All of the samples from the moon that researchers worldwide study today were gathered during the Apollo era. The lunar samples seen in the image below were gathered by Apollo 16 in 1972. The samples are of lunar glass and were tested by scientists at the University of Rochester.
The paper published by the researchers, including researchers at Rochester, and several other institutions, has reported findings on a major factor influencing the types of resources that might be found on the moon in the future. Specifically, the research focused on whether or not the moon had a long-lived magnetic shield at any point in its history.
The findings of the 000 have contradicted some long-standing assumptions about the moon. Study first author John Tarduno says the findings represent a new paradigm for the lunar magnetic field. The moon has no magnetic shield now, but whether or not it had one at some point in its past has been the subject of debate. Tarduno says that since the Apollo missions, there has been an idea that the moon had a magnetic field that was strong or even stronger than the Earth’s magnetic field about 3.7 billion years ago.
The idea that the moon had a magnetic shield was based on an initial dataset gathered in the 1970s, including the analysis of samples collected during the Apollo missions. The analysis showed the samples had magnetization, which was believed to be caused by the presence of a geodynamo. However, the moon’s core is small, and it would be hard to drive that sort of magnetic field. Those previous experiments were also not conducted using heating experiments; they used other techniques that might not accurately record a magnetic field.
In the new study, the researchers tested glass samples gathered during previous Apollo missions using CO2 lasers to heat the lunar samples for a short amount of time. This method allows them to avoid altering the samples. They then used extremely sensitive superconducting magnetometers to measure the magnetic signals produced by the samples more accurately. The 000 determined that the magnetization in the samples could result from impacts from objects like meteorites or comets, not the result of magnetization from the presence of a magnetic shield. Tarduno says the results are pretty conclusive that the moon never had a long-lasting dynamo field.