Science & Technology

Chandrayaan-2 in orbit, now focus on Sept 7 moon landing

The satellite will, in the next 23 days, burn its internal thrusters six times raising its height

By Akshit Sangomla
Published: Monday 22 July 2019
GSLV MkIII-M1/Chandryaan 2 vehicle night view at the Second Launch Pad. Photo: ISRO
GSLV MkIII-M1/Chandryaan 2 vehicle night view at the Second Launch Pad. Photo: ISRO GSLV MkIII-M1/Chandryaan 2 vehicle night view at the Second Launch Pad. Photo: ISRO

At a minute short of 3 pm on July 22, 16 minutes after its launch from the Satish Dhawan Space Centre at Sriharikota, Chandrayaan-2 satellite was successfully launched into Geostationary Transfer Orbit (GTO).

The GTO is 39,000 kilometres above the Earth’s surface. The Indian Space Research Organisation (ISRO) was able to achieve this feat despite an extremely narrow launch window of only a few minutes. Chandrayaan-2, which was ISRO’s second Moon mission, was the organisation’s most complicated yet.

“This is the beginning of a historical journey of India to the Moon,” ISRO’s chairman K Sivan announced after the satellite sent out its first signals from GTO.

The mission was originally scheduled for July 15 but the space agency had to cancel the launch when a leak in the helium tank of the Geosynchronous Satellite Launch Vehicle Mk III M1 (GSLV Mk III M1) was observed less than an hour before the launch.

“We fixed the technical snag observed on July 15 and bounced back with flying colours,” said Sivan. The entire process of identifying, analysing and fixing the leak took ISRO’s launch team only 24 hours after which they prepared for the launch on July 22, he added.

The GSLV Mk III M1’s performance was increased by 15 per cent for the current mission, which allowed it to carry the 3,850 kilometre satellite to the GTO, according to Sivan.

This is only the beginning. The mission’s actual success will be clear only when the lander craft touches down on the lunar surface at 2:58 am on September 7, 48 days from today.

The spacecraft will spend the first 23 days in Earth orbit during which it will burn its internal thrusters six times raising the height of its orbit each time. Around August 14, the transit to the lunar orbit will begin and end on September 1 when Chandrayaan-2 will settle into a 100-km orbit above the Moon.

It will take the satellite a total of 15 delicate maneuvers to achieve this, each coming with its own risk. The most difficult part of the mission will then begin as Vikram will first search for an appropriate landing site on the South Pole of the Moon, where no country has attempted landing before.

After identifying a site, Vikram will detach from the orbiter and commence its journey towards its destination, at all times remaining in constant contact with Chandrayaan-2. “After the last 15 minutes of terror the lander will touch the Moon,” said Sivan.

After this, ISRO’s indigenously-built rover Pragyan will survey the Moon’s surface and conduct experiments on chemistry, mineralogy and exosphere, especially collecting more evidence for the existence of water, for 14 lunar days or one Earth day.

While ISRO has achieved great success in all its missions till date, soft landing on the Moon will propel it into a new league all together. Only three other countries have achieved this in the past. It will also prove that India is ready for future missions which could establish a human base on the Moon.

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