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Chandrayaan-2: A giant leap for India’s Space Programme

India’s Geosynchronous Satellite Launch Vehicle GSLV Mk III-M1, successfully launched the 3840 kg Chandrayaan-2 spacecraft into an earth orbit on 22nd July 2019 . It  lifted off from the Second Launch Pad at the Satish Dhawan Space Centre SHAR (SDSC SHAR), Sriharikota in Andhra Pradesh at 2:43 pm. The spacecraft is now revolving round the earth with a perigee (nearest point to Earth) of 169.7 km and an apogee (farthest point to Earth) of 45,475 km.

What makes Chandrayaan 2 special?
  • First space mission to conduct a soft landing on the Moon’s south polar region
  • India will become Fourth country ever to soft land on the lunar surface
  • First Indian expedition to attempt a soft landing on the lunar surface with home-grown technology
  • First Indian mission to explore the lunar terrain with home-grown technology
About Chandrayaan-2
  • Chandrayaan-2 is India’s second mission to the moon, the first one being Chandrayaan-1
  • Chandrayaan 2 is unique because it will explore and perform studies on the south pole region of lunar terrain which is not explored and sampled by any past mission.
  • It comprises a fully indigenous Orbiter, Lander (Vikram) and Rover (Pragyan). The Rover Pragyan is housed inside Vikram lander.
Objectives
  • The mission objective of Chandrayaan-2 is to develop and demonstrate the key technologies for end-to-end lunar mission capability, including soft-landing and roving on the lunar surface.
  • It aims to further expand our knowledge about the Moon through a detailed study of its topography, mineralogy, surface chemical composition, thermo-physical characteristics and atmosphere leading to a better understanding of the origin and evolution of the Moon.

Geosynchronous Satellite Launching Vehicle Mk III
  • GSLV Mk III is a three-stage launch vehicle developed by ISRO.
  • The vehicle has two solid strap-ons, a core liquid booster and a cryogenic upper stage.
  • The vehicle is designed to carry 4 ton class of satellites into Geosynchronous Transfer Orbit (GTO) and about 10 tons to Low Earth Orbit (LEO).
  • The Chandrayaan-2 launch marks the first operational flight of the GSLV Mk III.
Working of GSLV Mark III
  • The first stage of the rocket consists of two strap-on solid motors. Designated as ‘S200’, each carries 205 tons of composite solid propellant. S200 booster uses an Hydroxyl-terminated polybutadiene (HTPB)  based propellant. Its ignition results in vehicle lift-off.
  • The second stage, designated as L110, is a liquid-fueled stage. It is powered by two Vikas 2 engines which uses Unsymmetrical Dimethylhydrazine (UDMH) as fuel and Nitrogen tetroxide (N2O4) as oxidizer.
  • The cryogenic upper stage, designated C25,  uses liquid Hydrogen as fuel (LH2) and liquid oxygen (LOX) as oxidizer.
Flight Sequence

  • The two strap-on motors (‘S200’) of GSLV Mk III are located on either side of its core liquid booster. Its ignition results in vehicle lift-off. S200s function for 131.30 seconds.
  • During strap-ons functioning phase, the two clustered Vikas liquid Engines of L110 liquid core booster will ignite 110.84 sec after lift -off to further augment the thrust of the vehicle. These two engines continue to function after the separation of the strap-ons.
  • The payload fairing separation will happen after 203.4 sec and the spacecraft is exposed space environment. [A payload fairing is a nose cone used to protect a spacecraft/payload  against the impact of pressure and heating during launch through an atmosphere. Once outside the atmosphere the fairing is opened, exposing the payload to the space environment.]
  • The liquid stage (L110 Core Stage) will shut off after 305.72 sec and will separate after 308.82 seconds.
  • The cryogenic C25 stage will be ignited then, after 311.22 seconds and it will shut off after 959.30 seconds.
  • Chandrayaan-2 spacecraft will be separated after 974.30 seconds, and at an altitude of 181. 656 km.

Injection of Chandrayaan – 2
  • About 16 minutes 14 seconds after lift-off, the vehicle injected Chandrayaan-2 spacecraft into an elliptical earth orbit.
  • In the coming days, a series of orbit manoeuvres will be carried out using Chandrayaan-2’s onboard propulsion system.
  • This will raise the spacecraft orbit in steps and then place it in the Lunar Transfer Trajectory to enable the spacecraft to travel to the vicinity of the Moon.
  • After the lift off of July 22, Chandrayaan will remain in the earth bound phase (under the influence of the earth’s gravity) for 23 days.
  • The trans lunar injection (leaving earth’s influence and heading towards the moon’s) will  happen on Day 23. The lunar transfer trajectory will be from Day 23 to Day 30, and the probe will enter the moon’s orbit (Lunar Orbit Insertion) on Day 30.
  • The Lunar Bound Phase will now be for 13 days.  Through a set of manoeuvres, the orbit of Chandrayaan-2 around the moon will be circularised at 100 km height from the lunar surface.
  • On Day 43, when it comes around 30 km away from the lunar surface,  the lander will separate from the orbiter and will begin deboosting .
  • On Day 48, it will start a powered descent, with its engines carefully controlling the speed of fall. Imaging of the landing site region prior to landing will be done for finding safe and hazard-free zones.
  • About 15 minutes later, the lander Vikram will soft-land on the moon’s surface.
  • Vikram will attempt to make a soft landing in a high plain between two craters — Manzinus C and Simpelius N — at a latitude of about 70° South on 7th September 2019.
  • When it land on the surface of moon,  the Rover ‘Pragyan’ will roll out from the lander and carry out experiments on the lunar surface

Orbiter 

  • Chandrayaan 2 Orbiter will be capable of communicating with Indian Deep Space Network (IDSN) at Byalalu as well as the Vikram Lander.
  • The orbiter had a lift-off weight of about 2,369 kg
  • The Orbiter carries eight payloads
  • The Orbiter will continue its mission for a duration of one year

Lander – ‘Vikram’

  • The Lander of Chandrayaan 2 is named Vikram after Dr Vikram Sarabhai, the Father of the Indian Space Programme.
  • It has a lift-off weight 1,471 kg
  • It is designed to function for one lunar day, which is equivalent to about 14 Earth days. Vikram has the capability to communicate with IDSN at Byalalu near Bangalore, as well as with the Orbiter and Rover.
  • The Lander is designed to execute a soft landing on the lunar surface.
  • The Lander carries three scientific payloads to conduct surface and subsurface science experiments.

Rover – ‘Pragyan’

  • Chandrayaan 2’s Rover is a 6-wheeled robotic vehicle named Pragyan, which translates to ‘wisdom’ in Sanskrit.
  • The rover will carry out experiments on the lunar surface for a period of 1 lunar day, which is equal to 14 Earth days.
  • It had a lift-off weight of 27 kg
  • The rover can travel up to 500 m with a speed of 1 cm per second and relies on electric power generated by its solar panel for functioning.
  • It can only communicate with the Lander.
  • The Rover carries two payloads to enhance our understanding of the lunar surface.
Payloads 
  • Chandrayaan-2 has 13 payloads, to facilitate a more detailed understanding of the origin and evolution of the Moon
  • The orbiter has 8 payloads, the lander has 3 and rover has 2,  all of which developed indigenously. Besides these, there is one passive experiment from American space agency NASA.
  • The Orbiter payloads will conduct remote-sensing observations from a 100 km orbit while the Lander and Rover payloads will perform in-situ measurements near the landing site.

Orbiter Payloads

  • Terrain Mapping Camera: Will generate a Digital Elevation Model (DEM) of the entire Moon
  • Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS): Will test the elemental composition of the Moon’s surface
  • Solar X-Ray Monitor: Will provide solar X-ray spectrum inputs for CLASS
  • Imaging IR Spectrometer: Will map the Moon’s mineralogy and confirm the presence of water-ice on the lunar surface
  • Synthetic Aperture Radar L&S Bands: Will map the polar region and confirm the presence of water-ice at the sub-surface level
  • Chandra’s Atmospheric Composition Explorer-2: Will examine the Moon’s neutral exosphere
  • Orbiter High Resolution Camera: Will conduct high-res topography mapping
  • Dual Frequency Radio Science Experiment: Will study the lunar ionosphere

Vikram Payloads

  • Instrument for Lunar Seismic Activity: Will characterise the seismicity around the landing site
  • Chandra’s Surface Thermo-physical Experiment: Will examine the Moon’s thermal conductivity and temperature gradient
  • Langmuir Probe: Will conduct ionosphere studies on the lunar surface

Pragyan Payloads

  • Alpha Particle X-ray Spectrometer: Will determine the elemental composition of the Moon
  • Laser Induced Breakdown Spectroscope: Will identify elemental abundance in the vicinity of the landing site

Passive Experiment

  • Laser Retroreflector Array (LRA): Will help us understand the dynamics of Earth’s Moon system and also derive clues about the lunar interior
Ground Facilities
  • The Ground Segment of Chandrayaan-2 consists of Indian Deep Space Network, Spacecraft Control Centre and Indian Space Science Data Centre.
  • They perform the important task of receiving the information as well as the scientific data from the spacecraft. They also transmit the radio commands to the spacecraft
Women and men behind Chandrayaan 2
  • ISRO Chairman: K. Sivan
  • Project Director : Muthayya Vanitha
  • Mission Director : Ritu Karidhal
  • Director of the UR Rao Satellite Center: Kunhikrishnan
  • Director of Vikram Sarabhai Space Centre : Somanath
  • Mission director for the launch: Jayaprakash
  • Vehicle director for the Chandrayaan-2 mission: C. Raghunatha Pillai
  • Associate vehicle director for the mission: M. Abraham
  • Associate project director for the Chandrayaan-2 mission: G.  Narayanan

Why Moon?

  • The Moon is the closest cosmic body at which space discovery can be attempted and documented.
  • It is also a promising test bed to demonstrate technologies required for deep-space missions.

Chandrayaan 2 attempts to foster a new age of discovery, increase our understanding of space, stimulate the advancement of technology, promote global alliances, and inspire a future generation of explorers and scientists.

Why explore the Lunar South Pole?

  •  The lunar south pole is of special interest to scientists because of the possibility of the presence of water in permanently shadowed areas around it.
  • The lunar south pole region features craters that are unique in that the near-constant sunlight does not reach their interior. It may also contain a fossil record of the early Solar System.

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