During its mission to collect samples on the far side of the moon, the Chang’e-6 lunar probe from China proudly displayed the Chinese flag. This symbolizes China’s important role and presence in exploring the moon.

About the Flag

The flag displayed by the Chang’e-6 lunar probe was made from an unusual material called basalt fibres, which are essentially rock. This unique choice of material adds to the significance of the flag as it represents China’s innovative approach to lunar exploration.

Basalt—a dark, fine-grained volcanic rock that is created by fast cooling of basaltic lava that is low in silica, but high in iron and magnesium content—is found in ocean basins and volcanic regions, basalt is commonly used in construction, road bases and concrete aggregates. Basaltic lava flows easily and covers wide areas, often forming broad, flat volcanic structures like shield volcanoes. Basalt’s dark colour and fine texture come from such minerals as pyroxene and plagioclase feldspar.

In Chinese, basalt rock is called Xuanwu rock, named after a mythical creature that symbolizes the north and the winter season.

“We crushed and melted the rocks to draw them into thin threads, each about one-third the diameter of a human hair,” explained Professor Zhou Changyi from the National Space Science Centre at the Chinese Academy of Sciences. He said this to China Global Television Network (CGTN), a state-run international media organization. According to Zhou the flag could last over 10,000 years on the moon because the material is very resistant to corrosion, heat and cold. He also mentioned that this material could be used to construct China’s future lunar research base since this type of rock is plentiful on the moon. According to information in the public domain, it took researchers over a year to develop the method for making basalt fibres.

Zhou said the purpose of hoisting the national flag was to instil patriotism among the Chinese masses worldwide. The country had also displayed its national flag during the 2020 Chang’e-5 mission. This flag was made from polymer fibre.

Explainer By Girish Linganna, Defence & Aerospace Analyst

Basalt Fibres—Strength & Durability from Plagioclase Feldspar

“Basalt contains a mineral, called plagioclase feldspar, which is responsible for forming threads or fibres when the rock is melted and extruded. These fibres, known as basalt fibres, are highly prized for their strength and durability. Plagioclase feldspar is a common mineral found in basalt, forming when magma cools and solidifies. This mineral enhances the strength and durability of basalt rock, making it ideal for creating basalt fibres,” Girish Linganna says.

According to him, these fibres are then widely used in construction and automotive industries for their toughness and reliability. In construction, basalt fibres are used in composites, reinforcing materials and concrete. They provide added strength and stability to structures, making them resistant to damages and increasing their lifespan.

In the automotive industry, basalt fibres are used for manufacturing parts that require high strength-to-weight ratio and heat resistance. These fibres can increase the structural integrity of vehicles while reducing their overall weight, thereby improving fuel efficiency.

“Overall, the unique properties of basalt fibres, derived from the mineral plagioclase feldspar, present in basalt make them a valuable material in various industries, contributing to the development of stronger and more resilient structures and products,” he states.