Chang’e-6 – Historic Lunar Sample Retrieval

In June 2024, China’s Chang’e-6 mission made headlines by successfully retrieving the first surface samples from the moon’s far side. This area, known for being perpetually hidden from Earth, has now provided critical vital information about the moon’s geological history. The samples reveal evidence of volcanic activity dating back 4.2 billion years, indicating a dynamic past for the moon.

Chang’e-6 Mission Overview

The Chang’e-6 spacecraft landed in the South Pole-Aitken Basin, an important impact crater on the moon. This region has a thinner crust, making it ideal for studying volcanic activity. The mission collected approximately 1,935 grams of lunar soil using a scoop and drill. After gathering the samples, the spacecraft returned to Earth, landing in Inner Mongolia.

Volcanism on the Moon

The samples revealed fragments of basalt, a type of volcanic rock. Researchers identified two distinct ages of the basalt – one dating to 4.2 billion years and another to 2.8 billion years. This suggests a prolonged period of volcanic activity that lasted at least 1.4 billion years. The findings indicate that the moon was once a more geologically active body than it is today.

Methodology for Analysis

To determine the ages of the volcanic rocks, scientists employed radioisotope dating techniques. These methods allowed for precise dating of the samples. The composition of the basalt from the far side differs from that of previously collected samples from the near side, suggesting different sources of magma.

Comparison with Near Side Samples

Prior missions, including those by the U.S. Apollo and Soviet Luna, gathered samples from the moon’s near side. These samples indicated volcanism had occurred up to 4 billion years ago. The Chang’e-6 findings suggest that the volcanic history may vary between the two sides of the moon.

The Decline of Lunar Volcanism

Currently, there is no active volcanism on the moon. The cessation of volcanic activity is attributed to the depletion of internal heat sources. Initially, volcanic eruptions were sustained by the decay of radioactive elements and residual heat from the moon’s formation. Over time, these heat sources dwindled, leading to a cooling and solidification of the lunar mantle. The moon’s smaller size compared to Earth contributed to this rapid cooling.

Implications for Lunar Studies

The Chang’e-6 samples provide a unique opportunity to study the moon’s volcanic history. About the differences in composition between the far side and near side samples can shed light on the moon’s formation and evolution. This research may also contribute to broader planetary science, enhancing our knowledge of volcanic activity in the solar system.

Questions for UPSC:

1. Discuss the significance of lunar volcanism in understanding the geological history of the moon.
2. Critically examine the differences in volcanic activity between the moon’s near side and far side.
3. Explain the factors that contribute to the cessation of volcanic activity on planetary bodies.
4. With suitable examples, discuss how the study of lunar samples can enhance our understanding of planetary formation.

Answer Hints:

1. Discuss the significance of lunar volcanism in understanding the geological history of the moon.

1. Lunar volcanism provides evidence of the moon’s dynamic geological past, indicating periods of important volcanic activity.
2. The Chang’e-6 mission revealed volcanic rock samples dating back 4.2 billion years, offering vital information about early lunar conditions.
3. About the timing and duration of volcanism helps reconstruct the moon’s thermal evolution and crust formation.
4. Volcanic activity on the moon suggests a complex mantle composition, influencing theories about its formation and differentiation.
5. Studying lunar volcanism aids in comparative analysis with other celestial bodies, enhancing our knowledge of planetary geology.

2. Critically examine the differences in volcanic activity between the moon’s near side and far side.

1. The near side has been extensively studied through Apollo and Luna missions, showing volcanism up to 4 billion years ago.
2. Chang’e-6 samples from the far side reveal volcanic activity that lasted at least 1.4 billion years, suggesting a more prolonged volcanic history.
3. Differences in basalt composition indicate distinct sources of magma between the two sides, hinting at varying geological processes.
4. The near side’s thicker crust may have influenced the style and duration of volcanic activity compared to the thinner crust on the far side.
5. About these differences can inform theories about the moon’s thermal history and geological evolution.

3. Explain the factors that contribute to the cessation of volcanic activity on planetary bodies.

1. Cessation of volcanic activity is primarily due to the depletion of internal heat sources, such as radioactive decay.
2. As planetary bodies cool, the mantle solidifies, reducing the ability of magma to reach the surface.
3. The size of a planetary body affects its cooling rate; smaller bodies like the moon lose heat faster than larger ones like Earth.
4. For the moon, the initial volcanic activity was sustained by residual heat from its formation, which diminished over time.
5. About these factors can help predict volcanic activity on other celestial bodies, such as Mars and Venus.

4. With suitable examples, discuss how the study of lunar samples can enhance our understanding of planetary formation.

1. Lunar samples, such as those from Chang’e-6, provide direct evidence of the moon’s geological history, aiding in models of planetary formation.
2. Comparative analysis of basalt from the near and far sides reveals variations in magma sources, informing theories of planetary differentiation.
3. Samples from different missions (Apollo, Luna, Chang’e) allow scientists to study the evolution of volcanic activity across time and space.
4. gained from lunar geology can be applied to other planetary bodies, enhancing our understanding of their formation and evolution.
5. Research on lunar samples contributes to broader planetary science, including the processes that shape terrestrial planets and their atmospheres.