An airborne spectrometer built to extend readable mineralogy to places NASA cannot yet reach, including Mars, spotted topaz from 65,000 feet. USGS geologists confirmed it on the ground near Barstow, and the protocol is exactly how Mars sample science will work.
In a wind-scoured outcrop near Barstow, California, three USGS geologists and a NASA-JPL sensor specialist crouched on the same patch of high desert to confirm something the airborne instrument had already hinted at from the stratosphere: a vein of topaz, hiding in plain sight, on public land with mineral potential. The find is small in scale. The protocol it just validated is not.
The pair-up is the latest move in a NASA-USGS field campaign that has spent the spring sending NASA's ER-2 high-altitude aircraft over the American West at roughly 65,000 feet. From that altitude, the Jet Propulsion Laboratory's AVIRIS-5 hyperspectral imager scans hundreds of square miles per flight, reading mineral fingerprints from reflected sunlight. When a signature matches something geologists care about, the plane's payload crew hands the coordinates to a team of USGS geologists with hand lenses and rock hammers.
Topaz matters here not for its own sake but as a pathfinder. The mineral tends to form in the same hydrothermal systems that produce porphyry copper deposits, the dominant source of a metal which NASA ranks as the third most used metal in the world after steel and aluminum. Those same deposits often carry molybdenum and tellurium, both on the U.S. critical minerals list, and tellurium is a feedstock for the cadmium-telluride cells used in utility-scale solar panels.
This is the connective tissue the Mojave campaign is meant to build. The Airborne Visible Infrared Imaging Spectrometer family dates to the early 1980s at JPL, and the current AVIRIS-5 is flying for the first time under the Geologic Earth Mapping Experiment (GEMx), a USGS-led effort under the broader Earth Mapping Resources Initiative. Since 2023, GEMx flights have covered more than 386,000 square miles of U.S. soil, including most of California, building what the agencies call the largest airborne surface mineralogy dataset gathered in a single NASA-USGS campaign.
What the campaign buys planetary science is harder to see from a press release but matters more than any single mineral find. Robert Green of NASA JPL, one of the original AVIRIS team members, has spent four decades turning a sensor into a translator between a spectral curve and a hand sample. That translation is exactly what a rover on Mars cannot yet do at scale: pick a candidate mineral, send humans or a follow-up mission to the outcrop, and decide whether the signature means what the team thinks it means. "It's like geologic CSI," Green told NASA of the work.
Erik Tharalson, one of three USGS geologists in the Mojave field party, made the slower point in the same release: "People have been prospecting this area for generations. But there's a lot more to discover." That gap, between the spectral claim and the ground truth, is what the campaign exists to close, one hammered outcrop at a time. The work has been substantial. NASA's ER-2, based at Armstrong Flight Research Center, completed a 26-flight, 125-hour spring deployment from Colorado Springs on June 5; in 2025 the same aircraft logged 36 science missions and more than 200 flight hours, producing what the agencies describe as 7 billion measurements in a single year.
The next question for the Mojave site is not whether the topaz is real, but what lies below it. Confirming a porphyry copper signature under the outcrop will require follow-up ground-penetrating work that the campaign itself does not include. The two agencies have not committed to a timeline, and the political and permitting contours of a federal critical-minerals push on public land are still being drawn.
What is already settled is the shape of the workflow. A JPL sensor, originally built to extend the readable mineralogy of places NASA cannot yet reach, was carried over California by a NASA Armstrong aircraft, fed into a USGS-led mapping initiative, and validated by USGS geologists with hand lenses. The same chain, with the same points of friction, will run again the next time a Mars rover returns a spectral anomaly that needs to be tied to a real rock.