Chandrayaan-3 countdown starts with craft now 6 days from Moon
The midnight trans-lunar injection (TLI) manoeuvre is expected to last between 28 and 31 minutes and onboard thrusters of the spacecraft will be fired when the spacecraft is at the closest point to Earth (perigee) and not when at the farthest point (apogee).
The pre-written and preloaded commands for TL will be enabled around five-six hours ahead of the time the thrusters are expected to fire. The firing of the thrusters, aside from helping the spacecraft change its orientation to begin the journey towards Moon, will also add to its velocity. Post TLI, Chandrayaan-3’s velocity is expected to be higher by around 0. 5km/second from what it was at perigee.
On average, it takes about 51 hours to travel 1. 2-lakh km. While the average distance between Earth and Moon is 3. 8-lakh km, the actual distance on any given day would vary based on the position of Earth and Moon. The range could be between 3. 6-lakh km and 4-lakh km.
Reaching Moon’s orbit is only one part of the mission — Isro had already put a satellite around Moon in 2008 (Chandrayaan-1) and 2019 (Chandrayaan-2) — and the more crucial part of Chandrayaan-3 would be after the spacecraft reaches Moon.
Once it captures a lunar orbit, Isro will have to carry out a series of manoeuvres to reduce the altitude of the spacecraft and put it in a 100km circular orbit where the propulsion module will be separated from the landing module, scheduled for August 17. It will attempt landing on August 23.
