Why Chandrayaan 2's Lunar Orbit Entry Is A Huge Landmark For India, And A Proud Moment For Us
Earlier last month, the Indian Space Research Organisation launched the Chandrayaan-2 mission to the Moon. The lander is now in lunar orbit and is expected to touch down on September 7. But the work that¡¯s gone into achieving this is astounding.
Earlier last month, the Indian Space Research Organisation launched the Chandrayaan-2 mission to the Moon.
The lander is now in lunar orbit and is expected to touch down on September 7. But the work that's gone into achieving this is astounding.
ISRO
For one, the entire mission was organised with a sparse budget of just about Rs 1,000 crore, less than half of what NASA spent on the Apollo Missions back in 1969. Sure, they had to do a lot of stuff for the first time ever, but adjusting that spending for inflation would make it a few billion dollars today.
But though the fact we managed to do it for cheap is impressive, it's not the most impressive thing. What you need to think about is how much precision is required to shoot a hunk of metal into space atop a multi-stage rocket, use the Earth's gravity to slingshot towards the Moon, brake in time to be captured by that orbit, and then slowly lower down to the surface with intermittently firing boosters in order to land gently.
Yeah, that's a lot.
Dr Satyendra Bhandari, a retired ISRO scientist, concurs saying that it's truly an incredible feat of planning and engineering. We asked him how best he could break it down for those of us not equipped with the knowledge of spaceflight procedure.
"If we take a stone, tie it at the end of a string and swing it in a circle," he said. "As long as we have the string and keep swinging it, it goes around in a circle. Now if we have to swing it out of the circular path along a particular trajectory, we have to release it with very precise speed and precise direction at the precise moment."
"Since the stone is moving briskly, any small error would either make it fall down or would make it swing away and would go out of desired path," he adds.
Which is exactly what ISRO had to do when moving Chandrayaan-2 from Earth orbit to lunar orbit. They wanted to make the mission cheaper and carry a number of instruments, including some for other countries. To do both those things, they had to use a smaller rocket loaded with less fuel, use the momentum of our planet's gravity to swing around, and then shoot towards the Moon.
Lander #Vikram has the capability to communicate with IDSN at Byalalu near Bangalore, as well as with #Orbiter and #Rover.
¡ª PIB India (@PIB_India) August 21, 2019
The Lander is designed to execute a soft landing on lunar surface. #Chandrayaan2 #ISRO pic.twitter.com/RtXFMItkh9
"Now in the case of Chandrayan 2, there is one more complication," Bhandari adds. "We have to release it in such a manner that it is easily captured by the Moon's gravity. Not too strongly to fly away, and not to weakly to fall into moon's gravitational well. Hence the criticality of the maneuver...timing, speed and, direction. All this while using incoming data online, analysing and guiding onboard software to decide and command to fire the onboard thrusters."
"Any small error in the loop would be a failure."
And that's what ISRO has just achieved. It's a delicate dance involve the angle of flight, speed, and the gravitational force acting on the satellite trying to pull it down. And that dance doesn't end until the satellite touches the surface of the Moon.
It brings to mind the Israeli Moon mission Beresheet, which launched earlier in February and was expected to gently touch down in April this year. What instead happened was that a malfunction caused the lander's main engine to shut down just as it was supposed to start firing in earnest to slow down the descent. At the same time, mission control also lost communications with the spacecraft.
ISRO
That resulted in the lander crashing into the surface of the Moon, eventually failing the last leg of its mission, and possibly even spilling thousands of resilient tardigrades onto the lunar surface. That's exactly the sort of thing ISRO has to avoid, and it's only one of the many ways things can go wrong with Chandrayaan 2.
So there's much respect to the teams at ISRO working around the clock to pull this mission off without a hitch.
