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15th November 2023

Welcome to Aakashvani, Aakashganga’s very own blog!

Every fortnight one blog will be posted and this is the first installment! Come along with us to dive into the world of Astronomy, Astrophysics and cosmology.

Today, we will look into the different types of payloads of Chandrayaan-3 and try to understand what they will do and what kind of data they will collect.

An Overview:

Chandrayaan-3 consists of a Lander and Rover configuration. It was launched by LVM3 (Launch Vehicle Mark-III, India’s heaviest space launch vehicle) from SDSC SHAR, Sriharikota (a barrier island of Tritupati district in Andhra Pradesh off the Bay of Bengal).

It had a Propulsion Module, PM, which carried the Lander Module, LM, from launch vehicle injection* till the final lunar 100 lm circular polar orbit and separated LM from PM. Additionally, the PM has a scientific payload which would function after separating from the LM.

(here, the launch vehicle is LVM3. Injection means translunar injection; it means that the launch vehicle exited Earth’s orbit and entered the lunar orbit)

Chandrayaan-3 has a mission life (lander & rover) of about 14 earth days, i.e. one lunar day. The lander, Vikram, landed at the coordinates 69.36 S and 32.34 N, the closest landing near the moon's south pole.

Science Payloads and Sensors:

There are a total of 7 science payloads. There are four on the lander, two on the rover and one on the PM.

Lander Payloads:

Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA):

Its main objective is “to measure the near-surface plasma density and its changes with time”. It is a Langmuir probe used to determine electron temperature, electron density and electric potential of plasma by inserting one or more electrodes into a plasma, with constant time-varying electric potential between the electrodes or between them and the surrounding vessel. Space Physics Laboratory SPL/VSSC developed this payload.

Chandra’s Surface Therma physical Experiment (ChaSTE):

Its main objective is to measure the thermal properties of the lunar surface near the polar region. SPL/VSSC developed this payload

Instrument for Lunar Seismic Activity (ILSA):

Its main objective is to measure the seismicity around the landing site and delineate the structure of the lunar crust and mantle. (basically, getting information about the different layers of the moon, where the exact boundaries of different layers lie). Laboratory for Electro-Optics Systems, LEOS (ISRO) developed this payload.

LASER Retroreflector Array (LRA):

Its main objective is to understand the dynamics of the Moon system. It has eight retroreflectors that will serve as a long-term geodesic station and a location marker on the lunar surface. (basically, a retroreflector is a device that reflects light to its source with minimum scattering; a geodetic station is used to accurately measure and understand the geometric shape, orientation in space and gravitational field of the celestial body it is on in this case, the moon.). It belongs to the National Aeronautics and Space Administration, NASA.

Rover Payloads:

LASER Induced Breakdown Spectroscope (LIBS):

Its main objective is to qualitatively and quantitatively analyse and derive the chemical composition and infer the mineralogical composition of the Lunar Surface. LEOS (ISRO) provided this payload

Alpha Particle X-ray Spectrometer (APXS):

Its main objective is to determine the elemental composition (Magnesium, Aluminium, Silicon, Potassium, Calcium, Titanium, and Iron) of lunar soil and rocks around the lunar landing site. Physics Research Laboratory, PRL provided this payload.

Propulsion Module Payloads:

Spectro-polarimetry of HAbitable Planet Earth (SHAPE):

Its main objective is to help discover smaller planets in reflected light that would allow us to probe into a variety of Exo-planets which would qualify for habitability or the presence of life.