Chandrayaan programme


The Chandrayaan programme also known as the Indian Lunar Exploration Programme is an ongoing series of outer space missions by ISRO for the exploration of the Moon. The program incorporates a lunar orbiter, an impactor, a soft lander and a rover spacecraft.
There have been three missions so far with a total of two orbiters, landers and rovers each. While the two orbiters were successful, the first lander and rover which were part of the Chandrayaan-2 mission, crashed on the surface. The second lander and rover mission Chandrayaan-3 successfully landed on the Moon on 23 August 2023, making India the first nation to successfully land a spacecraft in the lunar south pole region, and the fourth country to soft land on the Moon after the Soviet Union, the United States and China.

Background

The Indian space programme had begun with no intentions of undertaking sophisticated initiatives like human spaceflight and extraterrestrial missions during the initial days. It was only after ISRO developed the capabilities of creating satellites and orbital launch vehicles like PSLV, that the possibilities of India's first extraterrestrial exploration mission to the Moon were being explored in the early 2000s. The idea of a lunar scientific mission was first raised in 1999 during a meeting of the Indian Academy of Sciences which was then carried forward by the Astronautical Society of India in 2000. The robotic exploration programme is intended as a precursor until Indian astronauts land on the Moon to carry forward further explorations, with the robotic programme planned to continue beyond crewed landings as a support to the crewed missions.

History

First Mission

Soon after the proposals by the Indian Academy of Sciences in 1999 and by the Astronautical Society of India in 2000, a National Lunar Mission Task Force was set up which constituted ISRO and leading Indian scientists and technologists across the nation to conduct the feasibility study. The study report was then reviewed by a peer group of 100 scientists from various fields. The recommendations put forward were as follows:
  • The Indian Moon Mission assumes significance in the context of the international scientific community considering several exciting missions in planetary exploration, in the new millennium.
  • ISRO has the necessary expertise to develop and launch the Moon Mission with imaginative features and it would be different from the past missions. Hence ISRO should go ahead with the project approval and implementation.
  • Apart from technological and scientific gains, it would provide the needed thrust to basic science and engineering research in the country. The project would help return young talents to the arena of fundamental research.
  • The Academia, in particular, the university scientists would find participation in such a project intellectually rewarding. In this context, the scientific objectives would need further refinement to include other innovative ideas from a broader scientific community through Announcement of Opportunity, etc.
On 15 August 2003, then prime minister Atal Bihari Vajpayee announced the project which was estimated to cost. In November of the same year, the government approved the Chandrayaan project which would consist of an orbiter that would conduct mineralogical and chemical mapping of the surface. During the assembly of the orbiter only mission, then president A.P.J. Abdul Kalam visited the ISRO office and advised that orbiter alone would not suffice and proposed of another instrument that could be dropped on the surface. Following the advice, the scientists made design changes to the project and included an impact probe named Moon Impact Probe. The MIP was planned to be dropped from altitude and would acquire close-range images of the surface, collect telemetry data for future soft landing missions and measure the constituents of the lunar atmosphere.
The project required India set up its deep space network and the entire project cost. On 22 October 2008, Chandrayaan-1 was successfully launched aboard the PSLV rocket. After earth bound maneuvers and trans lunar injection, Chandrayaan-1 entered the lunar orbit on 10 November, making India the fifth nation to orbit Moon. Four days later, on 14 November, the Moon Impact Probe impacted near the Shackleton crater, in the lunar south pole, this made India the fifth country to reach the lunar surface. The MIP made the most significant discovery by confirming the existence of water on Moon. This discovery was not made public until NASA's Moon Mineralogy Mapper payload onboard Chandrayaan-1 orbiter confirmed the same on 24 September 2009. The mission was intended to last two years, but the contact with the orbiter was lost on 28 August 2009, which officially ended the mission.

Second Mission

After the success of the Chandrayaan-1 mission, a follow-up mission worth was already being planned and was targeted for a launch in 2012. Abdul Kalam suggested for collaboration between India and the United States for the Chandrayaan-2 mission, which would soft land near the lunar south pole and perform robotic penetrations into the surface to study more about the lunar water. However, an agreement had already been signed in the year 2007 by ISRO and Roscosmos, the Russian federal space agency, for the second lunar mission under the Chandrayaan-2 project.

Russian collaboration and back out

According to the agreement, ISRO had the responsibility of launching, orbiting, and deployment of the Pragyan rover while Russia's Roscosmos would provide the lander. The design of the spacecraft by ISRO was completed in 2009, the payloads were also finalized and the launch was targeted for 2013. The project then hit a roadblock when Russia delayed its development of the lander due to failure of its Fobos-Grunt mission which revealed technical issues in the similar parts that would be used in the lunar lander. Russia then proposed a few changes which required ISRO to decrease mass of its rover due to increase in the mass of the lander. A delayed timeline and the Russian request to accept the risk meant that India had to undertake the entire project independently. With Mars transfer window arriving in the 2013, ISRO repurposed the unused Chandrayaan-2 orbiter hardware for the Mars Orbiter Mission.

Indigenous development of the lander

With the Russian agreement falling apart, India was left alone and now had complete responsibility for the project including the development of lander technology. For which, ISRO created a mimic of Chandrayaan-2's lunar landing site in Challakere with craters that measured in diameter and were deep. This site was used for testing the electronics of the lander and rover. The project was now estimated to cost and was expected to launch in the first quarter of 2018 on GSLV MK-II. Later in 2017, India signed a deal with Japan's JAXA to conduct a feasibility study for another joint lunar roving mission named Lunar Polar Exploration Mission. For which a technical demonstration of soft landing was required to be conducted with Chandrayaan-2 mission.
In 2018, the mission faced its second delay after ISRO made design changes for the spacecraft as well as changes in its maneuver where the lander would orbit the Moon to assess the performance of various systems before performing landing. This was contrary to the previous plan where the lander would directly descend after arriving in the designated orbit. A fifth engine was added to the lander, the diameter of the landing legs was increased, two additional propellant tanks were added and additional support systems for power, structure, and thermal control were also provided. This significantly increased the mass of the composite and required ISRO to upgrade the GSLV Mk-II vehicle, but the scientists felt it would be risky to fly the test flight of the uprated Mk-II with Chandrayaan-2 payload, hence a more capable and already flown LVM3 vehicle was chosen.
During a landing test in February 2019, the lander suffered minor injuries in two of its legs due to a faulty orientation for the test, and the launch was then targeted for the second quarter of the year. Final cost for the Chandrayaan-2 project was around.

Flight

On 22 July 2019, Chandrayaan-2 was finally launched on LVM3 putting an end to several roadblocks that hit the mission during the decade. After orbit-raising maneuvers and finally the trans lunar injection, Chandrayaan-2 attained the lunar Orbit on 20 August. On 6 September 2019, during the descent to the surface, the contact with the lander was lost after it crash-landed. According to the chairman K. Sivan, the lander was operating as expected until it was just above the surface when it started deviating from the intended trajectory. Four years later, ISRO chairman S. Somanath revealed three major reasons for the failure, the presence of five engines that generated a higher thrust which made the errors accumulate over time, the lander being unable to turn very fast because it was not expected to perform at such a high pace turning and the final reason was the small 500x500 m landing site chosen that left the lander with less room for error.

Third Mission

Development

Two months after the failure of Chandrayaan-2, the third mission was proposed with the lander and rover being the primary components of the mission, unlike previously where the orbiter carried a greater scientific payload. The Chandrayaan-3 would be a re-attempt to demonstrate the landing capabilities needed for the LUPEX mission, a proposed partnership with Japan that was planned for 2025-26 time frame. ISRO sought from the government as initial funding for the Chandrayaan-3 project that included a propulsion module, a lander, and a rover. It was expected to launch a year later in November 2020. On 19 December 2019, P Veeramuthuvel was appointed as the director of the mission. The work on the project was underway come January 2020 and K. Sivan revealed that the launch may happen in early 2021 with the total cost of the project being. Later in March, the government confirmed that the launch could take place in the first half of 2021. The earlier addition of the fifth engine in the Chandrayaan-2's lander that caused the additional thrust was now removed from the design of Chandrayaan-3. Like Chandrayaan-2, the testing for the lander was to be conducted in Challakere where ISRO's previously built Moon like site with craters had deteriorated. A total of was spent on recreating the site with craters of similar dimensions.
The launch which was planned for early 2021, was then delayed to 2022 due to COVID-19 pandemic in India. The propulsion module which was ready before the pandemic had begun its testing, following which the lander and rover tests were to be conducted but the pandemic delayed the project and pushed its tentative launch date to the third quarter of 2022. Few more changes with strengthening the landing legs, improvisation in instruments, a failure-proof configuration and additional testing meant that the new schedule for the launch was moved to second quarter of 2023.
In May 2023, the spacecraft was in its final stage of the assembly of payloads at the U R Rao Satellite Centre with the launch targeted for the first or second week of July.