January 13, 2024 — Through NASA’s Commercial Lunar Payload Services (CLPS) initiative, Southwest Research Institute developed the Lunar Magnetotelluric Sounder (LMS) to characterize the structure and composition of the Moon’s mantle by measuring electric and magnetic fields. The LMS instrument — manifested on the Blue Ghost lunar lander developed by Firefly Aerospace and targeted to launch on January 15, 2025 — will be the first SwRI instrument to touch the lunar surface.
“For more than 50 years, scientists have used magnetotellurics on Earth for a wide variety of purposes, including to find oil, water, geothermal and mineral resources as well as to understand geologic processes such as the growth of continents,” said SwRI’s Dr. Robert Grimm, principal investigator of LMS. “The LMS instrument will be the first extraterrestrial application of magnetotellurics.”
NASA’s Artemis program is developing a series of increasingly complex missions to ultimately build a sustained human presence at the Moon for decades to come. To support these goals, LMS is part of a 14-day lunar lander mission to help understand the Moon’s subsurface in a previously unexplored location.
Mare Crisium is an ancient, 350-mile-diameter impact basin that subsequently filled with lava, creating a dark spot visible to the naked eye on the Moon. Early astronomers who dubbed dark spots on the moon “maria,” Latin for seas, mistook them for actual seas.
Mare Crisium stands apart from the large, connected areas of dark lava to the west where most of the Apollo missions landed. These vast, linked lava plains are now thought to be compositionally and structurally anomalous with respect to the rest of the Moon. From this separate vantage point, LMS may provide the first geophysical measurements representative of most of the Moon.
Magnetotellurics uses natural variations in surface electric and magnetic fields to calculate how easily electricity flows in subsurface materials, which can reveal their composition and structure. LMS will allow scientists to probe the interior of the Moon to depths up to 700 miles or two-thirds of the lunar radius. The measurements will shed light on the material differentiation and thermal history of our Moon, a cornerstone to understanding the evolution of solid worlds.
The LMS instrument ejects cables with electrodes at 90-degree angles to each other and distances up to 60 feet. The instrument measures voltages across opposite pairs of electrodes, much like the probes of a conventional voltmeter. The magnetometer is deployed via an extendable mast to reduce interference from the lander. The method reveals a vertical profile of the electrical conductivity, providing insight into the temperature and composition of the penetrated materials in the lunar interior.
“The five individual subsystems of LMS, together with connecting cables, weigh about 14 pounds and consume about 11 watts of power,” Grimm said. “While stowed, each electrode is surrounded by a ‘yarn ball’ of cable, so the assembly is roughly spherical and the size of a softball.”
The LMS payload was funded for delivery to the lunar surface through NASA’s CLPS initiative. SwRI designed the instrument, built the electronics box and leads the science investigation. Goddard Space Flight Center provided the LMS magnetometer to measure the magnetic fields, and Heliospace Corp. provided the magnetometer mast and four electrodes used to measure the electrical fields.
Under the CLPS model, NASA is investing in commercial delivery services to the Moon to enable industry growth and support long-term lunar exploration. As a primary customer for CLPS deliveries, NASA aims to be one of many customers on future flights. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the development of seven of the 10 CLPS payloads carried on Firefly’s Blue Ghost lunar lander.
For more information, visit Planetary Science or contact Deb Schmid, +1 210 522 2254, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.