NASA's new imaging spectrometer AVIRIS-5 has begun operational flights over the western United States to help geoscientists precisely map rocks containing lithium and other critical minerals. The flights are being conducted as part of the multi-year GEMx (Geological Earth Mapping Experiment) campaign in partnership with the U.S. Geological Survey (USGS). It is the largest airborne spectroscopic undertaking of its kind in the U.S., and the announcement of AVIRIS-5's start of operations arrived on December 9, 2025, the day before today's date (December 10, 2025). According to official data, the new generation of the instrument has already completed more than 200 flight hours over California, Nevada, and other states of the American West this year, as part of efforts to accelerate the discovery and assessment of resources important for the energy transition.

Small mass instrument, immense power

AVIRIS-5 (Airborne Visible/Infrared Imaging Spectrometer-5) is located in the nose of NASA's ER-2 aircraft and is comparable in dimensions to a microwave oven, yet its performance builds on the tradition of JPL's space spectrometers. Compared to the previous generation, it offers twice the spatial resolution, so at standard flight altitudes, it can resolve details from less than 30 centimeters to approximately 10 meters, depending on the mission configuration and imaging objectives. The basic product of the instrument is not "ordinary photographs," but so-called spectral "cubes" – series of images in hundreds of adjacent wavelength channels in the visible and short-wave infrared range. In such data, minerals, rocks, vegetation, and anthropogenic materials leave recognizable spectral "fingerprints" by which they can be distinguished and mapped with high reliability.

From Newton's prism to "black silicon"

The imaging spectroscopy technology behind AVIRIS-5 stems from a centuries-old understanding of light decomposition but also relies on the latest materials and micro-optical concepts. The device uses a combination of mirrors, detector arrays, and precisely etched gratings (electronically stacked), which direct and decompose reflected solar radiation into its constituent "colors." A critical role is played by surfaces made of so-called black silicon – one of the darkest artificial materials – whose micronanoscopic "forest" of needle-like structures captures stray light and prevents its scattering inside the instrument. This reduces noise and internal reflections and increases measurement accuracy, which is a prerequisite for clearly distinguishing very subtle absorption features later in processing that separate, for example, lithium clays from similar minerals without lithium.

Flying above 95% of the atmosphere

The operational platform for AVIRIS-5 is the ER-2 – the scientific version of the famous U-2 – which regularly reaches flight altitudes of around 18–20 kilometers, or approximately 60,000 feet. At these altitudes, more than 95% of the air is below the aircraft, significantly reducing atmospheric interference and noise in the images and providing a wide field of view. The home base is NASA's Armstrong Flight Research Center in Edwards (California). During 2025, serial flights were conducted over desert and semi-desert landscapes of California, Nevada, and neighboring states – terrains that are ideal for mineral spectroscopy because the exposed relief and lack of dense vegetation allow mineral "signatures" to come to the fore. The joint NASA and USGS team has collected data on more than 366,000 square miles (about 950,000 km²) from 2023 to date, providing a unique base for further analysis and field verification of findings.

GEMx and Earth MRI: multi-year synergy of NASA and USGS

GEMx is a research project planned for a period of four years. It is funded through the USGS Earth Mapping Resources Initiative (Earth MRI), into which substantial additional investment has been poured thanks to the federal Bipartisan Infrastructure Law. Earth MRI modernizes the mapping of the surface and subsurface of the U.S. and combines geological, geochemical, and geophysical approaches to build a three-dimensional insight into the terrain structure. Airborne imaging spectroscopy is a key "fast track" in this mosaic: it allows for wide-area narrowing of zones of interest and determination of priority locations for field research and drilling. In this way, costs are reduced, decision-making is accelerated, and – perhaps most importantly – potential environmental risks associated with mining activities are assessed in advance.

Early results: hectorite in tailings and a "second chance" for old dumps

Among the earliest highlighted findings of the first AVIRIS-5 flights in 2025 is the confirmation of the presence of hectorite – a clay mineral containing lithium – in the tailings of an abandoned mine in California and at several other locations. The importance of such a discovery is twofold. On the one hand, it shows that old mining dumps, perceived for decades merely as an environmental problem, can become a source of new stocks of strategic raw materials with modern processing technologies. On the other hand, the same data help identify places with the potential for the formation of acid mine drainage (when exposed rocks and tailings chemically change in contact with air and water and release acids and metals), which allows for earlier planning of remediation measures. NASA scientist Dana Chadwick points out that the same type of data, in addition to "mineral hunting," also serves land management, analysis of snow cover important for water resources, and fire risk assessment – so critical minerals are just the beginning of the wider application of AVIRIS-5.

Why "critical" minerals and how AVIRIS-5 can help

The USGS lists approximately 50 mineral raw materials as critical, the supply disruption of which would have a significant impact on the economy and national security. In practice, these are groups such as rare earth elements, lithium, cobalt, and nickel, fundamental for batteries, wind turbines, electric motors, high-efficiency electronics, and a range of military and space systems. Rapid and objective assessment of geological potential over large areas is essential also for the transparent management of expectations of local communities and investors. Imaging spectroscopy allows identifying geological contexts carrying greater potential from the air, without invasive works – for example, hydrothermally altered rocks, clay-rich argillites, carbonate zones with traces of metal loading – after which field teams specifically conduct mapping and sampling. This reduces costs and risks and increases the probability that limited resources will be directed toward promising targets.

Spectral "fingerprints" and science without guessing

AVIRIS-5 measures reflected solar radiation in a wide range of wavelengths from the visible to the short-wave infrared region. Each pixel of the surface gets its own continuous spectrum with more than two hundred channels, so very subtle absorption lines can be sought in processing. Lithium clay hectorite, for example, shows specific absorption features in the short-wave infrared region that differ from smectites without lithium; carbonates and sulfates have separate characteristic bands; iron oxides form recognizable changes in the visible and near-infrared part of the spectrum. When such signals appear consistently, on multiple adjacent pixels and in different lighting geometries, the probability that it is a true mineral "signature" increases significantly. Therefore, AVIRIS data "cubes" are often combined with geological maps, historical mining records, and field samples to confirm or reject hypotheses.

Heritage from other worlds

JPL's imaging spectrometers have marked numerous planetary missions. For example, the Moon Mineralogy Mapper instrument in 2009 was the first to reliably detect water on the Moon, while other related instruments mapped the Martian crust, discovered lakes on Titan, and tracked mineral-rich dust clouds over the Sahara. A new spectrometer is already on its way to Europa, Jupiter's ocean moon, to search for chemical ingredients linkable to prerequisites for life. AVIRIS-5 thus represents the latest step in a series of sensors that have been proven in space, and are now adapted for very precise science from the air above the Earth's surface.

From "classics" to the fifth generation

The AVIRIS family began flying in 1986 and over the decades has been located on multiple platforms: from the high-flying ER-2 via the Twin Otter turboprop and experimental Proteus to NASA's WB-57. "Classic" AVIRIS and the later AVIRIS-NG (Next Generation) have already proven themselves in numerous missions – from mapping the consequences of fires and eruptions to damage assessment after disasters, air quality analysis, and monitoring of agricultural crops. The fifth generation goes a step further: twice the spatial resolution, improved signal-to-noise ratio, and calibration stability shorten the time needed to distinguish target mineral groups, while simultaneously opening space for additional topics, such as assessing the state of vegetation or snow that preserves water resources of mountain areas.

Openness of data and users outside the scientific community

One of the greatest values of GEMx is open access to calibrated data and derived products. NASA publishes measured and processed data through its own portals, while the USGS regularly publishes thematic maps, reports, and press releases within Earth MRI. Thereby, industry, local authorities, private researchers, and universities gain access to standardized products – reflectance mosaics, mineral maps, and quality reports – which they can incorporate into their GIS systems and research plans. Such a model ensures transparency, reproducibility, and verifiability of findings, and since they are funded by public money, the results also contribute to the common good – from environmental protection to the education of future experts.

Ecology and social context

The search for minerals cannot be separated from the environmental and social framework. Precisely for this reason, GEMx simultaneously searches for potential deposits and records indicators of environmental risk, such as the spread of acid drainage, vegetation dryness that increases fire danger, or changes in snow cover important for water resources. The same tool that helps identify resources can, with responsible interpretation, also help in their sustainable exploitation. For communities living near old mines, this means earlier warning of possible problems, clearer information in environmental impact assessment procedures, and better quality negotiations on remediation or revitalization of the space.

What next in 2026

As GEMx enters the next phase, further integration of aerial data with geological maps, geophysics, and field sampling is expected, as well as increasing use of automated algorithms for detecting spectral signatures. The focus of flights remains on the dry areas of the American West, where the exposed relief allows for the best spectral readability. In perspective, the same procedures can be applied to other topics, such as soil degradation monitoring or pollution detection, but the backbone remains mission-oriented: to accelerate, facilitate, and make more transparent the search for mineral raw materials key to the energy transition, with the smallest possible environmental footprint.