Vikram Lander to attempt touch down on lunar surface on August 23 evening

Bangluru : The Chandrayaan 3 is expected to land on the south polar region of the moon. Russia-s Luna 25 is also expected to land in the same region. No other country has made a soft landing on the south polar region of the moon.

"Rocket "Soyuz" with "Progress" at the start! We share a photo from the removal of the Soyuz-2.1A rocket with the Progress MS-24 cargo ship. After being installed in a vertical position at the launch site of the 31st site, Roscosmos specialists continued to prepare it for launch. Progress MS-24 truck launch. " Roscosmos, the Russian space agency said, in its telegram channel.

Vikram Lander to attempt touch down on lunar surface on August 23 evening

In technical terms, deboosting refers to the process of decelerating the spacecraft's velocity to position it in an orbit where the closest point to the Moon (Perilune) is set at 30 km and the farthest point (Apolune) is maintained at 100 km. The Chandrayaan 3 completed its second and final deboosting today.

India's Chandrayaan-2, which had "partially failed" in 2019, might prove to be a key to Chandrayaan-3's success if the latter makes a "soft" and successful landing on the Moon's surface on August 23. Indian Space Research Organisation (ISRO) Chief S. Somnath said earlier this month.

Learning from the past experiences, the space agency has worked around the clock to deal with the complexities of the Moon's south pole which is said to have remained deprived of the sunlight for years.

As per the plan, lander Vikram was supposed to lose most of its velocity by the time it was 400 meters from the lunar surface. It was supposed to hover above the intended landing site in order to make a soft vertical descent at "walking pace," Indian Express reported. However, the lander crashed, or made a hard landing, on the Moon’s surface because of its high velocity.

Somanath earlier this year pointed out three mistakes that led to Vikram's hard landing

It had five engines which were used to give the reduction of the velocity, which is called the retardation. These engines developed higher thrust than what was expected. When such a higher thrust was happening, the errors on account of this differential were accumulated over some period. "All the errors got accumulated, which was on the higher side than what we had expected. The craft had to make very fast turns. When it started to turn very fast, its ability to turn was limited by the software because we never expected such high rates to come. This was the second issue," the ISRO chief said.

The third reason for failure was the small 500m x 500m site identified for landing the spacecraft. "The craft was trying to reach there by increasing the velocity. It was almost close to the ground and kept on increasing the velocity," Somanath said.

Five lessons related to Chandrayaan-2 that has helped Chandrayaan-3

1. The structural changes, built of the lander and evaluation of the amount of fuel and energy a spacecraft needs to fulfil the mission. The ISRO chief spoke about a greater “robustness in the lander" while introducing various features in it. He said the lander is heavier this time. Besides, the solar panels are bigger than last time. Also, Chandryaan-3 has more solar panels so as to generate more power, he added. Moreover, the "tanks have grown bigger... as it has more fuel this time,” he said. "Earlier we landed with a single engine, this time we are landing with two engine," he explained.

2. The "enhanced touchdown limit for the soft landing.” Learning from Chandrayaan-2's hard landing, Somnath said the space agency "ensured that at the touchdown speed of even up to 3 metres per second, it will not cause any harm to Chandrayaan. We make sure the vertical velocity is in limit so that it does not topple.”

3. Somnath said the landing site is "big this time in terms of dimensions.” He was quoted by PTI as saying, "We expanded the area of landing from 500m x 500m to 4km by 2.5km. It can land anywhere, so it doesn't limit you to target a specific point. It will target a specific point only in nominal conditions. So, if the performance is poor, it can land anywhere within that area." He added that this time, an image captured by Chandrayaan-2 orbiter was used for "better identification of the locations.” He said the landing site was "imaged properly.” While shedding light on how ISRO chose the landing site, Somnath recalled that last time "some other nation's image was used while planning for Chandryaan-2.”

4. The communication links are very important. The ISRO chief said Chandrayaan-2 orbiter is functioning very well and this will communicate with Chandrayaan-3 lander. This signal will reach the ground station. He explained, "The way we communicate from Moon to Earth is through ground station... we also connect with other nations... but ultimately, the signal comes from the orbiter."

5. Somnath emphasised the "on-orbit test and evaluations.” He said, in this new method, "... anything …can get tested, verified and in the orbit..." He said the entire procedure of bringing it down to the orbiter to the Moon and to the landing site has been substantially changed.