Chandrayaan 3: All set for countdown to begin for India’s third moon mission


Chennai, July 11

The countdown for the launch of India's third moon mission on July 14 is expected to begin soon with the completion of the "launch rehearsal" on Monday.

"The 'Launch Rehearsal' simulating the entire launch preparation and process lasting 24 hours has been concluded," said the Indian space agency on Monday.

And just after 2.50 p.m. on July 14, India’s Chandrayaan-3 spacecraft will begin its own long moon journey after being ejected by the rocket LVM3, it said.

After travelling about 3.84 lakh km, the Chandrayaan-3 spacecraft is expected to land on the lunar surface on August 23 or 24.

The Chandrayaan-3 spacecraft comprises a propulsion module (weighing 2,148 kg), a lander (1,723.89 kg) and a rover (26 kg), the Indian Space Research Organisation (ISRO) said.

Incidentally, the Chandrayaan-2 payload weighed about 3.8 ton with the orbiter weighing 2,379 kg, the Vikram lander 1,444 kg (including the Pragyan rover 27 kg).

The main purpose of Chandrayaan-3 is to safely land the lander on the moon soil.

Following that, the rover will roll out to do the experiments. The life of the payload carried by the propulsion module post ejection of the lander is between three and six months.

On the other hand, the mission life of the lander and the rover is 1 Lunar day or 14 earth days, the ISRO said.

According to the Indian space agency, the propulsion module has Spectro-polarimetry of Habitable Planet Earth (SHAPE) payload to study the spectral and Polari metric measurements of Earth from the lunar orbit. The lander payloads are: Chandra’s Surface Thermophysical Experiment (ChaSTE) to measure the thermal conductivity and temperature; Instrument for Lunar Seismic Activity (ILSA) for measuring the seismicity around the landing site; Langmuir Probe (LP) to estimate the plasma density and its variations.

A passive Laser Retroreflector Array from NASA is accommodated for lunar laser ranging studies. On the other hand, the rover will carry: Alpha Particle X-ray Spectrometer (APXS) and Laser Induced Breakdown Spectroscope (LIBS) for deriving the elemental composition in the vicinity of the landing site, the ISRO said.

According to ISRO, the moon mission is divided into three phases – the earth-centric phase (Pre-Launch, Launch and Ascent and Earth-bound Manoeuvre), the Lunar Transfer Phase (Transfer Trajectory), and the Moon Centric Phase (Lunar Orbit Insertion Phase, Moon-bound Manoeuvre Phase, Propulsion Module and Lunar Module Separation, De-boost Phase, Pre-landing Phase, Landing Phase, Normal Phase for Lander and Rover, Moon Centric Normal Orbit Phase (100 km circular orbit) for Propulsion Module.

During the first phase, India’s heavy lift rocket standing 43.5 metre height and weighing 642 ton LVM3, will carry the Chandrayaan-3 spacecraft. The rocket has an impeccable record of six consecutive successful missions.

This is the fourth operational flight of LVM3, and aims to launch the Chandrayaan-3 spacecraft to Geo Transfer Orbit (GTO).

At 2.35 p.m. on July 14, the three stage LVM3 rocket will blast off from the second launch pad at Sriharikota rocket port in Andhra Pradesh. While the first rocket’s first stage is powered by solid fuel, the second stage is by liquid fuel, and the third and final stage consists of a cryogenic engine powered by liquid hydrogen and liquid oxygen.

At the time of blast off, the 642 ton rocket will be having a total propellant mass of 553.4 ton-all three stages put together. Just over 16 minutes into its flight, the rocket will eject the Chandrayaan-3 spacecraft at an altitude of about 179 km.

The current mission is a follow up of the failed Chandrayaan-2 mission in 2019 when the lander named Vikram crashed on to the moon surface. As regards the changes made in the lander this time as compared to the one that crash landed on the moon during the Chandrayaan-2 mission, a senior ISRO official told IANS that the lander has four motors instead of five.

The space agency has also carried out some changes in the software.

Interestingly, ISRO is silent on naming the lander and rover this time around. During the Chandrayaan-2 mission, the lander was named as Vikram and rover as Pragyan.


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