by Dr. Jaipal Singh
India created a history in the space research and technology on the Wednesday, 23rd August 2023 (IST 18:03 Hrs), when the Indian Space Research Organization (ISRO)'s Chandrayaan-3 made a perfect soft-landing on moon's surface with an absolute precision. This august and rare success is also remarkable from the point of view that the landing was done on the south pole region of the moon where no other country of the so-called elite space club nations, has ventured ever in the past owing to its difficult and unpredictable terrain. With this feat, India became the fourth country to achieve a successful mission to moon; the other three being the USA, Russia and China. The part of spacecraft now positioned at the surface of moon contains the Vikram Lander and Pragyan Rover modules, which are likely to remain active for one full day on moon (i.e., equal to 14 earth days). During their active phase, they are likely to look for the traces of water/ice, minerals in the moon crust, etc., and send it back to ISRO control station through orbiter encircling the moon.
The Vikram Lander has already established communication links with the Missions Operation Complex of ISRO in Bengaluru, Karnataka. The Pragyan Rover was carried inside the lander, which soon rolled out on to the moon surface as scheduled sometime past midnight. The Pragyan Rover has been so designed as to leave an imprint of the National Emblem of India and ISRO's logo on the lunar surface wherever it goes on the moon surface. It is expected that it will roam over the rather bleak and unchartered terrain during the next few days while simultaneously sending back relevant data and visuals. Hopefully, India's bid to unravel mysteries on the so far unexplored side of the moon shall produce useful data and information for the global benefits and awareness, as also exclaimed by an elated ISRO Chairman S. Somnath amid applause immediately after the lander touched the moon surface: We have achieved soft-landing…India is on the moon…This is the beginning of the golden era.
About the Chandrayaan Programme
The Chandrayaan is the native or indigenous name given to the Indian Lunar Exploration Program, which is currently an ongoing series of outer space missions by the Indian Space Research Organization (ISRO) for the exploration of the earth's only natural satellite, Moon. So far, three missions to the moon have been undertaken and the current successful mission was third such attempt. Normally, apart from the launch rocket (propulsion module) with necessary fuel, such missions have four important modules, namely a lunar orbiter, an impactor, a soft lander and a rover spacecraft. Only the later two missions made serious attempt containing all modules; of which, the Chandrayaan-2 mission crashed on the moon surface at the last stage while the recent Chandrayaan-3 successfully soft-landed on the moon surface on its south polar region, thus enabling Bharat (India) to become only the fourth country in the world to have successful expedition involving landing on the moon following the US, Russia and China.
Idea about the Chandrayaan Project was conceptualized in 1999 with the former Prime Minister Atal Bihari Vajpayee himself announcing the mission. The Chandrayaan-1 was finally launched by the ISRO on 22 October 2008 from Satish Dhawan Space Centre, Sriharikota in Andhra Pradesh using a PSLV-XL rocket. The spacecraft included an orbiter and mission impact probe (MIP) largely using indigenous technology and the vehicle was successful placed in the lunar orbit on 8 November. Nearly a week later, the MIP was separated from the orbiter that hit the south pole region in a controlled manner on 14 November 2008, the location was named as Jawahar Point after the India's first Prime Minister Jawaharlal Nehru. The orbiter was expected to function for about two years during which it would explore three-dimensional topography and mapping of the moon surface for finding its chemical composition, trace of water, etc. However, it started experiencing technical issues and stopped communication with the earth station on 28 August, 2009, with the ISRO announcing of mission's closure after achieving its most intended objectives. Its achievement included detection of some water molecules, mapping and atmospheric profiling of the Moon.
Chandrayaan-2 was second such mission of the ISRO which was comprised of a lunar orbiter, the lander and a rover. Even before the launch of its first mission, the ISRO had signed an agreement with the Russian Space Agency Roscosmos mainly taking the latter's assistance in developing the lander module. However, Russia later expressed its inability to provide the lander in the stipulated timeframe; hence India decided to develop its lunar mission independently, including the lander module. The chief scientific objective was to map and study the lunar surface composition and availability of water. The second launch was also done from the Satish Dhawan Space Centre on 22 July 2019 by a LVM3 rocket. The spacecraft was successfully inserted in the lunar orbit on 20 August 2019 scheduling the lander and rover to land in the south polar region on 6 September 2019. However, at the final stage, the lander crashed deviating from its trajectory during landing on the scheduled date owing to some software glitch, as revealed by the Space Agency after due analysis. The orbiter of the Chandrayaan-2 is still operational and is expected to have over seven years of life collecting scientific data for the ISRO.
Chandrayaan-3 is the current and third Indian lunar mission undertaken by the ISRO after the partial success of the previous launch. After nearly four years preparations and hard work since 2019, Chandrayaan-3 was launched on 14 July 2023 from the Satish Dhawan Space Centre (SDSC), Sriharikota using an advanced LVM3 rocket. It consisted of the orbiter, the lander Vikram and the rover Pragyan; incidentally, the names of the lander and rover from the Chandrayaan-2 have been retained. After the successful launch, the spacecraft occupied the lunar orbit on 5 August and the lander Vikram soft-landed in the south pole region on 23 August 2023 as scheduled; thus, Bharat becoming only fourth nation to achieve this feat and first nation to land in the said region. The south pole region of the moon is of particular interest for the scientific exploration supposedly owing to the mountainous terrain, uneven & unpredictable lighting conditions and a large amount of ice, making the scientific probe a challenging yet more useful task. Though far-fetched for now yet a distinct possibility in future is that the ice on the moon could be tamed as a viable source of drinking water, hydrogen for fuel and oxygen for the crewed missions.
Chandrayaan-3: Technical Features & Objective
Technically, the Chandrayaan-3 is a follow-on mission to Chandrayaan-2 with an objective to demonstrate end-to-end capability in safe landing and roving on the lunar surface. It comprises of the Lander and Rover configuration but the propulsion module is also a crucial part of the mission, which consists of the latest variant of the LVM3 rocket to be launched from SDSC, Sriharikota. The latter would carry the lander and rover configuration till nearly 100 km lunar orbit along with the Spectro-polarimetry of Habitable Planet Earth (SHAPE) payload or orbiter to study the spectral and polarimetric measurements of Earth from the lunar orbit. Thus, the mission essentially carries largely indigenous built a Propulsion Module (PM) and a Lander Module (LM) with a Rover. The main purpose of the Propulsion Module is to carry the Lander Module from launch vehicle injection till final lunar 100 km circular polar orbit and separate the PM and LM, while the latter would soft-land on the moon surface at the specified site and deploy the Rover out in-situ for the data collection and chemical analysis of the lunar surface during the course of its mobility.
The mission objectives of the Chandrayaan-3 as formally revealed by the ISRO are: 1) To demonstrate safe and soft landing on the lunar surface; 2) to demonstrate Rover roving on the moon; and 3) to conduct in-situ scientific experiments. To achieve the aforesaid objectives, the ISRO has employed relevant advanced technologies in the Lander including state of the art altimeters, velocimeters, inertial referencing and accelerometer package, propulsion system, navigation, guidance & control devices and software, hazard detection & avoidance camera and processing algorithm, and landing leg mechanism. To make sure that the aforesaid advance technology systems flawlessly work with precision, elaborate testing were carried out successfully for long in simulating conditions. The Lander module was inter alia equipped with instruments to measure the thermal conductivity, seismic activity, plasma density and its variation, lunar laser ranging studies, and so on. Similarly, the Rover module was equipped with mechanism to analyse the elemental composition in the vicinity while roving with ease in the anticipated rugged terrain.
The anticipated mission life of the Lander Vikram and Rover Pragyan is one lunar day which is equivalent to about fourteen earth days while the prescribed range of the prime landing site is an area of 4 km x 2.4 km, and they are working satisfactorily after the successful landing while the author is penning these lines. The total estimated mass of the mission was 3900 kg, of which the PM was comprised about 2148 kg while the LM 1752 kg along with the Rover about 26 kg. While the most of readers may find specifications of the units of power generation, communication, sensors, actuators, propulsion system and lander mechanism too technical to grasp with sufficient interest, mention of its lander velocities might be of some interest as millions of onlookers were tied with the Lander's live landing on the scheduled date. Thus, the Lander touchdown specifications included a vertical velocity of approximately two meter per second while the horizontal velocity was 0.5 meter per second with near twelve-degree slope. continued……Boloji.com
