Not the post, but the wayward set of bristles snagged together, finding or crafting a divot and digging in. The DRT is never commanded nominally in a way that the post would make contact.

It was a very subtle thing, but you might look closely at these images: http://mars.jpl.nasa.gov/msl-raw-images/ms...0000E1_DXXX.jpg and http://mars.jpl.nasa.gov/msl-raw-images/ms...0000E1_DXXX.jpg

I don't think there was a press release pertaining to DRT or any operational issues with it since its original use, and so you can draw your own conclusions, but one might be hopeful that such a subtle thing would yield only a temporary engineering prohibition after some rework.

As I'm sure mars_armer knows, there are eight kinematic solutions, as we have shoulder in/out in addition to elbow up/down and wrist up/down. In practice, contact science is most often done shoulder in, elbow up, wrist up, as it has the best mix of near and far field reachability and wrist up means the wrist actuator isn't as much a terrain clearance concern. You also see shoulder out, elbow up, wrist down (far field) and shoulder out, elbow up, wrist up (near field and outcrop/more horizontal target). Any elbow down configuration would have us reaching up under an overhang (or to present the turret to a camera) rather than down to the surface.

Elbow/wrist up/down are easy to understand. Elbow is up if the elbow origin is higher than the wrist origin, wrist is up if the wrist origin is higher than the turret origin. Shoulder is in if you can move your model in such a way that you can swing the turret amidships over the deck (a tuck) with the az, assuming the stops are faithful. Shoulder out as you flip the elbow through 0 (arm fully extended) through to the other side. A bit confusing that, shoulder in/out is merely the sign of the elbow.


Just so. If you're there, you do it there. It would waste time to do contact science in shoulder in, flip the elbow, then go down for the shoulder out config to image, back up to stow. MaHLI sees no difference.