PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " For New horizons, this LABEL_REVISION_NOTE is used to keep track of when the template is used to generate a DATASET.CAT file for a data set. Brian Carcich - Publication date: 2014-11-12 - NH-internal archive software version: V2.0 " RECORD_TYPE = STREAM INSTRUMENT_HOST_NAME = "NEW HORIZONS" OBJECT = DATA_SET DATA_SET_ID = "NH-J-SDC-3-JUPITER-V3.0" OBJECT = DATA_SET_INFORMATION START_TIME = 2006-12-26T18:11:58.381 STOP_TIME = 2007-06-26T19:38:43.419 DATA_SET_DESC = " Data Set Overview ================= This data set contains Calibrated data taken by New Horizons Student Dust Counter instrument during the JUPITER mission phase. The mission of the SDC is to analyze the size and distribution of Interplanetary Dust Particles (IDPs) along the New Horizon trajectory to the Kuiper Belt. SDC comprises twelve thin, permanently polarized polyvinylidene fluoride (PVDF) plastic film sensors, with a combined area of about 0.1 m**2, mounted on the top surface of a support panel and normal to the spacecraft ram direction (flight velocity). In addition, there are two reference sensors, identical to the top surface sensors, mounted on the back side of the detector support panel and protected from any dust impacts, used to monitor background noise levels. An impacting IDP causes a depolarization charge when it penetrates the PVDF film on one of the sensors. That charge is then measured by that sensor's electronics (channel); if the measurement is above a preset level, the instrument records and stores the event for later downlink. The level preset is adjusted based on in-flight Noise Floor Calibrations, and there are extensive autonomy rules adjusting SDC behavior, even turning channels off for up to thirty days at a time, to avoid overloading the storage system with noise. Some time between instrument delivery to the spacecraft and launch, the detector on one channel began exhibiting symptoms of degraded electrical contacts to the PVDF; data from that channel (11) are still processed but should be ignored. SDC was designed to detect events for particles down to about one picogram at Pluto; that detection limit is lower earlier in the mission where the spacecraft velocity was higher. The SDC instrument has a temperature- and velocity-dependent calibration, first converting the raw measurement to charge, then converting charge to particle mass. The common data product is a binary table of downlinked event data: time; sensor channel; magnitude; threshold magnitude. Associated data products are housekeeping data such as instrument temperatures for calibration and near-in-time spacecraft thruster events, which may induce false positives i.e. SDC events not caused by IDPs. For the Jupiter encounter mission phase, SDC collected no science data during the Jupiter flyby, as the requisite spacecraft configuration prevented SDC from operating. There were some very sparse data taken from December, 2006 through April, 2007, and some of very short (or zero) duration after the Jupiter flyby from April, 2007 through June, 2007. Every observation provided in this data set was taken as a part of a particular sequence. A list of these sequences has been provided in file DOCUMENT/SEQ_SDC_JUPITER.TAB. N.B. Some sequences provided may have no corresponding observations. For a list of observations, refer to the data set index table; this is typically INDEX.TAB initially in the INDEX/ area of the data set; there is also a file SLIMINDX.TAB in INDEX/ that summarizes key information relevant to each observation, including which sequence was in effect and what target was likely intended for the observation. Version ======= This is VERSION 3.0 of this data set. The pipeline (see Processing below) was re-run on these data for each version since the first (V1.0). As a result, ancillary information, such as observational geometry and time (SPICE), may be updated. This will affect, for example, the calibration of the data if parameters such as the velocity or orientation of the target relative to the instrument, or the recorded target itself, have changed. See the following sections for details of what has changed over each version since the first (V1.0). Note that even if this is not a calibrated data set, the calibration changes are listed as the data will have been re-run and there will be updates to the calibration files, to the documentation and to the steps required to calibrate the data. SDC updates for JUPITER Data Sets V3.0 ============== Updated the electronics box temperature calibration; the full calibration, including all model parameters and coefficients, is described in [JAMESETAL2010]. Updated the dust impact velocity calculation to use the Ecliptic J2000 reference frame, instead of the Earth Mean frame, to estimate Keplerian orbits; this was a small correction as the spacecraft trajectory is generally near the line to the first point of Aries. Added the stimulus calibration table, in file DOCUMENT/SDC_STIM_Vnnnn.TAB, so the user can assess when these operations may have generated false positive events. SDC updates for JUPITER Data Sets V2.0 ============== None of the formats for the Calibrated data have changed. The data files look the same, including the data formats. The changes were improvements to the processing code. There were 3 changes made to the code: Change to dust impact velocity assumption ----------------------------------------- An assumption is needed for the the dust impact velocity to calculate its mass. Before this update the pipeline used only the normal component of the total velocity between the dust and instrument (assuming the particle is in Keplerian orbit). Now this has been changed to the total relative velocity of the particle (still assumed to be in Keplerian orbit) and the instrument. Using multiple sensors for temperature correction ------------------------------------------------- There are two thermistors on the analog board. The analog board temperature is used for calibrating a particular channel on the board. Before this update, for a given channel the temperature of the closest thermistor to a that channel. Now a linear fit to the temperatures is used. New charge-velocity-mass calibration curve ------------------------------------------ The calibrated data contains the mass of the particle. The charge to mass curve used to be Q=3.18E17*m^1.3*v^3.0 where m is the mass, Q is the charge and v is the relative speed. This was the Simpson-Tuzzolino curve. The new curve is a function of detector temperature as well: Q=(1.15E15+6.75E12*T)*m^1.052*v^2.883 where T is the temperature. A paper with this new calibration curve was published in 2010 [JAMESETAL2010]. Processing ========== The data in this data set were created by a software data processing pipeline on the Science Operation Center (SOC) at the Southwest Research Institute (SwRI), Department of Space Studies. This SOC pipeline assembled data as FITS files from raw telemetry packets sent down by the spacecraft and populated the data labels with housekeeping and engineering values, and computed geometry parameters using SPICE kernels. The pipeline did not resample the data. SDC data calibration is a two-step process: raw data numbers from a particle impact are converted to a charge, and the charge is converted to a particle mass via the ground calibrations obtained at a dust acceleration facility. Refer to the provided documentation for more information. The latest calibration procedure is described in James et al., (2010) [JAMESETAL2010]. Data ==== The observations in this data set are stored in data files using standard Flexible Image Transport System (FITS) format. Each FITS file has a corresponding detached PDS label file, named according to a common convention. The FITS files may have image and/or table extensions; see the PDS label plus the DOCUMENT files for a description of these extensions and their contents. This Data section comprises the following sub-topics: - Filename/Product IDs - Instrument description - Other sources of information useful in interpreting these Data - Visit Description, Visit Number, and Target in the Data Labels Filename/Product IDs -------------------- The filenames and product IDs of observations adhere to a common convention e.g. ALI_0123456789_0X0AB_ENG_1.FIT ^^^ ^^^^^^^^^^ ^^^^^ ^^^ ^\__/ | | | | | ^^ | | | | | | | | | | | +--File type (includes dot) | | | | | - .FIT for FITS file | | | | | - .LBL for PDS label | | | | | - not part of product ID | | | | | | | | | +-- Version number from the SOC | | | | (Science Operations Center) | | | | | | | +--ENG for CODMAC Level 2 data * | | | SCI for CODMAC Level 3 data * | | | | | +--Application ID (ApID) of the telemetry data | | packet from which the data come | | | +--MET (Mission Event Time) i.e. Spacecraft Clock | +--Instrument designator * For those datasets where the NH project is delivering CODMAC Level 1 & 2 data (REX & PEPSSI), ENG and SCI apply to CODMAC Level 1 & 2 data, respectively. Instrument Instrument designators ApIDs =========== ================================== ============= SDC SDC 0X700 * Not all values in this range are in this data set There are other ApIDs that contain housekeeping values and other values. See the documentation for more details. Here is a summary of the types of files generated by each ApID along with the instrument designator that go with each ApID: ApIDs Data product description/Prefix(es) ===== =================================== 0x700 - SDC Science Data/SDC Instrument description ---------------------- Refer to the following files for a description of this instrument. CATALOG SDC.CAT DOCUMENTS SDC_SSR.* SOC_INST_ICD.* NH_SDC_V###_TI.TXT (### is a version number) Other sources of information useful in interpreting these Data -------------------------------------------------------------- Refer to the following files for more information about these data NH Trajectory tables: /DOCUMENT/NH_MISSION_TRAJECTORY.* - Heliocentric /DOCUMENT/NH_TRAJECTORY.* - Jupiter-centric SDC Field Of View definitions: /DOCUMENT/NH_FOV.* /DOCUMENT/NH_SDC_V###_TI.TXT Visit Description, Visit Number, and Target in the Data Labels --------------------------------------------------------------- The observation sequences were defined in Science Activity Planning (SAP) documents, and grouped by Visit Description and Visit Number. The SAPs are spreadsheets with one Visit Description & Number per row. A nominal target is also included on each row and included in the data labels, but does not always match with the TARGET_NAME field's value in the data labels. In some cases, the target was designated as RA,DEC pointing values in the form ``RADEC=123.45,-12.34'' indicating Right Ascension and Declination, in degrees, of the target from the spacecraft in the Earth Equatorial J2000 inertial reference frame. This indicates either that the target was either a star, or that the target's ephemeris was not loaded into the spacecraft's attitude and control system which in turn meant the spacecraft could not be pointed at the target by a body identifier and an inertial pointing value had to be specified as Right Ascension and Declination values. The PDS standards do not allow putting a value like RADEC=... in the PDS TARGET_NAME keyword's value; in those cases the PDS TARGET_NAME value is set to CALIBRATION. Ancillary Data ============== The geometry items included in the data labels were computed using the SPICE kernels archived in the New Horizons SPICE data set, NH-X-SPICE-6-JUPITER-V1.0. Every observation provided in this data set was taken as a part of a particular sequence. A list of these sequences has been provided in file DOCUMENT/SEQ_SDC_JUPITER.TAB. In addition, the sequence identifier (ID) and description are included in the PDS label for every observation. N.B. While every observation has an associated sequence, every sequence may not have associated observations; that is, some sequences may have failed to execute due to spacecraft events (e.g. safing) and there will be observations associated with those sequences. No attempt has been made during the preparation of this data set to identify if any, or how many, such empty sequences there are, so it is up to the user to compare the times of the sequences to the times of the available observations from the INDEX/INDEX.TAB table to identify such sequences. Time ==== There are several time systems, or units, in use in this dataset: New Horizons spacecraft MET (Mission Event Time or Mission Elapsed Time), UTC (Coordinated Universal Time), and TDB Barycentric Dynamical Time. This section will give a summary description of the relationship between these time systems. For a complete explanation of these time systems the reader is referred to the documentation distributed with the Navigation and Ancillary Information Facility (NAIF) SPICE toolkit from the PDS NAIF node, (see http://naif.jpl.nasa.gov/). The most common time unit associated with the data is the spacecraft MET. MET is a 32-bit counter on the New Horizons spacecraft that runs at a rate of about one increment per second starting from a value of zero at 19.January, 2006 18:08:02 UTC or JD2453755.256337 TDB. The leapsecond adjustment (DELTA_ET = ET - UTC) over this dataset is 65.184s. The data labels for any given product in this dataset usually contain at least one pair of common UTC and MET representations of the time at the middle of the observation. Other portions of the products, for example tables of data taken over periods of up to a day or more, will only have the MET time associated with a given row of the table. For the data user's use in interpreting these times, a reasonable approximation (+/- 1s) of the conversion between Julian Day (TDB) and MET is as follows: JD TDB = 2453755.256337 + ( MET / 86399.9998693 ) For more accurate calculations the reader is referred to the NAIF/SPICE documentation as mentioned above. Reference Frame =============== Geometric Parameter Reference Frame ----------------------------------- Earth Mean Equator and Vernal Equinox of J2000 (EMEJ2000) is the inertial reference frame used to specify observational geometry items provided in the data labels. Geometric parameters are based on best available SPICE data at time of data creation. Epoch of Geometric Parameters ----------------------------- All geometric parameters provided in the data labels were computed at the epoch midway between the START_TIME and STOP_TIME label fields. Software ======== The observations in this data set are in standard FITS format with PDS labels, and can be viewed by a number of PDS-provided and commercial programs. For this reason no special software is provided with this data set. Contact Information =================== For any questions regarding the data format of the archive, contact New Horizons SDC Principal Investigator: Mihaly Horany, LASP, University of Colorado Mihaly Horanyi Laboratory for Atmospheric and Space Physics University of Colorado Boulder, CO 80302-0392 USA " CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= During the processing of the data in preparation for delivery with this volume, the packet data associated with each observation were used only if they passed a rigorous verification process including standard checksums. In addition, raw (Level 2) observation data for which adequate contemporary housekeeping and other ancillary data are not available may not be reduced to calibrated (Level 3) data. This issue is raised here to explain why some data products in the raw data set, NH-J-SDC-2-JUPITER-V3.0, may not have corresponding data products in the calibrated data set, NH-J-SDC-3-JUPITER-V3.0. Data coverage and quality ========================= Every observation provided in this data set was taken as a part of a particular sequence. A list of these sequences has been provided in file DOCUMENT/SEQ_SDC_JUPITER.TAB. N.B. Some sequences provided may have zero corresponding observations. Refer to the Confidence Level Overview section above for a summary of steps taken to assure data quality. Caveat about TARGET_NAME in PDS labels and observational intent =============================================================== A fundamental truth of managing data from some spacecraft missions is that the intent of any observation is not suitable for insertion into the command stream sent to the spacecraft to execute that observation. As a result, re-attaching that intent to the data that are later downlinked is problematic at best; for New Horizons that task is made even more difficult as the only meta-data that come down with the observation is the unpredictable time of the observation. The task is made yet even more difficult because uplink personnel, who generate the command sequences and initially know the intent of each observation, are perpetually under deadlines imposed by orbital mechanics and can rarely be spared for the time-intensive task of resolving this issue. To make a long story short, the downlink team on New Horizons has created an automated system to take various uplink products, decode things like Chebyshev polynomials in command sequences representing celestial body ephemerides for use on the spacecraft to control pointing, and infer from those data what the most likely intended target was at any time during the mission. This works well during flyby encounters and less so during cruise phases and hibernation. The point to be made is that the user of these PDS data needs to be cautious when using the TARGET_NAME and other target-related parameters stored in this data set. This is less an issue for the plasma and particle instruments, more so for pointing instruments. To this end, the heliocentric ephemeris of the spacecraft, the spacecraft-relative ephemeris of the inferred target, and the inertial attitude of the instrument reference frame are provided with all data, in the J2000 inertial reference frame, so the user can check where that target is in the Field Of View (FOV) of the instrument. Furthermore, for pointing instruments with one or more spatial components to their detectors, a table has been provided in the DOCUMENT/ area with XY (two-dimensional) positions of each inferred target in the primary data products; if those values are several thousand pixels off of a detector array, it is a strong indication that the actual target of that observation is something other than the inferred target, or no target at all e.g. dark sky. Review ====== This dataset was peer reviewed and certified for scientific use on TBD. " ABSTRACT_DESC = " This data set contains Calibrated data taken by the New Horizons Student Dust Counter instrument during the Jupiter encounter mission phase. This is VERSION 3.0 of this data set. " CITATION_DESC = " Horanyi, M., NEW HORIZONS Calibrated SDC JUPITER ENCOUNTER V3.0, NH-J-SDC-3-JUPITER-V3.0, NASA Planetary Data System, 2014. " DATA_OBJECT_TYPE = "TABLE" DATA_SET_COLLECTION_MEMBER_FLG = "N" DATA_SET_NAME = "NEW HORIZONS SDC JUPITER ENCOUNTER CALIBRATED V3.0" DATA_SET_RELEASE_DATE = 2014-11-12 DATA_SET_TERSE_DESC = " Calibrated data taken by New Horizons Student Dust Counter instrument during the JUPITER mission phase. This is VERSION 3.0 of this data set. " DETAILED_CATALOG_FLAG = "N" PRODUCER_FULL_NAME = "JOSEPH PETERSON" END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "NEW HORIZONS" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "JAMESETAL2010" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = "DUST" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = "NH" INSTRUMENT_ID = "SDC" END_OBJECT = DATA_SET_HOST END_OBJECT = DATA_SET END