consists of three segments — the orbiter (2,379 kg), Vikram (1,471 kg), and Pragyaan (27 kg). When it takes off, about 7,000 people will be watching at the launch site.
The GSLV Mark-III launch vehicle was moved to the launch pad on July 7. The 20-hour-long countdown will begin on Sunday.
Last-minute preparations are on, said sources. Isro completed launch rehearsals and pre-fill pressurisation of propellant tanks on Friday.
Scientists at Isro have developed the lander and the rover indigenously after the Russian promise to provide technology failed to come through. These have been tested in a simulated atmosphere. Sources said the testing area was prepared with rocks from Salem.
is designed to study lunar topography, seismography, mineral identification and distribution, surface chemical composition, thermo-physical characteristics of topsoil, and the composition of the tenuous lunar atmosphere.
Flight to the moon
About 16 minutes after take-off, the 640-tonne rocket will put the spacecraft — weighing about 3.8 tonnes, about the same as eight elephants — into orbit. A series of manoeuvres will project it into the lunar transfer trajectory.
If all goes according to schedule, Pragyaan and Vikram, marked with the Tricolour, the Ashoka Chakra and Isro’s logo, will touch down on the lunar surface on September 6 or 7. The distance between the Earth and the moon is 384,400 km.
On the day of the landing, the lander and the orbiter will separate and perform a series of complex manoeuvres. The six-wheeled rover will carry out two experiments on the moon for one lunar day, which equals 14 Earth days. The orbiter’s mission will continue for a year. There is also one experiment commissioned by the US space agency NASA.
The moon landing faces several challenges, such as trajectory accuracy, communication, trans-lunar injection, lunar capture and orbiting around the moon, soft landing, lunar dust, extreme temperatures, and vacuum.
The soft landing is the most crucial part, which Isro has never attempted before. The chairman of the space agency, K Sivan, earlier described the 15 minutes needed for this as the “most terrifying” part of the mission.
From an orbit of 30 km from the moon’s surface, the lander will drop softly. Its doors will open and the rover will roll out. This will take nearly four hours as the rover moves at a speed of 1 cm per minute. It will never go any further than 500 metres from from the lander.
Chandrayaan-1 (2008) and the Mars orbiter (2014) tested India’s ability for precise deep-space navigation. Chandrayaan-2 is way more intense, said K Radhakrishnan, former Isro chairman.
“Imagine the lander orbiting the moon at a speed of 6,000 kmph,” he said. “It has autonomous capability to break its speed and steer itself for a soft landing in uncharted terrain, at a precise site. The site will also be determined while descending.”
Radhakrishnan added this was the first step taken by the moon mission for robotic space exploration.
The success of Chandrayaan-2 will make India the fourth country in the world to land and explore the lunar surface.
Eye on the future
There is a renewed interest from many nations on lunar exploration, with particular focus on the south pole of the Earth’s only natural satellite.
Chaitanya Giri, fellow, space and ocean studies programme, Gateway House: Indian Council on Global Relations, said the poles of the moon were important for exploring the potential of human habitation.
In an article, Giri said the north pole of the moon had caves and underground channels with solid lava, while the south pole had ice and carbon dioxide. Both were important if humans were to consider living on the moon.
The moon is a nearby laboratory to look back at the Earth’s history, said P Sreekumar, director of SSPO, Isro.