Exercise 14 Mars Rover Planning

Transcription

1 Exercise 14 Mars Rover Planning Due: Thursday, March 15 at the start of class Data sets 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 current rover location: 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, 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. Part II. Engineering constraints 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.

2 These were presented at the 5 th 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.

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

4 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 s location at a certain point in the mission (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.

5 7. Click on the View Link Table icon in the Georeferencing toolbar, and then click on the Add Control Points icon (the one with the two Xs connected with a line). 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 colinear. 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. 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. 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, 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.

6 Part V. How does your route compare? 1. The image we used in today s lab was taken on Sol 1487 (or, October 2016). Since then, the rover has driven further upslope towards our target area. The following website will show you what Sol the mission is currently on: At the top, you should see the most up to date map of where the rover has driven during the mission (note: the rover location is only updated on the last Sol that it actually moved). Download the image to your data file that contains the complete traverse from Curiosity s initial landing site and add it to your map. You will once again have to georectify this image to your map as we already did in Part II.

7 The final products Map 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 pixels per inch at finished size (e.g., if the width is 11 inches, you need 11X150 or 1650 pixels in the width box). Take a screenshot of your route up Mt. Sharp overlain on top of the image of Curiosity s current location. Now, answer the following questions (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 first jpg map you georeferenced. Pay attention to what Sol each waypoint is marked at when determining this. 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 area 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. 4) Finally, list the current mission Sol and describe qualitatively how well your traverse lines up with the route that Curiosity has taken to date. What is the maximum distance between your two paths (for this measurement, only consider roughly equivalent upslope distances)? What are two factors (science or engineering related) that may influence decisions that the Curiosity mission team made when choosing their traverse?