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Comment by sean1524 | Hacker News Reader

I'm curious, their landing vehicle seems to have less moving parts than the respective US rovers that use a complex sky-crane. Is there a particular benefit to using the sky-crane?

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The parachute + inflatable bouncy ball landing vehicle worked for the spirit and opportunity rovers. I recall seeing something from NASA that the spirit size landing was about the maximum size that was viable for that. They were explaining why re using the same design for the new much larger RTG powered rovers would not be possible.

This book on Curiosity by it's chief engineer (who went on to work on Perserverance) covers that and other tradeoffs well:

https://www.amazon.com/gp/product/1588344037/

I thought the primary benefit of the sky-crane method was avoiding kicking up high-velocity rocks and dust that could damage the lander, by direct impact or by falling, during the last moments of the landing? It might allow for more sensitive instruments and tools, with less protection on them.

For example the helicopter was slung underneath the latest NASA lander, and though it had a protective shell, you still don't want a rock to whack that

Arguably, though sky-crane is cool and clever, it isn't so much more complex than a system in which the rover must drive off a landing platform after it is safely down. That also has a lot of moving parts and opportunities for failure

But if a sky-crane lander lands successfully, at least you can be sure it isn't already covered in grit and dust

I think overall they got a greater mass into Mars orbit than Perseverance. They have bundled a rather large orbiter and the rover into a single mission, whereas Perseverance payload is entirely the surface rover and related modules.

It appears it is about 3+ ton orbiter, and 400kg rover/lander.

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