EMIT (Earth Surface Mineral Dust Source Investigation)

A visible-to-shortwave-infrared imaging spectrometer mounted on the ISS. Designed for mineral dust source mapping (the science mission); turned out to be a breakthrough methane plume detector (the unanticipated win that’s reshaping greenhouse-gas monitoring).

What it sees

• 285 contiguous spectral bands from 380 nm to 2500 nm — true hyperspectral (vs Sentinel-2’s 13 bands or Landsat 9’s 9 bands).
• 60 m ground pixel; 75 km swath; SNR optimized for surface reflectance, not atmospheric paths.
• Spectral resolution (7.4 nm sampling) high enough to detect CH4 absorption features at 1700 nm and 2300 nm — the methane signature that earned EMIT its second life.

Why it matters

• First hyperspectral imager from a NASA platform at this combination of spatial coverage + access.
• The EMIT L2B methane product is the operational layer that UNEP-IMEO’s MARS workflow uses to attribute super-emitter sources to specific facilities. Has shifted methane policy globally.
• Mineral composition mapping at unprecedented spectral fidelity — feeds dust radiative forcing models.
• Demonstrates that ISS-mounted Earth-observation payloads can do flagship-quality science at a fraction of free-flyer cost.

Where to get the data

• earthaccess Python: short_name="EMITL2BCH4ENH" (methane enhancement), EMITL2BCH4PLM (vector plume polygons), EMITL2ARFL (surface reflectance), EMITL2BMIN (mineral abundance)
• EMIT Plume Viewer (JPL): methane.jpl.nasa.gov — public web app with searchable plume catalog
• UNEP-IMEO MARS dataset on Hugging Face: huggingface.co/datasets/UNEP-IMEO/MARS-Hyperspectral — QA’d plume detections

What it enables

• Point-source methane plume detection at ~60 m (oil/gas, landfills, livestock — anywhere with elevated CH4) (q02 →)
• Mineral composition mapping of arid landscapes (Sahara, Arabian Peninsula, Western US)
• Aerosol radiative forcing constraints (the original science mission)
• Algal bloom + cyanobacteria detection (HABs) — coastal hyperspectral
• Crop stress + nutrient deficiency at higher fidelity than multispectral

Gotchas

• No coverage above ±52° latitude. ISS orbit; no polar regions. If your science is Arctic or Antarctic, EMIT is unavailable.
• EMIT does not see at night (passive optical).
• The L2B methane product has false positives. Use the QA flag; UNEP-IMEO + JPL QA the public plume polygons before release. Raw enhancement product has more noise.
• Sub-pixel plume mixing in dense oilfield basins — multiple sources within one 60 m pixel are common.
• Revisit is irregular (ISS orbit, not sun-synchronous). Could be 16 days or could be longer with gaps.
• Mission life is finite. ISS payload mounted in 2022 with original 1-year baseline; extended through 2026+. Eventually the ISS de-orbits.

Related missions

• PACE OCI (s08 →) — hyperspectral cousin in ocean wavelengths.
• SBG (Surface Biology and Geology) — planned NASA Decadal Survey mission, ~2028+, the next-generation hyperspectral imager (EMIT’s institutional successor).
• Tanager-1 (Planet, commercial): higher-revisit hyperspectral, complementary.
• EnMAP (DLR): German hyperspectral; complementary global archive.

Related datasets