MESSENGER Software Interface Specification for the Neutron Spectrometer Experiment Data Records Version 4.4 Prepared by Raymond Espiritu Erick Malaret Applied Coherent Technology Corporation 112 Elden St. Suite K Herndon, VA 22304 http://www.actgate.com Document Review This document and the archive it describes have been through PDS Peer Review and have been accepted into the PDS archive. David Lawrence, MESSENGER NS Instrument Scientist, has reviewed and approved this document. Susan Slavney, PDS Geosciences Node Representative, has reviewed and approved this document. Susan Ensor, MESSENGER Science Operations Center Lead, has reviewed and approved this document. Revision History Version Number Date Section Changes 4 12/22/2008 N/A * Start of revision history: version included in MESSENGER PDS Release 4. 4.1 11/9/2009 5.3.4.9 * Changed ROW_BYTES from 79 to 80 for NS Calibration/Diagnostic EDR. The extra byte comes from the line-feed character that was missing previously. 4.2 6/15/11 Document Review, Revision History, 8 * Replaced signature page with document review information * Changed "periherm" to "apoherm" in description of orbit start times for orbit numbering. * Add section column to revision history table. 4.3 5/25/12 2, 7 * Change document name Data Management and Science Analysis Plan to Data Management and Archiving Plan. Update references. * Reference MESSENGER Data Management and Archiving Plan for release schedule and remove delivery schedule table from this document. 4.4 7/7/15 Title and various sections, 5.4.3 * Change "Experimental Data Record" to "Experiment Data Record" in document name and text. * Note use of clock partitions in time tags in product labels following January 8, 2013 S/C clock reset. Table of Contents 1. Purpose and Scope of Document 6 1.1. Purpose 6 1.2. Scope 6 2. Applicable Documents 6 3. Relationships with other Interfaces 7 4. Roles and Responsibilities 7 5. Data Product Characteristics and Environment 7 5.1. Instrument Overview 7 5.2. Data Product Overview 9 5.3. Data Processing 13 5.3.1. Data Processing Level 13 5.3.2. Data Product Generation 13 5.3.3. Data Flow 14 5.3.4. Labeling and Identification 17 5.4. Standards Used in Generating Data Products 24 5.4.1. PDS Standards 24 5.4.2. Coordinate Systems 24 5.4.3. Time Standards 24 5.4.4. Data Storage Conventions 25 5.5. Data Validation 25 6. Detailed Data Product Specification 25 6.1. Data Product Structure and Organization 25 6.2. Data Format Description 26 6.3. Label and Header Descriptions 26 6.3.1. PDS Label File Format 26 6.3.2. Table Object Keyword Definitions 28 6.4. File Naming Conventions 28 6.5. Directory Structure and Contents for Static Volumes 29 6.5.1. Directory Contents 30 6.6. Archive Volume and File Size 31 7. Archive Release Schedule to PDS 31 8. Appendices 32 8.1. NS_FULLSPE.FMT Table Fields 32 8.2. NS_SPE.FMT Table Fields 39 8.3. NS_EVT.FMT Table Fields 44 8.4. NS_GCR.FMT Table Fields 46 8.5. NS_GAB.FMT Table Fields 49 8.6. NS_SHORTSCI.FMT Table Fields 50 8.7. NS_TCC.FMT Table Fields 54 8.8. NS_STATUS.FMT Table Fields 55 8.9. NS_CAL_DIAG.FMT Table Fields 71 8.10. NS_CMDECHO.FMT Table Fields 73 8.11. SPICE Kernel Files used in MESSENGER Data Products 75 8.12. CODMAC/NASA Definition of Processing Levels 75 8.13. MESSENGER Glossary and Acronym List 76 1. Purpose and Scope of Document 1.1. Purpose This document will serve to provide users of the MESSENGER Neutron Spectrometer (NS) data products with a basic description of the Neutron Spectrometer instrument and Experiment Data Records (EDRs). The NS EDR data products are deliverables to the Planetary Data System (PDS) and the scientific community that it supports. Note that the Gamma Ray Spectrometer (GRS) and Neutron Spectrometer instruments are generally referred to together as the Gamma-Ray and Neutron Spectrometer (GRNS) instrument. However they are two separate instruments, each with its own Event Processing Unit (EPU) and the data products are described within the specific SIS of each instrument. This document is both an EDR data product SIS and an EDR archive volume SIS. 1.2. Scope This Software Interface Specification (SIS) document is of a very limited scope due to the EDRs being of a very low-level. It does not provide a description or understanding of the NS instrument or its EDRs at a detailed level. It is not intended for general use by data analysts outside of the MESSENGER project and it is not intended for the typical science user to access the EDRs routinely. Rather, the EDRs are mainly useful as an input to producing the Calibrated Data Record (CDR) and Reduced Data Record (RDR) products. There will be a separate PDS data archive for the CDR and RDR products and these products will be described by a separate RDR SIS. Data are converted to engineering and science units from raw EDR units (such as conversion of bins to energies and binary numbers to temperatures) in the CDRs, which will be accompanied by calibration reports describing the calibration process. CDR and RDR products planned to be produced are identified in the MESSENGER Data Management and Archiving Plan which also contains the schedule for their delivery to PDS. 2. Applicable Documents The MESSENGER NS SIS is responsive to the following Documents: * Planetary Data System (PDS) Standards Reference, Aug 1, 2003, Version 3.6. JPL D-7669, Part-2. * Neutron Spectrometer Flight Software Specification 7386-9042, June 2, 2003; Revision Memo SIE-04-008, January 13, 2004. * MESSENGER Data Management and Archiving Plan, The Johns Hopkins University, APL. Document ID number 7384-9019 * MESSENGER Mercury: Surface, Space Environment, Geochemistry, Ranging; A mission to Orbit and Explore the Planet Mercury, Concept Study, March 1999. Document ID number FG632/99-0479 * Appendix 7 to the discovery program Plan; Program Level Requirement for the MESSENGER Discovery project; June 20, 2001. * The MESSENGER Gamma-ray and Neutron Spectrometer, Space Science Reviews 131, 339-391, 2007. 3. Relationships with other Interfaces The NS data products are stored on Hard Disk and in an SQL (Structured Query Language) relational database for rapid mission access during mission operations. The data products will be electronically transferred to the PDS Geosciences Node according to the delivery schedule in the MESSENGER Data Management and Archiving Plan. The data in the EDR files themselves will be stored in a PDS binary table object with the exception of the NS Status and NS Calibration/Diagnostic EDRs. These two EDRs will consist of data stored in PDS ASCII table objects. 4. Roles and Responsibilities The roles and responsibilities of the instrument teams, Applied Physics Lab (APL), Applied Coherent Technology (ACT), and the Planetary Data System (PDS) are defined in the MESSENGER Data Management and Archiving Plan. 5. Data Product Characteristics and Environment 5.1. Instrument Overview The Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) mission is designed to orbit Mercury following two flybys each of Venus and Mercury. It launched in August 2004 and will use several flybys of Venus and Mercury to achieve an orbit insertion around Mercury on March 2011. Initial data collection will begin during the first two flybys of Mercury, and will primarily consist of global mapping and measurements of the surface, atmosphere and magnetosphere composition. MESSENGER will then remain in orbit for the rest of the nominal mission, which is scheduled to end in March 2012 [see MESSENGER Data Management and Archiving Plan for extended mission updates]. Once in orbit around Mercury it will begin a series of observations using multiple instruments. These observations will provide data to answer questions about the nature and composition of Mercury's crust, tectonic history, the structure of the atmosphere and magnetosphere, and the nature of the polar caps. The Neutron Spectrometer (NS) is one of the instruments onboard the MESSENGER spacecraft. It is designed to observe the neutrons emitted from Mercury's surface in the thermal, epithermal, and fast energy ranges, from ~0. 01 eV to 7 MeV, that are produced by nuclear reactions by the cosmic ray background (CRB). Elements that can be most readily identified by the NS include those that strongly moderate and absorb neutrons (hydrogen and rare earths). The approximate average element atomic mass can also be estimated. It may be feasible for the NS to measure the water content at Mercury's north pole. The MESSENGER NS consists of a sandwich of three scintillators that are optically decoupled from each other. The first and third scintillators are lithium (6Li)-glass scintillators (LiG) which respond to a combination of thermal and epithermal neutrons that span the range between 0 eV and about 1 keV. (Thermal neutrons correspond to 0 to ~ 0.025 eV and epithermal neutrons correspond to ~ 0.025 eV up to ~ several keV.) The middle scintillator is a borated plastic (BP) scintillator that responds only to epithermal and fast neutrons, since it is surrounded by thermal neutron absorbers (LiG on each end and wrapped with a sheet of gadolinium). Each of these scintillators generates a neutron spectrum (or histogram) When a neutron interacts with one of these scintillators, a charge is generated in its electronics. The charge is converted into one of 64 LiG channels (32 for the old NS spectra in Sec. 5.2) or 64 (BP) channels, which are correlated to the energy deposited in the scintillators. Over a commanded integration time period the distribution of events (neutron interactions) as a function of equivalent-electron energy (channel number) is recorded. The result is a histogram of the number of events in each channel accumulated over the integration period, which is designated as a singles prompt neutron spectrum. Three such spectra are produced, one by each lithium-glass (LiG) scintillator and one by the borated plastic (BP) scintillator. (Some of the neutrons detected in the BP scintillator will be downscattered to thermal energies and be detected in the LiG scintillators.) Time-correlated events in the BP scintillator provide a measure of the neutron energies of the flux of fast neutrons 0.7 MeV < E < 7 MeV). These events are defined by a time-correlated pair of interactions in the BP scintillator. The first pulse corresponds to a neutron that loses all of its energy (above detection threshold and thermal neutron energies) in the BP scintillator, since the second pulse corresponds to the energy released by the 10B(n,alpha)7Li reaction after the neutron has slowed down to thermal energies and has been absorbed in the scintillator. The signature of the time-correlated events includes the pulse height (measure of energy) of the first event (called the prompt energy, Ep), the pulse height of the second event that corresponds to the Q-value of the 10B(n,alpha)7Li reaction (called the capture energy, Ec), and the time between first and second events (or Time To Second Pulse, TTSP). When a fast neutron interacts with the BP scintillator, a charge is generated corresponding to Ep. The charge is converted into channels, which are correlated to neutron energy. Over a commanded integration time period the distribution of Ep events as a function of energy (channel number) is recorded. The result is a histogram of the number of Ep events in each channel accumulated over the integration period for TTSP values between 0.3 and 5.4 microseconds, which is designated as the time-correlated early spectrum corresponding to Ec. A time-correlated late spectrum histogram is also accumulated, for events whose second pulse occurs substantially later than expected, for TTSP values between 20 and 25 microseconds, as a measure of spectrum background. The two TTSP spectra each have 256 channels (8 quasilog channels for the old NS spectra in Sec. 5.2). In addition to the five spectra described above, the NS EDRs include a precommanded set of up to the first 256 events of BP event-mode data at higher precision Ep, Ec, and TTSP values (16 bits, 16 bits, and 8 bits respectively). (Ep has a precision of only 8 bits for the old NS events in Sec. 5.2.) The event-mode data (Ep, Ec, and TTSP) are event-by-event time-series data of fast-neutron events, rather than energy histograms. Over the integration time period, a set of event classification flags is polled to determine whether valid BP sensor events have occurred. An additional event mode produces the Calibration/Diagnostics data in higher precision along with data quality and event classification flags, up to the first 96 events, as generated in any of the LG or BP sensors. (Normally only the instrument engineer would activate the Calibration/Diagnostics mode and examine the subsequent data.) Neutron and gamma-ray burst modes are also available. The gamma-ray and neutron burst data packets are of astrophysical interest and are present when the corresponding mode is activated. Gamma-rays are detected by the NS sensors, as well as neutrons, and the BP sensor detects gamma-rays of the widest energy range with the highest efficiency, of the three sensors. Gamma-ray bursts are detected as BP counts that exceed a settable threshold over background as determined by a running average of a counter. The gamma-ray burst packet contains a time series of 1-s counts starting and ending at settable pre- and post-trigger times, along with the trigger time and other parameters. Neutron burst packets are not really detected bursts against some threshold but rather a subset of the normal neutron science packets called Short Science packets (fast neutrons only) that allows determination of neutron bursts as a reduced data set, enabling neutron burst mode to operate on much shorter time scales with little increase in data rate. These modes are useful for examining solar events, particularly solar neutrons. Another data mode, available only after the software upload decribed in Sec. 5.2, is the GCR (Galactic Cosmic Ray) mode, in which GCRs are identified by coincidence between each LiG sensor and the BP sensor (double coincidences) and/or by coincidences between all three sensors (triple coincidences). The two 64-channel spectra from the LiG sensors associated with these coincidences have a broad central peak that facilitates setting gains and discriminators for these sensors. The non-coincident LiG sensor spectra have no identifiable peak, making such settings difficult. The NS data rate is driven by the integration time for the spectra, since these EDRs constitute the largest amount of data. Since the orbital neutron flux is significantly higher than the gamma-ray flux, the NS integration times can be smaller than those for the GRS while still retaining statistical significance. Assumption of a reasonable 20-second integration time at low and moderate altitudes and correspondingly larger integration times at higher altitudes yields an estimated data rate of 4 Mbits per earth day. Further information on the NS instrument can be found in the MESSENGER instrument paper (not yet published). 5.2. Data Product Overview There are ten different types of NS data products. The data products are identified via the value for the STANDARD_DATA_PRODUCT_ID within each PDS label. The data products were modified by a software upload that occurred on 6/1/2006 (DOY 152). The upload occurred just after the NS was booted up on this date, so this upload applies to all data products generated on or after 6/1/2006. The NS Spectra was replaced by the NS Full Science Spectra in this upload, the NS GCR Spectra was created, and minor updates were made to some other data products. The NS Full Science Spectra and GCR Spectra have new ApIDs. The EDR format is designed to accommodate all data products before and after the software upload transparently. The data products are described as follows: Data Product Product Description NS Full Science Spectra * Detached PDS label file * Data file - contains 5 spectra histogram arrays, status and software countersfrom all three sensors in a binary table * Created as a result of 6/1/2006 flight software update.. Replaces NS Spectra EDRs till end of mission NS Spectra * Detached PDS label file * Data file - Contains 5 spectra histogram arrays, status, and software counters from all three sensors in a binary table * Replaced by NS Full Science spectra as a result of 6/1/2006 flight software update NS Events * Detached PDS label file * Data file - contains BP events time series in a binary table NS Galactic Cosmic Ray (GCR) * Detached PDS label file * Data file - Galactic Cosmic Ray spectra and counters from LiG sensors in a binary table * Created by 6/1/2006 flight software update NS Gamma Burst * Detached PDS label file * Data file - Gamma Burst BP time series in a binary table NS Short Science * Detached PDS label file * Data file - Contains 3 BP spectra histogram arrays in a binary table ("neutron burst mode") NS TC Counts * Detached PDS label file * Data file - Time-correlated "neutron burst mode" counts in binary table NS Status * Detached PDS label file * Data file - critical state information in an ASCII table NS Calibration / Diagnostic * Detached PDS label file. * Data file - events time series for all three sensors in an ASCII table Command Echo * Detached PDS label file. * Data file - command echo information stored in an ASCII table. NS Full Science Spectra EDR The STANDARD_DATA_PRODUCT_ID is "NS_FULLSPECTRA". Contains the five spectra histogram arrays, LiG1, LiG2, BPS, BPET, and BPLT (LiG sensors 1 and 2, BP singles, BP early time correlated, and BP late time correlated, respectively), and associated counters,, data collected by the NS in "Full Science" mode. Data is stored in a PDS binary table. This EDR replaces the NS Spectra EDR as a result of a flight software update in which the previous "Science Mode" packet is retired and replaced by the "Full Science Mode" packet. The Full Science Spectra data will be organized such that one EDR file will contain all the data with timestamps that correspond to a given Earth day. The LiG1, LiG2, and BPS spectra each have 64 bins, while the BPET and BPLT spectra each have 256 bins. Each spectrum has the following scaling capability: bin counts premultiplied by 2, and commandable divide by N (separate N for each spectrum). New BPET and BPLT software counters were added in the update, and the LG1/BPS and LG2/BPS software counters were removed; also sensor and LVPS temperatures were added. NS Spectra EDR The STANDARD_DATA_PRODUCT_ID is "NS_SPECTRA". Contains the five spectra histogram arrays, LiG1, LiG2, BPS, BPET, and BPLT, data collected by the NS in "Science Data" mode. Data is stored in a PDS binary table.This EDR is longer created past February 2006 as a result of a flight software update. The NS Spectra data will be organized such that one EDR file will contain all the data with timestamps that correspond to a given Earth day. The LiG1 and LiG2 spectra each have 32 bins, the BPS spectrum has 64 bins, and the BPET and BPLT spectra each have 8 quasi-log bins. Each spectrum has the following scaling capability: bin counts premultiplied by 2 and fixed power-of-2 divide. NS Events EDR The STANDARD_DATA_PRODUCT_ID is "NS_EVENTS". Contains event data time series collected by the NS in "Full Science" mode. Data is stored in a binary table. The data file is organized such that one EDR file will contain all the events data with timestamps that correspond to a given Earth day. . The events data are transmitted in the same science telemetry packet that contains the NS spectra data. An individual science telemetry packet will contain from 0-255 events. Events are not individually timetagged. Instead, the Mission Elapsed Time (MET) recorded by the science telemetry packet will be assigned to all N events. Thus 1-255 events will share the same MET time tag within a given EDR. The MET records the start of the reporting/accumulation period. As stated above in Sec. 5.1, Ep, Ec, and TTSP values have precision 16 bits, 16 bits, and 8 bits respectively. (Ep has a precision of only 8 bits for the old NS events prior to the software update.) NS Galactic Cosmic Ray EDR The STANDARD_DATA_PRODUCT_ID is "NS_GALACTIC_COSMICRAY". Contains LiG1 and LiG2 Galactic Cosmic Ray spectra and associated counters. Data is stored in a binary table. Each Galactic Cosmic Ray EDR file will contain all the data with timestamps that correspond to a given Earth day. This data product is not available before the software update. The two GCR spectra each have 64 bins and have the same scaling capability as mentioned for the Full Science Spectra above. Double or triple coincidence mode is commandable. NS Gamma burst EDR The STANDARD_DATA_PRODUCT_ID is "NS_GAMMA_BURST". Contains Gamma Ray burst data time series collected by the NS in "Gamma Burst" mode. Data is stored in a binary table. Each Gamma Burst EDR file will contain all the Gamma Bursts data with timestamps that correspond to one Earth day. NS Short Science EDR The STANDARD_DATA_PRODUCT_ID is "NS_SHORTSCIENCE". Contains data collected by the NS in "Short Science" mode, otherwise called "neutron burst" mode. In short science mode the data telemetered from the spacecraft is a subset of the data in "Full Science" mode. It may be generated as a result of telemetry constrained situations. The data includes 3 spectra histogram arrays - BPS, BPET and BPLT stored in a binary table. Each Short Science EDR file will contain all the data with timestamps that correspond to a given Earth day. This EDR essentially renames the "so-called" NS Neutron Burst Spectra EDR as a result of the flight software update. Also the BPS spectrum is added in the update. And the changes made in the relevant spectra and scaling by the update apply (mentioned above for the Full Science Spectra). NS Time-Correlated Counts EDR The STANDARD_DATA_PRODUCT_ID is "NS_TIME_CORRELATED_COUNTS". Contains data collected by the NS in "TC Counters" mode, otherwise called "neutron burst" counter mode. Contains the BP TC Early Counter, whose value equals the summation of every channel in the early time-correlated spectra, and the BP TC late counter, whose value equals the summation of every channel in the late time-correlated spectra. Data is stored in a binary table. Each Time-Correlated counters EDR file will contain all the Neutron burst counters with timestamps that correspond to one Earth day. This EDR essentially renames the NS Neutron Burst Counter EDR. NS Status EDR The STANDARD_DATA_PRODUCT_ID is "NS_STATUS". Contains critical state information recorded in the NS Status Telemetry packet. Data is stored in an ASCII table. Each Status EDR file will contain all the status data with timestamps that correspond to one Earth day. This EDR had some fields omitted, added, or modified by the software update. NS Calibration/Diagnostic EDR The STANDARD_DATA_PRODUCT_ID is "NS_CALIBRATION_DIAGNOSTIC". Contains the calibration event series data recorded in the NS Calibration/Diagnostic telemetry packet for all three sensors. Each Calibration/Diagnostic EDR file will contain all the diagnostic event data with a time stamp that corresponds to one Earth day. A calibration/diagnostic telemetry packet contains data for the first 96 events that are recorded in a given accumulation period. If less than 96 events are collected then the packet only contains data on the events that did occur. The event data collected by the calibration/diagnostic telemetry packet are not individually time tagged. Instead, the MET recorded by the packet, which corresponds to the start of the accumulation period, will be assigned to all 96 events (or the actual events that were recorded, if less than 96). Thus, 1-96 events will share the same MET time tag in a given Calibration/Diagnostic EDR. This mode is expected to be used only by the instrument engineer, for event diagnostics. NS Command Echo EDR The STANDARD_DATA_PRODUCT_ID is "NS_COMMAND_ECHO". Contains the commands executed by the spacecraft as well as information on command arguments, command success, and time tags of the command. Each EDR file will contain all the command echo data with timestamps that correspond to one Earth day. 5.3. Data Processing 5.3.1. Data Processing Level There is one EDR Data Archive Volume for the NS instrument. The data volume will contain level 2 CODMAC data products or EDRs. Each product will have a unique file name and conform to the file naming convention in section 6.4. All EDR products will be stored at the Applied Physics Laboratory/Science Operations Center (APL/SOC) during mission operations. The data volume will be electronically transferred to the PDS Geosciences Node following the procedure in section 5.3.3. 5.3.2. Data Product Generation The Neutron Spectrometer EDR files will be produced by the MESSENGER Science Operations Center (SOC) operated jointly by APL and ACT. Data downlink is telemetered through NASA's Deep Space Network (DSN) managed by the Jet Propulsion Laboratory in Pasadena, CA, and then forwarded to APL. Inputs to the SOC will consist of telemetry in the form of CCSDS packets. Level-1 NS raw spectral and engineering data is then broken out of the data stream and stored online at the SOC. The 'PIPE-NS2EDR' software packages the Level 1 CODMAC data to the PDS formats defined in this SIS (section 5.3.4 and Appendices). The resulting files are designated as Level 2 CODMAC data or EDRs. The EDR data products are made available to the MESSENGER Science Team for initial evaluation and validation. At the end of the evaluation and validation period, the data are organized and stored in the directory structure described in section 6.5 for transmittal to the Geosciences Node. The transmittal process is described in section 5.3.3. 5.3.3. Data Flow The MESSENGER SOC operates under the auspices of the MESSENGER Project Scientist to plan data acquisition and generate and validate data archives. The SOC supports and works with the Mission Operations Center (MOC), the Science Team, instrument scientists, and the PDS. The SOC will produce early versions of products that can be used by the science and instrument teams. The following chart shows the data flow from the different groups. The MOC handles raw data flow to and from the MESSENGER spacecraft and the SOC converts the telemetry into EDRs. The science team validates the EDRs and notifies the SOC if corrections are needed. Documentation and EDRs are delivered to the PDS Geosciences node. SPICE kernels are delivered to the PDS Navigation and Ancillary Information (NAIF) node. The MESSENGER SOC will deliver data for the NS EDR data volume to the PDS Geosciences Node in standard product packages. Each package will comprise data and files organized into directory structures consistent with the volume design described in section 6.5. The following describes the electronic transfer process of releasing data to PDS. This transfer process will be used for the first PDS delivery. Future data deliveries will be assumed to follow the same process unless otherwise noted in an update of this document. Given the long duration of the mission the project is reserving the option of exploring alternate data delivery methods for subsequent deliveries. As such, the method of electronic transfer may change and will be revised accordingly in the SIS. Any changes to the delivery process will be noted in an update to the SIS document and will include the specific dates which will use the new delivery process. The delivery of products to the data volume will follow the schedule in the MESSENGER Data Management and Archiving Plan. In the week prior to the delivery date the directory structure will be compressed into a single "zip archive" file for transmittal to the PDS node. The zip archive preserves the directory structure internally so that it can be recreated after electronic delivery to the PDS node. The zip archive file is transmitted to the PDS node via FTP to an account set up by the receiving node. Also transmitted will be a checksum file created using the MD5 algorithm. This provides an independent method of verifying the integrity of the zip file after it has been sent. Within days of transmittal the PDS node will acknowledge receipt of the archive and checksum file. If acknowledgement is not received, or if problems are reported, the MESSENGER SOC will immediately take corrective action to effect successful transmittal. After transmittal the PDS node will uncompress the zip archive file and check for data integrity using the checksum file. The node will then perform any additional verification and validation of the data provided and will report any discrepancies or problems to the MESSENGER SOC. It is expected that the node will perform these checks in about two weeks. After inspection has been completed to the satisfaction of the PDS node, the node will issue to the MESSENGER SOC acknowledgement of successful receipt of the data. Following receipt of a data delivery the PDS node will organize the data into a PDS volume archive structure within its online data system. Newly delivered data will be made available publicly from PDS once accompanying labels and other documentation have been validated. 5.3.4. Labeling and Identification For every EDR data file there exists a detached PDS label file. Detached means that the label file is separate from the data file, as opposed to being in the header portion of the data file. The following are examples of PDS labels for each of the NS EDRs. Details about the label format are specified later in Section 6.3. Each PDS label file will contain a pointer to an external format file. This format file describes the table structure of the EDR data file. Details for ach format file are found in the Appendices. 5.3.4.1. NS Full Science Spectra PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 1439 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 1514 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_FSP2006172ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2007-01-22T16:51:04 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_FULLSPECTRA" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "VENUS 1 CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2006-06-21T12:00:38.000 STOP_TIME = 2006-06-21T23:59:37.000 SPACECRAFT_CLOCK_START_COUNT = 59378381 SPACECRAFT_CLOCK_STOP_COUNT = 59421521 ^TABLE = "NS_FSP2006172ZZZ.DAT" OBJECT = TABLE COLUMNS = 38 INTERCHANGE_FORMAT = BINARY ROWS = 1439 ROW_BYTES = 1514 DESCRIPTION = " This table contains one set of spectra data, status, and software event counters collected from the MESSENGER Neutron Spectrometer (NS) and telemetered via the NS Full Science Data packet. A set is defined as all data with time stamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_FULLSPE.FMT" END_OBJECT = TABLE END 5.3.4.2. NS Spectra PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 1140 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 378 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_SPE2005108ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2006-07-14T17:59:54 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_SPECTRA" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "EARTH CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2005-04-18T14:00:17.000 STOP_TIME = 2005-04-18T23:59:46.000 SPACECRAFT_CLOCK_START_COUNT = 22319954 SPACECRAFT_CLOCK_STOP_COUNT = 22355923 ^TABLE = "NS_SPE2005108ZZZ.DAT" OBJECT = TABLE COLUMNS = 30 INTERCHANGE_FORMAT = BINARY ROWS = 1140 ROW_BYTES = 378 DESCRIPTION = " This table contains one set of spectra data, status, and software event Counters collected from the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with time stamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_SPE.FMT" END_OBJECT = TABLE END 5.3.4.3. NS Events PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 1090 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 1538 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_EVT2005108ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2006-07-14T18:00:46 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_EVENTS" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "EARTH CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2005-04-18T14:00:17.000 STOP_TIME = 2005-04-18T23:59:46.000 SPACECRAFT_CLOCK_START_COUNT = 22319954 SPACECRAFT_CLOCK_STOP_COUNT = 22355923 ^TABLE = "NS_EVT2005108ZZZ.DAT" OBJECT = TABLE COLUMNS = 6 INTERCHANGE_FORMAT = BINARY ROWS = 1090 ROW_BYTES = 1538 DESCRIPTION = " This table contains one set of events data collected from the MESSENGER Neutron Spectrometer. A set is defined as all data with timestamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_EVT.FMT" END_OBJECT = TABLE END 5.3.4.4. Galactic Cosmic Ray PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 379 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 288 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_GCR2006172ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2007-01-16T21:38:53 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_GALACTIC_COSMICRAY" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "VENUS 1 CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2006-06-21T12:00:37.000 STOP_TIME = 2006-06-21T15:09:37.000 SPACECRAFT_CLOCK_START_COUNT = 59378381 SPACECRAFT_CLOCK_STOP_COUNT = 59389721 ^TABLE = "NS_GCR2006172ZZZ.DAT" OBJECT = TABLE COLUMNS = 16 INTERCHANGE_FORMAT = BINARY ROWS = 379 ROW_BYTES = 288 DESCRIPTION = " This table contains one set of galactic cosmic ray spectra data collected from the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with time stamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_GCR.FMT" END_OBJECT = TABLE END 5.3.4.5. Gamma Burst PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 62 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 346 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_GAB2005133ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2006-03-10T15:42:19 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_GAMMA_BURST" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "EARTH CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2005-05-13T19:36:06.000 STOP_TIME = 2005-05-13T23:55:04.000 SPACECRAFT_CLOCK_START_COUNT = 24500110 SPACECRAFT_CLOCK_STOP_COUNT = 24515648 ^TABLE = "NS_GAB2005133ZZZ.DAT" OBJECT = TABLE COLUMNS = 8 INTERCHANGE_FORMAT = BINARY ROWS = 62 ROW_BYTES = 346 DESCRIPTION = " This table contains one set of Gamma burst data collected from the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with time stamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_GAB.FMT" END_OBJECT = TABLE END 5.3.4.6. Short Science PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 6 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 1184 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_SSP2006167ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2007-01-12T22:04:20 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_SHORTSPECTRA" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "VENUS 1 CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2006-06-16T13:08:39.000 STOP_TIME = 2006-06-16T13:11:09.000 SPACECRAFT_CLOCK_START_COUNT = 58950463 SPACECRAFT_CLOCK_STOP_COUNT = 58950613 ^TABLE = "NS_SSP2006167ZZZ.DAT" OBJECT = TABLE COLUMNS = 17 INTERCHANGE_FORMAT = BINARY ROWS = 6 ROW_BYTES = 1184 DESCRIPTION = " This table contains one set of spectra data collected from the MESSENGER Neutron Spectrometer (NS) and telemetered via the NS Short Science Data packet. A set is defined as all data with time stamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_SHORTSCI.FMT" END_OBJECT = TABLE END 5.3.4.7. Time-Correlated Counts PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 57 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 14 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_TCC2006068ZZZ_DAT" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2007-01-18T17:01:12 PRODUCT_TYPE = "DATA" STANDARD_DATA_PRODUCT_ID = "NS_TIME_CORRELATED_COUNTS" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "VENUS 1 CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2006-03-09T14:49:32.000 STOP_TIME = 2006-03-09T14:58:52.000 SPACECRAFT_CLOCK_START_COUNT = 50402916 SPACECRAFT_CLOCK_STOP_COUNT = 50403476 ^TABLE = "NS_TCC2006068ZZZ.DAT" OBJECT = TABLE COLUMNS = 4 INTERCHANGE_FORMAT = BINARY ROWS = 57 ROW_BYTES = 14 DESCRIPTION = " This table contains one set of time-correlated spectra counters collected from the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with timestamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_TCC.FMT" END_OBJECT = TABLE END 5.3.4.8. Status PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 1680 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 622 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_STA2005108ZZZ_TAB" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2006-07-14T21:24:46 PRODUCT_TYPE = "ANCILLARY" STANDARD_DATA_PRODUCT_ID = "NS_STATUS " SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "EARTH_CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2005-04-18T13:53:23.000 STOP_TIME = 2005-04-18T23:59:48.000 SPACECRAFT_CLOCK_START_COUNT = 22319540 SPACECRAFT_CLOCK_STOP_COUNT = 22355925 ^TABLE = "NS_STA2005108ZZZ.TAB" OBJECT = TABLE COLUMNS = 103 INTERCHANGE_FORMAT = ASCII ROWS = 1680 ROW_BYTES = 622 DESCRIPTION = " This table contains one set of status telemetry information gathered by the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with timestamps corresponding to a given Earth day. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_STATUS.FMT" END_OBJECT = TABLE END 5.3.4.9. Calibration/Diagnostic PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 58841 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_CAD2004225ZZZ_TAB" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2006-03-13T15:45:27 PRODUCT_TYPE = "ANCILLARY" STANDARD_DATA_PRODUCT_ID = "NS_CALIBRATION_DIAGNOSTIC" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "LAUNCH" TARGET_NAME = "CALIBRATION" START_TIME = 2004-08-12T20:44:41.000 STOP_TIME = 2004-08-12T21:22:01.000 SPACECRAFT_CLOCK_START_COUNT = 830719 SPACECRAFT_CLOCK_STOP_COUNT = 832959 ^TABLE = "NS_CAD2004225ZZZ.TAB" OBJECT = TABLE COLUMNS = 11 INTERCHANGE_FORMAT = ASCII ROWS = 58841 ROW_BYTES = 80 DESCRIPTION = " This table contains one set of calibration and diagnostic data collected from the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with timestamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_CAL_DIAG.FMT" END_OBJECT = TABLE END 5.3.4.10. Command Echo PDS Label PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ FILE_RECORDS = 59 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 125 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "NS_CMD2008214ZZZ_TAB" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2008-12-05T20:04:15 PRODUCT_TYPE = "ANCILLARY" STANDARD_DATA_PRODUCT_ID = "NS_COMMAND_ECHO" SOFTWARE_NAME = "PIPE-NS2EDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = "NEUTRON SPECTROMETER" INSTRUMENT_ID = "NS" DATA_SET_ID = "MESS-E/V/H-GRNS-2-NS-RAWDATA-V1.0" MISSION_PHASE_NAME = "MERCURY 2 CRUISE" TARGET_NAME = "CALIBRATION" START_TIME = 2008-08-01T14:46:19 STOP_TIME = 2008-08-01T15:22:28 SPACECRAFT_CLOCK_START_COUNT = 126089415 SPACECRAFT_CLOCK_STOP_COUNT = 126091584 ^TABLE = "NS_CAD2004225ZZZ.TAB" OBJECT = TABLE COLUMNS = 11 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 125 ROWS = 59 DESCRIPTION = " This table contains one set of the commands executed by the MESSENGER Neutron Spectrometer (NS). A set is defined as all data with timestamps corresponding to a given Earth day. The complete column definitions are contained in an external structure file found in the LABEL directory of the archive volume. Additional details are contained in the EDR SIS document. " ^STRUCTURE = "NS_CMDECHO.FMT" END_OBJECT = TABLE END 5.4. Standards Used in Generating Data Products 5.4.1. PDS Standards The NS EDR data products are constructed according to the data object concepts developed by the PDS. By adopting the PDS format, the data products are consistent in content and organization with other planetary data collections. In the PDS standard, the EDR data file is grouped into objects with PDS labels describing the objects. Each EDR data product consists of the following: * A data file containing an ASCII or binary table object, in fixed field format. ASCII table objects are additionally in comma separated value (CSV) format. This makes the ASCII data extremely easy to read by many commercial off-the-shelf programs. See section 5.2 for a listing of the data products and whether the data is contained in an ASCII or binary table object. * A label file which serves as a high-level description of the parameters which correspond to the data file. The label file contains a pointer to an external format file which details the structure of the table object in the data file. 5.4.2. Coordinate Systems SPICE kernels will be archived at the PDS NAIF node. Coordinate systems will be included in the appropriate RDR SIS documents. 5.4.3. Time Standards The MET field in the NS EDR tables matches the spacecraft time in integer seconds that is transmitted to MESSENGER subsystems by the Integrated Electronics Module (IEM). This is referred to by the MESSENGER project as Mission Elapsed Time (MET). MET = 0 is August 3, 2004, at 05:59:16 UTC, which is 1000 seconds prior to the MESSENGER launch. Relativistic effects and circumstances occurring during the mission would result in MET not being a true account of seconds since launch. Following a planned spacecraft clock reset1 on January 8, 2013, partition numbers (1/, or 2/) were added to product labels to disambiguate MET seconds after the spacecraft clock reset (if partition number is not present, SPICE defaults to partition 1/). For this reason the MESSENGER spacecraft clock coefficients file is archived at the PDS Navigation and Ancillary Information Facility (NAIF) Node. This file is used in conjunction with the leapseconds kernel file in order to calculate the conversion between MET and UTC. The conversion is easily done through the use of SPICE kernels and the CHRONOS Utility. CHRONOS is a utility included with the SPICE package that is distributed by the PDS NAIF node. The SPICE kernels are files that contain the information needed to perform the conversion. Two SPICE kernels are required. One is the Leapseconds Kernel (LSK) and the other is the MESSENGER Spacecraft Clock Kernel (SCLK). The SCLK file is used by CHRONOS to convert between spacecraft clock time and ephemeris time, while the LSK file is used to convert from ephemeris time to UTC time. The CHRONOS utility is self-documenting and the SPICE package itself contains full documentation on each of the utilities (including CHRONOS) and how they are used. 5.4.4. Data Storage Conventions The data are organized following PDS standards and stored on hard disk and an SQL (Structured Query Language) relational database for rapid access during mission operations. The MESSENGER SOC will transfer data to PDS via electronic transfer and delivery methods as detailed in section 5.3.3. After verification of the data transfer PDS will provide public access to MESSENGER science data products through its online data distribution system. 5.5. Data Validation The NS EDR data products will be validated by the NS Instrument scientist for science content and for compliance with PDS archive standards [MESSENGER Data Management and Archiving Plan]. 6. Detailed Data Product Specification 6.1. Data Product Structure and Organization The MESSENGER NS data set will be archived at the PDS Geosciences node as a data archive volume. The NS EDR products in the data archive volume are intended to store the data in a form closest to the raw telemetry data received from the spacecraft. The automated production and release of EDRs will follow the release schedule in the MESSENGER Data Management and Archiving Plan. There is only one NS EDR data archive volume which will be created at the first delivery to PDS. Subsequent deliveries to PDS will update this data volume. If errors are discovered the data will be replaced with corrected EDRs on the next scheduled delivery date. The EDRs are organized in the data archive volume according to the structure defined in section 6.5. First there is the top level directory. Then subsequent directories are organized into folders by year. In each year folder there are directories organized by month. The PDS START_TIME keyword in the EDR is used to determine the year and month directory in which the EDR will be placed. 6.2. Data Format Description Data is stored in ASCII table format or in binary table format. A detached PDS label file will provide a detailed description of the structure of each table. See section 5.2 for details on which EDR contains a binary table or an ASCII table. 6.3. Label and Header Descriptions 6.3.1. PDS Label File Format The following are the keyword definitions for the detached PDS label file. The detached PDS label file has the same name as the data file it describes, except for the extension .LBL to distinguish it as a label file. PDS_VERSION_ID Represents the version number of the PDS standards documents that is valid when a data product label is created. PDS3 is used for the MESSENGER Data products. RECORD_TYPE The record_type element indicates the record format of a file. The FIXED_LENGTH value is appropriate for the BINARY table object used for the MESSENGER NS EDR data products. FILE_RECORDS The file_records element indicates the number of physical file records, including both label records and data records. RECORD_BYTES The number of bytes in a physical file record, including record terminators and separators. PRODUCT_ID The product_id data element represents a permanent, unique identifier assigned to a data product by its producer. PRODUCT_CREATION_TIME Defines the UTC system format time when the product was created. PRODUCT_VERSION_ID Identifies the version of an individual product within a data set. Example: V1, V2, V3 Product_version_id will be incremented if a given EDR has to be regenerated and sent to PDS to replace a previously submitted EDR. PRODUCT_TYPE Identifies the type or category of a product within a data set. STANDARD_DATA_PRODUCT_ID Used to link a NS EDR file to one of the 7 types of NS data products defined within the NS EDR SIS. SOFTWARE_NAME Identifies the data processing software used to generate the EDR products. SOFTWARE_VERSION_ID Indicates the version of the data processing software used to generate the EDR products from the spacecraft telemetry. INSTRUMENT_HOST_NAME The full name of the host on which an instrument is based. In this case it is the MESSENGER spacecraft. INSTRUMENT_NAME The full, unabbreviated name of the instrument. INSTRUMENT_ID Unique id associated with the Neutron Spectrometer instrument. DATA_SET_ID The data_set_id element is a unique alphanumeric identifier for a data set or a data product. The data_set_id value for a given data set or product is constructed according to flight project naming conventions. There is only one data_set_id for the NS EDRs. MISSION_PHASE_NAME Provides the commonly used identifier of a mission phase. TARGET_NAME The target of the observation. START_TIME Provides the date and time of the beginning of an event or observation whether it be a spacecraft, ground-based, or system event) in UTC system format. STOP_TIME Provides the date and time of the end of an observation or event (whether it be a spacecraft, ground-based, or system event) in UTC system format. SPACECRAFT_CLOCK_START_COUNT Mission Elapsed Time (MET) corresponding to the first record in the data table. SPACECRAFT_CLOCK_STOP_COUNT Mission Elapsed Time (MET) corresponding to the last record in the data table. ^TABLE Pointer to the external data file which contains the table object. OBJECT Specifies that the PDS object containing the data. In the case of the NS EDRs the object is a binary or ASCII table. This object contains its own elements. NOTE: the end of the object definition is always marked with an END_OBJECT line. COLUMNS Identifies the number of columns (fields) in the table. INTERCHANGE_FORMAT Specifies the format of the table. ROWS The number of rows in the binary table. ROW_BYTES Specifies the number of bytes for each row in the table. ^STRUCTURE This is a pointer to the external file which provides the structure definition for the table object. 6.3.2. Table Object Keyword Definitions The following describes the keywords used to define the PDS table object: OBJECT = COLUMN Identifies this as a column in the table object. COLUMN_NUMBER Identifies the location of the column within the larger data object (such as a table). For tables consisting of rows (I= 1, N) and columns (j = 1, M) the column_number is the j-th index of any row. NAME Indicates a literal value representing the common term used to identify the column object. BYTES Specifies the number of bytes allocated for this particular column element. DATA_TYPE Specifies the internal representation and/or mathematical properties of the value being stored in this column. START_BYTE Identifies the location of the first byte of the particular column, counting from 1. ITEMS Defines the number of multiple, identical occurrences of a single object. Ex. For the NS Spectra EDR it indicates that column 8 is a 32-bin histogram. ITEM_BYTES Represents the size in bytes of an individual item. 6.4. File Naming Conventions The general form of the NS EDR file name is "NS_ZZZYYYYDDDWWW.XXX", where: NS instrument identifier: represents the NS instrument ZZZ EDR product identifier: FSP - Full Science Spectra EDR SPE - Spectra EDR EVT - Events EDR GCR - Galactic Cosmic Ray EDR GAB - Gamma Burst EDR SSP - Short Science EDR TCC - Time-Correlated Counts EDR STA - Status EDR CAD - Calibration/Diagnostic EDR CMD - Command Echo EDR YYYY The four digit year corresponding to the start time of the first record in the data table. DDD The three digit day of year corresponding to the start time of the first record in the data table. WWW Reserved 3 character string to use during the course of the mission as necessary to identify "special" data products. Nominal data products will be identified with 'ZZZ'. XXX The file extension: detached PDS label files will be 'LBL', the binary data files will be 'DAT', ASCII data files are 'TAB'. 6.5. Directory Structure and Contents for Static Volumes The following illustration shows the directory structure overview for the NS EDR Data Archive Volume. This volume contains the NS EDR data products, supporting documentation, and any additional files required for the volume to be compliant with PDS standards. The content of the volume is expected to be updated with periodic releases according to the schedule in the MESSENGER Data Management and Archiving Plan. Revised EDRs (if needed) will also be delivered according to the same schedule. Revised EDRs will have an incremented version number in the PDS label. Directory Structure Overview Directory Structure Overview | | ________________________________|____________ | | | | |