Data Set Information
DATA_SET_NAME ASTEROID (101955) BENNU SHAPE MODEL V1.0
DATA_SET_ID EAR-A-I0037-5-BENNUSHAPE-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : Asteroid (101955) Bennu was discovered in September 1999 by the LINEAR survey and designated 1999 RQ36. It is an Apollo Near-Earth Object (NEO) with a semi-major axis of 1.126 AU, an eccentricity of 0.205 and an orbital inclination of 6 degrees. Bennu has a mean diameter of 492 meters (uncertainty: 20 meters) and a sidereal rotation period of 4.29746 hours (uncertainty: 0.002 hours). Bennu is a B-type asteroid characterized by a linear, featureless spectrum with bluish to neutral slope at visible wavelengths. Spectral analysis suggests that the most likely meteorite analogs for Bennu are the CI or CM meteorites (Clark et al., 2011). This shape model of asteroid (101955) Bennu was created by Nolan et al. (2013) based on radar and optical photometric observations made in 1999 and 2005. The model resolution is approximately 25 meters between vertices, with regions of higher resolution around the location of a topographical 'boulder' and the symmetric region in the opposite hemisphere. The model has the format v x1 y1 z1 v x2 y2 z2 v x3 y3 z3 (etc.) f i1 j1 k1 f i2 j2 k2 (etc.) where the letter 'v' denotes a vertex and the letter 'f' denotes a triangular facet. The VERTEX_TABLE is the first part, describing the positions of the vertices of the shape model. The floating point numbers x1 y1 z1 are the coordinates of vertex 1, and so on (vertices are implicitly numbered beginning with 1). The origin is the center of mass, and the axes are the principal axes of the shape model. The z-axis is the spin axis or positive pole. The units are kilometers. The linking of vertices into facets is provided in the FACET_TABLE. The Asteroid (101955) Bennu Shape Model - 101955bennu.tab - file is equivalent to the wavefront or .obj format. The file can be opened by software such as Blender, MATLAB, JSC3D, or CAD programs, and can read directly by most 3D printing services. A variety of free .obj viewers are available for download online. Multi-axis views of the model - bennu-model.pdf - is a .pdf of views of the asteroid along its principal axes. The Pole Orientation - pole.tab - file contains the pole latitude, longitude, and uncertainty in degrees. The Rotation State - rotate.tab - file contains the rotation rate and uncertainty in hours. Nolan, M.C., C. Magri, E.S. Howell, L.A.M. Benner, J.D. Giorgini, and 6 others, Shape Model and Surface Properties of the OSIRIS-REx Target Asteroid (101955) Bennu from Radar and Lightcurve Observations, Icarus 226, 629-640, doi:10.1016/j.icarus.2013.05.028, 2013. [NOLANETAL2013] Clark, B.E., R.P. Binzel, E.S. Howell, E.A. Cloutis, M. Ockert-Bell, and 2 others, Asteroid (101955) 1999 RQ36: Spectroscopy from 0.4 to 2.4 um and meteorite analogs, Icarus 216(2), 462-475, doi:10.1016/j.icarus.2011.08.021, 2011. [CLARKETAL2011B] Hergenrother, C.W., M.C. Nolan, R.P. Binzel, E.A. Cloutis, M.A. Barucci, and 11 others. Lightcurve, Phase and Color Photometry of the OSIRIS-REx Target Asteroid (101955) Bennu. Icarus, 226, 663-670, doi:10.1016/j.icarus.2013.05.044, 2013.[HERGENROTHERETAL2013] Krugly, Yu.N., I.N. Belskaya, V.G. Shevchenko, V.G. Chiorny, F.P. Velichko, and 7 others, The near-Earth objects follow-up program: IV. CCD photometry in 1996-1999, Icarus 158, 294-304, doi:10.1006/icar.2002.6884, 1999. [KRUGLYETAL1999]
DATA_SET_RELEASE_DATE 2013-06-14T00:00:00.000Z
START_TIME 1999-09-21T12:00:00.000Z
STOP_TIME 2005-10-02T12:00:00.000Z
MISSION_NAME SUPPORT ARCHIVES
MISSION_START_DATE 2004-03-22T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME 101955 BENNU
TARGET_TYPE ASTEROID
INSTRUMENT_HOST_ID OBS240T1
OBS338T6
INSTRUMENT_NAME ARECIBO 2380 MHZ RADAR RECEIVER
ARECIBO PLANETARY RADAR TRANSMITTER
GOLDSTONE SOLAR SYSTEM RADAR RECEIVER
GOLDSTONE SOLAR SYSTEM RADAR TRANSMITTER
INSTRUMENT_ID I0037
I0038
I1833
I1834
INSTRUMENT_TYPE RADAR RECEIVER
RADAR TRANSMITTER
NODE_NAME Small Bodies
ARCHIVE_STATUS LOCALLY_ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : There exists some north-south symmetry in surface features of Benu. Because of the nearly-equatorial viewing geometry, this is an artifact of the radar data, and the varying degree of symmetry in different parts of the object may result from variable rotational coverage. As the asteroid rotates, the points on the equator move across the radar images, but points at the rotation pole remain motionless (Green, 1968). As a result, the Z dimension of the asteroid is less well determined than the X- and Y-dimensions: 'squeezing' the model in the Z direction does not change the radar images much. This coordinate system should not be used to define a cartographic system, as the principal axes are not uniquely determined due to the symmetry of the shape in terms of longitude. Uncertainties reported are 1-sigma, but for the shape parameters are conservative and somewhat subjective. Formal errors in the X- and Y- directions are of 10 meters, and in the Z-axis, 52 meters.
CITATION_DESCRIPTION Nolan, M.C., Magri, C., Howell, E.S., Benner, L.A.M., Giorgini, J.D., Hergenrother, C.W., Hudson, R.S., Lauretta, D.S., Margot, J.L., Ostro, S.J., and Scheeres, D.J., Asteroid (101955) Bennu Shape Model V1.0. EAR-A-I0037-5-BENNUSHAPE-V1.0. NASA Planetary Data System, 2013.
ABSTRACT_TEXT We present the three-dimensional shape of near-Earth asteroid (101955) Bennu (provisional designation 1999 RQ36) based on radar images and optical lightcurves (Nolan et al., 2013). Bennu was observed both in 1999 at its discovery apparition, and in 2005 using the 12.6-cm radar at the Arecibo Observatory and the 3.5-cm radar at the Goldstone tracking station. Data obtained in both apparitions were used to construct a shape model of this object. Observations were also obtained at many other wavelengths to characterize this object, some of which were used to further constrain the shape modeling (Clark et al., 2011; Hergenrother et al., 2013; Krugly et al., 1999).
PRODUCER_FULL_NAME ALESSONDRA SPRINGMANN
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