Comments by "红火树 RedFireTree" (@firetree2007) on "ISRO: India to be the 4th nation to touch Lunar surface | WION" video.
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The main difference between India's vikram lander and China's or USSR's moon lander, is the engine used. China and USSR use a major throttleable engine which can be restarted easily, China's with max power 7.5 tons for a 3.8 tons (changeable from 1.25 tons to 7.5 tons)（ variable thrust rocket engine; VTE.） （the same engine used 3 times on soft landing on the moon with 100% success, and the newer version of it used for China's mars landing too) lander , India cannot make such kind engine, so for Chandrayaan-2, the lander used 5 liquid fuel engines, and for Chandrayaan-3, it reduced 1 to use 4 liquid fuel rocket engines for landing, each with 800 kg so total 3.2 tons power for a 2 tons lander, it is much easier to control a single throttleable engine then control 4 separate liquid engines, since any tiny difference in throttle power among the 4 engines will make the lander tilted, lose stability and crash. In this sense, there is not much change between Chandrayaan-2 and Chandrayaan-3. therefore the fate will be similar too.
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for the moon landers, from US Apollo, to USSR Lunar, to China Changer, all use a single engine for landing, why India use multiple engines?? more engines simply mean more troubles, more possibility of failure.
2nd, for Chandrayaan-2, there were 5 engines, with one with the fixed throttle in the middle, the consideration is, due to the moon dust, 4 side engines will blow the dust, the one in the middle can blow the dust away, however, for Chandrayaan-3, ISRO took out the center one, then what about dust? no one knows,
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@jothiparam
1. India likes to boast its mars probe, what they do not know if all the navigation and instructions was from NASA not by ISRO.
2. China has done many times walk on the moon, and even at the back of the moon, recently NASA asked China's permission to use China satellite placed at the back space of the moon, China has agreed despite the US refuse to let China use International space station
3. for the reason why 2 is crashed is that all landing on the moon was done by the lander itself, no human control from the earth, so unlike mars probe (only 14.3 kg compare to China mars package with total 5000 kg) US cannot help
4. for the moon lander its needs all kinds of sensors to accurately measure the distance, and position, India with very little experience on that.
5. For China's moon lander, with 3.8 tons, China use a main engine that can be throttled from 1.5 to 7.5 Kilonewtons to conduct a single continuous landing burn. India Lander Module (Vikram): 1752 kg including Rover (Pragyan) of 26 kg India cannot make changeable throttle engine, for Chandrayaan 2, it used 5 small engines, did not work, crashed, for Chandrayaan 3 it reduced one, so only 4 engines, but the principle does not change at all, so it has high possibility of crash again.
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