Chandrayaan-3 countdown: Roadmap to lunar landing in August

The Indian Space Research Organisation (ISRO), Chandrayaan-3's operators, have outlined the mission's key objectives, which entail accomplishing a safe and precise soft landing in close proximity to the lunar south pole, deploying and demonstrating the capabilities of the rover, and executing vital in-situ scientific experiments during a single lunar day, equivalent to approximately 14 Earth days.

However, before Chandrayaan-3 can reach its destination on the moon, it must navigate through a series of crucial stages. The mission's approximately six-week journey from Earth to the moon can be divided into three distinct phases: Earth-centric, lunar transfer, and moon-centric phases.

The Earth-centric phase encompasses prelaunch and launch operations, followed by ascent periods completed upon liftoff and separation from its rocket.

The final orbit will set Chandrayaan-3 on a lunar transfer trajectory for the lunar transfer phase.

During the lunar transfer phase, Chandrayaan-3 will execute an engine burn to enter a circular orbit around 62 miles (100 kilometers) above the lunar surface. It will then disengage its lander and rover from the propulsion module.

Image: ISRO

The lander will gently touch down in the moon's south polar region at a speed of less than 5 mph (8 kph), while the propulsion module remains in orbit around the moon, maintaining communication with the rover and lander.

To achieve a lunar landing successfully, Chandrayaan-3 faces unique challenges. Unlike Earth, the moon has a sparse atmosphere, requiring spacecraft to gradually slow themselves down for a more controlled approach.

The final approach and landing are scheduled for August 23 or 24, timed to coincide with the lunar sunrise, providing approximately 14 to 15 days of daylight to conduct operations. If necessary, a contingency plan exists to postpone the landing by a month until September.

ISRO Chairman Sreedhara Panicker Somanath has shed light on some of the improvements made to avoid the issues faced during the Chandrayaan-2 mission's unfortunate crash.

These enhancements include reinforcing the lander's legs, increasing its landing-speed tolerance, and incorporating new sensors to measure approach speed accurately.

Following a successful landing, the Chandrayaan-3 rover will begin its mission, equipped with advanced scientific payloads for moon exploration. The rover features the LASER Induced Breakdown Spectroscope (LIBS), which analyses the chemical composition of the lunar surface, and the Alpha Particle X-ray Spectrometer (APXS), performing a similar task on lunar rocks and soil in the landing area.

Meanwhile, the lander will conduct its scientific investigations as well. The Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA) instrument will measure plasma at the lunar surface and observe its variations over time.

Additionally, Chandra’s Surface Thermophysical Experiment (ChaSTE) will analyse the thermal properties of the south polar region, while the Instrument for Lunar Seismic Activity (ILSA) will gauge the moon's seismicity, aiding in a comprehensive understanding of its crust and mantle structure.

While these activities unfold, a passive experiment known as the LASER Retroreflector Array (LRA), contributed by NASA, will silently collect data in the background, enriching our knowledge of lunar dynamics.

With Chandrayaan-3's trajectory set and its mission goals defined, the eyes of the world are eagerly fixed on India's next giant leap into the cosmos. The successful execution of this mission will not only elevate India's stature in the global space community but also contribute significantly to our understanding of Earth's celestial neighbor.