[X] My Assistant

[stewjack]

Now that we know where we are going, I thought we could use a topic about our future route. I hope that a few images will get the rover rolling - downhill.

READY START

BACKGROUND
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From Steve Squyres Misson Update
Octoberber 4, 2005

Extending eastward from the summit of Husband Hill is a broad ridge that we've named Haskin Ridge. It trends ENE from the summit, does a little dog-leg to the right, and then trends ESE for a bit. Right at the dog-leg there's a pretty steep step, which we're not certain we can get down. So we're going to descend the upper portion of the ridge, right to where the step is, and assess the situation. If we can see a safe route, then we'll continue down onto the lower portion of Haskin Ridge.
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My Image of Haskin Ridge
I tried to get the best image of Haskin ridge that was available, and this is a crop from a true color TIFF summit panorama, located on the the Cornell Pancam web site. I converted the tif file to a gif file to save some download time.

Warning : File Size : 1.7 MB
Cornell True Color Pan of Haskin Ridge

Reference
WEB page of Husband Hill Summit Panorama
Warning: File Size : 80 MB !!!!
Preliminary Spirit Pancam of "Husband Hill Summit" Panorama

Jack

PS If you can't see the "steep step" that Squyres mentions - try this orbital image. I believe that the "steep step" is the dark shadow cutting across the ridge that is located directly under the word CRATER. I think that it is also visible in the true color pancam image, but it is less obvious.

Orbital View of Husband Hill and Basin

[RNeuhaus]

Dot.dk already posted the info about "rawid" tool.

Let me add that a quick and easy way to know if a rover has moved or not is by checking the site/drive id on the image filenames.

Rodolfo,

You made a reference to the file 2N183087021EFFAH00P1755L0M1.JPG.
Pictures taken on a different place, regardless of sol, will have an id different of AH00.
Spirit is currently on site/drive AI00. After the next drive she will be at AJ00 or AIxx.

Tesheiner: Muito bem. Perfecto

I am starting to learn to interpret the columns : 15-16 (Site Number as site location), 17- 18 (Drive number -position within Site Count). About the Site Number, how do they name it? Every sol, a new site location or every stop for more than seversl minutes is a new site location or whatever else you tell me.

P.D.More details about MER File name code

Rodolfo

[fredk]

We can actually constrain the slope of the hidden dropoff ahead of us on Haskin ridge in a very simple way - we don't need to know the slope Spirit is currently on or the distance to the dropoff or anything.

The attached sketch shows Spirit at its current location heading downhill, with the hidden dropoff slope indicated by a "?". It's clear from the sketch that the angular slope of the hidden dropoff must be more than the angle I've called greek theta.

But theta is easy to measure from navcam imagery. This is the view ahead from the current position (according to the latest sol 640 imagery). To measure theta we simply count pixels from the horizon to the visible edge of the dropoff and convert to degrees. Doing this I find that the slope of the dropoff must be greater than about 16 degrees. The biggest uncertainty is in locating the horizon in the navcam image (I added a half degree for the horizon drop due to altitude).

This shows that there is plenty of room for an easily navigable dropoff - 16 to 20 degrees or even more should pose no problem, especially downhill. Off course this just gives a lower limit - an 80 degree cliff is certainly a possibility!

Attached thumbnail(s)

 

[jamescanvin]

(I added a half degree for the horizon drop due to altitude).

Unfortunately it's a good deal bigger than that!

I'm not sure what height difference to take for the surrounding plains in the summit JPL press release they say 82m but 106m above the landing site. I guess the 82m is the height of the summit above the plains right next to the hills, where as we need to know the height of the plains on the horizon which considering the difference in height to the lander could be quite different.

Being ]really conservative and using 60m as our current hight above the plains that still means the horizion is 10.5 degrees below the horizontal, and thus what you are really saying is that the steep slope is >26 degrees!

Note that in my previous post about the slope using the hazcam, 200 pixels below the top of the frame equates to 9 degrees below the horizontal and is the reason that the limits are different. (I now think that should have been using a higher number than 200 anyway as I had forgotton at the time that the rear hazcam is angled differently to the front, doh!

I still maintain however that it's not the steepness that will be the problem but rocky near vertical outcrops that could make up the slope.

James: waiting with great anticipation for the next 10m.

[fredk]

Unfortunately it's a good deal bigger than that! 

Being really conservative and using 60m as our current hight above the plains that still means the horizion is 10.5 degrees below the horizontal, and thus what you are really saying is that the steep slope is  >26 degrees! 

James: waiting with great anticipation for the next 10m.   

James, I think you must be out by a factor of ten or the like somewhere! For height h above a sphere of radius r, the horizon drops by squareroot(2h/r) radians, for small h/r.

Plugging in your conservative h=60m, and r=3 400 000m, I get 0.34 degrees. You really need to get to planetary heights to see horizons drop by 10 degrees!

[jamescanvin]

...the steep slope is  >26 degrees!  ...

For comparison here is a quote from Steves last update

But our position at the end of that second drive looked pretty dodgy: A very steep slope (we were pitched up more than 27 degrees) and some very loose-looking crud under the wheels.

>27 = very steep!

[jamescanvin]

James, I think you must be out by a factor of ten or the like somewhere!  For height h above a sphere of radius r, the horizon drops by squareroot(2h/r) radians, for small h/r.

Plugging in your conservative h=60m, and r=3 400 000m, I get 0.34 degrees.  You really need to get to planetary heights to see horizons drop by 10 degrees!

oops! more like a factor of 1000. (m => km)!

So what's going on with the horizon in the summit hazcams, let me get back to you...

[jamescanvin]

OK, it looks like the source I have frrom the angle the hazcams are mounted was in error.

Corrected gives Spirit a current tilt of 10 degrees with that 10 degree slope continuing to the edge.

[Tesheiner]

About the Site Number, how do they name it? Every sol, a new site location or every stop for more than seversl minutes is a new site location or whatever else you tell me.

The site number is named by the rover planners in advance to the drive. It's usually set upon significant stops, but its assignment may be quite subjective; you never know when it will happen.
Last sites for Oppy were:
60: Erebus Highway (sol 580)
61: South Shetland (sol 591)
62: South Shetland (sol 592)
63: big outcrop from where they started moving NW (sol 617)

The drive number is more or less related to "wheel steps". But those steps are not of fixed lenght so it's usually not possible to derive any driving distance from them, at least for me.

[jvandriel]

Going down Husband Hill.

A 360 degree Navcam panoramic view taken on Sol 638-639 with the L0 Navcam.

jvandriel

Attached thumbnail(s)

 

[jvandriel]

and another one taken on Sol 639-640 with the L0 Navcam.

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[Tman]

There are already new images from sol 642 on JPL's site! But not yet better visible where Spirit could go. A new big but rather transparent DD on or behind the ridge: http://marsrovers.jpl.nasa.gov/gallery/all...8P0655R0M1.HTML

[vikingmars]

(following post #116) Well... Before going down, we are first having a look on "white" rocks ! Yum-yum !

Attached thumbnail(s)

 

[vikingmars]

...And here is a color image of the rocks !
Enjoy !

Attached thumbnail(s)

 

[Tman]

According Steve it's called "Kansas":

(Update from 24.10) "At Gusev, Spirit is working her way nicely down the upper portion of Haskin Ridge. We're within a few tens of meters of the top of the step now, and we've stopped for a bit of IDD work on a new outcrop called Kansas. No idea what it's made of yet, but we should get some clues over the next couple of days".

[fredk]

A bit of downslope movement sol 642. From this latest navcam shot, my technique gives only a slightly tighter constraint on the dropoff slope of a half degree or so, so the slope must exceed 16 or 17 degrees.