A nerve-wracking 30-minute manoeuvre performed from the Indian Space Research Organization’s Mission Operations Complex here on Tuesday ensured that Chandrayaan-2, the Indian lunar lander-rover spacecraft, slid precisely into its planned orbit around its destination: the moon.
The Lunar Orbit Insertion was carried out at 9.02 a.m. from the ISRO Telemetry, Tracking and Command Network (ISTRAC).
In the defined orbit
In a media briefing after the event, K. Sivan, Chairman of ISRO, said, “Today Chandrayaan-2 crossed a major milestone. Around 9 a.m., a precise LOI [Lunar Orbit Insertion] manoeuvre was carried out for about 30 minutes to inject Chandrayaan-2 perfectly into the defined orbit.”
It now goes around the moon in a pole-to-pole ellipse of 114 km x 18,072 km.
Now that the orbiter is in place, the focus will shift to the Vikram lander riding on top with the small rover inside its belly.
Around 9 a.m., a precise LOI [Lunar Orbit Insertion] manoeuvre was carried out for about 30 minutes to inject Chandrayaan-2 perfectly into the defined orbit,” Dr. Sivan said. The spacecraft now goes around the moon in a pole-to-pole ellipse of 114 km x 18,072 km.
Now that the orbiter is in place, the focus will shift to the Vikram lander riding on top with the small rover inside its belly.
Dr. Sivan said, “We will now have four lunar burns starting tomorrow [Wednesday] at 1 p.m., followed by subsequent burns on August 28, August 30 and September 1. The orbit of Chandrayaan-2 will be reduced gradually from the present 18,072 km to make it orbit moon in a circle from a distance of around 100 km by September 1.”
He said the next major event was slated for September 2. On that day the lander is due to separate from the orbiter and start descending towards the lunar surface – like “a bridegroom separating from his parental home and entering the bride’s home.”
Precise actions with the latest LOI and the earlier TLI, besides improved sensors, guidance and navigation systems and repeated tests on them, he said, should enable Vikram to soft-land on the moon at 1.45 a.m. on September 7.
As for the manoeuvre to put the spacecraft in lunar orbit, Dr. Sivan said that at 3 p.m. on Monday, Chandrayaan-2 reached the vicinity of the moon and started picking up speed due to the moon’s gravity.
“The latest LOI manoeuvre was essential in order to reduce its speed from 2.4 km per second to 2.1 km per second. If we had not done it or done it improperly, we would have lost the spacecraft as it would have gone astray,” he said.
