AN outstanding feature of the Chandrayaan-2 mission is that it is totally indigenous. The launch vehicle, the orbiter, the lander Vikram and the rover Pragyaan have all been designed, developed and built in India. In fact, in 2007, India and Russia held discussions on Chandrayaan-2 as a joint lunar mission. The Indian Space Research Organisation (ISRO) was to build the launch vehicle, the orbiter and the rover for Chandrayaan-2 and Russia’s Federal Space Agency, Roskosmos, was to build the lander. Russia later said it would give the rover, too. But the joint project suffered a series of convulsions, making the Chandrayaan-2 mission a totally home-grown project. How it turned out to be so is a big story.

M. Annadurai, former Director of the U.R. Rao Satellite Centre, led an ISRO team to Russia in the last week of November 2007 to discuss the overall composition of the Chandrayaan-2 mission. He was then Project Director, Chandrayaan-1, which was put into orbit by the Polar Satellite Launch Vehicle (PSLV) of ISRO in October 2008. ISRO had built the orbiter for the Chandrayaan-1 mission, but some of the science instruments were sourced from different countries. During Annadurai’s visit to Russia in November 2007, the initial details about the Chandrayaan-2 project were discussed. While ISRO was to build the launch vehicle (Geosynchronous Satellite Launch Vehicle-Mk II) and the orbiter, Roskosmos was to build the lander and the rover. India was to take care of the mission operations as well until the lander-rover separated from the orbiter.

Annadurai played an important role in building the Chandrayaan-2 orbiter, the lander and the rover in the U.R. Rao Satellite Centre, until his retirement.

In the discussions held later, Russia wanted ISRO to build the rover, too. So, while India was to provide the launch vehicle, the orbiter and the rover, Russia would build the lander. An ISRO press release on August 30, 2010, confirmed this.

“…The lander and the rover are being built by ISRO,” it said. It was planned to have five scientific payloads on the orbiter and two in the rover. The orbiter was to weigh around 1,400 kilograms and the lander 1,250 kg.

However, after the failure of a joint Russia-China mission to the moon, “Russia wanted to make major changes in the configuration of its lander, which called for a big increase in the overall weight of the system”, Annadurai said. This happened soon after India started building the orbiter and the rover. Russia also wanted India to make changes in its rover. Annadurai said: “These changes envisaged a lift-off mass much more than what India’s GSLV-Mk II could put into orbit. Then Russia offered to build the launch vehicle, too. If we had accepted it, India’s contribution to the mission would have gone down. We would have done only the orbiter, which we had already done for Chandrayaan-1. We would not have done anything new. We decided to go on our own.”

(Russia also offered to build a 100-kg rover for the Chandrayaan-2 mission.)

When India decided to go it alone in the Chandrayaan-2 project, it meant that it would have to build the lander with its related technologies such as throttleable engines, sensors, control, guidance and navigation systems. This changed the schedule for the lift-off. Budget for the project went up by two times. Facilities for testing the lander and the rover were built.

“As per the outcome of the first phase of the tests, corrections in the overall system of the lander were called for,” Annadurai said. That increased the weight of the lander system and the fuel required by it. The weight of the composite module went up to 3.8 tonnes.

“This, in turn, went beyond the capability of the GSLV-Mk II to put the composite module into orbit. So we had to wait for the qualification of GSLV-Mk III,” he said. On July 22, 2019, a 640-tonne GSLV-Mk III M-1 rocket put the Chandrayaan-2 composite module into a perfect orbit.

T.S. Subramanian