The Moon has long attracted the attention of scientists: its craters serve as a visual reminder of past upheavals. But a recent study led by astrophysicist Jianqing Feng and his colleagues has revealed a different kind of chaos beneath the lunar surface – evidence of successive lava flows. This groundbreaking study, based on data from the Chang’e-4 Mars rover, has shed new light on the volcanic history of the Moon and its implications for our understanding of this celestial body.
Extending the results of previous studies
Feng and his team sought to build on previous studies of the lunar subsurface that were limited in scope. By analyzing a larger dataset from the Chang’e-4 spacecraft, they were able to penetrate deeper into the lunar surface using lower frequencies of the penetrating radar. This innovative approach allowed them to explore the layers beneath the eroded lunar surface and gain insight into volcanic activity that took place billions of years ago.
The role of lunar penetrating radar
One of the key instruments used in this study was the Lunar Penetrating Radar on board the Chang’e-4 rover. This instrument emits pulsed signals into the lunar interior as the rover traverses the Moon’s terrain. When these signals encounter a contrast between two subsurface materials with different properties, they are reflected back to the surface where they can be detected by a receiver.
Discoveries beneath the surface
The researchers found that there is nothing particularly unusual within the moon’s upper 40 meters (131 feet), other than an old crater hidden by debris and soil from nearby impacts. However, going deeper, below 90 m (295 feet), they made some intriguing discoveries. In the upper 300 meters, they found numerous layers indicative of a series of basalt eruptions that occurred billions of years ago.
Notes on lunar volcanism
Lunar volcanism has attracted much interest in recent years. The discovery of a mysterious hot spot on the far side of the Moon has suggested the presence of a buried mass of solidified magma resulting from a unique form of volcanism. In addition, the extraction of lunar rocks has revealed that lava has been flowing from lunar volcanoes for a billion years longer than previously thought.
The layers of solidified lava discovered by Feng and his collaborators provide further evidence of the moon’s volcanic history. Thicker layers were found at greater depths and gradually thinned toward the surface. This suggests that the internal thermal energy that stimulated lunar volcanism was depleted and that eruptions decreased in magnitude over time. The thickest layers were about 70 m wide, while lava flows narrowed to 5 m near the landing site.
Implications and future research
Although these results provide valuable insights into the Moon’s volcanic past, they do not allow us to determine the exact timing of these events. Nevertheless, they contribute to our understanding of recent bursts of volcanic activity on the Moon and the gradual fading of its thermal energy. Other recent studies also aim to refine our knowledge of lunar volcanism, further expanding our understanding of this fascinating celestial body.
