Chandrayaan-3 July 14 launch: What it will do

Once it descends on the moon next month, Chandrayaan-3 will seek to explore the lunar surface in great detail, examine the electrically-charged atoms in the lunar atmosphere and look for moon quakes to yield new insights into the origin and evolution of the Earth’s only satellite.

The planned touchdown site, 650 km from the lunar south pole, is unprecedented as no other lunar mission has ever explored that area where the temperature can go down to more than minus 230 degrees Celsius.

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Five instruments onboard the Vikram lander and rover will conduct experiments for 14 Earth days – one lunar day – beyond which the Indian Space Research Organisation doesn’t expect the devices to survive. The space agency has taken extra care to ensure that these sensors don’t die prematurely, but complete the mandated experiments.

“The rover will conduct two experiments that nobody has conducted so far. The first one is to study the constituents of the regolith (planetary surface) and the other one is to examine the ionised atmosphere’s behaviour in day and night,” ISRO chairman S Somanath said.

“We will also have instruments to study the regolith electrical and thermal characteristics and moonquakes. The rover will do an atomic evaluation of the surface by two instruments.”

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Since the Indian mission comes ahead of NASA’s Artemis programme in which the US space agency wants to send human astronauts close to the lunar south pole, the data from the Indian mission can provide vital inputs in planning the first human space flight to the satellite after 50 years.

While all the returned samples collected by the Apollo missions are from the equatorial region of the moon, there is little data from polar regions though scientific studies suggest highland compositions are more diverse than what is represented in the returned samples.

“The mission seeks to make an assessment of the tiny charged atmosphere, figure out the mineralogy and low-level seismic behaviour. It will map the surface and see what lies below the surface. Such data will be useful to know whether human habitation is ever possible on the moon,” astrophysicist Somak Raychaudhury, Vice Chancellor of Ashoka University told DH.

The instruments that the Vikram lander will carry are (1) Chandra’s Surface Thermophysical Experiment (ChaSTE) for measuring the surface thermal properties, (2) the Instrument for Lunar Seismic Activity (ILSA) to measure seismicity around the landing site and (3) the Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA) to study the gas and plasma environment.

Besides, there will be a passive laser retroreflector array provided by NASA for lunar ranging studies.

The rover will carry two instruments to study the local surface elemental composition, an Alpha Particle X-ray Spectrometer (APXS) and Laser Induced Breakdown Spectroscopy (LIBS). The Propulsion Module / Orbiter will carry out one experiment called the Spectropolarimetry of Habitable Planet Earth (SHAPE) to study Earth from lunar orbit. “The payloads for the lander and rover are the same as Chandrayaan-2,” he said.

Meanwhile, India is in talks with Japan for the next Chandrayaan, though an agreement has not been reached.