In a slight step or leap toward the ambitious future goal, the Vikram lander for Chandrayaan-3 was ordered to perform the hop test, which was successfully executed.
Lunar Landing
Chandrayaan-3 landed vertically like a helicopter. In the words of ISRO, the Director General of VSSC, Dr. S. Unnikrishnan Nair, said, “It was a soft landing like a feather.”
Let’s imagine that the lander in Chandrayaan-3 wishes to take off again and return. In this case, it would have to fire its engines and launch itself almost like a rocket to reach lunar orbit.
As a slight step or leap toward the ambitious future goal, the Vikram lander for Chandrayaan-3 was ordered to perform the hop test, which was successfully executed.
Think of the hop as a movement exercise – jumping from one point and landing a few centimeters next to the starting place. By performing this movement, ISRO reignited the Vikram lander’s engines and gathered valuable data about engine firing on the lunar surface.
Return of the Propulsion Unit!
All talks about Chandrayaan-3 ended by October, as it became clear that the spacecraft had completed its planned 14-day mission (one lunar day) and showed no signs of waking up (which ISRO partially hoped for as a bonus).
While there was no response from the lander and rover on the moon, the propulsion unit, which continued to fly around the moon, had more tricks up its sleeve.
The propulsion unit is the spacecraft that carried Chandrayaan-3 from Earth’s orbit to the moon’s orbit.
Therefore, it has a special set of engines and a fuel tank.
While the propulsion unit was not in a full orbit like that of Chandrayaan-2, ISRO performed an important operation using the propulsion unit. When ISRO realized that the propulsion unit had at least 100 kilograms of fuel left in its tank, after one month of flying around the moon, ISRO decided not to waste a drop of fuel and wanted to make the most of the mission.
The spacecraft that was flying around the moon was gradually directed out of the moon’s gravitational influence and closer to Earth.
The moon is about 3.84 lakh kilometers away from Earth. From lunar orbit, the propulsion unit traveled a distance of 2.34 lakh kilometers to reach a very high orbit above Earth.
According to ISRO, the unit was brought to an orbit of about 1.15-1.54 lakh kilometers above the Earth.
This is a very safe orbit where almost no operational satellites are present, meaning the propulsion unit can remain there until the end of its life and beyond, without any risk of collision.
Return to Earth and Future Importance
Like the hop test, this flight back for the propulsion unit aids ISRO’s future lunar exploration plans. It will be critical in future missions like Chandrayaan-4, which involves returning samples from the moon.
It also confirms ISRO’s planning of space mission operations, which includes the complex and precise calculations required to bring a spacecraft from the orbit of one celestial body to another.
Simply put, ISRO extracted greater value from Chandrayaan-3 than was initially expected and publicly known.
Source: Sidharth MP
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