urn:nasa:pds:clementine1_bistatic:img:66596dpr 1.0 1.21.0.0 Product_Observational 2000 This file contains a digital map of one of several quantities used in calculating observational geometry or parameters during the Clementine bistatic radar experiment. The southern hemisphere of the Moon was projected onto a plane tangent to the lunar surface at the South Pole. A 700x700 grid in the plane sampled the (orthographic) projection and allowed evaluation of incidence angles, Doppler frequency, incremental radar cross section, etc. These results, in turn, could be used to derive other quantities -- such as predicted spectra for given scattering functions -- and their variations with time. A rectangular coordinate system is defined in the plane; the South Pole is the origin. The x- and y-axes are the same as for the lunar fixed-body rotating coordinate system as defined by the Navigation and Ancillary Information Facility (NAIF). The x-axis is toward Earth; the y-axis is toward the east limb. Grid points are spaced by 5 km in both directions. The Pole at (0.,0.) is at the center of the grid, but equidistant from four grid points rather than being at a grid point itself. Quantities are evaluated at surface points which satisfy Rp*Rp - x*x - y*y > 0 where Rp = 1737.4 km is the adopted lunar radius. Values at points which do not meet this criterion are unpredictable (usually, but not always, large negative numbers). The VAL grid (see below) may be used as a mask for valid points. The map consists of 700 rows of signed 16-bit integers. The first row in the file is the row closest to Earth (most positive x); the first integer in each row corresponds to the westernmost grid point (most negative y). The 16-bit integers should have SCALING_FACTOR and OFFSET applied (see below) to recover true values. File names of the form sssssppp.IMG give the time and parameter in the map, where sssss is the time in seconds UT from 0h at the receiving station on 1994-04-09 and ppp is defined in the table below. For example, file 67596BET.IMG gives the bistatic angle at 18:46:36 Earth Receive Time (ERT) on 1994-04-09. ppp Parameter Definition for the Surface Point Associated with (x,y) --- ---------------------------------------------------------------- BET bistatic angle (degrees) DAR area (square meters) DBR offset from boresight at the (DSN) receiving antenna (degrees) DPR incremental received power (watts) from the surface element FQZ Doppler frequency relative to the South Pole (Hz) GAM tilt of the surface element (degrees) GRX receiving antenna gain at the surface element (dB) GTX spacecraft transmitting antenna gain at the surface element (dB) RRX distance from the receiving antenna (meters) RTX distance from the spacecraft transmitting antenna (meters) SBR offset from boresight at the spacecraft antenna (degrees) SG0 assumed specific radar cross section for calculating DPR THI incidence angle at the surface element (degrees) THS scattering angle at the surface element (degrees) VAL validity mask (1 = grid point within lunar disk; 0 = outside) DFQ time derivative of FQZ (Hz/sec) The VAL grid may be used to separate valid points on the lunar disk from points outside. VAL grid values equal to 1 correspond to valid surface points; VAL grid values of 0 denote points outside. Note that the VAL grid does NOT indicate whether points are mutually visible from receiver and transmitter; for this, the user can define a separate mask based on THI and THS. The assumed scattering function (SG0) was set to unity everywhere for these calculations; the user can construct a predicted echo spectrum for such a surface by summing echo contributions (DPR) after sorting by Doppler (FQZ). The time derivative of Doppler at time t0 (DFQ) is obtained by differencing FQZ grids at t0+100 and t0-100; there is no DFQ grid at the first (65696 s) and last (71496 s) times. More details can be found in Simpson and Tyler, Reanalysis of Clementine bistatic radar data from the lunar South Pole, Journal of Geophysical Research, 104, 3845-3862, 1999. Geometry was reconstructed using spacecraft ephemerides computed at Goddard Spaceflight Center; the geometry is summarized in file BSRGEOM.TAB elsewhere in this archive. 2024-04-23 1.0 Product migrated to PDS4 from PDS3. 1994-04-09T18:29:56Z 1994-04-09T18:29:56Z Deep Space Program Science Experiment Mission urn:nasa:pds:context:investigation:mission.deep_space_program_science_experiment data_to_investigation Clementine 1 Clementine 1 Host urn:nasa:pds:context:instrument_host:spacecraft.clem1 is_instrument_host Radio Science Subsystem Instrument urn:nasa:pds:context:instrument:clem1.rss is_instrument Moon Satellite urn:nasa:pds:context:target:satellite.earth.moon data_to_target image processing_information_to_data_object BSRGRID 1998-02-16 image display_settings_to_array Sample Left to Right Line Top to Bottom image cartography_parameters_to_image_object -180 180 0 -90 Orthographic 0 -90 Coordinate Pair 5000 5000 6.0646700848298964 6.0646700848298964 -1750000 1750000 Planetocentric Moon (2015) - Sphere 1737400 1737400 1737400 Positive East 66596dpr.img 1998-03-21T00:00:00 The Digital Map contains values of parameters calculated in conjunction with analysis of Clementine bistatic radar data. True values may be obtained by multiplying the sample in the map by SCALING_FACTOR and then adding OFFSET. image 0 2 Last Index Fastest SignedMSB2 1e-22 0.0 Line 700 1 Sample 700 2 66596dpr.lbl 0 PDS3 Original PDS3 label Carriage-Return Line-Feed