Exercise 14 – Mars Rover Planning

Due: Thursday, March 12 at the start of class

• HiRISE DEM and Hillshade: galemosaic and GaleHS GRID files

• CTX image covering the traverse route: B01_009861_1753_XI_04S222W.jp2

• Non-georeferenced image of the rover location on Sol 1487 (Oct. 12, 2016)

Curiosity_Location_Sol1487-full.jpg

Goal: The lower slopes of Mt. Sharp (photo below) present the biggest challenge for rover-driving to date

on Mars. Choosing a route must factor in the capability of the rover plus the expected science targets. You

will start with the engineering constraints and determine a route that have slopes that the rover can

manage. You will later factor in both surface materials (e.g., sand vs. rock).

The image above is a portion of a larger image taken by Curiosity's 100-millimeter Mast Camera on Aug. 23, 2012.

The dark rock highlighted in the box is approximately the same size as Curiosity. The pointy mound in the center of

the image, looming above the rover-sized rock, is about 300 m across and 100 m high.

http://photojournal.jpl.nasa.gov/catalog/PIA16105

Part II. Engineering constraints (nothing to turn in here) Curiosity is a very capable rover, but there are limitations to where it can drive. The kinds of slopes that it

can drive up and down depend on the material – on bare rock, the rover can traverse much steeper slopes

than it can in sand. Below, and on the next page, you’ll see several slides detailing the driving limitations.

These were presented at the 5th Mars Science Laboratory Landing Site Workshop in 2011 by Dr. Matthew

Golombek (JPL) and his colleagues.

Get familiar with rocky and sandy areas to help you plan your traverse in Part III. See the images below.

Black arrows in this DEM indicate sand dunes; red arrows indicate rock outcrops

Black arrows in this HiRISE image indicate sand dunes; red arrows indicate rock outcrops

Part II. Georeferencing an image 1. Add the HiRISE DEM and then the CTX image to an empty ArcMap project. For the CTX, to

get rid of the black space around the image go into Symbology and check the Display

Background Value 0 as no color box.

2. I downloaded a jpg of the rover location (Curiosity_Location_Sol1487-full.jpg). The problem is

that this image has no geographic information. That’s ok, we can use Georeferencing Tools to

properly place it on the map.

3. Add and dock the Georeferencing toolbar if it is not visible by right-clicking on the empty menu

bar.

4. Add your Curiosity_Location jpg to your base map if you haven’t already. You’ll get a warning

dialog box that the file has no spatial reference. That’s OK, because you’re going to add one by

georeferencing the file.

5. In the Georeferencing Toolbar, **make sure

that the target layer in the pulldown is your

traverse jpeg, and select Fit to Display from

the Georeferencing pulldown menu. Your

traverse jpeg will now fit inside the ArcMap

window.

6. The basic idea for georeferencing is that you are

going to find points on the traverse map that

match points on the HiRISE image. You’ll tell

ArcMap to match those points. Once everything

matches as well as possible, you will tell

ArcMap to write the files that contain the

georeferencing information.

7. From the Georeferencing toolbar, we will Add Control Points (the icon with the two Xs connected with a line). Also, click the View Link Table icon and leave it open.

a. Locate a point that you can see precisely in both the traverse jpeg and your CTX base image. Center the cursor cross exactly on the spot in the Curiosity Location jpeg. Click once. Then locate the same point in the CTX base image and click a second time. The control point will appear in your link table.

b. If you blunder and enter a bad point, go to the table, highlight the offending row, and Delete. If the image disappears, go to the TOC, and right click > Zoom to layer.

c. You will need to

choose several other

control points, and it is

best to spread them out.

You definitely do not

want them to be co-

linear. If things become

screwy, just delete

control points until you get rid of the bad ones.

d. This image georeferences quite nicely, so you should be able to do a good job with about 5 widely spaced control points.

e. Once you are happy with your results, go to the Georeferencing pulldown menu, and select Update Georeferencing. This process adds a World File to the jpeg (it’s one of those auxiliary files that shows up when you look at files such as this in Windows Explorer). As long as this world file stays with the jpeg, the image will be georeferenced, and ArcMap will know where to put it on any map of Mars. Add this georeferenced image to the map if it doesn’t

happen automatically

Part III. Developing slope maps If we make a slope map for the landing area and the lower slopes of Mt. Sharp, we can determine the

slopes that the rover can and cannot drive up or down. This is a critical component of traverse-planning

(although not the only component – the nature of surface materials and potential science targets are also

critical factors!).

A. Make a slope map

1. Make a slope map from your DEM in degrees. Be patient – this is a big DEM, and it might take a bit of time to run (few minutes).

B. Symbolize your slope map

1. Once you’ve symbolized the general data layer, make two more classified layers that show a useful depiction of the following, using the engineering inputs from above:a. A Driveable-Getting risky-Not driveable layer for the rover on sand

b. A Driveable-Getting risky-Not driveable layer for the rover on bare rock

*Use green for driveable, yellow for getting risky (close to not driveable), and red for not

driveable.

Part IV. Plotting a traverse route

1. Look at the map below. Your job is to create a line representing the safest path from the current

location (green dot here, but you can find it on your georeferenced jpg) to the target area (red

box) using the slope maps that you have created. Create your line by making an empty shapefile

and then editing it, like we did when we made polygons in the Bolivia Flood exercise. OR you

can turn on the drawing tools and create a line. When you’re done you can Covert Graphics to

Features and that will create a shapefile.

The final products

Create an ArcMap layout that showcases your safe traverse for Curiosity from its current location to the

target area. Include 2 dataframes with your rover traverse plotted on each – one with a slope map

containing a classified color scheme showing Driveable-Getting risky-Not driveable on sand and one next

to it showing Driveable-Getting risky-Not driveable on rock. Be sure that your maps are cartographically

complete and includes all components of a proper map layout.

Export your two-panel map as a jpeg with a resolution of 150-200 pixels per inch at finished size (e.g., if

the width is 11 inches, you need 11X150 or 1650 pixels in the width box).

Questions to hand in (make sure you include all parts):

1) Describe why you chose the traverse that you did from the rover’s location to the target area (one

thorough paragraph). Justify why this is a safe traverse plan for the rover, discussing the slopes and

amount of sand and rock the rover will be driving across given your assessment of the images, hillshade,

and slope maps.

2) How long do you expect your traverse to take in sols (Mars days)? Use the maximum driving distance

per day (sol) of the rover from the jpg map you georeferenced. Show your work.

3) Your qualitative discussions of a safe route will only be somewhat convincing to the engineers driving

the 2.5 billion dollar rover. They will want a more quantitative assessment! The best way to convince them

that your traverse options are safe would be to create a10-m-wide path around your traverse line and then

assess the slopes within that area. So crack to it! What is the min, mean, maximum and standard deviation

along the rover traverse, including within the 5 m on each side of your line? Report these values in a table.

Write an explanation of the work flow you used to determine these values. Finally, discuss the safety of

your traverse in light of this new buffered data.