India’s third lunar odyssey commences with perfect launch

Subject : Science and technology

Section: Space Technology

Concept :

The Chandrayaan 3 project from India was launched with the goal of landing a spacecraft on the lunar surface.

About Chandrayaan-3

The Satish Dhawan Space Centre in Sriharikota successfully launched Chandrayaan-3 using a Launch Vehicle Mark-3 (LVM-3) rocket.
In order to demonstrate end-to-end capability in safe landing and wandering on the lunar surface, it is a follow-up mission to Chandrayaan-2. Payloads

Payloads

The Chandrayaan-3 carries six payloads that would help ISRO understand the lunar soil and also get the blue planet’s photographs from the lunar orbit.
Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA) will measure the near-surface plasma density and its changes with time.
Instrument for Lunar Seismic Activity (ILSA) will measure seismicity around the landing site and delineate the structure of the lunar crust and mantle.
Laser-Induced Breakdown Spectroscope (LIBS) will determine the elemental composition of lunar soil and rocks around the landing site.
Alpha Particle X-Ray Spectrometer (APXS) will derive the chemical composition and infer the mineralogical composition of the moon’s surface.
Spectro-polarimetry of HAbitable Planet Earth (SHAPE) will study the spectro-polarimetric signatures of the earth in the near-infrared wavelength range.
This could be used in the search for life on exo-planets beyond the solar system.
Lunar lander Vikram will click photos of the rover Pragyaan as it studies the seismic activity on the moon by dropping some instruments.
Using laser beams, it would try to melt a piece of the lunar surface — the regolith — to study the gases emitted during the process.

Soft Landing

A soft landing on the Moon’s surface refers to a controlled and gentle touchdown of a spacecraft or lunar lander on the lunar terrain.
During a soft landing, the spacecraft undergoes a series of manoeuvres and braking techniques to reduce its velocity and align itself with the landing site.
This typically involves firing retro-rockets or thrusters to slow down the descent and make a controlled approach.
The goal is to land the spacecraft gently without causing any significant damage.

Process of soft landing for Chandrayaan-3

Following the separation from the launch vehicle, the propulsion module along with the lander would proceed for an over a month-long journey towards reaching the orbit of the moon until it goes 100 km above the lunar surface.
After reaching the desired altitude, the lander module would begin its descent for a soft landing on the moon’s south pole region.

Challenges to soft-landing

What happened to Chandrayaan 2?

During this mission, ISRO lost contact with the spacecraft’s lander Vikram.
While the orbiter entered into orbit around the moon, the surface mission failed when the lander crashed instead of executing a slow descent.
ISRO later identified a problem in the guidance software and unexpected dispersion in the propulsion system during certain phases of the descent.

How will Chandrayaan-3 be different?

In Chandrayaan-3, the rocket will place the payload in an elliptical orbit around the earth, where a propulsion module will take over and pilot the lander to a circular orbit around the moon.
To improve the chances of success at this stage, ISRO has strengthened the lander’s legs, lowered its minimum thrust, enhanced the availability of power, and upgraded the landing sequence.