New Delhi, August 22, 2023: As the clock ticks down to a pivotal moment, India braces itself for a nail-biting twenty minutes of tension and excitement. On this upcoming Wednesday evening, the Vikram lander is set to embark on a daring endeavor – a soft landing on the moon’s surface. This audacious feat, a part of India’s Chandrayaan-3 mission, carries the weight of history and the promise of scientific exploration. The final leg of Chandrayaan-3’s journey is akin to a heart-pounding T-20 match, with the outcome uncertain until the very last moment.
Chandrayaan-3’s Extraordinary Journey and Landing Procedure
The epic saga began with an awe-inspiring lift-off. ISRO’s mighty Bahubali rocket, also known as the Mark-3 launch vehicle, propelled Chandrayaan-3 into its orbit. The spacecraft circled the Earth in elliptical paths, gaining momentum and altitude.
On August 1, Chandrayaan-3 commenced its 384,000-kilometer journey to the moon. Five days later, on August 5, the spacecraft gracefully slid into lunar orbit, positioning itself for the historical event ahead. After attaining stability in the moon’s orbit, Chandrayaan-3 patiently awaited its moment.
In a critical maneuver executed with precision, the propulsion module and the Vikram lander, carrying the Pragyaan rover, separated on August 17. This separation occurred while the spacecraft was in an orbit measuring 153 km by 163 km. The propulsion module embarked on its separate lunar trajectory in the same orbit, while the Vikram lander initiated its descent.
As the Vikram lander approached the moon’s surface, it transitioned to an elliptical orbit measuring 134 km by 25 km. This marked a significant step forward, aligning with the approach successfully undertaken during the Chandrayaan-2 mission.
The D-Day: A Glimpse into the Heart-Stopping Moments
The day of reckoning arrives with the start of the “twenty minutes of terror.” Guided by commands from Bengaluru, the Vikram lander commences its descent from an altitude of 25 km above the lunar terrain.
The powered descent mode propels the Vikram lander at a staggering speed of 1.68 km per second, equivalent to roughly 6048 km per hour – nearly ten times the velocity of an airplane.
Gradually, the Vikram lander initiates a controlled deceleration, yet it maintains a near-horizontal orientation with respect to the moon’s surface. This phase, aptly named the “rough braking phase,” persists for approximately 11 nerve-wracking minutes.
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In a sequence of calculated maneuvers, the Vikram lander is skillfully adjusted to achieve a vertical posture relative to the lunar surface – heralding the start of the “fine braking phase.”
Recalling History and the Final Touchdown
It’s worth noting that during the Chandrayaan-2 mission, the fine braking phase proved to be a pivotal turning point, leading to the unfortunate loss of control and a subsequent crash of the Vikram lander.
At an altitude of 800 meters above the moon, both horizontal and vertical velocities are meticulously reduced to zero, causing the Vikram lander to hover momentarily, surveying the landing zone.
Further descent brings the Vikram lander to a temporary halt at 150 meters above the moon’s surface. During this pause, the lander captures images for hazard detection and meticulously scouts for an optimal landing site.
With a careful activation of just two engines, the Vikram lander finally makes contact with the lunar ground. The lander’s landing legs, designed to endure a maximum impact of 3 meters per second (roughly 10.8 km per hour), successfully cushion the touchdown.
As sensors on the landing legs detect contact with the lunar surface, the engines cease operation, signifying the conclusion of the heart-pounding twenty minutes of tension.
A New Chapter Unfolds
In the wake of landing, the lunar regolith – the dust stirred up by the landing – gradually settles, allowing the ramp to open. This paves the way for the slow descent of the Pragyaan Rover onto the moon’s surface.
As the rover establishes its presence on the lunar terrain, the Vikram lander captures images of the rover, while the Pragyaan rover returns the favor by snapping shots of the lander. These images mark India’s first-ever lunar selfies, destined to be beamed back to the nation with pride.
With the successful establishment of both the Vikram lander and the rover on the lunar landscape, the stage is set for a new era of scientific exploration. Powered by solar energy, both the lander and rover are designed to endure a single lunar day, equivalent to 14 Earth days.
If all unfolds as planned, India will join the ranks of the select few nations that have achieved the remarkable feat of a soft landing on the moon, opening doors to untold discoveries and advancements in space exploration.