Vital signs of the planet
NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) mission aboard the International Space Station has produced its first mineral maps, providing detailed images that show surface composition in areas of northwestern Nevada and Libya in the Sahara Desert.
Windy desert areas such as these are the sources of fine dust particles which, when blown into the atmosphere, can heat or cool the surrounding air. But scientists have not been able to assess whether mineral dust in the atmosphere has global heating or cooling effects on local, regional and global scales. EMIT’s measurements will help them advance computer models and improve our understanding of the impacts of dust on climate.
EMIT scientists from NASA’s Jet Propulsion Laboratory in Southern California and the US Geological Survey created the maps to test the accuracy of the instrument’s measurements, a crucial first step in preparing for full science operations .
Installed on the space station in July, EMIT is the first of a new class of high-fidelity imaging spectrometers that collect data from space and produce higher quality data at higher volumes than previous instruments.
“Decades ago, when I was in college, it took 10 minutes to collect a single spectrum from a geological sample in the lab. EMIT’s imaging spectrometer measures 300,000 spectra per second, with superior quality said Robert Green, Principal Investigator at EMIT and Principal Investigator at JPL.
“The data we get from EMIT will allow us to better understand the Earth’s heating and cooling, and the role that mineral dust plays in this cycle. It’s promising to see the amount of data we’re getting from the mission in such a short time,” said Kate Calvin, NASA Chief Scientist and Senior Climate Advisor. “EMIT is one of seven Earth Science instruments on the International Space Station that is giving us more information about how our planet is being affected by climate change.”
EMIT analyzes the light reflected from the Earth, measuring it at hundreds of wavelengths, from the visible to the infrared spectrum. Different materials reflect light in different wavelengths. Scientists use these patterns, called spectral fingerprints, to identify surface minerals and pinpoint their locations.
The Nevada map focuses on a mountainous area about 209 kilometers northeast of Lake Tahoe, revealing places dominated by kaolinite, a light-colored mineral whose particles scatter light upwards and cool the air when ‘they move through the atmosphere. The map and spectral fingerprint closely match those collected from aircraft in 2018 by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), data that was verified at the time by geologists. Researchers use this comparison and others to confirm the accuracy of EMIT measurements.
The other mineral map shows significant amounts of kaolinite along with two iron oxides, hematite and goethite, in a sparsely populated part of the Sahara about 800 kilometers south of Tripoli. Darker-colored dust particles from areas rich in iron oxide strongly absorb the sun’s energy and heat the atmosphere, potentially affecting the climate.
Currently, there is little or no information on the composition of dust from parts of the Sahara. In fact, researchers only have detailed mineral information on about 5,000 soil samples from around the world, which forces them to make inferences about the composition of the dust.
EMIT will bring together billions of new spectroscopic measurements from six continents, filling this knowledge gap and advancing climate science. “With this outstanding performance, we are on track to comprehensively map minerals from arid regions of the Earth – approximately 25% of the Earth’s land surface – in less than a year and achieve our of climatology,” Green said.
EMIT data will also be freely available for a wide range of investigations, including, for example, the search for strategically important minerals such as lithium and rare earth elements. Additionally, the instrument’s technology lays the foundation for the future Surface Biology and Geology (SBG) satellite mission, part of NASA’s Earth System Observatory, a set of missions aimed at combating the climate change.
EMIT has its roots in imaging spectrometer technology that NASA’s Airborne Imaging Spectrometer (AIS) first demonstrated in 1982. Designed to identify minerals on the Earth’s surface from a research aircraft at low altitude, the instrument provided startling results almost immediately. During initial test flights near Cuprite, Nevada, AIS detected the unique spectral signature of buddingtonite, a mineral that has not been seen on any previous geological maps of the area.
Paving the way for future spectrometers when it was introduced in 1986, AVIRIS – the airborne instrument that succeeded AIS – studied geology, plant functioning and alpine snowmelt, among other natural phenomena. He also mapped chemical pollution at Superfund sites and studied oil spills, including the massive Deepwater Horizon leak in 2010. And he flew over the World Trade Center site in Manhattan after the 9/11 attacks, locating uncontrolled fires and mapping the composition of the debris in the debris.
Over the years, as optics, detector arrays, and computing capabilities have advanced, imaging spectrometers capable of resolving smaller targets and more subtle differences have flown with missions across the solar system. .
An imaging spectrometer built by JPL on the Indian Space Research Organization’s Chandrayaan-1 probe measured signs of water on the Moon in 2009. NASA’s Europa Clipper, which will launch in 2024, will will rely on an imaging spectrometer to help scientists assess whether the icy Jovian moon has conditions that could support life.
Highly advanced spectrometers developed by JPL will be part of NASA’s upcoming Lunar Trailblazer – which will determine the form, abundance and distribution of water on the Moon and the nature of the lunar water cycle – and on satellites to be launched by the non-profit organization Carbon Mapper, aimed at pinpointing point sources of greenhouse gases from space.
“The technology has gone in directions I never imagined,” said Gregg Vane, the JPL researcher whose graduate studies in geology inspired the idea for the original imaging spectrometer. “Now, with EMIT, we’re using it to look at our own planet from space for important climate research.”
Learn more about the mission
EMIT was selected under the Earth Venture Instrument-4 solicitation of the Earth Science Division of NASA’s Science Mission Directorate and was developed at NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California. It was launched aboard a SpaceX Dragon resupply spacecraft from NASA’s Kennedy Space Center in Florida on July 14, 2022. Data from the instrument will be transmitted to the Land Processes Distributed Active Archive Center (DAAC) at the NASA for use by other researchers and the public.
To learn more about the mission, visit:
Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, California.
626-379-6874 / 818-354-0307