The new magnetotelluric sounder (LMS) will provide the first geophysical measurements of the Moon's internal structure in the unique Mare Crisium impact basin, contributing to the understanding of the evolution of our satellite.

Lunar Magnetotelluric Sounder (LMS), developed by the Southwest Research Institute (SwRI) as part of NASA's Commercial Lunar Payload Services (CLPS) program, will be the first instrument to use magnetotellurics beyond Earth. This technology, which measures natural variations in magnetic and electric fields, will allow the study of the Moon's interior to a depth of 1120 km, or two-thirds of its radius. Dr. Robert Grimm, principal investigator of the LMS, said this groundbreaking study opens a new era in the study of geophysical processes on other planets.
Mare Crisium, an ancient impact basin 560 km in diameter, was chosen because of its unique geological structure, which is different from the regions explored by the Apollo missions. This area on the near side of the Moon will provide data that is more representative of the larger part of its surface. The LMS will be mounted on the Lunar Lander Blue ghost by Firefly Aerospace, which launched on January 15, 2025.
The magnetotelluric method uses cables with electrodes to measure the electrical conductivity of the lunar soil. The uniqueness of the approach lies in the ability to determine the vertical profile of temperature and material composition, which sheds light on the processes of formation and thermal evolution of the Moon. Measurements of the voltage between the electrodes and magnetometer data will provide a comprehensive understanding of the structure of the lunar mantle.
The LMS instrument weighs only 6,4 kg and consumes 11 W of power, making it compact and energy-efficient. The design includes a magnetometer, a central electronic unit and four spring electrodes arranged at 90 degrees to each other. The cables are wound into compact “balls of yarn” for ease of transport and deployment.
The LMS program supports NASA's ambitious Artemis goals for sustainable lunar exploration. Mare Crisium, with its ancient lava plains, will open up a new layer of knowledge about the interior of Earth's moon. Dr. Grimm emphasizes: