Context: India’s Chandrayaan-3 and Russia’s Luna 25 are both in lunar orbit, preparing for a landing on the Moon next week. Luna 25 is expected to go first, on August 21, while Chandrayaan-3 is likely to touch down two days later, on August 23. 

• Both missions are aiming to land in a region where no spacecraft has gone before, near the South Pole of the Moon.

• Since the landing of the then Soviet Union’s Luna 24 in 1976, only China has been able to land a spacecraft on the Moon — Chang’e 3 and Chang’e 4 in 2013 and 2018 respectively. India and Russia are both trying to make their first soft landing.

About Luna 25 Mission

• Luna 25 is a lunar lander mission of Russia that is scheduled to land near the lunar south pole at the crater Boguslawsky.

• It was renamed to Luna 25 from Luna-Glob lander, to emphasize the continuity of the Soviet Luna programme from the 1970s.

• It is the first lunar probe that the Russian space agency ROSCOSMOS has sent to the Moon.

• It could be the first probe to land near the lunar South Pole.

Comparison between Luna 25 and Chandrayaan-3

• Luna-25 was launched using its Soyuz rocket after the launch of Chandrayaan-3.

• It would cover the journey in less time due to more direct trajectory towards the moon, lighter payload and more fuel storage.

• The lift-off mass for Luna 25 is less than India’s Chandrayaan-3.

• Launch Vehicle Mach-3 (LVM3) vehicle for India’s mission took circuitous route to make up for the lower fuel reserve.

• After being launched around the Earth, the orbit was increased in a series of manoeuvres to gain velocity.

• The spacecraft was then slingshot towards the moon to reach lunar orbit in 22 days after launch.

• Chandrayaan-3 will reduce its orbit and velocity around the moon to prepare for the soft landing to be attempted on August 23 at lunar dawn.

• One lunar day is equal to 14 Earth days and the payloads powered by solar panels ensures that the experiments get the full 14 earth days.

• The lunar dawn at landing site of Luna 25 will happen earlier than the Chandrayaan-3.

• Luna-25 does not carry a rover while, Chandrayaan-3 has a rover capable of moving around 500 meters.

• Luna 25 lander has eight payloads to study the soil composition, dust particles in the polar exosphere, and detect surface water.

• The Indian mission will last only one lunar day or 14 earth days due to absence of heating mechanism from the extreme cold temperatures during the lunar night.

• The Russian mission will work for a year due to heating mechanism and power source other than solar panels.

• India’s mission would land on South Pole as the craters remain in permanent shadow so it would be easier to find water-ice.

Experiments on Chandrayaan-3

Lander Experiments

• The Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA) has a Langmuir probe to study properties of electrons and ions like temperature and density.

• The Chandra’s Surface Thermo physical Experiment (ChaSTE) will study the thermal properties of the lunar surface near the polar region.

• The Instrument for Lunar Seismic Activity (ILSA) will measure the lunar quakes near the landing site and study the composition of the moon’s crust and mantle.

• The LASER Retroreflector Array (LRA) is a passive experiment of NASA to act as target for lasers and precisely track the spacecrafts.

Rover Experiments

• The LASER Induced Breakdown Spectroscope (LIBS) will determine the chemical and mineral composition of the lunar surface.

• The Alpha Particle X-ray Spectrometer (APXS) is for elements such as Magnesium, Aluminium, Silicon, Potassium, Calcium, Titanium, and Iron in the lunar soil and rocks.

Race to land humans on moon

• The discovery of water molecules by Chandrayaan-1 mission in 2008 has propelled another race to the moon.

• The United States and China plans to take humans to moon again, a first after the cold war era.

• To date, only 12 men aboard US’ Apollo Missions have set foot on the lunar surface.

• Although India has limited resources, it could catch up with countries having more advanced and older space agencies.

• India is yet to announce a sample return mission and is planning for a fourth mission to moon with Japan.

• Israel’s Beresheet had failed to land softly on the moon just a few months before Chandrayaan-2 in 2019.

• Two more landers from Japan and UAE couldn’t reach the lunar surface due to spacecraft failure.

• At least four more lunar missions would be attempted in future by United States, China, and Japan.