Spanning from the December of 2019 till 2025, numerous agencies from all over the world, including USA, Germany, Russia, China, Japan and South Korea have planned to conduct various lunar missions. However, why will the majority of them target only the lunar south pole?
Moon is a natural satellite of the Earth. It is the nearest cosmic neighbour. This has always interested numerous astronomers and space scientists globally. Since ancient times, we have been following the moon cycle. Even our calendar is based on the movements of the moon. With the evolution of more sophisticated instrumentation, we have comprehended the impact of moon on Earth’s water bodies, specifically on the deep oceanic phenomena. A detailed perception about its influence on our planet has been one of the biggest motivation for all the previous lunar missions.
Over 100 lunar missions have been carried out by space agencies around the world. Among them, about 40% of missions were unsuccessful, 10% were partially successful, thus accounting to only about 50% successful executions. These statistics clearly indicate that despite being the closest to the Earth, successfully accomplishing the lunar missions has been a challenging task! In May 2008, China launched two microsatellites named, Longjang-1 and Longjang-2, as a part of Chang’e 4 mission, as shown in the image below. Longjang-1 failed to enter into lunar orbit. But, Longjang-2 operated successfully till July 31, 2019.
The aim of this mission was to observe the cosmic background at very low frequencies. This is difficult from the Earth’s surface due to its ionospheric absorption. Longjang-2 operated near the lunar south pole. It do not face towards the Earth. Thus, satellite could receive the required celestial signals, without interference from the Earth’s signals. In conclusion, the lunar south pole is an ideal location for conducting deeper explorations of the space. These operations can be carried out at different radio frequencies, by avoiding unwanted frequency signals from the Earth.
Chandrayaan-1 was launched by the Indian Space Research Organisation (ISRO) in October 2008. This mission revealed the existence of water and hydroxyl containing molecules on the lunar surface. This experiment was done by the Moon Mineralogy Mapper. Chandrayaan-1 explored both lunar poles and additional regions of interest on the moon’s surface. The data obtained by Chandrayaan-1 enabled scientists to study the interaction between the solar wind and planetary bodies, like the moon, which lack magnetic field. The analysis of data gathered by Chandrayaan-1 was used in the execution of the subsequent mission of ISRO, the ‘Chandrayaan-2’. This was launched on July 22, 2019. The mission was 95% successful. One of the payload, the lander Vikram, Chandrayaan-2 was unable to display the desired landing on the moon’s surface. The communication with the lander was lost when it was merely 2.1 km above the moon’s surface, near the lunar south pole. Likewise, beginning from December 2019 till 2025, numerous space agencies from USA, Germany, Russia, China, Japan and South Korea have planned to execute various lunar missions.
Why only the lunar south pole?
According to the data collected from various lunar missions, the surface near the south pole of the moon contains water. The lunar south pole has a very cold surface, as it is permanently under the shadow. The sunlight strikes at a low angle due to the tilted axis of rotation (5 degrees) of the moon with the sun. This increases the probability of ice and volatile deposits on and under the moon’s surface, near the south pole. Water is the source of life. Finding water on any other cosmic body is a sign of the existence of life. Another reason is to establish a base station on the moon for upcoming far-off space missions.
Thus, the lunar south pole is important for interpreting newer facts based on the minerals present on the moon, to get access to low-frequency deep space signals and to probe a launch site for further missions, farther into the space, to explore various extraterrestrial bodies.
Editor: Dr. Prajakta Dandekar-Jain