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The caption in this Space dot com video says that Schiaparelli will drop the last two meters, and the shock will be absorbed by a crushable structure.

It is described in the text accompanying this video Schiaparelli's Descent to Mars in Real Time

In six minutes it will use a heatshield, parachute and thrusters to brake from 21 000 km/h to a near standstill 2 m above the surface, where a crushable structure on its underside will absorb the final shock.

However, the "Two Meters of Terror" look a little too fast in the video in this BBC website article considering Mars' low gravity. It looks a little more realistic here:

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above: GIF animation of Schiaparelli landing from here.

Since there are plenty of rocks on Mars of all sizes, how will Schiaparelli manage to land so that its crushable structure hits first? Am I understanding the image correctly - is the entire underside of Schiaparelli one big crushable-structure?

Looking at the images below the RDA assembly seems to be delicate instrumentation that will actually hit the surface first. I don't know why the crushed/damaged areas on the edge/periphery are representative, I'd expect the center to hit first.

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above: "Crushable Landing Structure after test drop – Photo: ESA" from here

Why is it only crushed on two opposite edges simultaneously, but not in the middle?

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above: "Crushable Landing Structure Design – Image: ESA" from here

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above: "Schiaparelli - View from Beneath" from here.

uhoh
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1 Answers1

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The Spaceflight101 article you linked to has this nice graphic:

Schiaparelli diagram showing that the entire underside is a crushable structure

So yes, the entire underside, except for a section in the middle where the radar sits, is a crushable structure.

The cross-section you added to the question shows the radar is attached to a flange that sits on a ridge of the crushable structure, and there's a void above the radar. So this happens when the radar hits the ground first: the forces are transmitted to the ridge, and the entire radar is pushed up into the void. The radar may also absorb some of the force by deforming.

Hobbes
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  • I've added another image. I really don't understand what is going on in the center - is that radar ranging instrumentation? Is it "crushable radar"? Isn't that where it will actually hit first? – uhoh Oct 19 '16 at 12:09
  • @uhoh I find it hard to understand what you're asking for - isn't it obvious that the radar is mounted underneath, but will not be needed after landing so damage to the radar does not matter? – Andy Oct 19 '16 at 12:27
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    @Andy perhaps I'm not smart like you. A crush zone absorbs energy. If it's the radar that hits and not the crush zone, then how is the energy dissipated. I think the "isn't it obvious" type comments don't really help. The answer says "the entire underside, except for a section in the middle..." and that it precisely the section that will hit the surface. In the image of the crushed structures in my question (please look carefully) there are two crushed areas - at opposite points on the periphery only. – uhoh Oct 19 '16 at 12:55
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    Oh, everything that is tan/yellow color in that image is crushable? OK got it. I understand now. That's actually a tall, extended flange of the stuff sticking out, and probably the radar fixture distributes the energy of the impact all the way around the circumference of that flange for maximum dissipation. Very nice - thanks!! – uhoh Oct 19 '16 at 13:38