Why in news?

• The Indian Space Research Organisation launched its third lunar mission - Chandrayaan 3 on-board the heavy lift LVM3-M4 rocket in Sriharikota on July 14.
• The Vikram lander of the mission is planned to soft land on the surface of the South Pole region of the Moon on August 23.
• A successful mission would see India enter an elite club of nations achieving such a feat. These nations are: the United States, China and the former Soviet Union.

What’s in today’s article?

• Chandrayaan 3
• Soft landing

Chandrayaan 3

• About
  • The Chandrayaan-3 is India’s third lunar mission.
  • It consists of an indigenous lander module (LM), propulsion module (PM), and a rover.
  • Its objective is to develop and demonstrate new technologies required for inter-planetary missions.
• Modules
  • The Chandrayaan-3 mission spacecraft will have three modules —Propulsion, lander, and rover.
  • The propulsion module is the one that will take the lander and the rover to the moon.
  • The lander module contains the rover. After the touchdown, the lander will remain stationary at the landing site, while the rover will explore the moon.
• 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.
• ISRO’s previous moon missions
  • Chandrayaan-3 is largely a replica of its predecessor, Chandrayaan-2, that was launched in July 2019 in the form of an orbiter and a lander (‘Vikram’) bearing a rover (‘Pragyan’).
  • Chandrayaan-1 was launched by ISRO in October, 2008.
    • The ISRO lost communication with Chandrayaan-1 on August 29, 2009, almost a year after it was launched.

Soft Landing

• About
  • 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
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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.