Description of the detailed plate model of the surface of Comet Wild 2 This data set presents the plate model of comet 81P/Wild 2, as derived from the Stardust Navigation camera images that were obtained around the time of closest approach to the comet. It was derived from the same set of images and same basic procedures described in the triaxial ellipsoid model and the general information about that model is the same for this plate model, with the exceptions and additions described here. The details of the modeling are described in Kirk et al., 36th Annual Lunar and Planetary Science Conference, March 14-18, 2005, #2244 (2005) [KIRKETAL2005]. Included here is a brief review of the model and the procedures that were used to create it. Some of the values that are presented here differ from the Kirk et al. results, and these are due to additional analysis that took place after that document was published. A detailed plate model was derived from two stereo pairs of images obtained near closest approach, with views of both the 'top' and 'underside' of the nucleus. Up to 20 other images were used to supplement the model for additional coverage and accuracy. The resulting model consists of 6432 points that are used to produce a plate model with 12514 plates. About 50% of the total surface was illuminated and observed during the encounter. The horizontal resolution is expected to be about 100 meters and the vertical precision is about 6 meters. Figure PLATE_FIGURE1 shows the topography of the nucleus, based on the shape model, as viewed from along the prinipal axes of the best-fitting triaxial ellipsoid. The original cartesian coordinate system (X', Y', Z') used for mapping was defined such that the +X' direction lay parallel to the direction of the spacecraft's motion relative to the nucleus, the +Z' axis was the vector from the spacecraft to the nucleus at closest approach, and the +Y' axis completed system by the right hand rule. USGS software, combined with the BAE SOCET SET software, was used to compute the coordinates of each pixel in these coordinates, producing the grid of points that represent the visible surface. A best-fitting triaxial ellipsoid was fit to these points using a least squares fit. (Note that this best-fitting ellipsoid differs from the ellipsoid shape model, which was simply the envelope that contained the visible surface of the nucleus.) This ellipsoid has the dimensions of 1.350 x 2.002 x 2.607 km. Elevations relative to this best-fitting ellipsoid range from -600 m to +250 m, with an RMS range of heights of 93 m. The orientation of the minor axis (positive pole) of this ellipsoid is at a right ascension of 112 degrees and a declination of -17 degrees (J2000.0). Ultimately, each of the surface points was translated and rotated to a body-centered coordinate system, with the X, Y and Z axes along the long, middle and short axes of the best-fitting ellipsoid. The body-centered coordinates are used in this data set. The following excerpt is a description of the additional analysis that took place after the LPSC abstract was published. It was written by Randall Kirk, and lists the last few steps that resulted in the final version of the model archived here. As described in our LPSC abstract, we initially set up our Cartesian system tied to the Stardust trajectory and closest approach. We found we had to collect most of the points, which were on the 'top' surface of the body in this system, in one set, and additional points at overlapping XY but different Z in separate models. These sets of points could then be merged for the Excel analysis. What we did in February-March was to set up two auxiliary coordinate systems, rotated 45 toward the inbound and outbound part of the trajectory, respectively. Working in these auxiliary coordinate systems (especially the one favoring the inbound hemisphere, which was where the 'underside' points were located) allowed us to characterize parts of the surface much better. We also used additional images to improve our view of various areas. We spent a considerable amount of time trying to stretch the images to see if we could measure surface features in shadows by light reflected from the coma or nearby nucleus points, but this was not feasible. The net result was to increase the total number of points from 5576 to 6932. The final step, done today, was to plug the resulting point set back into the Excel spreadsheet for analysis and final output. Two of the rotation angles changed by a degree (I did not adjust them more closely than the nearest degree to best fit) and the semiaxes changed by 10 to 25 m, for an overall volume decrease of the ellipsoid of roughly 2%. The range of relief was increased, with the lowest reported point now ~600 m below the ellipsoid versus ~400 m previously, but the RMS range of heights only increased slightly, from 86 to 93 m. While evaluating the plate model data set for ingestion into the PDS, a number of redundant grid points were found that apparently arose at seams where segments from different images were joined together. These redundant points were removed from the data set, reducing the total number of points to 6432. Three additional supplementary versions of the plate model are also included in the dataset. First, the XYZ coordinates, combined with the best-fitting ellipsoid, were used to produce a version of the model in latitude/longitude/elevation coordinates (planetocentric). In these first two versions, the non-visible portions of the nucleus are not represented in the model. The third and fourth versions of the model are simply copies of the Cartesian and lat/long/elevation versions, but they add a representation of the full nucleus. For regions of the nucleus that were not visible during the encounter, the best-fitting ellipsoid is used. The images used to derive this shape model are archived at the PDS Small Bodies Node, in the data set SDU-C-NAVCAM-2-EDR-WILD2-V1.0.