India’s upcoming lunar mission, scheduled for Friday, 14 July 2023, at 2:35 PM, marks the country’s third endeavour to reach the moon. The primary objective of this mission is to accomplish what the previous mission could not: a gentle landing on the lunar surface, followed by the exploration of the moon using a rover.
LVM3 M4/Chandrayaan-3 Mission:
Mission Readiness Review is completed.
The board has authorised the launch.
The countdown begins tomorrow.The launch can be viewed LIVE onhttps://t.co/5wOj8aimkHhttps://t.co/zugXQAY0c0https://t.co/u5b07tA9e5
DD National
from 14:00 Hrs. IST…— ISRO (@isro) July 12, 2023
If the soft landing of India’s lunar mission proves successful, it will position India as the fourth nation, following the United States, Russia, and China, to accomplish this remarkable achievement. This distinction is currently unclaimed since both Israel and India experienced crash-landings during their missions in 2019, while a Japanese spacecraft carrying a lander-rover and a UAE rover failed in 2022.
Although the mission’s goals remain unchanged, scientists at the Indian Space Research Organisation (ISRO) have incorporated valuable lessons from the previous mission. By conducting a series of tests, they have enhanced the design of the lander to ensure its performance in different scenarios. These tests simulated conditions such as an inability to reach the designated landing site, electronic or sensor failures, and excessive velocity. The insights gained from these experiments have informed improvements in the lander’s design and functionality.
What Is The Mission About?
Following its launch on 14 July 2023, the spacecraft will enter into an initial orbit around the Earth at an altitude of 179 km. Through a sequence of manoeuvers, the spacecraft will gradually elevate its orbit, enabling it to overcome Earth’s gravitational pull and set course for the moon. As the spacecraft approaches the moon, it will need to be captured by the moon’s gravity. Subsequently, a series of manoeuvers will be executed to reduce the spacecraft’s orbit to a circular path with dimensions of 100×100 km. At this stage, the lander, which houses the rover, will detach from the propulsion module and initiate its powered descent.
The entire process is estimated to span approximately 42 days, with the landing planned for 23 August 2023 during the lunar dawn. In lunar terms, a day and night each last for 14 Earth days. Considering the limitations of the lander and rover, which are designed to operate for only one lunar day, they are unable to withstand the extremely low temperatures experienced during lunar nights. Therefore, it is crucial for the landing to occur precisely at dawn to maximise the operational lifespan of the lander and rover.
The landing site for the mission has been adjusted slightly from its previous location on a plateau situated between two craters. The new site, positioned near the Southern pole of the moon at approximately 70 degrees S, was chosen due to the presence of several permanently shaded craters. It is believed that these craters harbour valuable minerals and potentially contain reserves of water ice. The decision to modify the landing site was influenced by the detailed mapping of the moon provided by the Chandrayaan-2 orbiter, which captured high-resolution images and supplied a clear understanding of the lunar surface.
While the current mission does not include an orbiter, it will utilise data from the Chandrayaan-2 orbiter. However, compared to the previous mission, the payload weight of the current mission has slightly increased, primarily due to the added weight of the lander. This additional weight is likely a result of modifications implemented to ensure a safe landing on the lunar surface.
What Are The Changes In Chandrayaan-3?
According to ISRO Chairperson S Somanath, the modifications made for the current mission were based on a “failure-based” approach. Rather than relying solely on a success-oriented design as in Chandrayaan-2, the focus for Chandrayaan-3 has been on anticipating potential failures and developing strategies to address them effectively. The mission has been structured to identify potential challenges and devise solutions to overcome them.
During the Chandrayaan-2 mission, the lander and rover encountered a crash landing on the moon instead of achieving a soft landing. ISRO Chairperson S Somanath explained that the primary issue stemmed from the lander’s five engines generating slightly higher thrust than anticipated. The lander’s task involved capturing images to determine the landing site while maintaining stability, which led to accumulated errors. As the spacecraft initiated course corrections, it needed to execute rapid turns; however, its ability to do so was constrained by its software. The spacecraft also faced conflicting requirements of reducing its descent velocity while accelerating forward to reach the intended landing site. Consequently, when it finally landed, it impacted the lunar surface with a higher velocity. The modifications to the current mission have been implemented with these past challenges in mind.
As a response to the previous mission’s landing challenges, the current mission has introduced an expanded landing area. Instead of aiming for a specific 500m x 500m patch as targeted in Chandrayaan-2, the instructions for the current mission allow for a broader landing zone of 4km x 2.4km. This adjustment provides greater flexibility, enabling the spacecraft to safely land in a wider area.
The lander has been equipped with a greater fuel capacity as part of the mission improvements. This enhancement allows the lander to cover longer distances to reach the intended landing site or, if required, an alternative landing site. By providing the lander with additional fuel, it ensures increased manoeuverability and the ability to adapt to different landing scenarios during the mission.
A notable change in the current mission is that the lander will not solely rely on images captured during descent to determine the landing site. Instead, high-resolution images obtained from the Chandrayaan-2 orbiter have been incorporated into the lander’s systems. The lander will utilise these images to verify its position and confirm that it has reached the correct landing location. This updated approach reduces the dependence on real-time imagery during descent and utilises pre-existing data for more accurate location confirmation.
Further modifications have been implemented in the physical design of the lander. These changes include the removal of the central thruster, resulting in a reduction from five to four thrusters. Additionally, the legs of the lander have been strengthened to enable safe landings even at higher velocities. To enhance power generation capabilities, additional solar panels have been incorporated into the lander’s body. These structural adjustments aim to improve the overall performance and resilience of the lander during the mission.
Experiments To Be Carried Out Onboard
The scientific payloads carried by the lander and rover for the current mission are unchanged from the previous mission. The lander will accommodate four scientific payloads dedicated to studying lunar quakes, thermal characteristics of the lunar surface, alterations in the plasma surrounding the moon’s surface, and a passive experiment aimed at precise measurements of the Earth-moon distance. One of the payloads is contributed by NASA thereby enhancing the collaborative nature of the mission’s scientific objectives.
The rover is equipped with two payloads dedicated to analysing the chemical and mineral composition of the lunar surface. These payloads aim to identify and study elements such as magnesium, aluminum, and iron in the lunar soil and rocks. Through these analyses, scientists hope to gain a deeper understanding of the lunar surface’s composition and its geological history.
A newly added experiment has been included in the propulsion module, which will remain in lunar orbit for a period of three to six months. Known as the Spectro-polarimetry of Habitable Planet Earth (SHAPE), this experiment aims to detect potentially habitable smaller planets by analysing the reflected light. By examining the characteristics of the reflected light, the experiment seeks to identify and study planets that may possess conditions suitable for sustaining life.
(With inputs from Indian Express)
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