ISRO: Chandrayaan-4 design final, samples from Moon by 2027

The Chandrayaan-4 sample return mission would be a complex mission involving several stages. After getting into lunar orbit, two of the modules will detach from the main spacecraft and make a landing on the Moon. They will help each other in collecting samples from the lunar surface. One of the modules will launch itself from the Moon’s surface and travel back to the main spacecraft in the lunar orbit. The samples will be transferred, and then flown back to an Earth re-entry vehicle that will be launched separately from the ground. The samples will be transferred again, and it is this re-entry vehicle that will bring them back to the Earth.

Somanath said designs for this mission have been finalised, and the project was awaiting the final government approval. ISRO has also finalised designs for the next Moon mission, Chandrayaan-5, but did not specify the objective or timeline of the mission, he said.

Chandrayaan-4 would involve docking of space modules twice during the Mission — when the modules fly back from the Moon to unite with the main spacecraft, and when the samples are transferred to the re-entry vehicle. ISRO has never docked spacecraft earlier. This capability will be demonstrated for the first time later this year, with the Spadex mission. Docking is a process where two spacecraft moving at extremely high speeds are aligned in a precise orbit and joined together.

According to senior ISRO scientists, two key capabilities required for the Chandrayaan-4 success had been demonstrated during the Chandrayaan-3 mission. “The hop experiment that was performed on the last day of Chandrayaan-3 mission (lander of Chandrayaan-3 was made to jump about 40 cm from the lunar surface and land 30-40 cm away) was done to understand whether we can lift off from the lunar soil. There were concerns about the legs of the lander getting deep inside the lunar surface, which would have made the ‘hop’ difficult to execute. But Chandrayaan-3 did that exceedingly well. There were no problems, and the results were according to our expectations,” one of the scientists said.

“The other capability was to get the spacecraft from the orbit of the Moon to the Earth’s. The Chandrayaan-3 propulsion module, which had carried the lander-rover to the Moon, was brought back to the Earth’s orbit to demonstrate this,” the scientist added.

While instruments from the Chandrayaan-3 studied soil and rock on the Moon’s surface, bringing back samples will allow scientists to study the samples with more complex and sensitive instruments. The senior scientist further said that all the samples brought back by the mission will be shared across different scientific laboratories in the country.