/* MSIEROS.TXT /* /* This file contains information from the original, submitted data set /* catalog file for the MSI optical shape models of 433 Eros. /* MSI Optical Shape Models of 433 Eros Produced by B. Carcich NEAR DATA_SET_ID: "NEAR-A-MSI-5-EROS-SHAPE-MODELS-V1.0" The files present shape models of the surface of 433 Eros in varying resolutions, including an alternative format. All models are based on the 2001012 base model solution. The full, original data set description follows. This description has been edited to contain the present names of the files and for changes made since the original delivery: Data Set Overview ================= This data set contains the Peter Thomas shape model for asteroid 433 Eros, based on optical data from the NEAR MSI instrument. The current version of this data set contains the following shape model files and PRODUCT_ID's eros001708.tab EROS001708 eros007790.tab EROS007790 eros010152.tab EROS010152 eros022540.tab EROS022540 eros088398.tab EROS088398 eros200700.tab EROS200700 erosrgst.tab EROSRGST Each shape model file also has a detached label file, with a suffix of .lbl, which describes the respective formats. The first six files are in a plate model format and only represent the model shape. The last file is in a modified Peter Thomas RGST model format and includes shape, gravity, slope and topographic information. N.B.: In the EROSRGST product, some radii starting from the model center intersect the surface in more than one point. This happens mostly around 160 degrees west longitude. That means that the RGST format used in that product is not able to adequately represent the shape model's surface. Caveat emptor. If this is an issue, users may use one of the plate models. All files represent the same Eros shape model (2001012) only the resolution and format changes between files. Parameters ========== A single data table contains both the cartesian coordinates of the vertices and the list of vertices defining triangular facets. Details of mapping and production of the model are given in the Processing section below, and further details are given in the relevant published paper. [THOMASETAL2002]. Processing ========== Shape model derived via stereogrammetry of 1,888 NEAR MSI images. The model is based on 31,532 observations of 6,328 control points. The actual plate models have triangular plates, with vertices interpolated from the control points. To transform the set of individual coordinates of control points into these plate model files, we make use of software internally called 'WaG,' currently being developed by Applied Research Associates NZ Limited. Coordinate System ================= The 433 Eros body-fixed planetocentric coordinate system is defined as follows: North Spin Pole with respect to the J2000 reference frame: RA = 11.350 Dec = 17.216, +/- 0.02 degrees Prime Meridian: W = 326.027 + 1639.38864745 d, degrees (d in days after the J2000 epoch, JD 2451545.0) The body-fixed ``Planetocentric'' coordinate system referred to here is defined for solar system bodies as follows: -- The x-axis of the Planetocentric coordinate system for a specified body lies both in the body's equatorial plane and in the plane containing the body's prime meridian. -- The z-axis is parallel to the body's mean axis of rotation and points North of the invariable plane of the solar system (regardless of the body's spin direction). The north pole is this pole of rotation. -- The y-axis is defined as the cross product of the z and x axes, in that order. Thus, the frame is right-handed. The above definition implies that the axes of a planetocentric system are time-varying. Thus a complete specification of the axes requires identification of an epoch as well as the body. This frame is relative to J2000. Software ======== The plate model format is compatible with software developed at Cornell. The two packages are POINTS, written by Jonathan Joseph, which is used to collect and solve for the control points that are the basis for the shape model, and ORBIT, written by Brian Carcich, which used the model to aid science planners when they created the sequences of images during the NEAR mission. None of these software packages will be archived with these shape models. Media/Format ============ These data are included as part of the NEAR mission archive, and are also available for Internet download. Confidence Level Overview ========================= The center of figure is within 50 m of the center of mass provided by the NEAR Navigation team at JPL. The control point RMS error is less than 10 m. The error at any point on the surface is typically less than 50 m. Reference: Thomas, P.C., J. Joseph, B. Carcich, J. Ververka, B.E. Clark, J.F. Bell, A.W.Byrd, R. Chomko, M. Robinson, S. Murchie, L. Prockter, A. Cheng, N. Izenberg, M. Malin, C. Chapman, L.A. McFadden, R. Kirk, M. Gaffey, P.G. Lucey, 2002. Eros: Shape, Topography and Slope Processes, Icarus, V. 155, 18-37.