KPL/IK RPWS Instrument Kernel ============================================================================== This instrument kernel (I-kernel) contains references to the mounting alignment, internal and FOV geometry for the Cassini Radio and Plasma Wave Science (RPWS) instruments. 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 ISS I-kernel might have an entry as follows: TEXT_KERNEL_ID += 'CASSINI_ISS V0.0.0 29-SEPTEMBER-1999 IK' | | | | | | | | KERNEL NAME <-------+ | | | | | V VERSION <-------+ | KERNEL TYPE | V ENTRY DATE RPWS I-Kernel Version: \begindata TEXT_KERNEL_ID += 'CASSINI_RPWS V0.1.0 23-APRIL-2001 IK' \begintext Version 0.1 -- April 23, 2001 -- Scott Turner -- Updated kernel to utilize new FOV ANGLES specification. Version 0.0 -- October 5, 2000 -- Scott Turner -- Initial Prototype Release for Review References ---------------------------------------------------------- 1. ``Cassini Science Instruments and Investigations'', Revised Second Printing. Stephen J. Edberg. 2. ``Kernel Pool Required Reading'' 3. JPL Cassini Project Web Page describing the instruments. 4. Cassini/NAIF SPICE Workship, November 8-9, 1999. 5. Email from Jeff Boyer regarding necessary data for footprint calculations. 6. Cassini Spacecraft Frames Definition Kernel 7. CASPER RPWS I-kernel Version 4.0 Contact Information ---------------------------------------------------------- Direct questions, comments or concerns about the contents of this kernel to: Scott Turner, NAIF/JPL, (818)-345-3157, sturner@spice.jpl.nasa.gov 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 and CSPICE routine furnsh_c load SPICE kernels as shown below: FORTRAN (SPICELIB) CALL FURNSH ( 'kernel_name' ) C (CSPICE) furnsh_c ( "kernel_name" ) In order for a program or subroutine to extract data from the pool, the SPICELIB routines GDPOOL 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 Cassini spacecraft ID number (-82) followed by a NAIF three digit code for the RPWS detectors. (RPWS = 730, RPWS_LP = 731 ). The remainder of the name is an underscore character followed by the unique name of the data item. For example, the RPWS boresight direction in the RPWS frame (``CASSINI_RPWS'' -- see [6] ) is specified by: INS-82730_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. RPWS description ---------------------------------------------------------- From [3]: The Radio and Plasma Wave Science (RPWS) instrument will be used to investigate electric and magnetic waves in space plasma at Saturn. Plasma is essentially a soup of free electrons and positively charged ions, the latter being atoms that have lost one or more electrons. Plasma makes up most of the universe and is created by the heating of gases by stars and other bodies in space. Plasma is distributed by the solar wind, and it is also "contained" by the magnetic fields (i.e., the magnetoshperes) of bodies such as Saturn and Titan. The Cassini RPWS instrument will measure the a.c. electric and magnetic fields in the interplanetary medium and planetary magnetospheres and will directly measure the electron density and temperature of the plasma in the vicinity of the spacecraft. The major components of the RPWS Subsystem are the electric field sensor, the magnetic search coil sensor assembly, the Langmuir probe sensor assembly, and the instrument main electronics. For information on these components, see below. (RPWS) The electric field sensor is made up of three deployable antenna elements, an associated preamplifier, and antenna deployment mechanism drive electronics. The antennas are composed of interlocking sections made from beryllium copper, and each antenna element is deployable separately to 10 meters with its own 400-Hz a.c. motor. The electric field preamplifier is used to add gain to the output signals from the antennas. The antenna deployment mechanism electronics convert ±15 volt primary power to 400-Hz a.c. power for the antenna drive motors. The magnetic search coil sensor assembly is composed of a triaxial sensor assembly and an associated preamplifier. The triaxial sensor consists of three orthogonal (i.e., perpendicular) metallic alloy cores with two sets of windings each, one to produce flux in the core and another to detect the flux. The magnetic search coil preamplifier adds gain to the output signal from the sensor assembly. The Langmuir probe sensor assembly consists of a sensor, a preamplifier, and associated control electronics. The Langmuir probe sensor is a 5-cm diameter sphere located at the end of a rod approximately 1 meter in length. The sensor rod is folded in a stowed state until deployed in flight. The probe sensor preamplifier adds gain to the output from the probe. The RPWS main electronics includes a digital data processing unit, a high-frequency receiver, a wideband receiver, a medium-frequency receiver, a low-frequency five-channel waveform receiver, the Langmuir probe bias circuitry, and a power converter. For information on these components, see below. (RPWS Main Electronics) The data processing unit (DPU) will control all instrument functions and will handle all communications with the orbiter. It will contain a large block of RAM to be used as waveform storage for the five-channel waveform receiver. Software in the DPU will be used to enhance the scientific return of the instrument by performing various analysis and data compression operations. The high-frequency receiver is a digital waveform processor that operates by digitizing a portion of the bandwidth received from the lectric field sensor antennas and deriving spectral and waveform vector information from the waveforms using digital signal processing techniques. The wideband receiver will obtain very high-resolution electric or magnetic field waveforms for selected time intervals that vary from under a minute to as much as an hour or more. The receiver has two selectable passbands: 50 Hz to approximately 10 kHz and 10 kHz to approximately 80 kHz. The wideband receiver uses high-rate telemetry to transfer waveform information in a given bandwidth from a selected sensor directly. The input signal is selectable from one of five inputs: two electric, one magnetic, a frequency-converted output from the high-frequency receiver, and the Langmuir probe. The medium-frequency receiver provides spectrum measurements over the frequency range from 25 Hz to 12.6 kHz. This receiver is attached to one of four sensor inputs (two electric and two magnetic) and uses double frequency conversion to convert the input bandwidth down to a low-frequency constant frequency band, where it is detected by an amplitude detector. The low-frequency five-channel waveform receiver provides high-resolution spectral measurements of electric and magnetic fields over the frequency range from 0.1 Hz to 2.5 kHz. It provides simultaneous waveforms from all five antennas (three magnetic axes and two electric axes). This receiver captures blocks of waveform data simultaneously from the five sensors and maintains a high-degree of phase and amplitude accuracy. The data is processed through five parallel amplifier and filter channels. The Langmuir probe bias circuitry...??(more to follow) The power converter converts d.c. power from the spacecraft power supplies to a.c. power to operate the instrument. The conversion frequency will be fixed at 100 kHz by locking onto a signal from the spacecraft bus interface unit. RPWS Field of View Parameters ---------------------------------------------------------- The field of view parameters for the two detectors that constitute the RPWS instrument are: -- Radio and Plasma Wave Science (RPWS) -- RPWS Langmuir Probe (RPWS_LP) Radio and Plasma Wave Science (RPWS) FOV Definition Since the RPWS detector's FOV is circular and it's diameter is 180.0 degrees. Looking down the X-axis in the CASSINI_RPWS frame, we have: (Note since the FOV is 180 degrees in diameter we have the whole Z>=0 halfplane in the FOV.) ^ Y | ins ^ | | | o | 90.0 | x---------------> X Z ins ins |-- 1.0 --| Plane X = 0 Now from here we see that one 'boundary corner' vector is a vector along the Y-axis: Boundary Corner Vector = ( 0, 1, 0 ) Utilizing the ANGLES FOV specification: \begindata INS-82730_FOV_FRAME = 'CASSINI_RPWS' INS-82730_FOV_SHAPE = 'CIRCLE' INS-82730_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82730_FOV_CLASS_SPEC = 'ANGLES' INS-82730_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 +0.0000000000000000 ) INS-82730_FOV_REF_ANGLE = ( 90.0 ) INS-82730_FOV_ANGLE_UNITS = 'DEGREES' \begintext RPWS Langmuir Probe (RPWS_LP) FOV Definition Since the RPWS_LP detector's FOV is also circular and it's diameter is 180.0 degrees. Looking down the X-axis in the CASSINI_RPWS_LP frame, we have: (Note since the FOV is 180 degrees in diameter we have the whole Z>=0 halfplane in the FOV.) ^ Y | ins ^ | | | o | 90.0 | x---------------> X Z ins ins |-- 1.0 --| Plane X = 0 Now from here we see that one 'boundary corner' vector is a vector along the Y-axis: Boundary Corner Vector = ( 0, 1, 0 ) Utilizing the ANGLES FOV specification: \begindata INS-82731_FOV_FRAME = 'CASSINI_RPWS_LP' INS-82731_FOV_SHAPE = 'CIRCLE' INS-82731_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82731_FOV_CLASS_SPEC = 'ANGLES' INS-82731_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 +0.0000000000000000 ) INS-82731_FOV_REF_ANGLE = ( 90.0 ) INS-82731_FOV_ANGLE_UNITS = 'DEGREES' \begintext RPWS Pixel Parameters: ---------------------------------------------------------- These parameters describe the pixel structure associated with the instruments and their fields of views. In some cases this is a generalization of the notion of pixel, in that instead of representing pixels on a CCD they may represent a collection of individual detectors. Radio and Plasma Wave Science (RPWS): \begindata INS-82730_FOV_CENTER_PIXEL = ( 0, 0 ) INS-82730_PIXEL_SAMPLES = ( 1 ) INS-82730_PIXEL_LINES = ( 1 ) \begintext RPWS Langmuir Probe (RPWS_LP): \begindata INS-82731_FOV_CENTER_PIXEL = ( 0, 0 ) INS-82731_PIXEL_SAMPLES = ( 1 ) INS-82731_PIXEL_LINES = ( 1 ) \begintext Instrument Mode Timing ---------------------------------------------------------- The following values were provided as samples in [5]. These values are defined in [5] as follows: ``The initial values for the following keywords are given per instrument number: INS[instrument number]_[instrument acronym]_MODE_NAME INS[instrument number]_[instrument acronym]_TRIGGER_OFFSET INS[instrument number]_[instrument acronym]_CYCLE_DURATION INS..._MODE_NAME contains the name of the instrument mode for the INS..._TRIGGER_OFFSET and INS..._CYCLE_DURATION keywords. INS..._TRIGGER_OFFSET specifies the reference time of the first instrument frame (to be calculated for a footprint) relative to the time of transacting the corresponding TRIGGER command. The units are SFOC duration. INS..._CYCLE_DURATION specifies the duration between successive instrument frames (from the first one) for the INS..._MODE_NAME.'' Radio and Plasma Wave Science (RPWS): \begindata INS-82730_MODE_NAME = 'NOMINAL' INS-82730_TRIGGER_OFFSET = '0:01:00.0' INS-82730_CYCLE_DURATION = '0:01:00.0' \begintext RPWS Langmuir Probe (RPWS_LP): \begindata INS-82731_MODE_NAME = 'NOMINAL' INS-82731_TRIGGER_OFFSET = '0:01:00.0' INS-82731_CYCLE_DURATION = '0:01:00.0' \begintext NAIF ID Code to Name Mapping ---------------------------------------------------------- \begindata NAIF_BODY_NAME += ( 'CASSINI_RPWS' ) NAIF_BODY_CODE += ( -82730 ) NAIF_BODY_NAME += ( 'CASSINI_RPWS_LP' ) NAIF_BODY_CODE += ( -82731 ) \begintext Platform ID ---------------------------------------------------------- The RPWS instrument is mounted on the the Cassini Spacecraft body. Therefore the values stored in the keywords below are -82000. \begindata INS-82730_PLATFORM_ID = ( -82000 ) INS-82731_PLATFORM_ID = ( -82000 ) \begintext