This Wednesday, the nation will endure an intense period of twenty minutes as the Vikram lander endeavors to softly touch down on the moon’s surface in the evening.
India’s Chandrayaan-3 is poised to make history by executing a gentle landing of the Vikram Lander with the Pragyaan rover aboard, near the moon’s southern pole. The gripping final twenty minutes of this endeavor have been coined as the “twenty minutes of intensity,” akin to the dramatic conclusion of a T-20 cricket match.
Following an impressive liftoff, ISRO’s formidable Bahubali rocket, also known as the Mark-3 launch vehicle, positioned Chandrayaan-3 into orbit. The mission involved multiple elliptical orbits around Earth, effectively gaining momentum.
On August 1, Chandrayaan-3 embarked on its 384,000-kilometer journey to the moon. By August 5, the satellite had gracefully settled into the moon’s orbit and stabilized there.
In a pivotal and intricate maneuver, the propulsion module and the Vikram lander carrying the Pragyaan rover separated on August 17 while the satellite occupied a 153 km by 163 km orbit. The propulsion module continued its path around the moon within the same orbit dimensions.
Subsequently, the Vikram lander was carefully maneuvered to approach the moon’s surface within a 134 km by 25 km elliptical orbit, a prerequisite for commencing the powered descent. This phase has been successfully executed in the Chandrayaan-2 mission.
The moment of reckoning arrives on the landing day, ushering in the intense twenty-minute sequence comparable to a T-20 cricket match finale. Upon commands issued from Bengaluru, the Vikram lander initiates its descent towards the moon’s surface from an altitude of 25 km.
During the powered descent, the Vikram lander accelerates toward the lunar surface at a speed of 1.68 km per second, approximately 6,048 km per hour – nearly ten times the velocity of an aircraft.
The Vikram lander then decelerates using its engines, although it remains nearly horizontal to the lunar surface. This phase, lasting around 11 minutes, is referred to as the “rough braking phase.”
By employing specific maneuvers, the Vikram lander is transitioned into a vertical position relative to the moon’s surface, signaling the commencement of the “fine braking phase.”
It was during the fine braking phase of Chandrayaan-2 that the Vikram lander lost control, leading to an eventual crash landing.
Approximately 800 meters above the lunar surface, both horizontal and vertical velocities are nullified, causing the Vikram lander to hover above the landing area while conducting hazard detection and surveying for an optimal landing site.
The Vikram lander further descends to hover once more at 150 meters, capturing images for hazard assessment and site selection.
Ultimately, it comes to a rest on the lunar surface, using just two engines, and its landing legs are designed to withstand an impact of up to 3 meters per second, about 10.8 km per hour.
As the legs’ sensors make contact with the lunar surface, the engines shut down, concluding the twenty minutes of intensity.
The lunar regolith stirred up during the landing settles, the ramp opens, and the Pragyaan Rover is carefully deployed.
Once the Pragyaan Rover is on the lunar surface, it gains the freedom to explore its surroundings.
The pivotal moment arises when the Vikram lander captures images of the rover, and reciprocally, the Pragyaan rover captures images of the lander, transmitting India’s first lunar surface selfies back to the country.
With this, the true scientific exploration commences. Both the Vikram lander and the rover are solar-powered and engineered to operate during one lunar day, equivalent to 14 Earth days.
If all proceeds according to plan, India will join the ranks of countries that have achieved a soft landing on a celestial body. This will mark a significant milestone for ISRO and a monumental leap for India in the realm of space exploration. Truly, a celestial leap reminiscent of Hanuman’s legendary stride for a nation of 1.4 billion people.