Galileo PLS Jupiter Calibrated Bundle Galileo PLS Jupiter Full Resolution Calibrated Collection PDS3 DATA_SET_ID = GO-J-PLS-3-RDR-FULLRES-V1.0 PDS3 DATA_SET_NAME = GALILEO JUPITER RDR FULL RESOLUTION PLASMA DATA V1.0 START_TIME = 1995-12-07T15:30 STOP_TIME = 2003-09-21T18:45 PDS3 DATA_SET_RELEASE_DATE = 2003-11-21 PRODUCER_FULL_NAME = DR. KENT ACKERSON References: Frank, L.A., Paterson, W.R., Ackerson, K.L., GALILEO JUPITER RDR FULL RESOLUTION PLASMA DATA V1.0, GO-J-PLS-3-RDR-FULLRES-V1.0, NASA Planetary Data System, 2000. Overview: ========= This collection contains data from the Plasma Science instrument (PLS) onboard the Galileo spacecraft during the Jupiter orbital operations phase (December 1995 to end of mission). These data have been edited and reformatted from the raw telemetry packets into a simple ASCII tabular structure to facilitate processing and analysis. Parameters: =========== This collection includes both high time resolution (LPW) data recorded during targeted encounters and real-time science (RTS) data acquired during the magnetospheric survey when telemetry was available. The Plasma instrument can collect either RTS data or LPW data but not both simultaneously. The basic data set parameters are the detector count rates in units of counts per second. Data are provided at the full instrument sampling rate in all sampling parameters (time, detector, E/Q, M/Q). The instrument has twenty (20) detectors (seven ion, seven electron, six mass spectrometer) and can sample E/Q or M/Q (mass spectrometer detectors only) in sixty-four (64) steps for each detector. Processing: =========== The final instrument packet files (IPF's) have been processed to decommutate the PLS telemetry into individual instrument modes. Each mode generally covers one spacecraft rotation and contains a number of energy spectra (or mass spectra) at a number of angles. In LPW mode an instrument cycle spans an interval of 4 RIM's (242.67 seconds). During this interval the instrument collects approximately 28 individual modes of data. In RTS operation the cycle is different, and longer, due to the severely reduced telemetry rates. The energies, accumulation times, and sectoring schemes all vary from mode to mode, as with the LPW data. A major accomplishment of the RDR processing is to recast the PLS data in a format that is independent of the details of the operating modes. The resulting RDR data records are much easier to use. The PLS telemetry system is sensitive to data gaps. Repairing data due to embedded data gaps cannot be automated. Consequently measurements with gaps in the middle of an individual modes are not included in the RDR file. Fortunately, such gaps occurred infrequently. The recovery of LPW data was generally good. Multiple playbacks were made on each LPW recording to fill gaps. Calibration: E_STEP_1.TAB E-steps for electron detectors 14,16,18, and 20. E_STEP_2.TAB E-steps for ion dets 3,5,9,11 and mass spec dets 6,7 E_STEP_3.TAB E-steps for electron detectors 15,17, and 19. E_STEP_4.TAB E-steps for ion dets 4,8,10 and mass spec dets 1,2,12,13 M_STEP_1.TAB M-steps for the mass spectrometer channels SECTOR.TAB AACS sector angles CALIB_1.TAB Calibration factors to convert count rates to differential flux for electron detectors 14,16,18, and 20 CALIB_2.TAB Calibration factors to convert count rates to differential flux for ion detectors 3,5,9,11 and mass spec detectors 6 and 7. CALIB_3.TAB Calibration factors to convert count rates to differential flux for electron detectors 15,17, and 19. CALIB_4.TAB Calibration factors to convert count rates to differential flux for ion detectors 4,8,10 and mass spec detectors 1,2,12 and 13. Spacecraft Events: A time ordered file extracted from the As-Run Spacecraft Events Files (ARSEF) that provides the timing of events that are significant to the plasma experiment. These events include whether or not the instrument is 'on', which type of data are being acquired (RTS or LPW), the time of thruster firings, etc. The 'xxx' in the file name is the orbit name (i.e. G01 for orbit Ganymede 1). Software: ========= There is no software provided with this archive. Media/Format: ============= The data files are stored in a simple ASCII table form that is described by a detached PDS label (Table Object). Each table has the following structure: Col# Name Format Description ----------------------------------------------------------------------- 1 Time A24 Spacecraft event time (UTC) 2 SCLK A11 Spacecraft clock counter (RIM:mf) 3 Rate 1PE8.2 Count rate (counts/sec) 4 DetId I2 Detector Id (1-20) 5 E-Step I2 E/Q analyzer step (0-63) 6 M-Step I2 M/Q analyzer step (0-63) 7 Sector I3 AACS rotor spin angle (0-255 =2 PI). 8 Sample I2 Sample number 9 Accum F6.4 Accumulation time in seconds Data Coverage/Quality: ====================== This collection contains gaps in coverage. Many of these gaps were planned (insufficient telemetry coverage to provide continuous data) and others were not (telemetry dropouts, station outages, etc.). Some files may not be completely continuous in time. This is a result of how the data is transmitted and received: The PLS instrument has two analyzers: A and B. Each analyzer has its own sensors, high voltage supplies, analyzer plates, and data paths. The two analyzers normally start a spin-mode at the same time. And they normally end a spin-mode at the same time. Both data streams are buffered internally by the PLS data system and sent out to the spacecraft in a packetized telemetry scheme. Generally, the two streams are interleaved on a minor-frame-by-minor-frame basis, but if one analyzer does not have data ready and the other does then the telemetry that is ready is sent. (Note that the two analyzers have different numbers of sensors and create different quantities of data.) On the ground, the PLS telemetry stream is decommutated and separated into A and B data-sets for each spin-mode. The time tag attached to each A-data-set and each B-data-set is the time of the first telemetry packet containing some of that data. As soon as a complete data set has been decommutated on the ground it is written to the output file. And this is the key to understanding what is happening. Sometimes the first data-set to appear in the telemetry stream is also the first one to be completed. And sometimes the first data-set to appear in the telemetry is the last to be completed. It is essentially a random thing. It is crucial to note that PLS takes all of its data in a spin- synchronized fashion, not in a SCLK-synchronized fashion. We went to great pains to ensure that the data were obtained in well-defined spin sectors and in repeatable directions. Differences of a couple of minor-frames are not significant. The spin-phase angles are the quantities of importance.