This file is intended as documentation of the Field(s) Of View (FOV(s)) for the detectors and/or slits and/or apertures comprising the instrument on the New Horizons (NH) spacecraft that generated the data archived in this data set. This file is a NH Project Solar Wind Around Pluto (SWAP) SPICE Instrument Kernel (IK), current at the time of delivery of this data set. It is only provided as a convenience to the user to visualize the FOVs of the instrument. This file will not be updated in this PDS data set as part of any SPICE kernel updates, and should therefore not be used as a SPICE kernel in any scientific investigation. Specifically, the references in the IK are not relevant to the graphic visualization of the FOV and will not be provided with this data set or archived elsewhere; therefore the references should be ignored in the context of the intended scope of this file as described above. As a SPICE IK, this file has much more information than just the FOV description (e.g. references to project documentation), but in the context of this PDS data set only the FOV description is relevant. For a more complete understanding of the geometry and timing issues of the New Horizons mission, the user is directed to the SPICE PDS data set for the mission, with a data set ID of NH-J/P/SS-SPICE-6-V1.0. CAVEATS: This file is the NH SWAP SPICE Instrument Kernel (IK), current at the time of delivery of this data set. It is only provided as a convenience to the user to visualize the FOVs of the instrument. This file will not be updated in this PDS data set as part of any SPICE kernel updates, and should therefore not be used as a SPICE kernel in any scientific investigation. Specifically, the references in the IK are not relevant to the graphic visualization of the FOV and will not be provided with this data set; therefore the references should be ignored in the context of this file. If the user wishes to do any data analysis requiring NAIF/SPICE IKs, they should not use this file, but rather get the most recent IK from the NH SPICE data set and use that. - This file is included in the document collection for this instrument as a convenience to the user because, in some of its sections, it documents the geometry of the SWAP instrument Field(s) Of View (FOV(s)). Other sections of this IK (e.g. the references) will have limited use in that scope. - The original name of the source of this file was NH_SWAP_V###.TI where ### is a version number. - The format of this file, starting five lines after this description, is a SPICE Kernel Pool text file - The Instrument Kernel itself is (or will be) formally archived with the New Horizons SPICE dataset. - See the SPICE documentation for details of that format - http://naif.jpl.nasa.gov/ - Even without understanding that format, the Instrument Kernel, and especially its comments, are human readable. Comments are any line for which one of the following three statements is true: 1) The line is before the first data marker line in the file 2) The line is in a section of lines between a text marker line and a data marker line with no intervening text or data marker lines 3) The line is in a section of lines between the last text marker and the end of the file with no intervening text or data marker lines - a data marker line has the single token '\begindata' on it with all other characters on the line being whitespace - a text marker line has the single token '\begintext' on it with all other characters on the line being whitespace - N.B. Because padding and a carriage return have been added to each line of this file, it may or may not be functional as a valid SPICE kernel. ######################################################################## ##################### SPICE IK Starts after next line ################## ######################################################################## KPL/IK SWAP Instrument Kernel ============================================================================== This instrument kernel (I-kernel) contains references to the mounting alignment, internal and FOV geometry for the New Horizons Solar Wind Around Pluto (SWAP) instrument. 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 SWAP I-kernel might have an entry as follows: TEXT_KERNEL_ID += 'NEWHORIZONS_SWAP V1.0.0 22-FEBRUARY-2007 IK' | | | | | | | | KERNEL NAME <-------+ | | | | | V VERSION <-------+ | KERNEL TYPE | V ENTRY DATE SWAP I-Kernel Version: \begindata TEXT_KERNEL_ID += 'NEWHORIZONS_SWAP V2.0.0 27-JANUARY-2015 IK' NAIF_BODY_NAME += ( 'NH_SWAP' ) NAIF_BODY_CODE += ( -98600 ) \begintext Version 2.0.0 -- January 27, 2015 -- Eric Zirnstein -- Corrected the SWAP FOV limits in elevation, change to +/- 5 deg. Version 1.0.0 -- February 22, 2007 -- Lillian Nguyen -- Promoting to version 1.0.0 denoting approval of kernel set by instrument teams. Version 0.0.2 -- October 4, 2006 -- Lillian Nguyen, JHU/APL -- Removed the 3-letter frame NH_SWA. Version 0.0.1 -- June 29, 2006 -- Lillian Nguyen -- Reversed the field of view elevations and added more text on the instrument orientation. Version 0.0.0 -- April 15, 2006 -- Lillian Nguyen -- Draft Version. NOT YET APPROVED BY INSTRUMENT TEAM. References ---------------------------------------------------------- 1. New Horizons Spacecraft to SWAP Interface Control Document, 7399-9047 Rev. A. 2. ``Kernel Pool Required Reading'' 3. APL New Horizons web site, http://pluto.jhuapl.edu/spacecraft/overview.html. 4. New Horizons Spacecraft Frames Kernel. 5. New Horizons Instrument Specification for the Solar Wind Around Pluto (SWAP) Instrument, 05310-03-SWAPSPEC-01 dated Jan. 5, 2005, taken from APL DOORS database. 6. E-mail exchange with Heather Elliot, Southwest Research Institute (SwRI) March and June, 2006. 7. Discussion at New Horizons CCB meeting Feb. 16, 2016, in which it was noted that normal instrument operations have the deflector turned off, in which case the FOV elevation is -5 to 5 degrees. Contact Information ---------------------------------------------------------- Lillian Nguyen, JHU/APL, (443)-778-5477, Lillian.Nguyen@jhuapl.edu Implementation Notes ---------------------------------------------------------- This file is used by the SPICE system as follows: programs that make use of this instrument kernel must ``load'' the kernel, normally during program initialization. Loading the kernel associates data items with their names in a data structure called the ``kernel pool''. The SPICELIB routine FURNSH, CSPICE routine furnsh_c, and IDL routine cspice_furnsh load SPICE kernels as shown below: FORTRAN (SPICELIB) CALL FURNSH ( 'kernel_name' ) C (CSPICE) furnsh_c ( "kernel_name" ) ICY (IDL) cspice_furnsh, 'kernel_name' In order for a program or subroutine to extract data from the pool, the SPICELIB routines GDPOOL, GCPOOL, and GIPOOL are used. See [2] for details. This file was created and may be updated with a text editor or word processor. Naming Conventions ---------------------------------------------------------- All names referencing values in this I-kernel start with the characters `INS' followed by the NAIF New Horizons spacecraft ID number (-98) followed by a NAIF three digit ID code for the SWAP instrument. The remainder of the name is an underscore character followed by the unique name of the data item. For example, the SWAP boresight direction in the SWAP frame (``NH_SWAP'' -- see [4] ) is specified by: INS-98600_BORESIGHT The upper bound on the length of the name of any data item is 32 characters. If the same item is included in more than one file, or if the same item appears more than once within a single file, the latest value supersedes any earlier values. SWAP description ---------------------------------------------------------- From [3]: ``SWAP (Solar Wind Around Pluto): Solar wind and plasma spectrometer; measures the composition and density of plasma (ions) escaping from Pluto's atmosphere. . . . SWAP will measure charged particles from the solar wind near Pluto to determine whether Pluto has a magnetosphere and how fast its atmosphere is escaping.'' From [1]: ``SWAP consists of [a] single assembly... SWAP measures the speed and density of the solar wind. A large aperture Electrostatic Analyzer (ESA) provides coarse energy selection. A Retarding Potential Analyzer (RPA) then makes a fine resolution energy measurement. The instrument has redundant Channel Electron Multiplier (CEM) detector. The optics and detectors are serviced by an array of redundant High Voltage Power Supplies that are fabricated on two separate boards: a multiplier board and a driver board. The control board, at the bottom of the stack, contains the low voltage power converters, a micro-controller, RS-422 drivers & receivers, as well as various analog control and monitoring circuits.'' From [5]: ``The Mission Science Requirements document states that SWAP will be used to meet the following three objectives. Group 1 Objective: Characterize the neutral atmosphere of Pluto and its escape rate. Group 2 Objective: Characterize Pluto's ionosphere and solar wind interaction Group 3 Objective: Characterize the energetic particle environment of Pluto and Charon The Mission Science Requirements document specifies that SWAP should make the following measurements. Measure solar wind standoff to ~ 3000 km. Measure solar wind speed. SWAP's goal is to have relative solar wind resolution ~ 0.5% on nominal 1 keV solar wind. Measure solar wind density. SWAP's goal is to resolve relative density variation to ~ 1%. Determine nature of solar wind interaction at Pluto. Distinguish between magnetic, cometary, & ionospheric interactions. The SWAP instrument measures the speed and density of the solar wind. It also measures pickup ions with E/Q less than 8 keV. The SWAP instrument consists of an RPA followed by an ESA. The RPA is a high-pass filter that can be used to make a very fine resolution E/Q measurement. The ESA is a coarse energy analyzer ((delta E)/E = 0.1). Its broad energy range is used to quickly find the center of the solar wind beam. The ESA also provides excellent UV rejection for the detectors. The instrument has redundant CEM detectors. Together, they are used to make a coincidence measurement that gives the instrument a very low background. The primary particle passes through a carbon foil, generating secondary electrons. The primary particle continues on and strikes the Primary CEM detector. Secondary electrons from the entrance side of the carbon foil are focused onto the Secondary CEM detector. If a primary event is followed by a secondary event within the specified time window, a coincidence event is detected. The electro-optics of the instruments is serviced by an array of redundant high voltage power supplies [(HVPS)]. The RPA, DFL [(Deflector)], and ESA each have two HVPS power supplies. The outputs of the supplies are diode OR-ed together. Each detector has its own HVPS, making the detectors redundant units. On the SWAP instrument control board, a microcontroller is used to process commands and generate telemetry. Instrument commands are received over redundant low speed RS-422 lines and telemetry is sent to two solid-state recorders on the spacecraft over redundant low speed RS-422 lines. Analog electronics on the control board generates the analog command levels to each HVPS as well as switching power on and off to each HVPS. The control board contains the charge amplifiers that are used to process the signals from the CEM detectors.'' SWAP Field of View Parameters ---------------------------------------------------------- From [6, 7], the SWAP field of view in the roll direction is 276 degrees, and -5 to +5 degrees in the deflection direction (deflector off), where the negative direction is towards the spacecraft. The negative deflection direction corresponds to the instrument +Z axis, so in instrument coordinates, the field of view in the deflection direction is +5 to -5 deg. The field of view can be described as a 276 degree portion of the complement of the cones depicted in the figure below, with the instrument +Y axis as the center of the field of view. In this view, we are looking into the center of the instrument aperture. The vector pointing out the top of the instrument is the instrument -Z axis, and is nearly aligned with the spacecraft -Z axis. ^ -Z | inst | | instrument top +Y points out of the page ___________|___________ inst `-.._ | _..-' `-.._ | _..-' 5 deg <----------------o----------------> X _..-' | `-.._ 5 deg inst ..-' | `-.. '-----------------------` | instrument bottom (spacecraft-facing side) ESA and electronics are here | | v In the instrument XY plane, the azimuth of the field of view is the 276 degree portion of the circle below. This diagram shows the view looking out from the spacecraft (view from the bottom of the instrument). The vector pointing out the top of the instrument (instrument -Z axis) points into the page here. When open, the instrument doors hang downwards in this view, or towards the -Y axis. ^ Y | inst | +Z points out of the page _..-+-.._ inst .' | '. / | \ | | | <------+-------o-------+------> X | ,'|`. | inst \ ,' | `. / .' doors `. ,' | `. .' o | o `. ' 42 | 42 ` v To describe the SWAP field of view, we will provide a set of unit vectors originating at the center of the instrument coordinate system that point along the edge of the field of view. The vectors will be listed in the order one would encounter them while traveling around the edge of the field of view. We will take 46 degree steps in azimuth as we traverse the edge from vector V0 to vector V6, then -10 degrees in elevation as we go from V6 to V7, then 46 degree steps again from V7 to V13. A projection onto the instrument XY plane of the fourteen unit vectors defining the field of view is shown below. Since we are looking upwards from the bottom of the instrument, the vectors below the plane of the page point towards the top of the instrument. Y ^ inst 'below' refers to vectors | below the plane of the page, V3 (above) or with negative Z component. V10 (below) V4 (above) | 'above' refers to vectors V9 (below).-+-.._ V2 (above) above the plane of the page, .' | '. V11 (below) or with positive Z component. / `. | .' \ | `.|.' | V5 (above)+- - - -o- - - -+ V1 (above)---> X V8 (below)| ,'|`. | V12 (below) inst \ ,' | `. / .' o| o `. V0 (above) V6 (above) 42 |42 V13 (below) V7 (below) | | v Instrument +Z axis points out of the page As an example, we illustrate the calculation to determine the coordinates of unit vector V2 here. The first diagram below shows a cross-section of the field of view. Note that the horizontal axis lies in the instrument XY plane but does not align with any of the instrument axes. The second diagram shows the vector V2 from the same perspective as the diagram above. Because the second diagram shows a projection of the vector V2 onto the instrument XY plane, its length is cos(5). All angles are in degrees. instrument bottom (spacecraft side) ^ Y ^ Z | inst | inst cos(5)*sin(44) +----------. V2 | | .'| sin(6) +------------_. V2 | cos(5)' | | 1 _.-' | | .' | | _.-' | | .' | |_.-' 5 deg | |.' 44 deg | X +-------------+-------> o----------+---------> inst cos(5) Z (out) cos(5)*cos(44) inst The X and Y components of the vectors V0 to V13 are: V0: (X,Y) = cos( 5 deg ) * ( cos(-48 deg), sin(-48 deg) ) V1: (X,Y) = cos( 5 deg ) * ( cos( -2 deg), sin( -2 deg) ) V2: (X,Y) = cos( 5 deg ) * ( cos( 44 deg), sin( 44 deg) ) V3: (X,Y) = cos( 5 deg ) * ( cos( 90 deg), sin( 90 deg) ) V4: (X,Y) = cos( 5 deg ) * ( cos(136 deg), sin(136 deg) ) V5: (X,Y) = cos( 5 deg ) * ( cos(182 deg), sin(182 deg) ) V6: (X,Y) = cos( 5 deg ) * ( cos(228 deg), sin(228 deg) ) V7: (X,Y) = cos( -5 deg ) * ( cos(228 deg), sin(228 deg) ) V8: (X,Y) = cos( -5 deg ) * ( cos(182 deg), sin(182 deg) ) V9: (X,Y) = cos( -5 deg ) * ( cos(136 deg), sin(136 deg) ) V10: (X,Y) = cos( -5 deg ) * ( cos( 90 deg), sin( 90 deg) ) V11: (X,Y) = cos( -5 deg ) * ( cos( 44 deg), sin( 44 deg) ) V12: (X,Y) = cos( -5 deg ) * ( cos( -2 deg), sin( -2 deg) ) V13: (X,Y) = cos( -5 deg ) * ( cos(-48 deg), sin(-48 deg) ) And since the field of view elevation is +5 to -5 degrees, the Z component of each of the 'above' vectors is V0 to V6: Z = sin ( 5 deg ) and the Z component of each of the 'below' vectors is V7 to V13: Z = sin ( -5 deg ) The fourteen boundary corner vectors given in the field of view definition below, starting with V0. \begindata INS-98600_FOV_FRAME = 'NH_SWAP' INS-98600_FOV_SHAPE = 'POLYGON' INS-98600_BORESIGHT = ( 0.0, 1.0, 0.0 ) INS-98600_FOV_CLASS_SPEC = 'CORNERS' INS-98600_FOV_BOUNDARY_CORNERS = ( 0.666584362385609360 -0.740316935054895600 0.087155742747658166 0.995587843197948020 -0.034766693581101821 0.087155742747658166 0.716602495223739090 0.692014985636304700 0.087155742747658166 0.000000000000000061 0.996194698091745550 0.087155742747658166 -0.716602495223739200 0.692014985636304590 0.087155742747658166 -0.995587843197948020 -0.034766693581101751 0.087155742747658166 -0.666584362385609590 -0.740316935054895490 0.087155742747658166 -0.666584362385609590 -0.740316935054895490 -0.087155742747658166 -0.995587843197948020 -0.034766693581101751 -0.087155742747658166 -0.716602495223739200 0.692014985636304590 -0.087155742747658166 0.000000000000000061 0.996194698091745550 -0.087155742747658166 0.716602495223739090 0.692014985636304700 -0.087155742747658166 0.995587843197948020 -0.034766693581101821 -0.087155742747658166 0.666584362385609360 -0.740316935054895600 -0.087155742747658166 ) \begintext