Ahead Of Chandrayaan-3's Moon Landing, Know Why Chandrayaan-2 Lander Failed

The Indian Space Research Organisation (ISRO) on Sunday said that India's third lunar mission Chandrayaan-3 is set to land on the moon on August 23 around 6:04 PM IST.

"The soft landing of Chandrayaan-3 is a monumental moment that not only fuels curiosity but also sparks a passion for exploration within the minds of our youth," ISRO said in a statement.

The Indian space agency on Sunday said it has successfully reduced the orbit of the Chandrayaan-3 mission's lander module, and it is now expected to touch down on the surface of the Moon at 1804 hours on Wednesday.

It said the lander module would undergo internal checks ahead of the planned soft landing.

Following its launch on July 14, the Chandrayaan-3 spacecraft entered into lunar orbit on August 5.

Chandrayaan-3 is a follow-on mission to Chandrayaan-2 to demonstrate end-to-end capability in safe landing and roving on the lunar surface.

Chandrayaan-3 consists of an indigenous Lander module (LM), a Propulsion module (PM) and a Rover with the objective of developing and demonstrating new technologies required for Inter planetary missions.

The mission objectives of Chandrayaan-3 are to achieve safe and soft landing on the lunar surface, to demonstrate the rover's mobility on the Moon, and to conduct in-situ scientific experiments.

Chandrayaan-3 is aiming to achieve something which its predecessor Chandrayaan-2 could not.

According to the information on ISRO's website. the Chandrayaan-2 mission was successfully launched on July 22, 2019, by GSLV MkIII-M1 from Satish Dhawan Space Centre (SDSC), Sriharikota. 

The spacecraft was inserted into lunar orbit on August 20, 2019. The Chandrayaan-2 mission was India's first attempt to land on the lunar surface. However, the lander Vikram hard-landed in September 2019.

Then ISRO chief K Sivan had said that the Chandrayaan-2 mission has achieved 98% of its objectives.

Four years ago, on September 2, Vikram lander separated from the Orbiter and a de-orbiting maneuver was performed to reduce the orbit to 35 km x 101 km.

Vikram landing was attempted on September 7 and it followed the planned descent trajectory from its orbit of 35 km to around 2 km above the surface.

"Communication with lander and ground station was lost. All the systems and sensors of the Lander functioned excellently until this point and proved many new technologies such as variable thrust propulsion technology used in the Lander," the information on ISRO's website states.

Chandrayaan-2's Vikram lander hard-landed as reduction in velocity during its descent was more than the designed parameters, the government had said in the Parliament.

In a written reply to a question in the Lok Sabha, Jitendra Singh, the minister of state in the Prime Minister's Office, who looks after the Department of Space, said the first phase of descent was performed nominally from an altitude of 30 kilometres to 7.4 km above the moon's surface and velocity was reduced from 1,683 metres per second to 146 metres per second.

"During the second phase of descent, the reduction in velocity was more than the designed value. Due to this deviation, the initial conditions at the start of the fine braking phase were beyond the designed parameters. As a result, Vikram hard-landed within 500 metres of the designated landing site," he said.

Earlier this month, ISRO chairman S Somanath said that Vikram, the lander of Chandrayaan-3, will be able to make a soft landing on the lunar surface on August 23 even if all the sensors and two of its engines do not work.

During a talk on 'Chandrayaan-3: Bharat's Pride Space Mission', hosted by the non-profit organisation Disha Bharat, Somanath said that the entire design of the lander Vikram has been made in a manner that makes sure that it would be able to handle failures.

“If everything fails, if all the sensors fail, nothing works, still it (Vikram) will make a landing. That’s how it has been designed -- provided that the propulsion system works well,” news agency PTI quoted Somanath as saying.

(With PTI inputs)