Mineral dust on the Earth's surface is an important climatic factor that can reflect or absorb the sun's radiation, which affects the temperature of the atmosphere and the earth's surface. However, due to the lack of precise information on the source areas of mineral dust, it is difficult for scientists to accurately assess their role in climate change. To address this, the National Aeronautics and Space Administration (NASA) launched a mission called EMIT in 2022 to use imaging spectrometers to make high-resolution observations of mineral dust from the International Space Station (ISS) in the Earth's arid regions. EMIT, short for Survey of Mineral Dust Sources on the Earth's Surface, is an innovative instrument developed by NASA's Jet Propulsion Laboratory (JPL) in Southern California that identifies the mineral composition of the earth's surface based on how different minerals reflect and absorb light. This mission addresses an important need for climate scientists to have more detailed information on the mineral composition of the earth's surface, and also provides a new source of data for research in other fields.
The main goal of the EMIT mission is to map the distribution of 10 critical minerals in the arid regions of the planet that can affect the climate when suspended into the air as dust storms. These minerals include hematite, gooseite, kaolinite, quartz, calcite, dolomite, chlorite, montmorillonite, illite, and feldspar. EMIT used data up to November 2023 to create the first global map of hematite, gooseite, and kaolinite in the Earth's arid regions. The three minerals are among the 10 key substances studied by this mission, which are thought to influence climate change. Hematite is a mineral rich in iron oxide, which varies in color from red to brown, and it absorbs the sun's energy, warming the surrounding air. Gesmine is a mineral containing iron sulfide, which varies in color from yellow to brown, and it can also absorb the sun's energy, but not as strongly as hematite. Kaolinite is a white or gray clay mineral that reflects the sun's energy and cools the air.
EMIT surveys the Earth's surface from an altitude of about 250 miles (410 kilometers) and scans vast areas that cannot be surveyed by geologists on the ground or instruments carried by aircraft, but it effectively achieves the same level of detail. EMIT's imaging spectrometers can capture 242 different wavelengths of light, from visible to near-infrared, which can characterize minerals on the surface. EMIT's data resolution is 30 meters, which means it can distinguish mineral differences within an area the size of a football field. To date, the mission has photographed more than 55,000 images in its study area"Scenario"A 50 x 50 mile (80 x 80 km) image of the surface of the Earth, including an arid region within a 6,900-mile (11,000 km-wide) zone in the middle of the Earth. Taken together, these scenarios include billions of measurements, enough to map the composition of the earth's surface.
The data from the EMIT mission will not only help scientists understand the distribution of minerals on the surface, but also help them assess the impact of mineral dust on climate and ecosystems. Mineral dust is an important aerosol that can directly or indirectly affect the Earth's energy balance. Direct impact refers to the fact that mineral dust can reflect or absorb the sun's radiation, which can affect the temperature of the atmosphere and the earth's surface. Indirect effects are when mineral dust can affect the formation and properties of clouds, which can affect precipitation and radiation. However, it has been unknown whether these effects will have a net warming or net cooling effect. This depends on the composition, size, shape, distribution, and optical properties of mineral dust, as well as their interactions with other aerosols and clouds. For the first time, the EMIT mission provided a mineral map of Earth's dust source regions, allowing scientists to model the role of these particles in climate change, among other things.
Natalie Mahowald, an Earth System Scientist at Cornell University in Ithaca, N.Y., an associate principal investigator at EMIT, said:"We will put the new map into our climate model. From this, we will know that aerosols absorb heat and reflect heat in a much larger proportion than we used to know. "She also said that EMIT's data could help scientists better understand the effects of mineral dust on clouds, as different mineral dusts can act as cloud condensation nuclei, promoting or inhibiting cloud formation. In addition, EMIT's data can also help scientists assess the uncertainty of mineral dust on Earth's radiative forcing, a measure of climate change.
In addition to using EMIT's mineral data to improve Earth's climate modeling, scientists can also use this information to study the effects of dust on the ecosystems where it falls. There is conclusive evidence that particles depositing in the ocean stimulate phytoplankton blooms, which can have an impact on aquatic ecosystems and the Earth's carbon cycle. Scientists have also found that mineral dust originating in the Andes Mountains of South America, as well as in northern Africa and the Sahara Desert, also has an important impact on the growth and biodiversity of the Amazon rainforest, as they can provide nutrients to poor soils. EMIT's data can help scientists quantify these processes and assess the impact of climate change on them in the future.
EMIT Mission Demonstrates the Potential of Imaging Spectroscopy The EMIT mission not only provides valuable data for climate science, but also demonstrates the potential of imaging spectroscopy. An imaging spectrometer is an instrument capable of measuring multiple wavelengths of light at the same time, revealing the chemical and physical properties of matter. EMIT was the first mission to use an imaging spectrometer to observe the Earth's surface from the International Space Station, with higher resolution and coverage than any previous similar mission. Developed by NASA's Jet Propulsion Laboratory (JPL) in Southern California, EMIT's imaging spectrometer is an innovative instrument that identifies the mineral composition of the earth's surface based on how different minerals reflect and absorb light. The EMIT's data, which will be freely available to a wide range of researchers, also lays the groundwork for a future Surface Biology and Geology (SBG) satellite mission as part of NASA's Earth System Observatory, a group of missions designed to address climate change.
Robert Green, principal investigator at EMIT and senior research scientist at JPL, said: "The EMIT mission is a milestone in imaging spectroscopy technology, providing us with unprecedented details of the Earth's surface that are critical to understanding the causes and consequences of climate change. We hope that EMIT's data will inspire more scientific exploration and also provide more protection for our planet. EMIT maps the world's mineral dust source areas