Countdown on for Chandrayaan 3 launch today

Mangalore Today News Network

Bengaluru, July 14, 2023: The Indian Space Research Organisation (ISRO) will embark on its second attempt to carry out a soft touchdown of a robotic lander on the surface of the moon on Friday with the launch of the Chandrayaan 3 spacecraft on board the LVM3 rocket from Satish Dhawan Space Centre at Sriharikota.

 

If the soft-landing succeeds, India will become the fourth country in the world to have achieved this.

Ahead of the launch, scheduled for 14.35 pm Friday from the second launch pad at Sriharikota in Andhra Pradesh, the countdown for the launch began Thursday afternoon with the mission authorisation board clearing the launch.

Announcing this, ISRO said that the mission readiness review had been completed and the “board has authorised the launch”.

The first part of the Chandrayaan 3 mission, spread over nearly 40 days with a possible moon rendezvous scheduled for August 23, will, on Friday, involve the launching of ISRO’s heavy lift LVM3 rocket into space with the Chandrayaan 3 spacecraft onboard to an altitude of 179.192 km in a flight spanning 969.42 second (over 16 minutes).

During this period, the LVM3 rocket will carry its 3895-kg payload using three different rocket power stages with a maximum thrust of 10.242 km/sec (over 36000 km/hr) being provided by the indigenous cryogenic C-25 engine fired on the rocket in the final phase — just ahead of the separation of the Chandrayaan 3 spacecraft from the rocket.

The rocket will be fired by a pair of solid fuel booster engines at the beginning for lift- off and for a duration of 108 seconds followed by a liquid fuel stage for around 90 seconds before the cryogenic stage kicks in after 307 seconds of flight and fires for over 10 minutes.

“If we have to land on the first (earth) day of sunshine on the moon (that is the first of the 15 earth days of sun on the moon) then we will have a life of at least 15 days for the mission. This is the date on which we are going to land and if everything goes well the date would be August 23 and it could be August 24 also. It cannot be August 25 or 26. Then what we will do is we will not land and we will wait for a month when there is going to be 15 days of sun again then the date could be September 20 or later,” ISRO chairman S Somanath said on July 7 at a press conference in Bengaluru.

Learning from past attempts

There are learnings, ISRO said, from the last failed mission in 2019. The lander’s design has been finetuned to increase the speed threshold for landing and its energy-absorbing capability. If all goes well, the landing date has been worked out to be August 23 or 24.

The launch phase of the Chandrayaan 3 mission is all about the LVM3 rocket which has so far flown six consecutive missions. The LVM3 rocket is a variation of the GSLV Mk III rocket which has a capacity of carrying upto 4000 kg into a geo transfer orbit (GTO) in space.

The GSLV Mk III had its first successful flight in December 2014 when it successfully launched the Chandrayaan 2 mission on July 22, 2019.

The mission, however, failed in its lunar phase when its Vikram lander crashed into the surface of the moon following anomalies in the braking system in the lander as it attempted a soft landing.

The 2019 mission was originally scheduled for launch on July 15 but the launch was aborted due to technical anomalies detected at the final hours. The problems were fixed and the mission was launched a week later.

A successful launch of the Chandrayaan 3 into an earth-centric orbit by the LVM3 on Friday will be followed by five orbit-raising measures — spread over three weeks — where the spacecraft is brought closer to the orbit of the moon and later transferred into the moon’s orbit (by firing of engines on a new propulsion module of the spacecraft).

These steps to transfer the Chandrayaan 3 spacecraft into the orbit of the moon before the propulsion module takes the lander to a final 100-km orbit of the moon are meant to conserve fuel and use a principle called the Oberth effect.

The Chandrayaan 3 mission does not have an orbiter module like the Chandrayaan 2 module and contains only the lander and a rover within the lander. The orbiter from Chandrayaan 2 which is still alive in space will provide back communication connectivity for Chandrayaan 3.

“Due to the precise launch and orbital manoeuvres, the mission life of the Orbiter is increased to seven years. The data received from the Orbiter is being provided continuously to the scientific community,” ISRO had stated following the failure of the Chandrayaan 2 mission on September 7, 2019.

The Chandrayaan 3 mission has incorporated several technical learnings from the failed 2019 mission and has built redundancies for calculating and adjusting the lander’s approach speed to the surface of the moon and braking system to facilitate a soft landing.

The lander in the Chandrayaan 2 spacecraft had to drop its speed — through automated systems — from over 6000 km/hr to around 7.2 km/hr for a successful soft landing but went out of control during a fine braking phase and crashed.

“The first thing was to get rid of the problems. We have reviewed it and strengthened various aspects. The design of Chandrayaan 2 was for a landing at a speed of 2m/sec (7.2 km/hr) with a small margin of increase but we have now increased the speed threshold for landing. We have created energy absorbing capability,” the ISRO chairman said last week.

ISRO chairman S Somanath and scientists connected with the Chandrayaan 3 mission visited separate temples in Andhra Pradesh on Thursday to seek blessings for the science mission. The ISRO chairman visited a temple in Sullurpet near the Sriharikota launch site while a group of scientists linked to the project visited the Tirupati temple.

The seeking of blessings at temples ahead of missions has become customary at ISRO.

Courtesy: Indian Express