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InSight Surface Operations, 26 Nov 2018-
serpens
post Sep 1 2019, 02:01 AM
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In this we are assuming that the void is due to soil properties. There is the possibility that the void was created by vibrating in place if the mole encountered a large rock similar to that exposed by InSight's exhaust.


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tanjent
post Sep 1 2019, 05:07 AM
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I don't see how any amount of vibration in place could produce a void in the complete absence of adhesion between the soil particles. If there is a subsurface rock like the one pictured - too big to circumvent and too solid to punch through, then there is no path to success in this location. Transplanting the probe will have to be considered. Digging a new hole elsewhere initially as a source of loose fill (assuming that the shape of the scoop and the force it can exert allow this) might make transplantation possible as a last resort.
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James Sorenson
post Sep 1 2019, 04:29 PM
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QUOTE (tanjent @ Aug 31 2019, 09:07 PM) *
If there is a subsurface rock like the one pictured - too big to circumvent and too solid to punch through, then there is no path to success in this location. Transplanting the probe will have to be considered.

As a last resort in that event, there is one option that I can think of to try and extract the mole which would be extremely dangerous to the mole, but would be better than giving up completely. Something that could first be tested of coarse in the test bed to see if it could be possible to do. There are three things in our favor, We have a long arm that can Kinematically move linearly in three axis of motion, we have a 5 fingered grapple and the mole is a cylinder. The machinist in me is talking here like how a lathe chuck holds round bar stock, how about try and grab the top of the mole with the grapple with enough closing force to to grasp it and try pulling it out? The arm and grapple then could vertically position it to a new location. Once positioned above a new location, the arm could lower the mole with the tip of it just touching the surface. After this is done, the mole could start hammering with the arm feeding down with it at the same rate as the hammer cycle. Once enough of the mole is in the subsurface and not at risk of toppling over, the grapple can release slightly but still help guide it down. The grapple is on a lanyard, so really guiding it with the grapple during this step might not work well, so really just releasing it completely would be better.

The biggest issue in all of this is that delicate flex print cable, grabbing it heavily risks hitting or severing it, but if the cable could fit in the space between two fingers, could that be possible? Also since the mole is not currently vertical but tilted, grabbing it would be a challenge unless the scoop could first be used to try and tug on one side to straighten it out. If that could be done, the only obstacles would be getting around that cable with the grapple and clamping around it with enough force to hold it and not slip. Anyone know what the clamping force the grapple has? I know it uses paraffin wax actuators which obviously have allowed the grapple to lift the weight of the science instruments to the surface. In a video that I had seen, one engineer had said when it closes around a pin and the wax cools, the fingers lock around the pin which prevents any inadvertent release. How about that for thinking outside the box? wink.gif
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