More than three months ago, the Indian Space Research Organization (ISRO) achieved a major success by safely landing the Vikram lander on the lunar surface. India thus became the fourth country to achieve a soft landing on the moon, further igniting India's interest in space exploration. But it turns out that this is not the end of the "Chandrayaan-3" mission. In a surprising announcement on Monday, the Indian Space Research Organization (ISRO) announced that it has successfully returned the propulsion module used by the spacecraft to a high orbit around the Earth.
The experimental phase of the mission tested key capabilities required for future lunar missions, including the possibility of returning lunar rocks to Earth, ISRO said in a statement.
The main task of the propulsion module is to send the Vikram 3 lander into a low lunar orbit 100 kilometers above the lunar surface. After completing this mission in August, the propulsion module entered a lunar orbit at an altitude of 150 kilometers. There, its remaining operational goal is to support a science experiment called SHAPE to observe Earth.
However, after a month in this orbit, Indian mission operators discovered that the spacecraft still had more than 100 kilograms of propellant reserves. The propulsion module is powered by monomethylhydrazine and nitric oxide-based oxidizers, carrying 1,696 kilograms of fuel and oxidizer at launch, with remaining propellant increasing the possibility of additional maneuvers.
Engineers knew that the SHAPE mission could observe Earth's atmosphere from another orbit. By observing Earth from a distance, this innovative scientific experiment attempts to set a baseline for the atmospheric characteristics of exoplanets that could potentially support life. Therefore, Indian engineers reasoned, it would be best to demonstrate that their spacecraft has the ability to return to Earth orbit.
"We decided to utilize the available fuel in the spacecraft to obtain more information for future lunar missions and demonstrate operational strategies for sample return missions," the Indian Space Agency said on Monday.
return to earth orbit
On October 9, the propulsion module raised the lunar orbit from 150 kilometers to 5,112 kilometers. Four days later, it burned its engine again and began to leave the lunar orbit. In its new orbit around the Earth, the propulsion module reached perigee for the first time on November 22, less than 154,000 kilometers from the Earth’s surface. Over time, the orbit will change, with the lowest perigee being 115,000 kilometers. ISRO said such a high orbit would not pose a threat to any operating satellites around the Earth. This is also a good orbit in which the SHAPE payload can continue its observations of the Earth's atmosphere.
What's next?
India has yet to announce its future lunar plans, apart from the Lunar Polar Exploration Mission jointly with the Japan Aerospace Exploration Agency (JAXA). The mission is planned to carry a lunar lander and rover to the lunar south pole later this decade, but no earlier than 2026.
However, a lunar sample return mission seems to be a good option for the future. NASA, with the help of astronauts, returned about 800 pounds of rock during the Apollo missions. In the 1970s, the Soviet Union completed three robotic sample return missions, and China's Chang'e 5 lunar lander also brought back samples three years ago.
Given the collapse of the Soviet Union and lackluster Russian missions beyond low Earth orbit, India now has the third most advanced deep space exploration program in the world.