March 27, 2023 — Southwest Research Institute recently delivered the Lunar Magnetotelluric Sounder (LMS) to Firefly Aerospace in Cedar Park, Texas, for integration into the Blue Ghost lunar lander scheduled to arrive at the Moon in 2024. The sounder will determine the electrical conductivity of the interior of the Moon by measuring low-frequency electric and magnetic fields.
“For more than 50 years, scientists have used magnetotelluric techniques, which use natural characteristics of the Earth’s electromagnetic fields to determine the electrical resistivity of the subsurface for research and resource exploration,” said SwRI’s Bob Grimm, principal investigator of the instrument. “LMS will be the first extraterrestrial application of magnetotellurics.”
NASA’s Artemis program is series of increasingly complex missions to build a sustained human presence at the Moon for decades to come. To support these goals, LMS is part of a 12-day lunar lander mission to help understand the Moon’s subsurface in a previously unexplored location. LMS is being funded and delivered to the lunar surface via NASA’s Commercial Lunar Payload Services (CLPS) initiative and is expected to land in Mare Crisium, an ancient, 350-mile-diameter impact basin on the Moon that subsequently filled with lava. It is a dark circular spot in the northeast region of the Moon’s nearside that stands apart from the large, connected areas of dark lava to the west of where most of the Apollo missions landed.
These vast, linked lava plains are now thought to be compositionally and structurally anomalous to the rest of the Moon. From its vantage point at Mare Crisium, LMS may provide the first geophysical measurements representative of the overall Moon.
Electromagnetic fields penetrate to greater depths with decreasing frequency, allowing LMS to probe the interior of the Moon to depths up to 700 miles or two-thirds of the lunar radius. The electrical conductivity depends on the temperature and composition of the materials traveling through the field. The measurements will shed light on the differentiation and thermal history of our Moon, a cornerstone to understanding the evolution of solid worlds.