Dr Vikram Sarabhai, founder of India’s space programme, while justifying the need for a space programme in a developing nation, famously stated, “We do not have the fantasy of competing with the economically advanced nations in the exploration of the Moon or the planets or manned space flight. But we are convinced that if we are to play a meaningful role nationally and in the community of nations, we must be second to none in the application of advanced technologies to the real problems of man and society.”
This vision led to a robust, application driven space programme in the domains of satellite based Earth observation, meteorology, communications and navigation. With the improvement in the higher technical education and research facilities along with the country’s economy, the quest for scientific exploration is coming to the forefront. Inception and progress of the Moon exploration programme of ISRO is a shining example. Here we take you through the journey of three Chandrayaan missions as seen by somebody who had the opportunity to be a part of the first mission from inside and who has been closely watching ISRO’s efforts in planetary exploration.
Chandrayaan-1 Announced by AB Vajpayee
The idea of an Indian scientific mission to the Moon was first raised in 1999 during a meeting of the Indian Academy of Sciences. The Astronautical Society of India carried forward the idea in 2000. Subsequently, ISRO set up the National Lunar Mission Task Force which concluded that ISRO has the technical expertise to carry out an Indian mission to the Moon. In April 2003, over 100 famous and respected Indian scientists in the fields of Planetary and Space Sciences, Earth Sciences, Physics, Chemistry, Astronomy, Astrophysics, Engineering and Communication Sciences discussed and approved the Task Force’s recommendation to launch an Indian probe to the Moon. The then Prime Minister of India, Atal Bihari Vajpayee, announced the Chandrayaan 1 project in his Independence Day speech on August 15, 2003. In November 2003, the Indian Government gave approval for the mission.
Journey of Chandrayaan-1
Chandrayaan-1 was the first Indian lunar probe under the Chandrayaan programme. Launched in October 2008, and operated until August 2009, the mission included a lunar orbiter and an impactor. Impactor was added on specific guidelines provided by the then President of India Dr APJ Abdul Kalam. ISRO’s proven launch vehicle PSLV in its heaviest configuration XL was used to launch the spacecraft. It is to be noted that India does not have powerful enough rockets to directly launch satellites to the Moon. Thus, it was a major test for the famous slingshot (apogee boosting) technology, mastered by ISRO in launching communication satellites to geostationary orbits, to reach trans lunar orbits. The mission was a major boost to India’s space programme, as India researched and developed indigenous technology to explore the Moon. On November 14, 2008, the Moon Impact Probe separated from the Chandrayaan orbiter and struck the South Pole in a controlled manner. With this mission, ISRO became the fifth national space agency to reach the lunar surface.
The Chandrayaan-1 mission, apart from the objective of reaching lunar orbit and carrying out scientific observations from there, had the stated objectives of preparation of a three-dimensional atlas (with high spatial and altitude resolution of 5–10 m or 16–33 ft) of both the near and far sides of the Moon and chemical and mineralogical mapping of the entire lunar surface at high spatial resolution, mapping particularly chemical elements like magnesium, aluminum, titanium and radioactive elements.
Among its many achievements, Chandrayaan-1 was credited with the discovery of widespread presence of water molecules in the lunar soil. It carried scientific instruments developed by many centers of ISRO as well as those provided by NASA, ESA, Bulgaria among others. The Moon Meteorology Mapper (MMM), developed by NASA/JPL, was the main instrument used for detecting the presence of water molecules on the surface of the Moon. The Terrain Mapping Camera (TMC) carried out stereo imaging of the surface and provided high resolution visuals, used for identifying new surface features (like caves, boulders and faults) and by the later missions for identifying landing sites. The mission provided a unique opportunity to scientists from India to interact with planetary science teams from all over the world, exchange their experiences and align their activities. While Indian scientists have been collaborating with their international peers in working on lunar data from Apollo and Luna missions for a long time, this time the collaboration was from a position of data provider. Chandrayaan data sets have been formatted in a globally accepted Planetary Data Archival System (PDS) format and made freely available through the Planetary data archival facility of ISRO.
In 2008, the International Lunar Exploration Working Group awarded the Chandrayaan-1 team the International Co-operation Award for accommodation and tests of the most international lunar payload ever (from 20 countries including India, the European Space Agency of 17 countries, US, and Bulgaria).
Scientific Goals of Chandrayaan-2
Chandrayaan-2, the second lunar exploration mission developed by the ISRO, took off from where the Chandrayaan 1 had left. The main differences were in addition to a lander and a rover. Chandrayaan-2 was much heavier than Chandrayaan-1 and required the services of a heavier LVM3 rocket. Soft landing technologies were new to ISRO. Initially a collaboration with Russia, it was worked out for the development of Rover. The mission finally consisted of a lunar orbiter, the Vikram lander and the Pragyan rover, all of which were developed in India. The main scientific objective was to map and study the variations in lunar surface composition, as well as the location and abundance of lunar water. The scientific goals of the Chandrayaan-2 orbiter included study of lunar topography, mineralogy, elemental abundance, the lunar exosphere, and signatures of hydroxyl and water ice as well as preparation of 3D maps of it. The lander, developed by Russia, was not placed on Chandrayaan-2 due to delays and increased weight. It was later sent by Russia as Luna 25 with the help of a powerful Soyuz rocket in August 2023 to land on Moon near its South Pole. It failed to achieve its mission in the final stages as a result of prolonged firing of the thruster in the descent orbit. The original Orbiter meant for Chandrayaan 2 found its place in India’s Mars Mission which took place before Chandrayaan’s flight and has amply contributed to the understanding of the Red planet.
Former PM Atal Bihari Vajpayee announced the Chandrayaan 1 project in his Independence Day speech on August 15, 2003. In November 2003, the Indian Government gave approval for the mission
After a number of standoffs and one mission abort on the launchpad, the spacecraft was launched on July 22, 2019, and reached the Moon’s orbit on August 20, 2019. The lander and the rover were scheduled to land on the near side of the Moon, in the South Polar region. As is now well known, the lander crashed when it deviated from its intended trajectory while attempting to land on September 6, 2019. This event was seen live on television by millions of people across the world. Inability to carry out a soft landing has created an impression that the Chandrayaan-2 mission has failed. To put facts into perspective, the orbiter of Chandrayaan-2 is performing extremely well and its data is being effectively used for preparing Lunar maps and for many scientific studies. It has even performed a collision avoidance maneuver on October 18, 2021, to avert possible collision with Lunar Reconnaissance Orbiter as both spacecrafts were coming dangerously close to each other on October 20, 2021, over the Lunar North Pole. The Chandrayaan-2 orbiter was used as an orbiter for Chandrayaan-3 as well. All communications of the lander and rover of Chandrayaan-3 are being routed through Chandrayaan-2 orbiter.
Chandrayaan-3 Mission
Chandrayaan-3 is the third and most recent Indian lunar exploration mission under the Chandrayaan programme of ISRO. It consists of a lander named Vikram and a rover named Pragyan similar to Chandrayaan-2. Its propulsion module acts like an orbiter until the spacecraft is in a 100 km lunar orbit. It does not have an orbiter to perform lunar observations from space. The launch of Chandrayaan-3 took place on July 14, 2023, at 2:35 pm (IST). The lander performed a textbook landing near the lunar South Pole region on August 23, 2023. The Lander and Rover have established contact with the Chandrayaan 2 orbiter and shall be communicating with the mission control through it.
Chandrayaan-3 comprises three main components:
Propulsion module: The propulsion module will carry the lander and rover configuration till 100 km lunar orbit. It is a box-like structure with one large solar panel mounted on one side and a large cylinder on top (Intermodular Adapter Cone) that acts as a mounting structure for the lander.
Lander: The lander is responsible for soft landing . It is also box-shaped, with four landing legs and four landing thrusters of 800 newtons each. It will be carrying the rover and various scientific instruments to perform in-site analysis.
Rover: The Chandrayaan-3 rover is expected to make a number of important scientific discoveries, including the composition of the lunar surface, the presence of water ice in the lunar soil among others.
Mission Objectives for Chandrayaan-3
The aim behind launching Chandrayaan-3 was getting a Lander to land safely and softly on the surface of the Moon, observing and demonstrating the rover’s loitering capabilities on the Moon and in-situ observation and conducting experiments on the materials available on the lunar surface to better understand composition of the Moon. Having successfully completed the first objective, all eyes were on the performance of Rover. The data received from the sensors onboard the Rover Pragyan will be analysed and become the knowledge base for further exploration of the Moon. Most sought after data will be related to the presence of water ice and to the presence and abundance of radioactive elements. The technologies validated in this mission will become part of ISRO’s arsenal to achieve greater heights. Propulsion module carries a payload called Spectro-polarimetry of Habitable Planet Earth (SHAPE) to study the spectral and polarimetric measurements of Earth from the lunar orbit in the near-infrared (NIR) wavelength range (1-1.7 m). Thanks to a huge saving in fuel in the propulsion module, it is expected to provide valuable data from SHAPE and further the characterisation of planet Earth as a habitable planet. Also, this may be an opportune time to stop being apologetic about a grand vision for space exploration. Because we can now boldly search, research and reach where no human has been!
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