Chandrayaan-3 Now Only 25 KM Away from the Moon: Final Deboosting Reduces Spacecraft Speed, Landing Attempt at 6:04 PM on August 23

The second and final deboosting operation of Chandrayaan-3 was successfully completed during the early hours of Saturday to Sunday. Following this operation, the minimum distance between the lander and the Moon’s surface is 25 kilometers, while the maximum distance is 134 kilometers. Deboosting involves reducing the spacecraft’s speed.

ISRO (Indian Space Research Organisation) shared on social media platform X (Twitter) that the internal checks of the lander will now take place, and the wait will continue until sunrise at the landing site. The attempt to perform a soft landing at an altitude of 25 kilometers will be made at 6:04 PM on August 23.

Pragyan Rover to Leave the Mark of the Ashoka Pillar on the Moon

According to M. Annadurai, the project director of Chandrayaan-1 and Chandrayaan-2 missions, it will take 15 to 20 minutes for Chandrayaan-3’s lander to reach the Moon’s surface from an altitude of 25 kilometers during the evening of August 23. This time frame is expected to be the most critical.

Afterward, the Vikram lander will release the six-wheeled Pragyan rover through a ramp, and once it receives commands from ISRO, the rover will traverse the Moon’s surface. During this phase, the rover’s wheels will imprint the national symbol, the Ashoka Pillar, and ISRO’s logo on the lunar soil.

Lander Captures Images of the Moon

Before this, on August 17, the propulsion module of Chandrayaan-3 was separated from the lander-rover. After separation, the lander communicated with the propulsion module saying, “Thanks for the ride mate.” During this period, the cameras on the lander also captured images of the Moon along with those of the propulsion module.

Answers to 4 Important Questions…

  • How was the deboosting accomplished: The spacecraft’s speed was reduced using four thrusters with a combined thrust of 800 Newtons located on each leg of the lander. These thrusters were used in two stages.
  • Challenges in landing: The landing process from an altitude of 25 kilometers will start. The lander’s velocity needs to be reduced from 1680 meters per second to 2 meters per second.
  • Why the landing on August 23: Both the lander and the rover will utilize solar panels for power generation. Currently, it is nighttime on the Moon, and sunrise will occur on the 23rd.
  • What will Chandrayaan-3 do: The propulsion module will study the radiations coming from Earth. The lander-rover will conduct various experiments, including the search for water on the lunar surface.

On August 5th, Chandrayaan reached the lunar orbit

After a journey of 22 days, Chandrayaan reached the lunar orbit around 7:15 PM on August 5th. At that time, its speed was reduced to enable the spacecraft to be captured by the Moon’s gravity. To decrease the speed, ISRO scientists fired the thrusters for about 1,835 seconds, or roughly half an hour, by flipping the face of the spacecraft. This firing began at 7:12 PM.

Chandrayaan Captured Images of the Moon

During its initial entry into the lunar orbit, Chandrayaan had an orbit of 164 km x 18,074 km. While entering the orbit, its onboard cameras also captured images of the Moon. ISRO created a video of this event and shared it on their website.

“I am Chandrayaan-3… I can feel the Moon’s gravity”

Providing information about the mission, ISRO wrote in an X post, “I am Chandrayaan-3… I can feel the Moon’s gravity.” ISRO also mentioned that Chandrayaan-3 has successfully entered the lunar orbit. Before the landing on August 23rd, Chandrayaan needs to reduce its orbit a total of 4 times. It has already reduced its orbit once on Sunday.

Thrusters Fired When Chandrayaan was Closest to the Moon’s Orbit

ISRO explained that the command for the perilune retro-burning maneuver was given by the Mission Operations Complex (MOX), ISTRAC, Bangalore.

Perilune refers to the point where a spacecraft is closest to the Moon’s orbit. Retro-burning involves firing the thrusters in the opposite direction. Thrusters are fired in the opposite direction to slow down the spacecraft.

Chandrayaan-3’s Journey So Far…

This mission can be divided into three phases:

  1. Journey from Earth to Lunar Orbit
  • On July 14th, Chandrayaan was placed in Earth’s orbit at 170 km x 36,500 km.
  • On July 15th, its orbit was increased for the first time to 41,762 km x 173 km.
  • On July 17th, it was increased again to 41,603 km x 226 km.
  • On July 18th, it was increased for the third time to 51,400 km x 228 km.
  • On July 20th, it was increased for the fourth time to 71,351 km x 233 km.
  • On July 25th, it was increased for the fifth time to 1,27,603 km x 236 km.
  1. Journey from Earth’s Orbit to Lunar Orbit
  • During the nights of July 31st and August 1st, Chandrayaan progressed from Earth’s orbit towards the lunar orbit.
  • On August 5th, Chandrayaan-3 entered the lunar orbit at 164 km x 18074 km.
  1. Journey from Lunar Orbit to Landing
  • On August 6th, Chandrayaan’s orbit was reduced for the first time to 170 km x 4313 km.
  • On August 9th, its orbit was reduced for the second time to 174 km x 1437 km.
  • On August 14th, Chandrayaan’s orbit was further reduced for the third time to 150 km x 177 km.
  • Around August 16th, Chandrayaan arrived in an approximately circular orbit of about 153 km x 163 km.
  • On August 17th, the propulsion module of Chandrayaan-3 was separated from the lander-rover.
  • On August 18th, the Vikram lander entered an orbit of 113 km x 157 km through the deboosting process.
  • On August 20th, the Vikram lander entered an orbit of 25 km x 134 km through the deboosting process.

Answers to 4 Crucial Questions Related to the Chandrayaan Mission…

  1. What will India gain from this mission?

According to ISRO scientist Manish Purohit, through this mission, India aims to demonstrate its capability to soft-land on the Moon and operate a rover there, which will boost global confidence in India’s commercial space ventures. This achievement can contribute to enhancing commercial business prospects. India has launched Chandrayaan using its Heavy Lift Launch Vehicle (LVM3-M4), which has already showcased its capabilities to the world.

Recently, Jeff Bezos’ company, Blue Origin, showed interest in utilizing ISRO’s LVM3 rocket. Blue Origin intends to use the LVM3 for commercial and tourism purposes. Using the LVM3, Blue Origin plans to take its crew capsule to a Planned Low Earth Orbit (LEO) space station.

  1. Why was the mission sent to the South Pole?

The polar regions of the Moon are significantly different from other regions. There are parts where sunlight never reaches, and temperatures drop to as low as -200 degrees Celsius. Scientists speculate that water might still exist here in the form of ice. India’s Chandrayaan-1 mission in 2008 hinted at the presence of water on the Moon’s surface.

The landing site for this mission is the same as Chandrayaan-2’s. It is located near the South Pole of the Moon, around 70 degrees latitude. However, the area has been expanded. While Chandrayaan-2’s landing site was 500 meters x 500 meters, this time it is 4 kilometers x 2.5 kilometers.

If everything goes well, Chandrayaan-3 will become the world’s first spacecraft to achieve a soft landing near the South Pole of the Moon. Previous spacecraft that landed on the Moon were in the equatorial region, slightly north or south of the lunar equator.

  1. Why four engines instead of five in the lander?

This time, the lander is equipped with four engines (thrusters) placed on all four corners, while the fifth engine placed in between was removed. The final landing will be executed with the help of two engines to ensure their operation even in emergency situations. During the Chandrayaan-2 mission, the fifth engine was added at the last moment. The removal of this engine allows for carrying more fuel.

  1. Why is the mission only for 14 days?

Manish Purohit explained that the Moon experiences 14 days of daylight followed by 14 days of darkness. During the lunar nights, temperatures drop to as low as -100 degrees Celsius. The lander and rover of Chandrayaan will generate power through their solar panels. Therefore, they will be able to generate power for 14 days, but the power generation process will halt during the night. Without power generation, the electronics won’t be able to withstand the extreme cold and might get damaged.

If the soft landing is successful and the mission is deemed a success, India will become the fourth country in the world, after the United States, Russia, and China, to achieve this feat. Both the United States and Russia faced spacecraft crashes before successfully landing on the Moon. China is the only country to have achieved success on its first attempt with the Chang’e-3 mission in 2013.

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