As a final backup, the lander Vikram has a 'salvage mode' to land on the moon
India's lunar mission Chandrayaan-3 is nearing its exciting climax. It is the closest to the moon before the tricky landing manoeuvre is attempted on August 23.
The Russian lunar probe Luna-25, too, is also closing in and will attempt a landing between August 21 and 23. Both Russia and India are targeting to land nearer the south pole of the moon.
Is there an Indo-Russia race to the moon?
The Indian Space Research Organisation (ISRO) feels there is no such race. Both nations will have a new 'meeting point' on the moon.
Here are the key details of the Chandrayaan-3 mission:
Chandrayaan-3 was launched on July 14 from Sriharikota using the Launch Vehicle Mark-3. It reached the moon's orbit on August 5, and has been orbiting it since then.
Today, Chandryaan-3 was put in an orbit of 153 km by 163 km and all lunar-bound manoeuvres were completed. On August 17, the propulsion module and the lander Vikram will separate. The propulsion module will continue its journey in the same orbit.
On August 23, after the preloaded commands are triggered, the lander Vikram will attempt a soft landing on the moon's surface. ISRO has done many tests to ensure a failsafe landing.
As a final backup, the lander Vikram has a 'salvage mode' to land on the moon.
After the lander touches down and the lunar dust settles, the Pragyaan rover will be rolled down. Lander Vikram will take images of the Pragyaan rover and the rover will take images of the lander - the first Indian selfies from the lunar surface will arrive.
From then, the 14 Earth day planned scientific exploration of the moon begins.
Key details of the Russian moon probe 'Luna 25'
In a surprise move, Russia launched its lunar satellite named 'Luna 25' on August 11 - 47 years after the USSR last sent a lunar mission.
Russia used a heavy-lift rocket that sent the Luna 25 satellite directly on its journey to the moon, unlike India which used a circuitous slingshot route.
The Luna 25 probe is likely to enter the moon's orbit on August 16. Russia seeks to attempt a soft landing between August 21 and 23.
Both Luna-25 and Vikram are trying to land close to the south pole of the moon.
The Luna 25 satellite weighed 1,750 kg at lift-off and carries 30 kg of nine scientific experiments. It is only a robotic lander and has no rover in it. The expected mission life of Luna-25 is one year.
Luna 25 is powered by a radioactive generator, so it can last longer. Its journey from the Earth to the moon will last 10 days. The Russian spacecraft will conduct a study of the moon soil and look for water and ice.
Comparison: Chandrayaan-3 and Luna 25
Chandrayaan-3 will take 40 days to reach the moon surface, while Luna 25 will take just 10 days.
Russia used a heavier rocket, so it could send its lunar satellite directly to the moon; India used a medium-lift rocket and took a circuitous route; Chandryaan-3 weighs 3,921 kg and Luna 25 weighs 1,750 kg,
Chandrayaan-3 carries both the lander Vikram the rover Pragyaan. Luna 25 is only a lander mission, without a rover.
The lander Vikram weighs 1,745 kg and the Luna 25 lander weighs 800 kg. The expected mission life of Vikram lander is 14 Earth days; Luna 25 will last one year
Both the Russian and Indian lunar probes want to set the record of the first successful soft-landing near the moon's south pole.
India purposefully crash-landed its moon impact probe as part of Chandryaan-1 in 2008; Russia conducted its last lunar mission in 1976.
Russia has plans to conduct the Luna 26 and 27 mission. India has not announced any more lunar probes after Chandrayaan-3.
Russia and China together want to set up a lunar research base. India has also joined hands with the US by signing the Artemis Accords, which could lead to a permanent habitation on the moon.