Chandrayaan-2: Tense 48-day journey begins

As

Chandrayaan-2

sunbathes and stargazes its way to Moon, Isro scientists will be on the edge of their seats till the September 7 landing. Once on Moon, lander and rover will spend 14 earth days looking for water, minerals and just about anything interesting.


While Chandrayaan’s entry into the initial orbit had Isro scientists at Sriharikota lean back on their chairs, it brought around 100 scientists and engineers to the edge of their seats at the Isro Telemetry, Tracking and Command (Istrac) centre in Bengaluru.


“It’ll be like this for the next 62 days (48 during the journey and 14 days after the rover touches down on Moon),” said a scientist at Istrac.

Chandrayaan-2 is now under Istrac’s control, and the centre is using all its ground stations in Bengaluru, Lucknow, Mauritius, Sriharikota, Port Blair, Thiruvananthapuram, Brunei, Biak (Indonesia) and the deep space network stations which will provide tracking support.

It will be giving commands to guide the spacecraft to Moon, land and unload the rover. “Since we don’t have coverage everywhere, USowned ground stations will be helping us,” said another scientist.

Istrac has got control of the spacecraft, which used its onboard sensors to correct course and align itself with Sun. “We have turned on the star sensor onboard the module,” the scientist said.

In between these operations, the solar panels were deployed allowing the craft to ‘sunbathe’. While solar energy is key for its survival through the journey to Moon, the other sensor does ‘star gazing’ for coordinates to ensure it goes in the right direction. “Without gazing at the stars continuously, the spacecraft won’t be able to know where it is going. The sensor puts in the satellite’s memory patterns of stars that tell it where to go,” another scientist explained.

Istrac will give commands for the orbit-raising manoeuvres. After these, the team will give commands for trans-lunar injection, putting Chandrayaan in the path of Moon.

“From there on, we will push it closer to Moon with multiple engine burns and insert it into the lunar orbit,” the scientist explained. Isro chairman K Sivan was reflecting the excitement when he said the final descent “fifteen minutes of terror.”

If Chandrayaan-2 was launched without a glitch on July 15, it would have reached the lunar orbit in 22 days and gone around Moon for 28 days. As per the revised schedule, the module will remain in the 100km x 100km orbit for 13 days.

The orbiter, which will have the lander and rover integrated, will orbit Moon before the lander with the rover inside it separates from it. Four days after the separation, Vikram (lander) will land on the 48th day—and four hours after that, the rover (Pragyan) will crawl out of the lander.

While this marks the completion of the mission’s first objective, scientists at Istrac have another 14 Days of work with Pragyan —which is not autonomous — as it moves on the lunar surface for one lunar day (14 Earth days).

“Pragyan has to be guided through every step. While everything that needs to be done has been done, we have to wait to see how the systems perform when they actually land on Moon,” the scientist said.