![India's Chandrayaan-3 lunar spacecraft undergoes accoustic testing. The propulsion module can be seen at the bottom.](https://cdn.arstechnica.net/wp-content/uploads/2023/07/c3isro-800x531.jpg)
ISRO
Somewhat greater than three months ago the Indian space agency, ISRO, achieved a significant success by putting its Vikram lander safely down on the surface of the Moon. In doing so India became the fourth country to realize a soft landing on the Moon, and this further ignited the country’s interest in space exploration.
Nevertheless it seems that shouldn’t be the tip of the story for the Chandrayaan 3 mission. In a surprise announcement made Monday, ISRO announced that it has successfully returned the propulsion module utilized by the spacecraft right into a high orbit around Earth. This experimental phase of the mission, the agency said in a press release, tested key capabilities needed for future lunar missions, including the potential for returning lunar rocks to Earth.
A capable module
The first task of the propulsion module was to deliver the Vikram 3 lander right into a low-lunar orbit, 100 km above the surface of the Moon. After doing this in August, the propulsion module moved to an orbit across the Moon at an altitude of 150 km. There, its remaining operational goal was to support a science experiment, often called SHAPE, to watch the Earth.
Nonetheless, after a month of flying on this orbit, Indian mission operators found that the spacecraft still had a reserve of greater than 100 kg of propellant. The propulsion module, which is powered by monomethylhydrazine and a nitric oxide-based oxidizer, had launched with 1,696 kg of fuel and oxidizer. This excess of propellant raised the potential of additional maneuvers.
The engineers knew that the SHAPE mission could perform its observations of Earth’s atmosphere from a distinct orbit. By taking a look at Earth from a distance, this modern science experiment seeks to set a benchmark for what to anticipate from the atmospheric signatures of exoplanets which may be able to supporting life. So, the Indian engineers reasoned, it will be good to reveal the aptitude of their spacecraft to return to Earth orbit.
“It was decided to make use of the available fuel within the PM to derive additional information for future lunar missions and reveal the mission operation strategies for a sample return mission,” the Indian space agency said Monday.
Back to Earth orbit
On October 9 the propulsion module raised its lunar orbit from 150 km to five,112 km, and 4 days later it burned its engine again to start exiting lunar orbit. In its recent orbit around Earth, the propulsion module reached its first perigee on November 22, coming to inside 154,000 km of the planet’s surface. Over time the orbit will vary, with a minimum perigee of 115,000 km. Such a high orbit won’t threaten any operational satellites around Earth, ISRO said. It is usually a nice orbit from which the SHAPE payload can proceed to perform its observations of Earth’s atmosphere.
![The Chandrayaan 3 spacecraft returns to Earth orbit.](https://cdn.arstechnica.net/wp-content/uploads/2023/12/returning-to-earth-orbit.jpg)
The Chandrayaan 3 spacecraft returns to Earth orbit.
ISRO
So what’s next?
India has not declared its future plans for the Moon beyond the Lunar Polar Exploration Mission, a joint operation with the Japanese space agency, JAXA. That mission is planned to hold a lunar lander and rover to the south pole of the Moon later this decade, but no sooner than 2026.
Nonetheless, a lunar sample return mission would appear a superb bet for the longer term. NASA, with the assistance of its astronauts, returned about 800 kilos of rocks in the course of the Apollo missions. Within the Nineteen Seventies, the Soviet Union accomplished three robotic sample return missions, and China’s Chang’e 5 lunar lander brought back samples three years ago.
Given the demise of the Soviet Union and Russia’s lack of successful missions beyond low-Earth orbit, India now credibly has the third most advanced deep-space exploration program on the earth. India placed a spacecraft into orbit around Mars in 2014, and its Vikram lander achieve December after Russia’s Luna 25 spacecraft crashed into the Moon in August.