“Our project was not directly linked with Chandrayaan 3. We have shared our findings with the Indian Space Research Organisation (Isro) but have no idea if they used it in this mission,” Amitava Gupta, professor of power engineering, clarifies as The Telegraph Salt Lake walks into the building on the Salt Lake campus of Jadavpur University.
At the microprocessor laboratory on the top floor, he and four postgraduate students have created a simulator which can be used for any planetarory exploration. It simulates the powered descent phase of a lunar lander using a representative physical model, which they built using Lego bricks, and lunar imagery which Isro had supplied to them.
“Our project was called ‘Vision guided auto lander for planatery explorations’. It was part of Isro’s Respond programme through which they involve universities and take research inputs from them,” Gupta said.
A spacecraft, he explained, has different components run by different technologies, developed by separate groups. “Some groups work on thrusters, some on image processors, some on sensors... All these have to be integrated at the lab scale and run on real time. That is the work of a real-time simulator. Our job was to create a workable model which could process the digital images and match the outputs of the controller.”
A spacecraft trying to land on the moon,” he said, is “like us trying to grope our way through a dimly lit room at home”. “We match the images of the furniture in our memory to the shapes we see and negotiate our way,” Gupta said, showing the simulation of a landing on his laptop screen which looked exactly like the landing of Chandrayaan 3 that was broadcast live on screens across the country and on the internet.
As the spacecraft moves closer to the surface, at a height of about 100m, it starts hovering to check if there are boulders on the landing spot. “It creates a 3D image of the surface. Any obstacle bigger than 30cm on the surface would require the spacecraft to retarget the landing as it would topple otherwise,” Gupta said.
Chandrayaan 3 did not require retargeting, he added, as it did not encounter an obstacle at the chosen landing spot.
Gupta's co-investigator Sayan Chatterjee, professor of electronics and telecommunication, had worked on the initial part of the image processing.
“With my research scholar Surajit Sarkar and two undergraduate students, he did fantastic work on creation of an image database. After that, we developed the controller module here, along with some mechanical engineering students, and we could simulate the last 10-15 minutes of landing, moment by moment, of a lunar lander.”
The JU team had got on board when a team from Isro's Space Applications Centre in Ahmedabad came for a visit in 2016. “They noticed the deep space simulation project done by our student Diptyajit Chowdhury on earth to moon communication and offered to pass on related work,” Gupta recalled. While discussions had started in mid-2017, the project ended in 2022.
Even though congratulations have come their way too as the city, along with the rest of the country, celebrated the successful landing of Chandrayaan 3, Gupta pointed out that the credit for assimilating university research in its missions and flying a rocket on the moon was a much bigger task than developing a simulator. “The credit for that goes to Isro alone,” he summed up.