Rocky 7 - Mojave Desert Field Experiments March 1997 Helicopter Flights Science Plan

MISSION SCENARIO

The helicopter hovered over four proposed Rocky 7 waypoints (designated A, B, C, and D) and acquired images at altitudes of 10,600 ft, 5,472 ft, 2,828 ft, 1,542 ft, 650 ft, 269 ft, 144 ft, 62 ft, and 23 ft above ground level (AGL). These images simulate the type of data to be acquired by the MARDI descent imaging system that is part of the Mars Surveyor Program 98 Lander mission. Note that MARDI calls for images at 11,050 ft and 22146 ft AGL as well; however, the helicopter could only achieve a maximum altitude of 10,600 ft AGL, so images were acquired at that height in lieu of these higher altitudes. At each waypoint, two targets measuring 3 meters by 3 meters were positioned on the ground before the images were taken. These targets are aligned with true north. At waypoints A and D the targets are white and at waypoints B and C they are black.

Figures 1 and 2 below show sites for acquisition of descent data as camera waypoints (marked as rectangles on the image) and proposed traverse lines and waypoints. These are superimposed on a Landsat false color TM mosaic (bands 2,4,7 as blue, green, and red). The mosaic has 25 m pixels, good to 50 m lateral location. Thus, for the Rocky 7 site, there are four areas for which simulated descent images were acquired: one on the basalt (at the rover's starting position for the 1 km traverse), two on the playa, and one on a felsic alluvial fan (at the rover's finish point for the 1 km traverse). Center latitude and longitude locations for the boxes are given in Table 1 below.

After the helicopter images were taken they were processed at the Remote Sensing Laboratory at Washington University. Using the PCI image processing program, the helicopter images were first corrected for geometric distortions due to the camera's orientation, position, and altitude. This process is called orthorectification. The orthorectified images were then georeferenced (each pixel in the image was tied to a latitude and longitude coordinate). The images were georeferenced to a UTM 11 S projection appropriate for the California area. Now coordinates and distances for any positions on the images could be obtained. Some of these processed images were also converted to digital maps.

TABLE 1

Latitute-longitude locations for Rocky 7 waypoints for May 1997 tests shown in tabular form.

FIGURES

The figures below are Landsat Thematic Mapper (TM) composite images, in which TM bands 2, 4 and 7 are assigned to the blue, green, and red channels. Click on the images to see them in full resolution.

Figure 1 (109 KB JPEG). Broader view of the Pisgah volcanic field and Lavic Lake area. The proposed Rocky 7 traverse at the southern side of Lavic Lake is shown in red. The pixel size is 25 m, and a geographic lat/lon cylindrical projection is used with the local datum set to the North American Datum of 1927 for California. North is at the top of the image, and the latitude and longitude of the NW corner of the image is 34deg 49' 53.58" N, 116deg 37' 24.26" W; of the NE corner is 34deg 49' 53.58" N, 116deg 14' 35.87" W; of the SE corner is 34deg 38' 04.68" N, 116deg 14' 35.87" W; and of the SW corner is 34deg 38' 04.68" N, 116deg 37' 24.26" W. The image is 34 km across in the east/west direction and 22 km across in the north/south direction.

Figure 2 (22 KB JPEG). Proposed route for Rocky 7 during the May field test superimposed on a Landsat Thematic Mapper color composite image (bands 2, 4, and 7 correspond to blue, green, and red). The rover will start on the basalt flow at the bottom of the image, travel down onto the playa, and end up on the alluvial fan near the top of the image. This image is approximately 4 km across. Boxes A through D represent sites for which simulated descent imaging will be acquired.