Chandrayaan-3: India Moon mission's propulsion module returns to Earth's orbit
Dec 5: India's space agency Isro says it has successfully brought back into Earth's orbit a part of the rocket that carried its historic Moon mission recently.
The "propulsion module" had detached from the Vikram lander after ferrying it close to the Moon where it finally touched down on 23 August.
After a series of complex maneuvers, the module re-entered Earth's orbit.
The experiment is significant for Isro's plans to bring back manned missions in the future.
The module will continue to keep an eye on Earth from its new perch, Isro said.
When Chandrayaan-3's lander, carrying the Pragyaan rover in its belly, touched down, India became the first country to land near the little-explored lunar south pole region. It also joined an elite club of countries to achieve a soft landing on the Moon, after the US, the former Soviet Union and China.
The lander and the rover spent two weeks gathering data and images, after which they were put into 'sleep mode' at lunar nightfall.
The propulsion module, meanwhile, continued to orbit the Moon, keeping an eye on Earth through a scientific instrument it's carrying - Spectro-polarimetry of HAbitable Planet Earth (SHAPE) - and capturing and sending information back to Isro.
The space agency says that after it had operated in the lunar orbit for a month, the propulsion module still had more than 100kg of fuel and it was decided to use it to carry out some "unique experiments" that will help provide "additional information" for future lunar missions.
"When the lander separated from the propulsion module, it was in a very tight orbit around the Moon," says Mila Mitra, a former NASA scientist and co-founder of Stem and Space, a Delhi-based space education company. So, the module's complex multi-step reverse journey began on 9 October and the first step involved increasing the orbit from 150km to 5,112km.
In a press release, Isro says the module orbited the Moon several times before exiting the lunar sphere of influence on 10 November and since 22 November, it has been orbiting Earth.
The space agency says the module remains at a height of more than 115,000km - way above the 36,000km orbit where geostationary satellites are located - to avoid any threats of collision. Its payload - SHAPE - continues to function, observing Earth and sending data back for analysis.
In September, Isro said the Vikram lander had performed a successful "hop experiment". The agency said the lander was "commanded to fire its engines, it rose up by about 40cm [16 inches] and landed at a distance of 30-40cm", which meant the spacecraft could be used in the future to bring samples back to the Earth or for human missions.
The latest experiment, Ms Mitra says, takes Isro another step closer to a return mission. "The experiment is significant as it holds a lot of promise to bring back manned missions and space samples and also for future inter-planetary missions."
Moreover, once the module runs out of fuel, it would have crashed onto the lunar surface where it would have remained forever as debris. By bringing it back, Isro has also addressed this important issue, she adds.