Plans for India’s second unmanned mission to the moon have been unveiled by the Indian Space and Research Organisation. Chandrayaan-2 will take off aboard the GSLV MK-III rocket at 0251 hours on 15 July from the Satish Dhawan Space Centre at Sriharikota in Andhra Pradesh.
The Chandrayaan-2 will attempt a soft landing on the unmapped southern pole of the moon. An extremely complex manoeuvre, a soft landing is a slow, gradual landing which has been achieved only by the US, the former Soviet Union, and China so far. This type of descent means the spacecraft will suffer no damage as it slows down during descent, requiring complex control over its speed.
Interestingly, all earlier lunar missions, manned or unmanned, have touched down on the better known northern hemisphere of the moon. Speaking to the media, ISRO Chairman K Sivan said, “It is also an interesting area. It receives low sunlight, so there are better chances of finding water here. The region, however, gets more hours of sunlight, thereby giving more time for the probes to carry out their experiments.”
The final moon landing is expected to take place between September 4 and 6.
Chandrayaan-2 is made up of three parts: an orbiter, a lander, and a rover. As it enters the lunar orbit, it will separate out into two parts, the orbiter and the lander.
The orbiter will continue to travel around the moon and is responsible for studying the moon’s exosphere. Equipped with a three-dimensional camera and an X-ray spectrometer, it will pick up the moon’s X-ray radiations, which will help scientists understand the moon’s surface elements and minerals.
The lander, meanwhile, will descend towards a designated spot on the surface of the moon.
It is this landing that will be the team’s greatest challenge. Lunar gravity is lumpy because of an uneven distribution of mass under the moon’s surface. The spacecraft has to break away from this uneven gravity, slow down from its initial speed and get into what is called a “descent trajectory” or the path followed for a touchdown.
“Slowly the lander will come and land at a place near the south pole,” explained Sivan. “From the 30 km [initial orbiting speed] to breaking of speed to landing will take 15 minutes. This 15 minutes will be the most terrifying moment for all of us. Not only Indian. ISRO has never undertaken such a complex flight.”
Once the lander has touched down, its doors will open and the moon rover will come out and land on the lunar surface. “From the time of landing to this moment, it will take four hours,” said Sivan.
The rover will move at a speed of 1 cm per second and will scan the surface for water minerals and an element called helium-3. The lander will inject a probe 10 cm deep into the moon’s surface to study seismic activity, manifested as lunar quakes.
Both the lander and rover have a life of one lunar day, or 14 earth days, while the orbiter can remain in function for an entire earth-year.
The cost of the entire mission, Sivan said, is Rs 600 crore.
The mission will also help integrate relations between ISRO and NASA, The Times of India reported. “NASA’s passive payload Laser Retroreflector, integrated with Vikram lander, will be ‘carried for free’ and help calculate the distance between the earth and the Moon,” K Sivan said. “It will also find the exact location of the lander on the Moon. This Nasa payload will work for long and Nasa will share the data generated from this payload with us.”
Launched on October 22, 2008, Chandrayaan-1 discovered water molecules on the lunar surface and orbited the moon over 3,400 times. The spacecraft completed its life cycle and lost communication with Earth on 29 August 2009.