a team at the Jet Propulsion Laboratory (JPL) shared that EMIT has identified more than 750 emissions sources over the last 16 months, making it a key resource in the fight against climate change.
EMIT’s Compact Wide-swath Imaging Spectrometer (CWIS).
Credit: JPL/Caltech/NASA
Not all methane sources are super obvious. We know that oil and gas facilities, landfills, and meat and dairy farms emit a good deal of methane, but lesser-known sources are also to blame. (Coal mine vents, for instance, appear to emit more methane than gas and oil vents, despite the common assumption that it would be the other way around.) EMIT’s discoveries are also vital to helping sources—previously known or otherwise—know how much they contribute to atmospheric greenhouse gas accumulation.
Across the 750 sources previously mentioned, EMIT has captured more than 50,000 “scenes,” or methane emission plumes. JPL maps these scenes on the Emit Open Data Portal. For each scene, JPL includes maximum plume concentration data, concentration uncertainty levels, and the time the plume was observed. While some plumes are worryingly large, others, like one in southeastern Libya in September 2022, are surprisingly small at “just” 979 pounds of methane per hour.
EMIT is still performing its original duties; it’s just picked up a side gig on the ISS. Good thing, too: Since NASA canceled its GeoCarb emissions-monitoring mission last year, the agency has been short on ways to track greenhouse gas production from space. EMIT might not capture the carbon dioxide and carbon monoxide emissions GeoCarb would’ve monitored, but methane is a noble start.
