At 4.56am on Tuesday, Chandrayaan spacecraft entered the main highway to the moon and began its 96-hour flight towards the lunar orbit. It was the fifth and final orbit raising manoeuvre before the spacecraft entered the orbit on Saturday.
A jubilant Chandrayaan project director Mylaswamy Annadurai told TOI from Bangalore the spacecraft's 440 Newton liquid engine was fired for about two-and-a-half minutes and Chandrayaan entered the moon highway with an apogee (farthest point to earth) being 3,80,000 km.
Annadurai recalled the final moments before the spacecraft entered the moon highway also known as lunar transfer trajectory. "I was at Isro's telemetry, tracking and command network (Istrac) at Bangalore since early morning and we were going step by step very carefully. As soon as we received a signal that Chandrayaan had successfully entered the main highway to the moon, there was a jubilation in the mission control room," he said. Istrac director S K Shivakumar told TOI, "Yes, we all had a sense of satisfaction, but let me tell you that there were no clapping and embracing because the lunar orbit insertion (LOI) was still left," Shivakumar said.
He said commands are flashed to the spacecraft in the form of a digital message. "The return key in a keyboard is hit and the message is processed by the computer and transmitted to the spacecraft. Let me assure you that the person who will be hitting this return key on Saturday for the LOI is under no pressure," he said.
Annadurai said the health of the spacecraft was being continuously monitored from the spacecraft control centre at Istrac with support from the Indian Deep Space Network antennas at Byalalu. "I am happy to say that the spacecraft is performing normally," Annadurai said.
Asked if the Chandrayaan team was nervous about the LOI on Saturday, he said the orbit raising manoeuvre on Tuesday was equally crucial. "I am hoping that the manoeuvre will go off smoothly on Saturday too," he said.
He said in all probability the LOI will occur between 5pm and 6pm on Saturday. Space scientists said this manoeuvre can be a hair-raising one because 30% of lunar missions of US and the former Soviet Union have failed because of some problems during LOI.