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This is sky crane:

enter image description here Mars has 1/3 of Earth's gravity, so how was sky crane tested on Earth? Did they even test it at all? Did they repeatedly do the math, and make sure everything works so that they are 100% sure it would operate without testing it?

As per this stack exchange answer, sky crane uses Hydrazine Monopropellant thrusters which is capable of 400 - 1300 N of thrust. How did they test these engines?

To be clear, I don't expect a video or footage of the sky crane being tested, but any official NASA or JPL article that touches on this topic would be sufficient.

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  • $\begingroup$ Here's a test sans the thrusters: youtube.com/watch?v=YasCQRAWRwU I would imagine the engines were tested as any engine would be. $\endgroup$
    – Organic Marble
    Commented Aug 2, 2019 at 23:36
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    $\begingroup$ @OrganicMarble Thank you but I've seen that. That's to test whether the rocker-bogie wheels deploy correctly. $\endgroup$
    – Star Man
    Commented Aug 2, 2019 at 23:39
  • $\begingroup$ Just the engines? Or the assembled descent vehicle? $\endgroup$
    – Paul
    Commented Aug 3, 2019 at 0:22
  • $\begingroup$ @Paul Whatever you can find. $\endgroup$
    – Star Man
    Commented Aug 3, 2019 at 0:29

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The sky crane engines were tested individually. This is common practice for small thrusters like the ones used in almost every launch vehicle and satellite, where test firings of the whole assembly are impractical.

Other subsystem tests looked at the interaction between the engine exhaust and Mars' soil, for instance. Full-up tests are difficult. You need a vacuum chamber large enough to fit the sky crane, plus the rover dangling underneath it. But the system is designed for Mars' 1/3 G, not for Earth, so you have to use development vehicles that weigh 1/3 as much. You can't use a winch to take up 2/3 of the system weight, because one of the big questions was how would the sky crane behave with a rover dangling underneath, and if you suspend the sky crane that changes the dynamics.

Instead of physical tests, lots of simulations were done.

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  • $\begingroup$ I remember seeing a documentary on TV with a video of a test of the crane part in a lab building. $\endgroup$
    – Uwe
    Commented Aug 3, 2019 at 13:55
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    $\begingroup$ I've found tests where they dropped the rover from the crane, but no propulsion tests of the crane. $\endgroup$
    – Hobbes
    Commented Aug 3, 2019 at 14:36

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