The Top of Vera Rubin Ridge Part 2, Site 67-73, sol 1944-2297, 24 Jan 2018-22 Jan 2019 Options

[jvandriel]

The Navcam L view on Sol 2120.

Jan van Driel

[PaulH51]

This RMI and NavCam from sol 2123 indicate that the drill did not penetrate the bedrock deep enough to obtain a sample. This hematite-rich rock is tough stuff... The full frame HazCams from sol 2122 may provide a few clues, but have not made it to the public server yet.

[serpens]

Perhaps the minerology of the Duluth drill sample from the lower, Blunt's Point member of the ridge, compared to previous breakdowns will provide a few clues about the trends leading to the extremely hard rock in the upper levels.

[djellison]

The full frame HazCams from sol 2122 may provide a few clues, but have not made it to the public server yet.

The Navcams and Hazcams get out on the public server within an hour or two (Often much less) of reaching the ground.

If they’re not on the public website, they’re almost certainly not on the ground yet.

[serpens]

Just wondering if they have done any analysis with the Curiosity test rig to determine the likely Mohs scale hardness of these rocks?

[jvandriel]

Sol 2122
The Front Hazcam view of the drilling ( or trying to drill )

Jan van Driel

[jvandriel]

Sol 2123

Chemcam looking at the result of the drilling.

Jan van Driel

[PaulH51]

Sol 2126: Curiosity continues to seek a place to obtain a powdered rock sample from the Pettegrove Point member. Today it was a long drive back to the west ~68 meters and is now close to the spot where she arrived during sol 2102. I'm not sure yet if this is the new drill site or just a waypoint closer to the target location. Fingers crossed for more favourable drilling conditions in the coming days.

[serpens]

If they find a location soft enough to drill, the question is would it really be indicative of the extremely hard Pettegrove Point member?

[Floyd]

They are drilling in with some drift, but why can't they just keep drilling for 4x or 10x longer time? My experience with drilling materials on earth (plastics and metals on my garage bench) is that even when the drill is bouncing around and making a mess at the surface, as the hole gets deeper, the lateral drift get smaller and you eventually get a clean hole down a ways into the material.

[PaulH51]

....why can't they just keep drilling for 4x or 10x longer time?

I think the amount of available energy may just be a limiting factor to drilling for longer. In a recent mission update I recall they mentioned that after drilling the rover would spend most of the next day recharging its batteries. So one could deduce that the entire drilling exercise is power hungry, if that's the case, then running the drill for 4 or x times longer may not be an available option? Just thinking out loud... as for representing the harder Pettegrove Point rock, probably not, but they may be able to gather some additional data using LIBS and APXS to support the SAM and CheMin data from less hard location?

[nprev]

Just out of curiosity (rimshot), does anyone know if there's a published max hardness for drillable rock on the Moh's scale? Be interesting to contrast that with the power constraints of the drill and other factors like the ChemCam-derived composition.

[jvandriel]

The Navcam L view on Sol 2126.

Jan van Driel

[serpens]

Given all the variables that influence drilling and the differing constituents of the sedimentary target, hardness on the Moh's scale is not really an appropriate metric. I guess when the status reports talk about how hard the rock is the brain goes into auto and embraces the Moh's scale. But a difficult rock to drill might not be all that hard.
We can be certain that the drill bit design and drill power (torque, thrust etc) will have been optimised for anticipated sedimentary rock targets and despite workarounds it is obvious that the system works on appropriate targets. But the Pettegrove Point Member resists drilling. Whether this relates to matrix strength, nature of cementation, mineralogy, clast size, lack of voids or something else is, at present, a mystery.

[mcaplinger]

We can be certain that the drill bit design and drill power (torque, thrust etc) will have been optimised for anticipated sedimentary rock targets...

The original design could drill into basalt successfully, but obviously it can no longer be operated thst way.

I'm not sure if "optimized" is the right word -- given all the things it has to do, the design is a series of compromises.