4th leg in the trek to Endeavour, After science stop @ Kasos Options

[Nirgal]

using patches of bedrock to move

if I remember correctly, the increase in RF currents was less pronounced (or even non-existant) when driving on firm bedrock in the past (Paolo, correct me if I'm wrong) ...

[Poolio]

No, I think we will stop at the end of the next drive. Wherever that might be.

What is the reasoning behind this? Is it due to excessive concern over the RF wheel currents, or because the future path alternatives diverge at this point? The reason I ask is that I would have thought it a priority to reach bedrock before stopping for any length of time (to maximize the science return during the rest).

Mike

[RoverDriver]

What is the reasoning behind this? Is it due to excessive concern over the RF wheel currents, or because the future path alternatives diverge at this point? The reason I ask is that I would have thought it a priority to reach bedrock before stopping for any length of time (to maximize the science return during the rest).

Mike

The only thing that helped reducing the RF current now seems to be resting for a week or two. The higher wheel currents indicate that the motor is subject to more mechanical resistance. I have not been following MER-B closely but was told that the nearest bedrock is about 200m away. At the current rate that would be about one week of driving.

Paolo

[jamescanvin]

Just catching up a bit. Drive direction mosaics for sols 1897 to 1904 (all images link to the same blog entry)


Sol 1897

Sol 1898

Sol 1900

Sol 1902

Sol 1904



James

[SpaceListener]

The higher wheel currents indicate that the motor is subject to more mechanical resistance.

I am suppossing that by driving on bedrock, the wheels traction will require less mechanical resistance than over the sand. Is there any difference of wheel currents between bedrock and sand?

[RoverDriver]

I am suppossing that by driving on bedrock, the wheels traction will require less mechanical resistance than over the sand. Is there any difference of wheel currents between bedrock and sand?

The RF currents drop to almost nominal (~50% reduction) on bedrock but all other wheels change only a slight amount (10% reduction).

Paolo

[Nirgal]

The RF currents drop to almost nominal (~50% reduction) on bedrock
Paolo

Ah, this is very encouraging ! suggesting the RF problem will be greatly alleviated once we reach the firmer "parking-lot" type of terrain about 2 kms ahead (which is expected to be similar in driveability to the "easy" ground between Eagle and Endurance) ... so it sure is the most sensible approach to drive defensively in order to reach the "parking lot" with an intact RF

[Floyd]

I thought I was looking at Spirit tracks. What the .... salts or silica in the middle of nowhere

[RoverDriver]

I thought I was looking at Spirit tracks. What the hell--salts or silica in the middle of nowhere
...

Funny, isnt' it? The penultimate drive tripped the average wheel current limit which is in place to stop the rover when it is close to being embedded. This is the first time this limit was triggered while not extricating the rover from an embedding event. Looking at the tracks, I think this was a good thing.

Paolo

[Astro0]

That's very interesting and very pretty

[nprev]

Hmm. I see some apparent slip marks in the white patch. Given the wheel current spike, is the white stuff therefore more slippery than standard soil?

(And does this hold any clues for Spirit's situation? How many kinds of white stuff have been noted to date over in Gusev?)

[Shaka]

The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand.

[briv1016]

The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand.

Looks too clumpy to be just bedrock.

[Floyd]

The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand.

No I would agree with briv1016 that it is not bedrock. I think we hit a patch of crumbly salt nodules. I think the larger rock/patch would also crumble if driven over. Paolo also indicated that wheel current was up from moving over/into soft soil--I don't think you would get that with a thin layer of sand over bedrock.

I wonder if Opportunity will do any IDD work to explore the composition of the light material?

[fredk]

I don't see any sign of slippage in these images. The linear wheel track on the right isn't defined as well where it goes over the messy tracks from the turn in place. The lighter patches may just be patches where the compacted smooth fine soil is catching reflections of sun/skylight?