Chandrayaan-3 Vs Luna-25, Who will win the race?

Introduction

India is on the verge of making history by landing successfully on South pole of Moon. There are only three countries in the world which have landed on the moon without any difficulty, but none have tried on South pole. ROSCOSMOS, Russian space agency is seems to be in race with India for exploring South pole, as it has launched Luna-25 spacecraft on 11^th of August, 28 days after India’s Chandrayaan-3 was launched from Sriharikota on July 14. Luna is expected to land on the Moon around the same time as of Chandrayaan-3, on August 23.

Difference between Chandrayaan-3 Vs Luna-25

Chandrayaan-3

Chandrayaan-3 launched on 14^th July 2023 at 2:35 p.m., on a GSLV Mark 3 (LVM 3) heavy lift launch vehicle from Satish Dhawan Space Center in Sriharikota (SDSC), India. This will be followed by a number of maneuvers and will take around 40 days to bring it to the Moon. It was in the Earths bound orbit till end of the July, and at the beginning of August with translunar injection it came in the orbit of Moon. As per latest information from ISRO, on 5^th August it entered into Lunar orbit, and as of August 9, it reached even closer to the Moon, it’s orbit is reduced to 174 km x 1437 km following a third manuevre performed.

With bitter memories of unsuccessful landing of Chandrayaan-2, due to technical glitch, primary objective of Chandrayaan-3 will be soft landing on South pole of Moon’s surface.

Chandrayaan-3 is expected to land on Moon on 23^rd August 2023, near Manzinus crater.

For further live update of Chandrayan-3, you can visit official website of ISRO on the link : https://www.isro.gov.in/Chandrayaan3.html

Luna-25

The Luna-25 mission lifted off on 11^th August 2023, at 7:10 p.m. at 23:10 GMT on a Soyuz-2.1b rocket from the Vostochny Cosmodrome, Russian spaceport situated in Russia’s far eastern Amur Region. Earlier attempt of Russia to reach Moon is almost 47 years before in 1976, when Luna-24 successfully came back with some grams of Moon samples on Earth.

According to ROSCOSMOS, if everything will go as per plan then Luna-25 will be in Earth’s orbit for 5 days, then will enter into Moon’s orbit to remain there for another five to seven days. The spacecraft then try to land on South polar region of the Moon, near Boguslavsky Crater. Southwest of Manzini Crater and south of Pentland A Crater are back up plans, if situation worsen.

The launch of Luna-25 was delayed by nearly 2 years, mainly because of the Russia’s invasion of Ukraine. European Space Agency (ESA) was expected to provide the Pilot-D navigation camera, specifically designed to help Luna-25 for precision landing on Moon. Due to Russian invasion, ESA cancelled to provide camera, as well as other technical help for the mission.

Why Chandrayaan-3 taking more time as compared to Luna-25??

With powerful rocket engine, Luna-25 is expected to reach the Moon’s surface in just 12 to 13 days, whereas Chandrayaan-3 is taking around 40 days for the same.

Unlike Luna-25, Chandrayaan-3 does not have a rocket powerful enough to put it on a direct path to the Moon. Chandrayaan-3 is using series of Earth orbits and engine burns to gradually increase the spacecraft’s speed and position for a lunar insertion. After successful insertion into lunar orbit, with few initial orbit reduction maneuvers, it will perform 100×100 km circular orbiting before landing.

LVM-3 used by India is capable launch vehicle but does not have same power and payload capacity as Soyuz of Russia. Whereas Luna-25 with powerful engine will reach moon with less orbit reduction maneuvers.

ISRO used concept of gravity cleverly

While orbiting the Earth, speed of the spacecraft keeps changing across different points due to the variation in the Earth’s gravitational pull. The closer the spacecraft to the Earth (this point is called as ‘perigee’), the more the gravitational pull, and the greater the speed. Each time the spacecraft reaches the perigee, the onboard engines are fired, increasing its speed even more, pushing it into a higher, more elongated orbit. Series of such firing resulted spacecraft to reach escape velocity and eventually insertion into lunar orbit.

ISRO is currently in the process of gradually lowering the orbit of the module around the Moon to bring it closer to the surface. When it is in a 100 km circular orbit around the Moon, the propulsion module will separate from the lander, which will continue its journey towards the lunar surface.

Mission Life

Mission Life (Lander & Rover) of Chandrayan-3 is one Lunar Day (which is equivalent to 14 earth days), whereas that of Luna-25 is 1 Earth year.

Landing Sites

Chandrayaan-3 is expected to land near Manzinus crater on South polar region of Moon, whereas Luna-25 primary landing site is Boguslavsky crater. Both these regions are around 120 km apart.

Why South Polar Region??

The Polar regions of the Moon are called as Permanent Shadowed Region (PSRs). The Sun light does not reach here. The temperature of this region is around -230 degree Celsius since millions of years. It was confirmed from Chandrayaan-1 mission that, there are very large craters on polar region, and are abundantly filled with ice molecules. The scientists are of the opinion that, due to continuous existence of freezing temperature, it is possible to get evidences of initial era of solar system in frozen ice molecules. In addition, until today, no one has successfully landed on this place, and it remained unexplored.

Why it is difficult to land of Polar region of Moon??

Most of the lunar missions till date are launched to explore equatorial region of the Moon. This area is relatively plane, and does not contain large craters. The Sun light is also available which can be used for scientific instruments to operate.

On the contrary, soft landing is very difficult in polar area due to number of reasons. This area consists of large numbers of craters, which vary in sizes from few meters to few kilometers in diameter. The terrane in this area is uneven, which makes it difficult for lander to calculate landing distance precisely.

One of the major reason is that the moon has no atmosphere, so parachutes cannot be used while descending to control landing speed.

Continuous freezing temperature is another hurdle for the equipment to perform well for a longer period. As this region is Permanent Shadowed Region (PSR), the sun rays does not reach here, which makes it difficult for the scientific instruments to acquire solar energy.

Key differences:

Sr.No.	Criteria	Chandrayaan-3	Luna-25
1	Launch Vehicle	LVM Mark-III M4 Rocket	Soyuz-2.1b Fregat booster
2	Pay laod Mass	3895 kg	1800 kg
3	Cost	650 Cr. Rs (Less than budget of Hollywood Sci-Fi movie)	Not officially disclosed. (Estimated to be 200 million USD)
4	Landing site	Manzinus crater	Primary: Boguslavsky crater, Secondary: Manzini Crater or south of Pentland A Crater
5	Mission Life	One Lunar day(14 Earth days)	One Earth year
6	Mission Objectives	As per ISRO, demonstrate a safe and soft landing on the lunar surface, rover mobility, and in-situ scientific experiments.	According to NASA, study the composition of the lunar polar surface material, the plasma and dust components.