KPL/FK SMAP Spacecraft Frame Definitions Kernel ============================================================================== This frame kernel contains the SMAP spacecraft, and science instrument definitions. Version and Date ---------------------------------------------------------- The TEXT_KERNEL_ID stores version information of loaded project text kernels. Each entry associated with the keyword is a string that consists of four parts: the kernel name, version, entry date, and type. For example, the SMAP Frame-kernel might have an entry as follows: TEXT_KERNEL_ID += 'SMAP_FRAMES V0.0.1 29-SEPTEMBER-2010 FK' | | | | | | | | KERNEL NAME <-------+ | | | | | V VERSION <-------+ | KERNEL TYPE | V ENTRY DATE SMAP Frame Kernel Version: \begindata TEXT_KERNEL_ID += 'SMAP_FRAMES V1.2 12-FEB-2014 FK' \begintext Version 1.2 -- February 12, 2014 -- Boris Semenov - added name/ID mappings for TDRS spacecraft Version 1.1 -- August 28, 2013 -- Boris Semenov - added RTN frame Version 1.0 -- August 27, 2013 -- Boris Semenov - added frames for engineering low-gain antennas Version 0.9 -- July 30, 2013 -- Vance Haemmerle - made frame SMAP_INSF use angles instead of matrix, for easier use of small offsets Version 0.8 -- May 23, 2013 -- Boris Semenov - fixed SRF frame name (SMAP_SCF->SMAP_SRF); - redefined ANT_ZERO and ANT_BIC to be consistent with the ANT_BEAM frame in the zero and BIC positions; - removed comments related to direct CK-based connection between the s/c and the antenna beam frames; - changed RELATIVE frame for SMAP_SWATH (ITRF93->J2000); - deleted name/ID mappings for SMAP_SRF/-205001 and SMAP_SWATH/-205002 (SMAP_SRF and SMAP_SWATH are dynamic frames and as such don't need to have physical object name/ID pairs associated with them) - edited comments (indentation/wrapping, removed TABs, added diagrams, etc.); Version 0.7 -- March 15, 2012 -- Vance Haemmerle -- Add NAIF body codes for frames Version 0.6 -- October 20, 2010 -- Vance Haemmerle -- Fix Antenna beam frames Version 0.5 -- October 17, 2010 -- Vance Haemmerle -- Remove LT+S correction from Dynamic frames due to LT being from Earth center Version 0.4 -- October 13, 2010 -- Vance Haemmerle -- Add Dynamic swath frame (Earth-prime) Version 0.3 -- September 2, 2010 -- Vance Haemmerle -- Fix SRF frame. Version 0.2 -- August 24, 2010 -- Vance Haemmerle -- Dynamic SRF frame, ANT_ZERO, ANT_BIC. Version 0.1 -- July 20, 2010 -- Vance Haemmerle -- Different definitions according to May 2010 PPPCS. Version 0.0.2 -- July 7, 2010 -- Vance Haemmerle -- INF, INR, SRF, ANT_ZERO and ANT_BEAM frames. Version 0.0.1 -- Jun 29, 2010 -- Vance Haemmerle -- Initial Release, just spacecraft frame. References ---------------------------------------------------------- 1. ``C-kernel Required Reading'' 2. ``Kernel Pool Required Reading'' 3. ``Frames Required Reading'' 4. SMAP Pointing, Positioning, Phasing & Coordinate Systems, Volume 0, May 18, 2010 5. E-mail from Chi-Wung Lau regarding LGA mounting, 08/16/13 6. SMAP MPF SIS, section 2.10.2, October 10, 2012 Contact Information ---------------------------------------------------------- Direct questions, comments, or concerns about the contents of this kernel to: Vance Haemmerle, SMAP/JPL, (818)-393-0691, Vance.R.Haemmerle@jpl.nasa.gov Boris Semenov, NAIF/JPL, (818)-354-8136, Boris.Semenov@jpl.nasa.gov Implementation Notes ---------------------------------------------------------- This file is used by the SPICE system as follows: programs that make use of this frame kernel must `load' the kernel, normally during program initialization. The SPICELIB routine FURNSH loads a kernel file as shown below (see [2]): FORTRAN: (SPICELIB) CALL FURNSH ( frame_kernel_name ) C: (CSPICE) furnsh_c ( frame_kernel_name ); IDL: (Icy) cspice_furnsh, frame_kernel_name MATLAB: (Mice) cspice_furnsh( frame_kernel_name ) This file was created and may be updated with a text editor or word processor. SMAP NAIF ID Codes -- Definitions ---------------------------------------------------------- This section contains name to NAIF ID mappings for the SMAP spacecraft and instruments and TDRS spacecraft. Once the contents of this file is loaded into the KERNEL POOL, these mappings become available within SPICE, making it possible to use names instead of ID codes in the high level SPICE routine calls. \begindata NAIF_BODY_NAME += ( 'SOIL MOISTURE ACTIVE AND PASSIVE' ) NAIF_BODY_CODE += ( -205 ) NAIF_BODY_NAME += ( 'SMAP' ) NAIF_BODY_CODE += ( -205 ) NAIF_BODY_NAME += ( 'SMAP_SC' ) NAIF_BODY_CODE += ( -205000 ) NAIF_BODY_NAME += ( 'SMAP_INSF' ) NAIF_BODY_CODE += ( -205101 ) NAIF_BODY_NAME += ( 'SMAP_INSR' ) NAIF_BODY_CODE += ( -205102 ) NAIF_BODY_NAME += ( 'SMAP_ANT_BEAM' ) NAIF_BODY_CODE += ( -205201 ) NAIF_BODY_NAME += ( 'SMAP_ANT_ZERO' ) NAIF_BODY_CODE += ( -205202 ) NAIF_BODY_NAME += ( 'SMAP_ANT_BIC' ) NAIF_BODY_CODE += ( -205203 ) NAIF_BODY_NAME += ( 'SMAP_SLGA' ) NAIF_BODY_CODE += ( -205301 ) NAIF_BODY_NAME += ( 'SMAP_XLGA' ) NAIF_BODY_CODE += ( -205302 ) NAIF_BODY_NAME += ( 'TDR3' ) NAIF_BODY_CODE += ( -124 ) NAIF_BODY_NAME += ( 'TDR5' ) NAIF_BODY_CODE += ( -132 ) NAIF_BODY_NAME += ( 'TDR6' ) NAIF_BODY_CODE += ( -136 ) NAIF_BODY_NAME += ( 'TDR7' ) NAIF_BODY_CODE += ( -137 ) NAIF_BODY_NAME += ( 'TDR8' ) NAIF_BODY_CODE += ( -138 ) NAIF_BODY_NAME += ( 'TDR9' ) NAIF_BODY_CODE += ( -139 ) NAIF_BODY_NAME += ( 'TDR10' ) NAIF_BODY_CODE += ( -141 ) NAIF_BODY_NAME += ( 'TDR11' ) NAIF_BODY_CODE += ( -220 ) NAIF_BODY_NAME += ( 'TDR12' ) NAIF_BODY_CODE += ( -221 ) NAIF_BODY_NAME += ( 'TDR13' ) NAIF_BODY_CODE += ( -222 ) \begintext SMAP Frames ---------------------------------------------------------- The following SMAP frames are defined in this kernel file: Frame Name Relative To Type Frame ID ======================= =================== ======= ======== Spacecraft Body Frame: ---------------------- SMAP_SC J2000 CK -205000 Nominal Pointing Frames: ------------------------ SMAP_SRF J2000 DYNAMIC -205001 SMAP_SWATH J2000 DYNAMIC -205002 SMAP_RTN J2000 DYNAMIC -205003 Instrument Frames (-2051xx): ------------------------ SMAP_INSF SMAP_SC FIXED -205101 SMAP_INSR SMAP_INSF CK -205102 Science Antenna Frames (-2052xx): --------------------------------- SMAP_ANT_BEAM SMAP_INSR FIXED -205201 SMAP_ANT_ZERO SMAP_INSF FIXED -205202 SMAP_ANT_BIC SMAP_INSF FIXED -205203 Engineering Antenna Frames (-2053xx): ------------------------------------- SMAP_SLGA SMAP_SC FIXED -205301 SMAP_XLGA SMAP_SC FIXED -205302 SMAP Frames Hierarchy ---------------------------------------------------------- The diagram below shows the SMAP frames hierarchy: 'ITRF93' (EARTH BODY FIXED) | | <--- pck | 'J2000' INERTIAL__________________________________ | | | | | | <--- dynamic | <--- dynamic | <--- dynamic | | | | | 'SMAP_SRF' 'SMAP_SWATH' 'SMAP_RTN' | | <--- ck | 'SMAP_SC'________________________ | | | | | <--- fixed | <--- fixed | | | | 'SMAP_SLGA' 'SMAP_XLGA' | | <--- fixed | 'SMAP_INSF'_________________ | | | | | <--- fixed | <--- fixed | | | | 'SMAP_ANT_ZERO' 'SMAP_ANT_BIC' | | <--- ck | 'SMAP_INSR' | | <--- fixed | 'SMAP_ANT_BEAM' Spacecraft Frame (SMAP_SC) ---------------------------------------------------------- The SMAP spacecraft (SMAP_SC) frame is defined in [4] as follows: ``1) The SC coordinate system is Cartesian and right handed with its three axes mutually orthogonal. 3) The SC X-Y plane is at the interface between the spacecraft Launch Vehicle Adaptor (LVA). 5) The SC Z-Axis is normal to the X and Y axes directed from the LVA toward the instrument and is nominally parallel to the launch vehicle centerline. 6) The +Xsc axis is directed from the center of the bus toward the stowed reflector side of the bus (it notionally points along the velocity vector during nominal science operations mode) 7) The +Ysc axis is directed from the center of the bus toward the solar array side of the bus (it notionally points in the general direction of the sun) 8) The -Zsc axis notionally points in the direction of geodetic nadir during normal science operations mode'' This diagram illustrates the SMAP_SC frame: .-'\ .-' \ Spun Antenna .-' .-' .-' .-' .-' .-' .-' .-' .-' .-' \ .-' \.-' \ \ \ \ \ \ \ \ -. ______ | \ / __|__\ / _|_____||| ------| |------ SMAP Spacecraft / | | | | \ / | | | | \ -----> / | |+Zsc | | \ Velocity | | | ^ | | | | | | | | | | |_______ |_| | |_| _______| | | `----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | Ysc points into Nadir | the screen or page. V Because the spacecraft bus attitude with respect to an inertial frame is provided by a C kernel (see [1] for more information), the SMAP_SC frame is defined as a CK-based frame. \begindata FRAME_SMAP_SC = -205000 FRAME_-205000_NAME = 'SMAP_SC' FRAME_-205000_CLASS = 3 FRAME_-205000_CLASS_ID = -205000 FRAME_-205000_CENTER = -205 CK_-205000_SCLK = -205 CK_-205000_SPK = -205 \begintext Science Orbit Reference Frame (SMAP_SRF) ---------------------------------------------------------- The Science Orbit Reference Frame (SMAP_SRF) is defined in [4] as follows: ``The SRF is Cartesian and right handed with its three axes mutually orthogonal and is defined such that the origin is at the spacecraft center of mass (CM). The +Z axis points toward Geodetic Nadir. Due to the oblateness of the Earth, the vector from the spacecraft to the geometric center of the Earth (Geocentric Nadir) is different from the vector from the spacecraft to the local WGS84 ellipsoid normal (Geodetic Nadir). The +X axis is coplanar with both the +Z axis and the spacecraft inertial velocity vector (and is in the general direction of the spacecraft inertial velocity vector). The +Y axis completes the right-handed, orthogonal coordinate system (see Figure 7), and is normal to the orbit plane with positive sense in the direction opposite the orbit angular momentum vector (generally in the anti-sun direction).'' In the nominal science operations pointing mode the SMAP_SC frame is rotated 180 degrees about +X from the SMAP_SRF frame as shown on this diagram: .-'\ .-' \ Spun Antenna .-' .-' .-' .-' .-' .-' .-' .-' .-' .-' \ .-' \.-' \ \ \ \ \ \ \ \ -. ______ | \ / __|__\ / _|_____||| ------ |------ SMAP Spacecraft / | +Ysrf / | (cm)-----> +Xsrf -----> / | | \ Velocity | | +Zsc ^ | | | | | | | | | |_______ |+Zsrf v |_| _______| | | ----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | Ysc points into Nadir | the screen or page. V Ysrf points out of the screen or page. The SMAP_SRF frame is defined as a dynamic frame with its +Z axis pointing toward the sub-observer point on Earth, +X axis pointing along the inertial spacecraft velocity. \begindata FRAME_SMAP_SRF = -205001 FRAME_-205001_NAME = 'SMAP_SRF' FRAME_-205001_CLASS = 5 FRAME_-205001_CLASS_ID = -205001 FRAME_-205001_CENTER = -205 FRAME_-205001_RELATIVE = 'J2000' FRAME_-205001_DEF_STYLE = 'PARAMETERIZED' FRAME_-205001_FAMILY = 'TWO-VECTOR' FRAME_-205001_PRI_AXIS = '+Z' FRAME_-205001_PRI_VECTOR_DEF = 'TARGET_NEAR_POINT' FRAME_-205001_PRI_OBSERVER = -205 FRAME_-205001_PRI_TARGET = 399 FRAME_-205001_PRI_ABCORR = 'NONE' FRAME_-205001_SEC_AXIS = '+X' FRAME_-205001_SEC_VECTOR_DEF = 'OBSERVER_TARGET_VELOCITY' FRAME_-205001_SEC_OBSERVER = 'EARTH' FRAME_-205001_SEC_TARGET = -205 FRAME_-205001_SEC_ABCORR = 'NONE' FRAME_-205001_SEC_FRAME = 'J2000' \begintext Science Swath Frame (SMAP_SWATH) ---------------------------------------------------------- In the calculation of an Earth prime coordinate system that allows the spacecraft swath to be more easily approximated, one can define a spheroid Earth prime where the sub-spacecraft swath defines the equator with the same Radius of Curvature at the nadir point in the S/C velocity direction, and a polar dimension with a radius defined by the Radius of Curvature in the direction perpendicular to the velocity direction. This means the -X direction points to the nadir direction and the -Y direction points in the velocity direction. This will mean the sub-sc nadir point has a lat, long of 0, 0. If the sub-sc nadir point would be the prime meridian with the along-track along the Earth equator, then Earth-prime would be the same as Earth. \begindata FRAME_SMAP_SWATH = -205002 FRAME_-205002_NAME = 'SMAP_SWATH' FRAME_-205002_CLASS = 5 FRAME_-205002_CLASS_ID = -205002 FRAME_-205002_CENTER = -205 FRAME_-205002_RELATIVE = 'J2000' FRAME_-205002_DEF_STYLE = 'PARAMETERIZED' FRAME_-205002_FAMILY = 'TWO-VECTOR' FRAME_-205002_PRI_AXIS = '-X' FRAME_-205002_PRI_VECTOR_DEF = 'TARGET_NEAR_POINT' FRAME_-205002_PRI_OBSERVER = -205 FRAME_-205002_PRI_TARGET = 399 FRAME_-205002_PRI_ABCORR = 'NONE' FRAME_-205002_SEC_AXIS = '-Y' FRAME_-205002_SEC_VECTOR_DEF = 'OBSERVER_TARGET_VELOCITY' FRAME_-205002_SEC_OBSERVER = 'EARTH' FRAME_-205002_SEC_TARGET = -205 FRAME_-205002_SEC_ABCORR = 'NONE' FRAME_-205002_SEC_FRAME = 'ITRF93' \begintext Radial-Transverse-Normal frame (SMAP_RTN) ---------------------------------------------------------- The Radial-Transverse-Normal frame (SMAP_RTN) is defined in [6] as follows: ``SMAP defines a radial-transverse-normal (RTN) frame using the following equations. The states vectors are evaluated in Earth Mean Equator of J2000 (EME200) using the SPK file defined in the file. R = p N = R x v T = N x R where: p is the unit vector of the position of SMAP relative to the Earth in EME2000. v is the unit vector of the velocity of SMAP relative to the Earth in EME2000.'' The SMAP_RTN frame is defined below as a dynamic frame with its +X axis (R) pointing along the inertial geometric position vector of SMAP relative to the Earth center and +Y axis (T) pointing in the direction of the inertial geometric velocity vector of SMAP relative to the Earth center. \begindata FRAME_SMAP_RTN = -205003 FRAME_-205003_NAME = 'SMAP_RTN' FRAME_-205003_CLASS = 5 FRAME_-205003_CLASS_ID = -205003 FRAME_-205003_CENTER = -205 FRAME_-205003_RELATIVE = 'J2000' FRAME_-205003_DEF_STYLE = 'PARAMETERIZED' FRAME_-205003_FAMILY = 'TWO-VECTOR' FRAME_-205003_PRI_AXIS = '+X' FRAME_-205003_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-205003_PRI_OBSERVER = 399 FRAME_-205003_PRI_TARGET = -205 FRAME_-205003_PRI_ABCORR = 'NONE' FRAME_-205003_SEC_AXIS = '+Y' FRAME_-205003_SEC_VECTOR_DEF = 'OBSERVER_TARGET_VELOCITY' FRAME_-205003_SEC_OBSERVER = 399 FRAME_-205003_SEC_TARGET = -205 FRAME_-205003_SEC_ABCORR = 'NONE' FRAME_-205003_SEC_FRAME = 'J2000' \begintext Instrument Frame Definitions ---------------------------------------------------------- This section of the frames kernel defines the SMAP instrument frames. Note the angles in the fixed-offset frame definitions are specified for the ``from antenna to (relative to) base frame'' transformation. SMAP Instrument Fixed Frame (SMAP_INSF) As described in [4], the Instrument Fixed frame (SMAP_INSF) has its origin at the intersection of the spin axis and the spacecraft top desk and is nominally co-aligned with the SMAP_SC frame. This diagram illustrates the SMAP_INSF frame: .-'\ .-' \ Spun Antenna .-' .-' .-' .-' .-' .-' .-' .-' .-' .-' \ .-' \.-' \ \ \ \ \ \ +Zinsf \ ^ \ | | | x------> +Xinsf +Yinsf ___ ------ |------ SMAP Spacecraft / | | | | \ / | | | | \ -----> / | |+Zsc | | \ Velocity | | | ^ | | | | | | | | | | |_______ |_| | |_| _______| | | `----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | +Ysc and +Yinsf point into Nadir | the screen or page. V The SMAP_INSF frame is defined as a fixed offset frame relative to the SMAP_SC frame. \begindata FRAME_SMAP_INSF = -205101 FRAME_-205101_NAME = 'SMAP_INSF' FRAME_-205101_CLASS = 4 FRAME_-205101_CLASS_ID = -205101 FRAME_-205101_CENTER = -205 TKFRAME_-205101_SPEC = 'ANGLES' TKFRAME_-205101_RELATIVE = 'SMAP_SC' TKFRAME_-205101_ANGLES = ( 0.0, 0.0, 0.0 ) TKFRAME_-205101_AXES = ( 3, 2, 1 ) TKFRAME_-205101_UNITS = 'DEGREES' \begintext SMAP Instrument Rotating Frame (SMAP_INSR) As described in [4], the Instrument Rotating frame (SMAP_INSR) is a single angle rotation about Zinsf which follows at the same rate as the rotating platform. As the instrument spins, the positive scan/azimuth angle increases. The rotation is in a counter-clockwise direction, meaning a positive rotation angle. The actuator allows the instrument to rotate, so to make proper use of this frame requires a C-kernel (or set of C-kernels) with appropriate coverage for the epochs of interest. From [4], The Beam Scan / Azimuth Angle Theta, is defined as the angle between -Xinsr and +Xinsf. ``Beam Index Crossing (BIC) is defined to occur when -Xinsr = +Yinsf. This also corresponds to an Azimuth angle of 90 deg where an Azimuth of 0 deg is defined as when -Xinsr = +Xinsf = +Xsc.'' - Section 2.7 Since the SMAP_INSR rotates about its Z axis at a design rate of about one revolution per 4 seconds (12.3 to 14.6 rpm), the transformation from fixed instrument frame into the rotating frame follows: INSR [ ] [ Beam azimuth angle + 180 ] [ ] [ ] [ ROT ] = [ or ] [ 0.0 ] [ 0.0 ] [ ] [ 360 * ROT * T(min) + 180 ] [ ] [ ] INSF Z X Z where [x]i represents the rotation matrix of a given angle x about axis i, time T = 0 when Theta = 0, and ROT = rotation rate, 12.3 - 14.6 rpm. The origin of the SMAP_INSR frame is nominally at the intersection of the spin axis and the base plane of the instrument spin platform structure. This diagram shows the SMAP_INSR frame in the zero azimuth position: .-'\ .-' \ Spun Antenna .-' .-' .-' .-' .-' .-' .-' .-' .-' .-' \ .-' \.-' \ \ \ \ \ \ ^ +Zinsr \ ^ +Zinsf \ | | +Xinsr <------o +Yinsr x------> +Xinsf +Yinsf ___ ---- |------ SMAP Spacecraft / | | | | \ / | | | | \ -----> / | |+Zsc | | \ Velocity | | | ^ | | | | | | | | | | |_______ |_| | |_| _______| | | `----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | +Ysc and +Yinsf point into Nadir | the screen or page. V +Yinsr points out of the screen or page. The instrument rotating frame is a defined as a CK-based frame. \begindata FRAME_SMAP_INSR = -205102 FRAME_-205102_NAME = 'SMAP_INSR' FRAME_-205102_CLASS = 3 FRAME_-205102_CLASS_ID = -205102 FRAME_-205102_CENTER = -205 CK_-205102_SCLK = -205 CK_-205102_SPK = -205 \begintext Science Antenna Frame Definitions ---------------------------------------------------------- This section of the frames kernel defines the SMAP spacecraft antenna beam frames. These frames represent the Antenna beam frame in which the beam electrical boresight vector is defined as the +Z axis. The first frame, SMAP_ANT_BEAM, is the generic frame defined as a fixed rotation from the SMAP_INSR frame and as such needs the SMAP_INSF-to-SMAP_INSR C-kernel to be loaded in order to compute its orientation. To connect the SMAP_ANT_BEAM frame with the SMAP_SC frame SPICE follows the frame tree branch including SMAP_INSF-to-SMAP_INSR CKs: SMAP_SC ------- | |<--- fixed (nominally co-aligned) | V SMAP_INSF --------- | |<--- c-kernel | V SMAP_INSR --------- | |<--- fixed | V SMAP_ANT_BEAM ------------- The other two frames, SMAP_ANT_ZERO and SMAP_ANT_BIC, are specific fixed frames when the beam azimuth angle is 0 and 90 degrees respectively. These frames are defined as fixed transformations from the SMAP_INSF frame and do not need the SMAP_INSF-to-SMAP_INSR CKs. SMAP Antenna Beam Frame (SMAP_ANT_BEAM) The antenna beam points nominally along the spacecraft -Zinsr axis, but the XY plane is rotated up and out of the XYinsr plane by 35.5 degrees about the Yinsr axis. For the antenna beam frame, we would like +Z to be the electrical boresight vector. This requires that the +Z axis be rotated 180-35.5 = 144.5 degrees about Y. The rotation matrix that takes vectors represented in the antenna beam frame to the SMAP_INSR frame follows: INSR [ ] [ ] [ ] [ ] [ ROT ] = [ 0.0 ] [ 144.5 deg ] [ 0.0 ] [ ] [ ] [ ] [ ] BEAM Z Y X where [x]i represents the rotation matrix of a given angle x about axis i. This diagram shows the SMAP_ANT_BEAM frame in the zero azimuth position: .-'\ .-' \ Spun Antenna .-' ' .-' .> .-' .-' +Xbeam .-' o-' .-' +Ybeam \ \ .- \ \.-' \ \ v +Zbeam \ \ |<-->\ 35.5 deg \ \ \ ^ +Zinsr \ ^ +Zinsf \ | | +Xinsr <------o +Yinsr x------> +Xinsf +Yinsf ___ ---- |------ SMAP Spacecraft / | | | | \ / | | | | \ -----> / | |+Zsc | | \ Velocity | | | ^ | | | | | | | | | | |_______ |_| | |_| _______| | | `----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | +Ysc and +Yinsf point into Nadir | the screen or page. V +Yinsr and +Ybeam point out of the screen or page. The SMAP_ANT_BEAM frame is defined below as a fixed offset frame relative to the SMAP_INSR frame. \begindata FRAME_SMAP_ANT_BEAM = -205201 FRAME_-205201_NAME = 'SMAP_ANT_BEAM' FRAME_-205201_CLASS = 4 FRAME_-205201_CLASS_ID = -205201 FRAME_-205201_CENTER = -205 TKFRAME_-205201_SPEC = 'ANGLES' TKFRAME_-205201_RELATIVE = 'SMAP_INSR' TKFRAME_-205201_ANGLES = ( 0.0, 144.5, 0.0 ) TKFRAME_-205201_AXES = ( 3, 2, 1 ) TKFRAME_-205201_UNITS = 'DEGREES' \begintext SMAP Antenna Zero-Articulation Base Frame (SMAP_ANT_ZERO) This fixed frame represents the Antenna Beam frame with an articulation azimuth of 0 degrees. At this azimuth, in the SMAP_INSF frame, the antenna beam is in the -Xinsr direction which is equivalent to the +Xinsf direction. This is accomplished by a negative rotation (i.e. clockwise) about the +Yinsf axis. The rotation matrix that takes vectors represented in the antenna zero frame to the SMAP_INSF frame follows: INSF [ ] [ ] [ ] [ ] [ ROT ] = [ 180.0 ] [ 144.5 deg ] [ 0.0 ] [ ] [ ] [ ] [ ] ZERO Z Y X where [x]i represents the rotation matrix of a given angle x about axis i. This diagram shows the SMAP_ANT_ZERO frame in the zero azimuth position: .-'\ .-' \ Spun Antenna .-' ' .-' .> .-' .-' +Xzero .-' o-' .-' +Yzero \ \ .- \ \.-' \ \ v +Zzero \ \ |<-->\ 35.5 deg \ \ \ ^ +Zinsr \ ^ +Zinsf \ | | +Xinsr <------o +Yinsr x------> +Xinsf +Yinsf ___ ---- |------ SMAP Spacecraft / | | | | \ / | | | | \ -----> / | |+Zsc | | \ Velocity | | | ^ | | | | | | | | | | |_______ |_| | |_| _______| | | `----|----' | | x------> +Xsc | | | +Ysc | | | | | -------- -------- | | +Ysc, +Yinsf and +Yzero point into Nadir | the screen or page. V +Yinsr points out of the screen or page. The SMAP_ANT_ZERO frame is defined below as a fixed offset frame relative to the SMAP_INSF frame. \begindata FRAME_SMAP_ANT_ZERO = -205202 FRAME_-205202_NAME = 'SMAP_ANT_ZERO' FRAME_-205202_CLASS = 4 FRAME_-205202_CLASS_ID = -205202 FRAME_-205202_CENTER = -205 TKFRAME_-205202_SPEC = 'ANGLES' TKFRAME_-205202_RELATIVE = 'SMAP_INSF' TKFRAME_-205202_ANGLES = ( 180.0, 144.5, 0.0 ) TKFRAME_-205202_AXES = ( 3, 2, 1 ) TKFRAME_-205202_UNITS = 'DEGREES' \begintext SMAP Antenna Beam Index Crossing Frame (SMAP_ANT_BIC) This fixed frame represents the Antenna Beam frame at the moment of Beam Index Crossing. This occurs at a beam azimuth of 90 degrees, when the -Xinsr axis aligns with the +Yinsf axis. Thus, the rotation to the beam frame is a rotation about the +Xinsf axis. The rotation matrix that takes vectors represented in the SMAP_INSF frame into the SMAP_ANT_BIC frame follows: INSF [ ] [ ] [ ] [ ] [ ROT ] = [ 90.0 ] [ 144.5 deg ] [ 0.0 ] [ ] [ ] [ ] [ ] BIC Z Y X where [x]i represents the rotation matrix of a given angle x about axis i. This diagram shows the SMAP_ANT_BIC frame in the BIC azimuth position: .-'\ .-' \ Spun Antenna .-' ' .-' .> .-' .-' +Xbic .-' o-' .-' +Ybic \ \ .- \ \.-' \ \ v +Zbic \ \ |<-->\ 35.5 deg \ \ \ ^ +Zinsr \ ^ +Zinsf \ | | +Xinsr <------o +Yinsr +Xinsf o------> +Yinsf _________ | |--. SMAP Spacecraft | | || | | || |+Zsc | || | ^ | || Solar Array | | | || | | |_|| `----|----' || o------> +Ysc +Xsc || || .. | | +Xsc, +Xinsf, +Yinsr, and +Ybic Nadir | point out of the screen or page. V The SMAP_ANT_BIC frame is defined below as a fixed offset frame relative to the SMAP_INSF frame. \begindata FRAME_SMAP_ANT_BIC = -205203 FRAME_-205203_NAME = 'SMAP_ANT_BIC' FRAME_-205203_CLASS = 4 FRAME_-205203_CLASS_ID = -205203 FRAME_-205203_CENTER = -205 TKFRAME_-205203_SPEC = 'ANGLES' TKFRAME_-205203_RELATIVE = 'SMAP_INSF' TKFRAME_-205203_ANGLES = ( 90.0, 144.5, 0.0 ) TKFRAME_-205203_AXES = ( 3, 2, 1 ) TKFRAME_-205203_UNITS = 'DEGREES' \begintext Engineering Antenna Frame Definitions ---------------------------------------------------------- This section of the frames kernel defines the SMAP engineering antenna frames. Note the angles in the fixed-offset frame definitions are specified for the ``from antenna to (relative to) base frame'' transformation. S-Band Low-gain (SLGA) and X-band Low-gain (XLGA) Antenna Frames The SLGA and XLGA antenna frames are defined as follows: - +Z axis is along the antenna boresight; - +X axis is along the antenna pattern clock angle reference line; - +Y completes the right-handed frame; - the origin of the frame is at the antenna phase center. This diagram shows the SMAP_SLGA and SMAP_XLGA frames (based on [5]): .-'\ .-' \ Spun Antenna .-' .-' .-' .-' .-' .-' .-' .-' .-' .-' \ .-' \.-' \ \ \ \ \ \ \ \ -. ______ | \ / __|__\ / _|_____||| | |--. SMAP Spacecraft | | || | | || |+Zsc | || | ^ | || Solar Array | | | || +Yslga | | |_|| <. /----|----' || `-. / o------> +Ysc +Yxlga <------o +Xsc || /| +Xslga || / | +Xxlga .. / | v v +Xsc, +Xslga, and +Xxlga point +Zslga +Zxlga out of the screen or page. | 30 deg | Nadir /<------>| | V As seen on the diagram a single rotation of +150 degrees about X is needed to co-align the spacecraft frame with the SLGA frame while a single rotation of 180 degrees about X is needed to co-align the spacecraft frame with the XLGA frame. The SMAP_SLGA and SMAP_XLGA frames are defined below as a fixed offset frames relative to the SMAP_SC frame. \begindata FRAME_SMAP_SLGA = -205301 FRAME_-205301_NAME = 'SMAP_SLGA' FRAME_-205301_CLASS = 4 FRAME_-205301_CLASS_ID = -205301 FRAME_-205301_CENTER = -205 TKFRAME_-205301_SPEC = 'ANGLES' TKFRAME_-205301_RELATIVE = 'SMAP_SC' TKFRAME_-205301_ANGLES = ( 0.0, 0.0, -150.0 ) TKFRAME_-205301_AXES = ( 3, 2, 1 ) TKFRAME_-205301_UNITS = 'DEGREES' FRAME_SMAP_XLGA = -205302 FRAME_-205302_NAME = 'SMAP_XLGA' FRAME_-205302_CLASS = 4 FRAME_-205302_CLASS_ID = -205302 FRAME_-205302_CENTER = -205 TKFRAME_-205302_SPEC = 'ANGLES' TKFRAME_-205302_RELATIVE = 'SMAP_SC' TKFRAME_-205302_ANGLES = ( 0.0, 0.0, 180.0 ) TKFRAME_-205302_AXES = ( 3, 2, 1 ) TKFRAME_-205302_UNITS = 'DEGREES' \begintext End of FK file.