With the integration of the Chandrayaan-3 spacecraft and the GSLV-Mk3 launch vehicle, ISRO is on track to undertake India’s third lunar mission. The modifications and enhancements made to the lander, along with the comprehensive testing, reflect ISRO’s commitment to achieving a successful soft landing on the lunar surface.
In an important development, the Indian Space Research Organisation (ISRO) announced on Wednesday that it has successfully integrated the Chandrayaan-3 spacecraft with the GSLV-Mk3 launch vehicle, also known as LVM3. ISRO is now preparing for a mid-July launch window, between July 12 and 19, for India’s third lunar mission. This mission aims to make a second attempt at achieving a soft landing on the lunar surface.
Unlike its predecessor, Chandrayaan-2, the upcoming mission will not include an orbiter. Instead, ISRO has replaced it with a propulsion module. The spacecraft will carry a lander named Vikram and a rover called Pragna. Based on lessons learned from the Chandrayaan-2 mission, ISRO has implemented several modifications to improve the chances of a successful landing.
One notable upgrade is the strengthening of Vikram’s legs to enable it to withstand higher landing velocities than before. During the previous mission, the lander experienced a failed landing attempt in September 2019. ISRO has addressed this issue by enhancing the landing velocity from 2 meters per second to 3 meters per second. This enhancement ensures that even at 3 meters per second, the lander will not crash or damage its legs.
In addition to the strengthened legs, ISRO has made other improvements to the lander. The agency has increased the amount of fuel onboard to provide more resilience and flexibility in handling disruptions during the mission. Furthermore, ISRO has incorporated a new sensor called the laser Doppler velocity meter, which will analyze the lunar terrain. This sensor will provide valuable data on three velocity vectors and enhance the redundancy in measurement capabilities.
The software used for the mission has also been enhanced to increase tolerance to failures, such as engine disruptions, thrust disruptions, and sensor failures. ISRO has also made the decision to remove the central or fifth engine, which was added at the last minute during the Chandrayaan-2 mission. With the increase in the lander’s mass by approximately 200 kilograms, a minimum of two engines will now be required for the landing.
To ensure power generation even in diverse landing orientations, ISRO has extended the solar panels and increased the panel area. This improvement will enable Vikram to generate power efficiently, even if it does not directly face the Sun upon landing.
The launch of Chandrayaan-3 is scheduled between July 12 and 19, with the subsequent journey to the Moon taking approximately 45 days. The chosen landing day is crucial to maximize the available working time on the lunar surface, as ISRO aims to take advantage of the full 15-day lunar day. The selection of the launch date primarily depends on aligning the landing day with the start of the lunar day.
ISRO Chairman, S Somanath, emphasized the extensive testing conducted in preparation for the mission. Over the past two years, the focus has been on rigorous testing to ensure the mission’s success. Autonomous flights, helicopter flights, crane-mode landing simulations, drop tests, and software simulation testbeds were extensively employed to evaluate potential failures and recovery options.
Chandrayaan-3 Mission holds great promise for India’s space exploration endeavors and will contribute to advancing our understanding of the Moon.