Dark Side of the Moon: Russia’s Luna-25 was not a complete failure, revealed something crucial

Russia’s latest attempt, Luna-25, to land a spacecraft on the Moon didn’t quite go as planned. The whole thing ended up crashing on the lunar surface, according to the Russian space agency Roscosmos. It’s a real reminder of how tricky it can be to pull off a gentle landing on the Moon.

You’d think by now, with over 20 successful landings, including six with actual humans on board, we’d have this whole Moon landing thing down.

It’s still a bit of a challenge. Interestingly, if you look back, apart from three Chinese landings in the last 10 years, all the successful Moon landings happened in a relatively short span between 1966 and 1976. Clearly, landing on the Moon is a tough nut to crack.

The Zone of Terror
Landing on the Moon has become difficult than it was before. However, that doesn’t mean it was easy, ever. The final 15 minutes of any Moon mission is often referred to as “15 minutes of terror.” When the Chandrayaan-2 crashed, K Sivan, the then chairman of ISRO said that a lot of things can go wrong.

Most landing modules need to slow down from enormous speeds to almost a standstill. The Chandrayaan-2 for example, had to slow down from a speed of 21,000 kmph to 7 kmph when it began its final landing stage. Naturally, anything that is off even by a fraction, will cause failure.

When things go wrong
During soft landings, a lot of things can go wrong. That is the reason why satellites keep on taking pictures of their landing zone for a few days before they even consider attempting a landing.

From equipment malfunctioning to how much fuel is the lander carrying, all of these things come into play. Then, there is the approach angle of the Lander module, which depends on whether it was at the right orbit, at the right angle or not.

Finally, there are the air brakes, or the deboosters themselves. Not only do they need to be timed meticulously, they also need to be used with extreme precision. Although Russia hasn’t made it official, leaked reports suggest that the Luna 25 failed because one of the booster engines had an extra thrust of half a per cent, which completely threw the balance off.

This increase of half a per cent was because the Luna lander lost communication from Roscosmos for some time, and was following a predetermined set of instructions. Normally, these instructions are corrected and modified as the actual landing takes place.

Why do radio signals break
The Luna 25, like the Chandrayaan 2, tried to land at the Lunar south pole, a region that can be considered the dark side of the Moon. The Moon’s lunar regions are not visible from the Earth, so all of our knowledge of the lunar south pole comes from space-based observatories.

All polar regions, on all planets and extraterrestrial bodies, have bizarre magnetic and gravitational properties. Keeping track of an anomaly in real time is a technical nightmare.

With most of the recent landings targeting the polar regions, especially the south pole, things are only bound to get more difficult than regular landings. That is why despite so many attempts, no country or space mission has had a successful soft landing at the southern polar regions.

Also, as a satellite or a lander gets closer to the lunar surface, the radio signals it uses to communicate with the Earth, experience some severe interference, again, because of the polar regions’ magnetic fields and gravitational forces. Given the speed of the lunar module, and the changes in G-Force that it experiences, the components on the module experience a lot of stress, and become prone to malfunction.

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