Data Set Information
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| DATA_SET_NAME |
CASSINI COSMIC DUST ANALYZER CALIBRATED/RESAMPLED DATA
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| DATA_SET_ID |
CO-D-CDA-3/4/5-DUST-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : This data set includes all data from the Cassini Orbiter Cosmic Dust Analyzer (CDA), with the exception of the High Rate Detector (HRD) data which will be included in a separate data set. All data products in this data set are in tabular format. Each of the data products (or product types) are described below. CDA Area Table - The sensitive area of the CDA Impact Ionization Detector (IID) and Chemical Analyzer Target (CAT) is tabulated as a function of the incident angle with respect to the instrument axis. CDA Status History - Cassini mission and CDA configuration, tests and other events. Records are triggered by change in status affecting the sensitivity of the different CDA subsystems and mission events. CDA events Table - Detector responses and derived quantities from the Cassini dust detector as well as spacecraft geometry information for noise or dust events. CDA Spectra Table - Time-of-flight mass spectra peaks for individual impact events. CDA MP Signal Tables - (multiple files) Time-of-flight mass spectra signals for individual impacts. CDA QI Signal Tables - (multiple files) Ion signals for individual impacts. CDA QT Signal Tables - (multiple files) Electron signals for individual impacts as detected on the IID target. CDA QC Signal Tables - (multiple files) Electron signals for individual impacts as detected on the CAT target CDA QP Signal Tables - (multiple files) Induced charge signal for individual impacts at the entrance grid. CDA Table Settings - Table of voltages corresponding to voltage level codes and Coulomb threshold settings. CDA Counter Table - CDA impact counter time history file. There are 19 possible counter values. Each event is evaluated on-board by the flight software and receives one counter value. During the mission, successive improved versions of the flight software were uploaded. Hence, the event evaluation by the counter values evolved with time, allowing a better classification of the events. Calibration Issues : 1. Calibration of the Impact Ionization Detector The calibration principle of the impact ionization detector is similar to the Galileo instrument and Ulysses instrument [GRUENETAL1992A],[GRUENETAL1992B] (see CDAREFS.CAT). The calibration of the velocity-dependence of the signal rise times as well as the calibration of the mass-velocity-dependence of the plasma charge yields is based upon impact experiments in ground based laboratory accelerators. In such facilities, impacts of particles with known mass and velocity onto the flight spare unit can be studied. Besides laboratory experiments, in-flight measurements in the well-understood environment at 1 AU as well as measurements of Jovian stream particles contributed to the instrument calibration. Up to now the interference of the inner target (CAT) with the outer target (IID) is not entirely understood. Therefore, future calibration work will be focused on this issue. 2. Calibration of the Mass Analyser The calibration of the TOF mass spectrometer is still preliminary. In order to determine the mass resolution as well as the instrument characteristics, particles of known composition were shot in the Heidelberg dust accelerator onto the flight spare unit. Calibration data for both subsystems, will be provided in subsequent deliveries. Amplification Changes : The amplification factors of three instrument channels changed. Affected are the channels QC (Electron signal, Chemical Analyser Target), QA (Ion signal, Chemical Analyser Grid) and QT (Electron signal, Impact Ionisation Target). The amplification factor determines the amount of measured impact charge and is given by the conversion from dn-values to charge values (Coulomb). QT channel ---------- In total, two amplification changes were observed. The amplification droped by a factor of 195 at a time between 2008-039T14:13:55 and 2008-039T19:50:15 (noise analysis of channel QT). The time of 2008-039T18:00:00 is taken for the change in conversion. A second change in amplification occured in the timeframe 2009-224T18:30:00 and 2009-224T23:30:00 (noise analysis). The drop factor after this time range is 22. The time of this change for archiving purposes is set to 2008-224T22:00:00. Possible background/explanation: -------------------------------- A RPXing occured at 2008-039T17:51 at 3.46 Saturn radii distance. On day 224T21:06 the Enceladus flyby occured (E4, rev 80) with an altitude of only 50 km above the surface. QC channel ---------- Amplification dropped by factor of 140 at a time which lies between 2008-283T16:02:41 and 2008-283T21:31:02. The time of change for archiving is set to : 2008-283T20:00:00. Background: ----------- An Enceladus flyby occured at 2008-283T19:06 (E5, rev 88) with an altitude of 25 km and FSW 12.2 was used. Status as of 212-2009: Drop factor still 140 (amplitude of TP3 : 131 dn) QA channel ---------- The noise level of channel QA changed as well. However, this channel is not digitized and no raw data information is available. A noise test showed, that channel QA became insensitive in the time range between 2008-208 and 2008-261. For overall calibration this change has no effect and no changes in data processing is required for DPS work.
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| DATA_SET_RELEASE_DATE |
2005-07-01T00:00:00.000Z
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| START_TIME |
1997-03-25T12:00:00.000Z
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| STOP_TIME |
N/A (ongoing)
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| MISSION_NAME |
CASSINI-HUYGENS
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| MISSION_START_DATE |
1997-10-15T12:00:00.000Z
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| MISSION_STOP_DATE |
N/A (ongoing)
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| TARGET_NAME |
DUST
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| TARGET_TYPE |
DUST
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| INSTRUMENT_HOST_ID |
CO
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| INSTRUMENT_NAME |
COSMIC DUST ANALYZER
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| INSTRUMENT_ID |
CDA
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| INSTRUMENT_TYPE |
COSMIC DUST ANALYZER
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| NODE_NAME |
Small Bodies
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| ARCHIVE_STATUS |
LOCALLY ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Events table ----------------- Some values described in the PDS label table could not be provided in this volume and are set to their missing constant value. PLEASE CONTACT THE CDA TEAM BEFORE USING THE DATA FOR AN UPDATE OF THE CONFIDENCE LEVEL. Efforts will be made to have those data provided in the subsequent delivery. The missing values are: - Particle speed and particle speed error factor The reliable determination of the impactors velocity depends on ground calibrations. For technical reasons, calibrations could be performed only with a limited amount of material. In particular, calibration data for ice particles are not available. However, recent measurements of icy E ring particles during the early Cassini tour reveal a strong dependance of the impact velocity determination upon impactor material, and allow in-flight calibration. Calibrated velocity data will therefore be provided only in future delivery, when a better understanding of the instrument response will be reached. - Particle mass and particle mass error factor As the mass determination of an impacting particle requires the determination of its impact velocity, the particle mass can not be derived accuratly right now. - Target flag This flag, indicating where a dust particle impacted on the target, should be provided in a future delivery, as identification routines become more reliable. - Event quality This flag, evalutating the quality of an event, should be provided in a future delivery, as event evaluation routines become more reliable. - Particle charge This value will be provided in a future delivery. - Particle charge error This value will be provided in a future delivery. While the counter value is provided for each event, as returned by the flight software, a detailed documentation about the meaning of the different counter values is missing. However, the CDA team plan to provide this documentation a bit later. This comment is also valid for the counter table. CDASPECTRA table ----------------- As of the delivery date, the data contained in this table can not be provided. Some data (like the number and position of peaks in the TOF spectra) need more time to be derived reliably, and do not belong to the minimum PDS requirement, as level 2 data. However, they will be provided in a future delivery.
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| CITATION_DESCRIPTION |
Altobelli, N., S. Kempf, and R. Srama, Cassini Cosmic Dust Analyser Data V1.0, CO-D-CDA-3/4/5-DUST-V1.0, NASA Planetary Data System, 2005.
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| ABSTRACT_TEXT |
The Cosmic Dust Analyzer (CDA) is an instrument on the Cassini Orbiter that studies the physical properties of dust particles hitting the detector. This data set includes all data from the CDA with the exception of the High Rate Detector (HRD). Please refer to [SRAMAETAL2004B] (see CDAREFS.CAT) for a detailed CDA description.
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| PRODUCER_FULL_NAME |
NICOLAS ALTOBELLI
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| SEARCH/ACCESS DATA |
Asteroid/Dust SBN Website
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