Chandrayaan-2: Decoding the 48-day-expedition to the Moon

Chandrayaan-2 was scheduled to launch on 15th July but was called off an hour before the launch time because of a few technical issues. Finally, it was launched on 22nd July from Satish Dhawan Space Center at Sriharikota aboard a GSLV MK-III and will land on the moon on 7th September, 48 days later.

ISRO has described the details of the path which will take a longer time compared to Moon Missions by other space agencies. The path involves more revolutions around the Earth by injecting it into an Earth Parking Orbit 170 x 39120 km wide to be able to take advantage of the Earth’s Gravity in performing a slingshot maneuver to get into the Lunar Transfer Trajectory while escaping Earth’s sphere of influence. The spacecraft will then be slowed down by onboard thrusters as it enters the Moon’s sphere of influence for Lunar Capture. The Orbit of Chandrayaan-2 around the Moon will be circularized to 100x100 km orbit through a series of orbital maneuvers. After which the moon lander Vikram will land near the South Pole on 7th September. The rover Pragyan will roll out and carry out operations for 1 Lunar Day (14 Earth Days) while the orbiter will be operational for a year.

The Mission takes longer to reach the Moon compared to other missions because of the longer path that it had to take because of the lack of a powerful propulsion system. In Apollo 11, the first manned mission to Moon it took them 4 days 6 hours, and 45 minutes to land on the Moon. The reason for lesser time is that NASA’s Saturn V that was used to launch the command, service, and lunar modules into the Lunar Transfer trajectory had a lifting capacity of 43 tonnes at a speed of 39,000km per hour. The Saturn V launcher and lunar craft were powerful enough to do travel to the Moon in just 4 days, but they were that expensive too. While IRSO has gone the cost-efficient route by taking more time but investing less money into the mission. ISRO is known for its economical missions worldwide successfully.

Chandrayaan-2 might just be another successful frugal mission by ISRO, but it is a testament to the ability of each person that was involved with the mission. No matter the time it takes the Endgame of the mission must be the centre of attention which is leaving bigger footprints in space and contributing to the scientific community.

Chandrayaan 2: Discoveries to look out for on Moon by ISRO’s lunar mission

Chandrayaan 2 Scientific Payloads

Chandrayaan 2 mission is designed for a series of scientific experiments planned using special to type test equipment mounted on Orbiter, Lander and the Rover module. These scientific payloads are:-

Orbiter Payload

Terrain Mapping Camera for mapping the Lunar surface in the panchromatic spectrum. The results shall help in creating 3D maps of the Lunar surface to deduce Moon’s evolutionary process.
Large Area soft X-ray Spectrometer to detect Mg, Al, Si, Ca, Ti, and Na molecules on the surface using characteristic X-rays emitted by each when activated by solar energy.

Solar X-ray meter (XSM) measures X-rays from the Sun and its corona and calculates the solar radiation intensity.
High-Resolution Camera onboard captures high-resolution images of the landing site for a safe Lander touch down. Digital Elevation Models (DEMs) of the landing site are created to identify craters or boulders at the touch-down area.

Imaging IR Spectrometer shall carry out global mineralogical and volatile mapping of Lunar surface and for complete characterization of water/hydroxyl features.

Dual-frequency Synthetic Aperture Radar (DFSAR) for high-resolution lunar mapping in Polar regions, quantitative estimation of water-ice in the polar regions, and bedrock thickness measurements.

Atmospheric Composition Explorer Spectrometer for exosphere composition & distribution study.

Dual Frequency Radio Science (DFRS) experiment for electron density distribution in the Lunar ionosphere.
Lander Payload

Radio Anatomy of Moon Hypersensitive ionosphere & Atmosphere (RAMBHA) to study Lunar ionosphere which is a dynamic plasma environment as per Solar conditions.

Chandra’s Surface Thermophysical Experiment (ChaSTE) to measure temperature gradient and thermal conductivity on the Lunar surface using a probe inserted up to 10cm on Lunar bedrock.

The instrument for Lunar Seismic Activity is a tri-axial seismometer to measure Lunar quakes.

Rover Payload

Alpha particle X-ray spectrometer uses X-ray emission/fluorescence spectroscopy to detect the elements on Lunar surface like Sodium, Mg, Ca, Ti, Fe and other trace elements like Strontium, Yttrium, and Zirconium.

Laser-induced Breakdown Spectrometer fires high-powered Lasers pulses at various locations around the landing site to analyze the radiation from decaying plasma characteristics.

Passive Experiment

Laser Retroreflector Array to take the Earth-Moon measurement and understand Lunar interior using Laser ranging techniques.

The Rover is fully capable of undertaking in-house payload experiments. It is designed to communicate with the Lander only due to its limited resources onboard, but Lander and Orbiter shall have direct communication with ISRO’s Indian Deep Space Network. Hence, Rover reported information shall be transmitted in a relay mode via the Lander module.

Moon has been an enigmatic celestial body for centuries and the effect of the Lunar cycle on Earth and its organisms’ circadian rhythm has been a well-known fact. Hence, to understand Life on Earth, further Moon study is critical since the effect of bonding of the two heavenly bodies is yet to be understood. Presently, the main focus of the Chandrayaan 2 scientific payload shall be to study the Moon for the following:-

Water Molecules: Lunar South Pole is on the darker side of the moon and Chandrayaan 1 discovered water molecules in the icy form there. This possibility of the presence of tons of icy water over and under the surface has made this region of primary research interest for the world scientific community. Chandrayaan 2 aims at finding more details on the distribution of this icy water and study its composition up close using the Lander and its Rover unit.

Lunar Craters and Meteorites: The impact craters on the Moon make for an intriguing geological study as their formation is attributable to extra-terrestrial bodies hitting the surface and being assimilated as Moon edifice. As the Moon has a sparse atmosphere to obstruct any impact, asteroids/meteoroids and comets of all sizes and shapes hit the moon's surface regularly. The Lunar surface preserves these incoming celestial items, unlike on Earth, where such bodies undergo atmospheric entry annihilation. Meteorites discovered on the moon could be from celestial zone far beyond our solar system, and likely to be in the form of well-preserved rock samples, etc. and their analysis shall provide unique scientific data.

Moon’s Origin: The main theory of Moon’s origin visualizes the impact of a large body with Earth several billion years ago, and the resulting sheared debris created by this impact finally accumulated to form the Earth’s natural satellite. Though, an understanding of the origin of the moon has been evolved by scientists this model requires further verification. Moon surface is a serene undisturbed ancient yet-to-be-discovered environment. Experiments on the moon might throw up definitive clues on the Universe and Earth’s own history like a fossilized fingerprint of the Solar system.

Lunar Dust: Lunar dust needs a critical study since it could be the building material of the future Lunar stations. Lunar dust samples are required to be studied up close to understand its character. The future scientific Lunar stations constructed using Lunar dust may have radio telescopes (located on farther side from Earth face to reduce the influence of Earth’s magnetic signatures) and various other special experiment setups for Lunar study.

The upcoming Moon Landing as part of Chandrayaan 2 is a historical event for India and the discoveries made on the Moon shall launch new research and Ph.D. thesis for the scientific community. These studies shall form the backbone of further Lunar missions/experiments, thereby keeping India in the forefront of exclusive space research.

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