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A lightweight X-ray telescope could soon deliver the first complete chemical map of the Moon. Numerical simulations prove the compact sensor can successfully map key geological elements across the entire lunar surface within a few years
Understanding how the Moon formed and evolved requires an accurate map of its surface chemistry. Scientists use X-ray fluorescence imaging to identify elements, detecting unique X-ray signals emitted by lunar soil when it is hit by solar radiation.
Past space missions, including Apollo and Chandrayaan, produced only partial elemental maps.
Creating a complete global survey has been hindered by technical limitations, such as weak solar illumination near the lunar poles and the gradual degradation of delicate space sensors.
The compact telescope strategy: An X-ray telescope
To resolve these illumination and durability issues, a research team from Tokyo Metropolitan University designed an ultra-compact X-ray telescope unit. While conventional space telescopes are too heavy and bulky for long-term deployment on satellites, this new imaging unit weighs less than 10 kilograms.
The sensor has already passed testing under radiation conditions far harsher than those found in lunar orbit, ensuring long-term stability. Its compact scale allows it to utilise brief, highly intense solar flares to capture wide-area, high-resolution chemistry data across previously unmappable regions.
Simulation validates mapping timelines
The researchers used a detailed numerical simulation to test how the telescope would perform on a realistic lunar satellite mission. Modelling a baseline environment of 300 solar flares per year, the simulation showed that a single orbiting telescope can map five major elements (oxygen, iron, magnesium, aluminium, and silicon) across the entire Moon within two years at a grid resolution of 70 by 70 kilometres.
Because the telescope design is exceptionally light, a satellite could easily carry multiple units at once. The simulation revealed that upgrading the spacecraft to house a five-by-five array of 25 telescopes would improve the grid resolution to 30 by 30 kilometres. This multi-sensor configuration would cut the mapping time for the primary five elements down to a single year, while successfully adding a global map of sodium within two years.
A breakthrough for lunar geology
The study, published in Earth, Planets and Space, establishes a practical framework for upcoming lunar exploration missions.
Delivering the first-ever complete map of elemental abundance will allow planetary scientists to evaluate chemical variations across the entire lunar surface, including vital polar landing sites.
This comprehensive geochemical data will help resolve long-standing mysteries surrounding the geological origin and structural differentiation of the Moon.