PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = " 2014-04-27, W. Kurth, C. Piker, Revision 1; 2014-04-28, W. Kurth, general edits; 2014-05-02, G. Hospodarsky, calibration updates; " OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = JNO INSTRUMENT_ID = WAV OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "Waves" INSTRUMENT_TYPE = "PLASMA WAVE SPECTROMETER" INSTRUMENT_DESC = " Instrument Overview =================== Instrument Id : WAV Instrument Host Id : JNO Principal Investigator : WILLIAM KURTH PI PDS User Id : WKURTH Instrument Name : Waves Instrument Type : PLASMA WAVE SPECTROMETER Build Date : 2014-10-14 Instrument Manufacturer Name : THE UNIVERSITY OF IOWA The Waves instrument consists of one electric dipole antenna, one magnetic search coil, two pre-amplifiers, three receivers, and a digital processing unit. Taken together these components can detect and digitize wave electric fields from 50 Hz to 41 MHz and wave magnetic fields from 50 Hz to 20 kHz. At the highest duty cycle, Waves can record one sweep per second across all spectral bands while simultaneously capturing 5 waveforms in various bands. Electric fields are detected via an electric dipole antenna deployed from the aft flight deck in a 'V' configuration with a tip-tip length of about 4 meters. The signal from the electric antenna is conditioned in the electric preamplifier which has three frequency bands and each band has an attenuator that can be selected or not, to limit the input to the receivers under strong signal conditions. Wave magnetic components, are detected via a magnetic search coil which is also mounted to the aft flight deck. The signals from the search coil are conditioned by a magnetic preamplifier located close to the sensor, but within the spacecraft thermal environment. The instrument includes three receivers to detect signals from the sensors. The first is a 3-channel low frequency receiver that is used to analyze plasma waves. Two channels measure electric fields in the frequency ranges of 50 Hz to 20 kHz and 10 to 150 kHz, and one channel measures magnetic fields in the range of 50 Hz to 20 kHz. All measurements are collected simultaneously. This low frequency receiver produces a digitized waveform from each channel which is either sent directly to the ground (after compression) in burst mode or spectrum analyzed in the Waves digital signal processor to produce spectra with ~ 10 logarithmically-spaced channels per decade of frequency. The low frequency receiver also has a noise input from the spacecraft power distribution unit (PDDU). By subtracting this noise channel from the channel from either antenna, a noise cancellation process can be carried out. Based on in-flight experience, there is insuffient spacecraft noise as determined from the line from the PDDU to merit this additional processing; this will be re-evaluated at Jupiter. Waves also contains two high frequency receivers, each of which may be operated either as a spectrum analyzer (survey mode) or as a waveform receiver (burst mode). In survey mode, a high frequency receiver measures overall spectral intensity across a 1 MHz band. This band is stepped from 3 MHz to 41 MHz over the course of a second. In burst mode, a high frequency receiver over-samples the waveform of a single 1 MHz band that includes the electron cyclotron frequency, as derived from on-board MAG measurements. These samples are compressed and transmitted to the ground for processing into a 4096 channel spectra covering the 1 MHz band. In either mode, waves high frequency receivers also produce a digitized waveform in the range of 0.1 to 3 MHz. In survey mode these waveforms are reduced to a 16-channel spectrum using a Fourier transform before transmission to the ground, while in burst mode the waveforms are merely compressed but otherwise transmitted 'as-is' as part of the burst data set. During burst mode operations, when the electron cyclotron frequency happens to fall in the range of 0.1 to 3 MHz, this 'base band' waveform is transmitted to the ground instead of one of the higher frequency bands mentioned above. Conversion of digitized waveforms to spectra is handled by a digital signal processing unit implemented in a field-programmable gate array. The signal processing unit also provides loss-less compression of waveforms in burst modes. Platform Mounting Description ----------------------------- The Waves instrument utilizes two sensors. For the detection of the electric component of waves, an electric dipole antenna is used. The antenna is mounted on the aft flight deck, centered under solar panel wing #1 which has the Magnetometer boom at its end. Each element of the dipole is 2.8 m long. The two elements are deployed shortly after launch in a plane that is tilted aft of the aft flight deck by 45 degrees and with a subtended angle between the two elements of 120 degrees. An electric preamp is housed at the root of the two dipole elements. The symmetry axis of the dipole projected into the aft flight deck plane is parallel to the Magnetometer solar panel. The antenna pattern of the dipole for low frequencies is approximately a dipole with maximum sensitivity to electric fields parallel to the Y-axis of the spacecraft, i.e. perpendicular to both the MAG boom axis and the spin axis. For the detection of the magnetic component of waves, a magnetic search coil (MSC) is used. The search coil consists of a rod of mu-metal (permalloy) material 15 cm long with 10,000 turns of copper wire on a bobbin surrounding the rod. The coil is attached to the aft flight deck with its preamplifier mounted close by. The long axis of the MSC is parallel to the spacecraft Z axis (along the high gain antenna axis), hence, the antenna pattern is approximately that of a dipole with maximum sensitivity parallel to the spin axis of the spacecraft. Since Juno's spin axis is mostly perpendicular to Jupiter's strong magnetic field, this configuration minimizes the variation of signal at the spin frequency. The Waves electronics (other than the preamplifiers mentioned above) reside in the main electronics box in the Juno radiation vault, which is located directly behind the high-gain antenna. Lead Co-Investigator ---------------------- The Lead Co-Investigator for the Waves instrument is William Kurth. Scientific Objectives ===================== One of the four overarching science objectives of the Juno mission is to explore, for the first time, the three-dimensional structure of Jupiter's polar magnetosphere and auroras. The Waves investigation directly supports this theme. The Waves science objectives supporting this overarching objective are to (1) determine the nature of coupling between Jupiter's internal magnetic field, the ionosphere, and the magnetosphere, (2) investigate and characterize the three-dimensional structure of Jupiter's polar magnetosphere, and (3) identify and characterize auroral processes at Jupiter. These main objectives are further broken down into the following: * Locate and determine the nature of the auroral acceleration region. * Identify the major current systems coupling the magnetosphere to the ionosphere. * Determine the role wave-particle interactions play in the Jovian aurora. * Measure radio and plasma wave phenomena (auroral hiss, electron and ion phase space holes, auroral radio emissions, etc.) emission characteristics (intensity, electric and magnetic fields) inside source regions. * Identify and characterize emission processes. * Determine the fundamental differences between aurora associated with + The breakdown of co-rotation in the middle magnetosphere + The solar wind + Io (or other Galilean satellite) flux tube * Determine the beaming properties of Jovian radio emissions at high latitudes. * Determine the source locations for Jovian auroral radio emissions. Additional issues to be addressed by the Waves investigation include (1) the determination of dust flux in the region above the atmosphere and below Jupiter's ring system at and near the Jovigraphic equator and (2) to look for lightning-generated whistlers. Operational Considerations ========================== Juno's highly elliptical orbit will carry the Waves instrument through very different environments at very different velocities. Near perijove full electric spectra from 50 Hz to 41 MHz and full magnetic spectra from 50 Hz to 20 kHz will be collected with a temporal resolution of one to two seconds. For the remainder of the orbit this rate will be stepped down to one sweep per ~30 seconds. An intermediate cadence of a complete electric and magnetic spectrum every 10 seconds is available for distant plasmasheet crossings and/or for regions just outside the periapsis region. For the auroral regions burst-mode high rate waveform measurements are made. The burst mode is automatically triggered inside regions of interest based on the detection of intense waves in various bands. The majority of the data collected by Waves during each pass occurs during the ~12 hours near perijove. Most of these are stored for later transmission through out the remainder of the orbit. Calibration =========== The Juno Waves instrument was calibrated in two by applying known amplitude and frequency signals to the input of the receivers and sensors, and recording output of instrument. This results in lookup tables of input signal strength for instrument output data number. Calibrations were performed on the individual receivers and sensors, and also end-to-end calibrations were performed on the sensors plus receiver system. Calibrations and tests were performed at the extremes of the expected operating range of the instrument (-35C and +75C), and at the expected typical operating temperature of +22C which is used as the primary calibration. The individual sensor and receiver calibrations were combined and compared to the end-to-end calibrations and found to be in good agreement. Magnetic Search Coil (MSC) sensor and preamplifier calibrations: The calibration of the MSC sensor and preamplifier was performed using a solenoid drive coil to produce a known magnetic field strength over the amplitude and frequency range of the sensor while the output voltage of the sensor was recorded, producing a transfer function over frequency of the output voltage of the preamplifier for a strength of the wave magnetic field in nT. Electric Preamplifier Calibrations: The Electric Preamplifier was calibrated by applying a known voltage to the input of the preamplifier over the amplitude and frequency range of the instrument and recording the output voltage of the preamplifier, producing a transfer function over frequency of the output voltage of the preamplifier for a given input voltage. Receivers: Each of the Waves receivers were calibrated by applying a known voltage to the input of the receiver over the amplitude and frequency range of the receiver and measuring the output data number of the instrument. End-to-End Calibrations: Calibrations were then performed with the MSC sensor and preamplifier, and electric preamplifier attached to the Waves instrument. Input signals of known amplitude and frequency were applied to the MSC sensor and the electric preamplifier and the data number out of the instrument were recorded to produce calibration tables showing the measured electric or magnetic field for each data number out of the instrument. Operational Modes ================= Though highly programmable, the Waves Instrument is expected to operate in four basic modes, in order of increasing data volume: Apojove Mode, Intermediate Mode, Perijove Mode, Burst Mode The major mode commands associated with each operational mode are listed below. This list of operating modes is not exhaustive. For a complete listing and for more detail on each mode command, consult the Waves User's Guide on the JNOWAV_1000 volume in the DOCUMENT directory. Apojove Mode ------------ This will be used for most of the orbit. * Full electric sweeps from 50 Hz to 41 MHz, once per 30 seconds. * Full magnetic sweeps from 50 Hz to 20 kHz, once per 30 seconds. * No waveform data are transmitted outside the instrument. Major mode commands which place Waves into this state: APO1, APO2, APO3, APO9, AP0A, APS1, APS2, APS3 Perijove Mode ------------- This mode is intended for use in the roughly 12 hours centered on Jupiter closest approach. * Full electric sweeps from 50 Hz to 41 MHz, once per second. * Full magnetic sweeps from 50 Hz to 20 kHz, once per second. * No waveform data are transmitted outside the instrument. Major mode commands which place Waves into this state: PER1, PER2, PER3, PER9, PERA, PES1, PES2, PES3 Intermediate Mode ----------------- This mode is intended for use in selected distant plasmasheet crossings and possibly before and/or after perijove intervals. * Full electric sweeps from 50 Hz to 41 MHz, once per 10 seconds. * Full magnetic sweeps from 50 Hz to 20 kHz, once per 10 seconds. * No waveform data are transmitted outside the instrument. Major mode commands which place Waves into this state: INT1, INT2, INT3, INS1, INS2, INS3 Burst Mode ---------- The Burst Mode is a highly flexible mode and is executed in two distinct methods. The Binning Mode assigns n buffers (or bins) of fixed length and, with the assistance of the spacecraft data system and Waves determination of 'quality factors' based on wave intensities in selectable bands, the 'best' N buffers are retained for transmission to the ground based on the quality factors for the data within each buffer. Typically, the instrument is in a Binning Mode for an interval of time much longer than the sum of the time that can be stored in the n buffers. The quality factors allow the instrument to find the 'best' intervals to record. The primary use of this mode is to record wave phenomena on auroral field lines. It is expected that auroral field line crossing may take only seconds, but likely can't be targetted in time any better than 30 to 90 minutes. This mode typically records waveform data from all of the low frequency receiver bands and one of the high frequency receiver bands selected on the basis of the onboard determination of the electron cyclotron frequency. The Record Mode method of the Burst mode simply records for a specified interval in time. The primary use for this mode is to collect data centered on the jovigraphic equator near periapsis to target the region where dust impacts are expected. Because this location can be accurately targetted, the selection featurs of the Binning Mode are not needed. Also, it is anticipated that only the electric field in the range of 50 Hz to 20 kHz will be recorded, as this channel is expected to respond best to dust impacts. Record Method: This method was designed with crossings of the Jovian equator near perijove in mind. Typically data from just the LFR-Lo (E) channel will be recorded to be used to identify micron-sized dust particle impacts with the spacecraft as Juno crosses the ring plane. * Full electric sweeps from 50 Hz to 41 MHz, once per second. * Full magnetic sweeps from 50 Hz to 20 kHz, once per second. * Waveform data are collected in a programmed frequency band. Major mode commands which place Waves into this state: REC1, REC2, REC3, REC9, RECA, RES1, RES2, RES3 Note this this is a layered mode which may only be triggered on top of an existing Perijove Mode. It adds in basic waveform data collection ability. Binning Method: When configured to this this state, Waves looks for intense, broadband signatures of crossings of auroral field lines carrying a host of intense wave modes. It continuously sends waveform data, to the Juno Command and Data Handling (C&DH) system which stores them in two or more buffers sized to hold approximately a minute's worth of waveform data. Waves also characterizes such broadband bursts with a quality index, which the C&DH uses to determine whether to keep or over-write a buffer. At the end of the binning session, the buffers with the highest quality indices will be formatted by the C&DH for transmission to the ground. * Full electric sweeps from 50 Hz to 41 MHz, once per second. * Full magnetic sweeps from 50 Hz to 20 kHz, once per second. * Waveform data are collected in bands that automatically track the electron cyclotron frequency. * Waveform data bins are ranked in order of most to least activity Major mode commands which place Waves into this state: BUR1, BUR2, BUR3, BUR4, BUR9, BURA, BUS1, BUS2, BUS3, BUS4 Note that this is a layered mode which may only be triggered on top of an existing Perijove Mode. It adds in selective waveform data collection ability. Major Mode Names ---------------- It should be noted that the last two characters in the Major Mode names have more to do with how the instrument is set up than the final data products from that mode. For example modes xxx1 include noise cancellation, modes xxx2 include noise cancellation and the un-filtered, filtered, and noise channel data are all returned for diagnostic purposes. Modes xxx3 and xxx4 do not utilize noise cancellation. Modes with xxSx do an instrument reset in the course of setting up the mode. Also, periapsis modes all execute with 1-second cadence except for xxx2. Because of the additional overhead required to handle the additional diagnostics data, the cadence is 2 seconds for this mode. " END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "KURTH2015" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END