Researchers from Tokyo Metropolitan University have used simulations to show that a newly developed, compact X-ray telescope could be used to map the chemical composition of the entire lunar surface, a vital breakthrough for understanding its geological evolution. Detailed modeling of the detector and a realistic satellite mission show that two years would be enough to map five key elements, while an array of 5-by-5 detectors could improve resolution and get results faster.
The geological evolution of the moon remains a mystery to scientists. This reflects how challenging it is to get accurate information, such as a complete map of the geochemistry of the lunar surface. Since we cannot readily go and collect samples from anywhere, scientists use a technology known as X-ray fluorescence imaging, in which detectors directed at the moon are used to pick up X-rays released by specific elements when they are hit by solar rays.
While observations during the Apollo and Chandrayaan missions have successfully yielded partial maps, we are nowhere near a comprehensive map that might illuminate lunar geology. This is due to significant technical challenges, including a lack of sufficient illumination by solar rays during the lifetime of a mission and degradation of the detector. The illumination issue is particularly pronounced in polar regions, where solar X-rays are much weaker.
A compact telescope solution
To overcome these challenges, a team led by Airi Toida and Prof. Yuichiro Ezoe at Tokyo Metropolitan University proposes using a compact X-ray telescope that could be mounted on a satellite mission around the moon. A telescope would enable wide-area observation of the lunar surface during powerful solar flares. While conventional X-ray telescopes are prohibitively heavy and large, the team’s newly designed compact unit, intended for observations of Earth’s magnetosphere, weighs less than 10 kilograms and might be easily deployed as part of long-term satellite observation.
The detector has also been tested under significantly more severe radiation environments than lunar orbit, enabling robust, wide-area, high-resolution imaging of the lunar surface over extended mission durations.
What the simulations found
Now, the team has incorporated the specifications of its X-ray telescope into a numerical simulation to see whether a satellite mission might successfully map the lunar surface. Assuming 300 solar flares per year and a single telescope on a satellite mission orbiting the moon, the researchers found they could map the whole lunar surface for five elements—oxygen, iron, magnesium, aluminum and silicon—over two years with a grid size of 70 x 70 kilometers.
The telescope unit is so compact that it is feasible to have a 5-by-5 array of them on a single satellite. The team’s simulations also revealed that this 25-telescope system might reduce the mission time to a year, with a map of sodium as well within two years, both with a grid size of 30 x 30 kilometers.
If either is realized, it would be the first complete map of elemental abundance over the whole surface of the moon, a revolutionary step forward in understanding lunar geology. https://phys.org/news/2026-06-lunar-orbiter-concept-reveal-key.html
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