On the afternoon of July 22, 2019, a Geosynchronous Satellite Launch Vehicle Mark III (GSLV MkIII) rocket lifted off from the Satish Dhawan Space Centre (SDSC) in Sriharikota carrying India’s ambitious mission to the Moon, Chandrayaan-2. This is India’s second mission to the Moon and was previously scheduled to be launched on July 15. However, that time the launch vehicle suffered a technical snag about 56 minutes before lift-off and it was rescheduled for July 22. The 20-hour countdown began on the evening of July 21 at 18:43 hours IST for the launch which was planned on July 22 at 14:43 hours IST.

“On July 15, 2019, ISRO intelligently observed a technical snag. Team ISRO worked out and corrected the snag within 24 hours. For the next one and a half days, the required tests were conducted to ensure that corrections made were proper and in the right direction. Today ISRO bounced back with flying colours,” said Dr K. Sivan, Chairman, ISRO, after GSLV MkIII-M1 successfully injected Chandrayaan-2 spacecraft into the Earth orbit, having completed all three stages of the launch vehicle.

The spacecraft is now revolving round the Earth with a perigee (nearest point to the Earth) of 169.7 km and an apogee (farthest point to the Earth) of 45,475 km. This launch marks the first operational flight of the GSLV MkIII.

“Today is a historical day for Space Science and Technology in India. I am extremely happy to announce that GSLV MkIII-M1 successfully injected Chandrayaan-2 into an orbit of 6,000 km more than the intended orbit and is better. It is the beginning of a historic journey of India to the Moon and to land at a site near its South Pole to carry out scientific experiments,” Sivan added.

The mission objective of Chandrayaan-2 is to develop and demonstrate the key technologies for endto-end lunar mission capability, including soft-landing and roving on the lunar surface

Embarked on a GSLV MkIII-M1, the 978-crore mission is aimed to land on the Moon on September 7, after several orbital phases. The three-stage GSLV MkIII, is India’s most powerful launcher till date and is capable of launching four-tonne class of satellites into the Geosynchronous Transfer Orbit (GTO). For Chandrayaan-2, the GSLV MKIII-M1 will be carrying an Orbiter, a Lander (named Vikram) and a Rover (named Pragyaan) in a mission aiming to unveil information related to the lunar surface.

People from across the country registered to watch the launch from the SDSC spaceport in Sriharikota in Andhra Pradesh, where a special gallery was made specifically for the launch. Many people had also gathered outside the launch centre and thousands were glued to their screens for live streaming. ISRO also continued to update about each development on its twitter handle and shall continue to do so throughout the mission.

WHAT HAPPENS NOW?

About 16 minutes 14 seconds after lift-off, the vehicle injected Chandrayaan-2 spacecraft into an elliptical Earth orbit. Immediately after separation of the Orbiter from the launch vehicle, the solar array of the spacecraft automatically got deployed and ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru, successfully took over control of the spacecraft.

Now the spacecraft would go around the Earth for about 23 days. After this, a series of manoeuvres would be carried out to gradually raise the orbit and put Chandrayaan-2 on the lunar surface trajectory, which might take up to five days. Dr K. Sivan said that Chandrayaan-2 will perform 15 crucial manoeuvres in the days to come.

Once it has been injected into the lunar orbit, the Chandrayaan-2 would go around the Moon for a period of about 12 days. On the 48th day, i.e. on September 7, the landing on the surface of the Moon would be attempted. For this, the Lander would separate from the Orbiter and start what Dr Sivan said, will be ‘the most terrifying 15 minutes of this mission’.

During these 15 minutes, Vikram would try to soft-land at an identified site on the lunar South Pole, which is a completely unexplored section of the Moon. This will indeed be the world’s first space mission to conduct a soft landing on the Moon’s South Polar Region, according to ISRO. The surface area in the South Polar Region of the Moon that remains in shadow, is much larger compared to that in the North Polar Region. This makes the Moon’s South Pole an area of special interest, hinting at the possibility of the presence of water in permanently shadowed areas around it. ISRO also informs that in addition, the South Pole region has craters that are cold traps and contain a fossil record of the early Solar System. Moon’s South Polar Region is also where India’s first Moon mission, Chandrayaan-1 had detected traces of water.

Prime Minister Narendra Modi congratulated the ISRO team and also tweeted about this unexplored expedition.

Post the landing of the lander Vikram, the Rover Pragyaan will roll out and conduct experiments on the lunar surface for one lunar day which is equivalent to 14 Earth days while the orbiter will continue its mission for one year. The instruments on the Rover will analyse the surface and send back data. The orbiter will move around the Moon for remote sensing, while the various science payloads will gather information on lunar topography, mineralogy, elemental abundance, lunar exosphere and signatures of hydroxyl and water-ice. The landing is crucial also because it marks the beginning of the 14-daylight period on the Moon, which is critical for conducting experiments by the solarpowered Lander and Rover.

The mission objective of Chandrayaan-2 is to develop and demonstrate the key technologies for end-to-end lunar mission capability, including soft-landing and roving on the lunar surface. On the science front, this mission aims to further expand our knowledge about the Moon through a detailed study of its topography, mineralogy, surface chemical composition, thermophysical characteristics and atmosphere leading to a better understanding of the origin and evolution of the Moon.

The orbiter had a lift-off weight of about 2,369 kg, while the lander and rover weighed 1,477 kg and 26 kg respectively. The rover can travel up to 500 metres and relies on electric power generated by its solar panel for functioning.

Chandrayaan-2 has several scientific payloads with the Orbiter carrying eight payloads, the lander carrying three and the rover two. Besides, a passive experiment is included on the lander. The Orbiter pwayloads will conduct remote-sensing observations from a 100 km orbit while the Lander and Rover payloads will perform in-situ measurements near the landing site.

The ground facilities constitute the third vital element of Chandrayaan-2 mission. They are performing the important task of receiving the health information as well as the scientific data from the spacecraft. They are also transmitting radio commands to the spacecraft. The Ground Segment of Chandrayaan-2 consists of Indian Deep Space Network, Spacecraft Control Centre and Indian Space Science Data Centre.

This is India’s maiden attempt to land on the lunar soil. As of now, only Russia, USA, and China have been successful in achieving soft-landing on the Moon. If successful, India would be the fourth country to achieve this feat!