Data Set Information
DATA_SET_NAME STARDUST DFMI WILD 2 ENCOUNTER EDR DATA
DATA_SET_ID SDU-C-DFMI-2-EDR-WILD2-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview: : This data set contains raw data collected by the Dust Flux Monitor Instrument (DFMI) flown on board the STARDUST spacecraft during the Wild 2 comet encounter on January 2, 2004. The data in this archive are organized into one table in standard PDS format. This table records dust events which resulted from the encounter with the particles surrounding comet Wild 2. The data in the table spans a 33 minute period surrounding the encounter with Wild 2. Parameters : The primary data parameters contained in the DFMI data table are counts of the particle impacts measured by the instrument sensors. Note Regarding Acoustic Sensor Counts ------------------------------------- At the external peer review reviewers noted that the acoustic sensor values around close approach, particularly the high and low bumpers, did not seem reasonble because the cumulative count was not strictly monotonically increasing. The DFMI team provided the following clarification: The acoustic sensor counters counted the number of time intervals that the signal from the sensor exceeded a certain threshold. This meant that a large impact would produce a large number of counts and a small one a small number. Since the count rate was generally expected to be very low, the possibility of confusion (i.e. not knowing if the number of counts was due to one, two or more actual impacts) was not expected to be a major problem. The strength of this approach was that an indication of the mass of particles could be obtained even when the peak signal from the sensor saturated the instrument. The disadvantage was the possibility of multiple impacts in a counting period (0.1 to 1 sec depending on PVDF trigger) and the possibility of multiple counter overflow. As the acoustic subsystem was a last minute addition after the data rates had already been fixed, the counters had a full range of only 0 to 255. This explains the steps in the counts. The counters start at zero and increment each time there is an impact. Several times during the encounter (~9), the counters overflow. From the statistical analysis it looks as if there are no multiple overflows (i.e., counts greater than 256 within a time interval). Processing : The Stardust DFMI instrument output consisted of binary data records containing counter values for each of the sensor channels. On board the spacecraft these records were packetized by the spacecraft's flight software and downlinked within packets in the spacecraft telemetry stream. A suite of software -- developed and run by the Stardust Data Management and Archive Team (DMA) and collectively referred to as Stardust Science Telemetry Processing Software -- retrieved packets with DFMI data from the Telemetry Data Server(s)(TDS) used by the Stardust Project, stripped off ground system and spacecraft packet headers, extracted counter values and housekeeping information from the packets, augmented them with a number of geometry parameters computed using mission SPICE geometry data and operating temperature information extracted from channelized telemetry, and output all the above-mentioned parameters in PDS text table format. Data : The DFMI data file provided in this data set contains counts of the particle impacts measured by the instrument sensors, housekeeping values downlinked in the same packets as counts, housekeeping values downlinked in the channelized telemetry, and a number of geometry parameters computed using SPICE kernels. This file is a plain ASCII text file containing a single PDS-style table with fixed-width, comma-delimited columns. The table is preceded by a CSV header. The file is accompanied by a detached PDS label, described in detail in the ONLABELS.TXT document included in the archive. The format of the table columns is defined by an external table format file, pointed to by the label. Calibration : The best available calibration data as of this writing (October 2005) are the values listed in Table 4 of Tuzzolino, et al. (2003). The DFMI team note: The main uncertainty in calibration comes from the fact that the calibration was done for soda lime glass and aluminum particles but real particles are of different composition and we do not know how well this calibration reproduces, say, organic, ice, or carbon particles. Also, the calibration samples were spheres whereas the real particles are irregular. The influence of this is also hard to estimate quantitatively. The team is convinced that the slope of the calibration lines is correct but the reference point can be shifted up or down by the way they cannot estimate. Ancillary Data : Each of the records in the DFMI table includes a number of derived geometry parameters. These parameters were computed using the following SPICE kernels, archived in the Stardust SPICE data set, SDU-C-SPICE-6-V1.0: Kernel Type File Name ------------ ------------------------ LSK naif0007.tls PCK pck00007.tpc SCLK sdu_sclkscet_00105.tsc FK sdu_v17.tf SPKs sdu_l_2003_w2.bsp sdu_w2_opnav.bsp CKs sdu_sc_rec_2003_w2_v2.bc sdu_sc_rec_w2_opnav.bc ------------ ------------------------ Coordinate System : The geometry items provided in the EDR table are relative to the ecliptic reference frame of J2000 (Ecliptic North/Equinox vector of 2000 JAN 01 12:00 TDB.) Software : The data in this data set are in standard PDS format and, therefore, can be displayed by a number of PDS-provided tools or loaded into commercial programs that support comma-delimited formats. For this reason no special processing software is included in this data set. Contact Information : For any questions regarding the data in this archive, contact: Dr. Tony Tuzzolino, Stardust DFMI Science Lead
DATA_SET_RELEASE_DATE 2004-07-02T00:00:00.000Z
START_TIME 2004-01-02T07:08:15.442Z
STOP_TIME 2004-01-02T07:41:17.725Z
MISSION_NAME STARDUST
MISSION_START_DATE 1999-02-07T12:00:00.000Z
MISSION_STOP_DATE 2006-01-16T12:00:00.000Z
TARGET_NAME 81P/WILD 2 (1978 A2)
TARGET_TYPE COMET
INSTRUMENT_HOST_ID SDU
INSTRUMENT_NAME DUST FLUX MONITOR INSTRUMENT
INSTRUMENT_ID DFMI
INSTRUMENT_TYPE DUST IMPACT DETECTOR
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : During the processing of the data in preparation for delivery with this volume, the structure of each data packet was verified. This verification included detection of both the sync word and the length of each packet, which assured that all packets were complete and not damaged. Samples of the data were plotted to help validate them. Review : This data was reviewed by the DFMI science team members as part of the post-encounter data analysis activities. Data Coverage and Quality : This set includes all data produced by the DFMI instrument during the time it was on for the Wild 2 encounter. None of the packets used in the production of this data were damaged in any way. Limitations : None.
CITATION_DESCRIPTION Semenov, B.V., A.J. Tuzzolino, J.A.M. McDonnell, H.W. Taylor, and C.H. Acton, STARDUST DFMI WILD 2 ENCOUNTER EDR DATA, SDU-C-DFMI-2-EDR-WILD2-V1.0, NASA Planetary Data System, 2004.
ABSTRACT_TEXT This data set contains raw data collected by the Dust Flux Monitor Instrument (DFMI) flown on board the STARDUST spacecraft during the Wild 2 comet encounter on January 2, 2004. The data in this archive are organized into one table in standard PDS format. This table records dust events which resulted from the encounter with the particles surrounding comet Wild 2. The data in the table spans a 33 minute period surrounding the encounter with Wild 2.
PRODUCER_FULL_NAME STARDUST DATA MANAGEMENT AND ARCHIVE TEAM
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