ISRO's Chandrayaans will build capability to land humans on moon and return safely: Chairman Somanath

ISRO chairman S Somanath

ISRO's upcoming missions - Chandrayaan 4 and 5 - will be important for India's aim to send humans to the Moon and bring them back safely within the next 20 years, Indian Space Research Organisation (ISRO) chairman S Somanath said on August 23.

"The journey of Chandrayaan 3 is going to continue. The model of Chandrayaan 4 is ready. We have proven how to reach Moon. But we have to now prove how to come back from there," S Somanath said at an event in New Delhi to mark the first National Space Day.

"It is important to take the next step because we have an added vision of sending humans to Moon and bring them back safely. So, we have to incrementally progress in the next 20 years to build that capability to land there and come back safely," Somanath added.

The National Space Day commemorates the anniversary of the successful landing of Chandrayaan-3 near the South Pole of the Moon.

Also read: Chandrayaan 4-5 design complete; 70 satellites likely to be launched in 5 years, says ISRO head

On August 23, 2023 India made history after Chandrayaan-3's Vikram lander  was the first to land successfully on the South Pole of the Moon. Over the next couple of weeks, the Pragyan rover explored the lunar surface and conducted experiments.

How Chandrayaan 4 will work

Later speaking to media persons on the sidelines of the event, Somanath explained what Chandrayaan 4 mission will do.

"To bring back the spaceship (from Moon), we need another technology. We have to escape the gravity of the moon, then we have to orbit around the moon, then come back and re-enter (Earth's) orbit. Re-entering is also very difficult because of Earth's atmosphere. So you have to have materials to protect everything," he said.

"So it will go there, land, then take off from there and come back. So this is the technology. So if you have to send a man to moon, we will definitely need this technology. But we don't have so much of money to spend at this moment. So we will prove it in a model -- we will prove the complex system in Chandrayaan 4 and scale up to send human beings later," he explained.

The 'energy' factor

Somanath emphasised that the ISRO has to complete Chandrayaan 4 by 2027, as it gives "the least energy opportunity" to take up the mission.

Somanath further explained, "See, the mission to moon is always not the same. Every day it changes slightly -- the orientation of the moon, the trajectory of the craft, etc. So we calculate what is the best date with the minimum energy you can go

"So 2027 is one of the time period is found to be the best. Similarly, we have opportunities for Mars. That comes very occasionally. But luckily, moon you can go every year. But Mars means you cannot go every year," he said adding that there is a wide window for 2027 for Chandrayaan 4 mission

Bharatiya Antariksh Station

India's proposed space station - Bharatiya Anatariksh Station (BAS)- is being planned as a scientific platform for experiments. "There will a be a huge number of collaboration between academia and industry," he added.

Somanath said that the first module of the BAS, will be launched by 2028. The first module will be a smaller one which will not have any human entry capability, Somanath explained. "It will be more robotic," he said adding that the smaller module will fit inside the ISRO's LVM-3 launch vehicle.

"Then it will take few years to build the other modules. Meanwhile, we have to have a new rocket where we can put the bigger modules," he added.

"So our objective is we'll have five different modules. All will dock in space. And we will have an astronaut going there and living for a long time and doing experiments in various areas, material science, biology, and space manufacturing," he said, adding that all the government is aiming to have all the five modules operational by 2035.

Debris free satellite mission

During the inaugural session of the National Space Day, President Droupadi Murmu announced that India, by 2030, will also launch a debris free satellite mission.

Expanding on that announcement, Somanath said, "So we have made an announcement that we will not litter space. After launching and once they stop functioning, we will bring them back."

"Firstly, we will ensure that we will not collide with anyone. And we will not cause explosion in space," he said.

In this regard, ISRO has launched the Zero Debris Mission, which Somanath, said India wants all nations to follow that so that space can remain debris-free.

Chandrayaan-3 data

Somanath said that there were were five experiments on Chandrayaan 3 which delivered "excellent data". With the help of insights gained from Chandrayaan 3 project, Somanath said, the agency was able to discover that the lunar surface was once filled with magma.

"Today we have 55 GB of data from Chandrayaan 3," he said. The ISRO chief said that the data has been reviewed and analysed and is going to be made public.

With a larger aim of landing Indians safely on the Moon, the ISRO chief said the agency will work on different technologies required for the same, including developing launch vehicles that are cost effective.

Somanath also said that the government is trying to make India's human space flight mission, Gaganyaan, sustainable, and aims to create a pool of astronauts.

Also read: Indian astronaut-designates Shubhanshu Shukla, Prashanth Nair selected for NASA-ISRO mission to ISS