Chandrayaan-3, India’s third spacecraft began its journey towards the Moon on 14 July 2023. India’s first mission to be Moon Chandrayaan- 1, was successfully launched in 2008 and subsequently, the second mission called Chandrayaan-2 was launched in 2019, which was a partial success. Now, the Indian Space Research Organisation (ISRO) has successfully completed the third mission with the aim to erase the failure of the soft landing which happened in 2019. It would take another 40 to 42 days of travel for the mission to reach the Moon, enter the lunar orbit and once again attempt the lunar landing. It is expected to happen around 23/24 August 2023.
This third mission’s launch was a perfect copybook launch. ISRO’s first mission to the Moon was an orbiter mission, which means that when a satellite was launched towards the Moon surface it stayed in the orbit of the Moon and undertook various observations almost for a year. In collaboration with the US space agency NASA, this mission was successful towards identifying the presence of water on the Moon. The second mission was an orbiter and lander & rover mission. During this mission, ISRO was able to put the orbiter successfully in lunar orbit. Initially, ISRO had predicted that this orbiter would survive in the lunar orbit for one year. However, the launch of the mission and journey towards the moon was so perfect that no additional fuel got used during the travel towards the Moon and hence that orbiter continues to operate even today and is expected to be operational till 2026. However, ISRO was not able to achieve a perfect landing on the Moon for its lander and rover unit.
During the last four years, ISRO has worked hard first to identify what went wrong with the Chandrayaan-2 lander (+rover) landing on the Moon, then reworked both software and hardware-related challenges and finally undertook an expensive process of simulations and testing. As per ISRO, they have worked almost on all ‘known unknowns’ and feel that this time the mission should get a success provided no ‘unknown unknowns’ play a spoilsport at the last moment.
The launch vehicle used for this mission was LMV-3. When ISRO is launching satellites into low earth orbit, they use this version of GSLV-Mk-3. Recently, LMV-3 was used for undertaking two commercial launches for the UK-based company called OneWeb which is providing satellite-based internet facilities. During each mission, 36 satellites were launched into low earth orbit. LMV-3 is a three-stage vehicle. S200 solid strap-ons (two in number), Core Stage (L110, liquid propellant) and Upper Stage (C25), which is a cryogenic stage. While using LMV-3 for Chandrayaan-3, ISRO has smartly used this opportunity to validate the capacity of this vehicle to undertake human missions. During this mission, they used human-rated solid strap-on motors. It has been also reported that the L110 Vikas engine is also human-rated. Possibly, all this would bring confidence for undertaking future unmanned and manned missions for the Gaganyaan project.
As of date ISRO’s LMV-3 has put the Chandrayaan-3 module at an altitude of 180 km and for reaching the Moon it must travel about 384,400 km up in the sky. To do this, ISRO would undertake around five Earth orbit-raising manoeuvres. With this, the craft would reach about 100,000 km. Subsequently, ISRO would take a slingshot to make it reach a trajectory to the Moon. After it establishes itself in a lunar orbit further activity of reducing the altitude would start for attempting soft-landing on the Moon’s surface.
Chandrayaan-3 mission has two main components: a Propulsion Module and a lander & rover unit (lunar module). This time the mission is not carrying any orbiter, since the orbiter launched during 2019 can be used for this mission too. The structure of the lander-rover system is nearly the same as the Chandrayaan-2 mission. The lander has three payloads (sensors) and the rover has two. Broadly, all this equipment would study the thermal properties of the lunar surface and undertake an analysis of the chemical and mineral composition of the lunar surface. Also, some seismological assessments of the Moon would be conducted.
Since India’s first mission to the Moon was able to find the presence of water on the Moon, ISRO is keen to expand on this research finding and hence decided to put its lander and rover unit close to the south pole of the Moon. To date, the US, Russia and China are the only states which have been successful towards putting their robotic equipment on the Moon’s surface. However, most of the missions have landed close to the Moon’s equator. Such landing requires a bit less fuel and the sun is available over there, which helps continuous charging of the solar panels. South pole landing is a bit tricky owing to the typical topography of the region. There are areas out there which have not received sunlight for millions of years. It is expected that water in some form (ice) could be present over there. ISRO is keen to verify any such possibilities.
For the next forty days or so, ISRO’s mission will be facing various challenges. If around 23 August 2023 ISRO manages to perform a soft landing on Moon’s surface, then it would become the fourth country in the world to achieve this distinction. Much depends on the success of this mission, for India to expand on its future Moon agenda.