Why Russia and India both crashed near the moon's south pole before India nailed the first soft landing there

• India landed the first spacecraft near the moon's south pole, after it and Russia both crashed there on prior missions.
• Landing on the moon, Mars, or any other space object, is one of the most complex parts of spaceflight.
• A first moon landing is extra tough, especially near the south pole, where permanent shadows harbor ice.

India landed a small robot near the moon's south pole on August 23, becoming the first nation to touch down at the strategic spot and the fourth nation to ever land on the moon.

The feat comes just days after Russia crash-landed there, and four years after India's first attempt crashed into the lunar south pole region.

"Spaceflight is hard, and landing on another planetary surface is among the hardest things that we do in spaceflight. So it's the hardest of the hard," Robert Braun, head of space exploration at Johns Hopkins Applied Physics Laboratory, told Insider.

Braun has worked on landing and descent teams for multiple NASA missions to Mars, including the Mars Polar Lander, which lost communication during its descent and was presumed crashed.

"It's not that people didn't try. It's not that people didn't do their all. It's not that they weren't supported. They probably were," he added.

There are countless tiny reasons a landing might fail, but in these cases, it boils down to a simple reality: Russia and India were trying to do something incredibly difficult, for the first time, in a place nobody has done it before.

India's success, especially in light of the much better-funded Russia's failure, is a huge triumph.

Why Russia was shooting for the moon

A lot was riding on the Russian mission, called Luna-25. It was Russia's first attempt to land on the moon in decades, since the Soviet Union fell.

It was the country's first bid at the lunar south pole, which is especially valuable space real estate because of its frozen-water reserves. 

Moon-minded nations are eyeing those reserves, because the water can be broken down into oxygen and hydrogen. That can serve as fuel to launch rockets from the moon toward Mars, without the gravity burden of an Earth-based launch.

Both the US and China also hope to land near the lunar south pole before the end of the decade.

If it had succeeded, Luna-25 was also poised to prove that Russia doesn't need Europe or the US to become a major power in deep space. The European Space Agency was previously a collaborator on the mission, but backed out after Russia invaded Ukraine last year.

Landing on the moon for the first time is extra hard

India had never landed on the moon before. The Soviet Union completed its last lunar landing in 1976. That was Luna-24.

So Luna-25 is "almost like a first" for Russia, Braun said. Because it's been so long, it's likely that most of the people involved have never participated in a moon mission before.

With no prior experience, they must build and program the lander system to push itself out of orbit, point itself in the right direction, and map and assess the ground below as it plummets toward the surface, while continuously re-orienting itself to find a safe spot.

Once it's very close to the surface, a lander must slow down and, often, spin around and deploy its legs. Then, once it makes contact with the surface, the system has to be strong enough to withstand the shock.

"So many of these things are proven out via simulation," Braun said. "It's very hard to make a high-fidelity or an accurate simulation of something you've not experienced."

During landing, time is compressed, so every little bit flip, calculation, and robotic movement must happen exactly on time, in the correct order. Any error, any flaw in the hardware or software, could cause a crash.

The moon's dust, rocks, and uneven terrain can interfere

The very end of a landing is the hardest part, because the spacecraft starts to interact with the moon's surface, Braun previously told Insider.

If a lander's leg hits a boulder, it could tip over and that would be the end of the mission. Lunar dust can even cloud up the instruments and tip the scales toward failure.

The lunar south pole is uniquely hazardous

The very thing that makes the moon's south pole so desirable — the permanently shadowed regions that harbor water ice — also makes it more difficult to land on.

Descent vehicles and landers often use cameras to assess the ground below them in real-time in those final minutes, as they approach the lunar surface. Visibility helps identify boulders and craters they should avoid so they don't tip over.

Near the south pole, "they're probably flying through some pretty long shadows, even if they don't land in a shadowed region," Braun said.

That doesn't seem to have played a factor in the south-pole attempts so far, but the shadows could menace future moon missions.

Also, before India landed there, no nation had ever been to the moon's south pole region. Compared to the equator region, where the Apollo missions landed, it's uncharted territory.

"Having been a part of both successes and failures at Mars, I learned way more from the failures than from the successes," Braun said. "You pick yourself up, you dust yourself off, you think hard about everything you did right and whatever it is that you and the team did wrong, and you make improvements, and you do better."

Correction: August 28, 2023 — An earlier version of this article misstated Robert Braun's title. He is head of space exploration at Johns Hopkins Applied Physics Laboratory, not head of a Space Exploration Center there.

Correction September 1, 2023: An earlier version of this article misstated where India landed on the moon. India is the first country to ever successfully land a spacecraft softly near the lunar south pole. 

This story has been updated. It was originally published on August 23, 2023.