EMIT Instrument's First Light

The mineral map shows an area of southwestern Libya in the Sahara Desert observed by NASA's Earth Surface Mineral Dust Source Investigation (EMIT) mission as it maps the world's mineral dust sources, gathering information about surface composition as the instrument, designed at NASA's Jet Propulsion Laboratory in Southern California, orbits aboard the International Space Station.

The instrument works by measuring reflected solar energy from Earth across hundreds of wavelengths from the visible to the infrared range of the spectrum. The intensity of the reflected light varies by wavelength based on the material. Scientists are using these patterns, called spectral fingerprints, to identify surface minerals and pinpoint their locations on a map.

The map is among the first produced by scientists with EMIT data. Analysis of the patterns indicate that the surface contains kaolinite, a light-colored clay mineral, and goethite and hematite, two varieties of iron oxide, which is darker.

When dust from the kaolinite-dominated areas is lofted into the atmosphere, the particles tend to scatter sunlight and reflect it back to space, cooling the air. The opposite effect occurs with airborne particles of iron oxide, which tend to absorb heat and warm the surrounding air.

Over the course of its 12-month mission, EMIT will collect measurements of 10 important surface minerals – kaolinite, hematite, goethite, illite, vermiculite, calcite, dolomite, montmorillonite, chlorite, and gypsum – in arid regions between 50-degree south and north latitudes in Africa, Asia, North and South America, and Australia. The data EMIT collects will help scientists better understand the role of airborne dust particles in heating and cooling Earth's atmosphere on global and regional scales.

EMIT was developed at NASA's Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California. It launched to the space station in July 2022.