MESSENGER MASCS UVVS Calibrated and Derived Data Record Software Interface Specification Version 5.2 February 22, 2016 Prepared by: Noam Izenberg Applied Physics Laboratory Jennifer Ward PDS Geosciences Node Washington University Document Review This document and the archive it describes have been through PDS Peer Review and have been accepted into the PDS archive. William McClintock, MESSENGER Cognizant Co-Investigator/MASCS, has reviewed and approved this document. Noam Izenberg, MESSENGER MASCS Instrument Scientist, has reviewed and approved this document. Lyle Huber, PDS Atmospheres Node Representative, has reviewed and approved this document. Susan Ensor, MESSENGER Science Operations Center Lead, has reviewed and approved this document. Document Change History Revision Number Revision Date Author Section Remarks 1.5 4/7/09 Start of revision history. Version submitted to PDS for Release 4. 1.6 1/8/10 J. Ward, GEO 5.3.4, Tables 3a & 3b, 6.3.2, Appendix B 1. Replaced sample PDS labels with new versions containing PRODUCT_VERSION_ID. 2. Added PRODUCT_VERSION_ID to UHCINDEX.TAB and USCINDEX.TAB column lists. 3. Updated UVVSSCIC.FMT columns to match file delivered in PDS Release 5. 1.7 9/15/10 J. Ward, GEO 5.2, 5.3.4.1, 5.3.4.2, 6.1.2, 6.1.3, 6.1.4, 6.3.2, Appendix B 1. Updated to describe new macro-based files. 2. Updated data product naming convention. 3. Added EXTRAS directory tables. 4. Removed subdirectories from CDR directory structure. 1.8 12/6/10 J. Ward, GEO 6.3.1, 6.3.2, Appendix A, Appendix B 1. Corrected formula for MIDSTEP_TIME. 2. Appended statement to PACKET_SUBSECONDS description. 1.9 5/5/11 J. Ward, GEO 6.1.3, 6.1.4 Updated to reflect new data directory structure. 2.0 6/10/11 J. Ward, GEO 6.1.4 Updated EXTRAS directory contents. 2.1 6/14/11 S. Ensor, SOC Document Review Replaced signature page with Document Review information. 2.2 6/17/11 J. Ward, GEO 6.1.4 Renamed SUPERTABLE.XLS TO MASTER_CRUISE_TABLE.XLS. 2.3 1/24/12 N. Izenberg, MASCS; J. Ward, GEO 2, Table 2, 6.1.4, 6.3.2, Appendix B 1. Added reference to calibration update document. 2. Temperature and solar scattering correction added to EDR to CDR processing steps table. 3. Added new documents to DOCUMENT and EXTRAS directory contents. 4. Spare column in UVVSSCIC.FMT converted to PMT temperature. 2.4 3/26/12 W. McClintock, MASCS; J. Ward, GEO All Converted to CDR/DDR Data Product SIS, adding new DDR data product. Draft version. 2.5 4/10/12 J. Ward, GEO 5.3.4.2, 6.3.1.2, Appendix B Revised CDR sample label and format file. 2.6 4/13/12 W. McClintock, MASCS; J. Ward, GEO; R. Espiritu, ACT Figures, Section 7 1. Added figures 2a-2c. 2. Deleted "UVVS position vectors in the inertial J2000 coordinate frame" figure. 3. Renumbered all figures. 4. Removed Section 7 Archive Release schedule. 5. Revised DDR index table columns. 2.7 4/20/12 N. Izenberg, MASCS; R. Vervack, MASCS 5.2.2, 5.3.4, 6.1.2, 6.1.3, 6.1.4, 6.3.2, Appendix C 1. Deleted DDR HDR file references (no DDR HDR file). 2. Revised DDR SCI file structure and description. 3. Renumbered sections/appendices. 4. Inserted new directory structure figure. 2.8 4/30/12 J. Ward, GEO 5.2.2, 5.3.4, 6.1.3, 6.1.4 Formatting and consistency edits. 2.9 5/3/12 J. Ward, GEO Appendix C Updated UVVSSCID.FMT. 3.0 5/11/12 A. Merkel, MASCS; J. Ward, GEO 5.3.4.3, 6.3.2.1, Appendix C 1. Format file edits. 2. Changed DDR file naming convention. 3.1 5/14/12 J. Ward, GEO Appendix C Fixed typo in UVVSSCID.FMT. 3.2 5/16/12 S. Ensor, SOC 2, 3, 4, 5.3.3, 5.5 Updated Applicable Document 4 name and references to it. Referenced Applicable Document 4 for delivery schedule. 3.3 5/18/12 J. Ward, GEO 6.1.4, Figure 4, Tables 3a-3c 1. Edited catalog directory contents. 2. Minor edits to directory structure. 3. Removed length column from index table contents table. 3.4 5/30/12 J. Ward, GEO 5.2.1, 5.3.4 Minor typo. 3.5 7/17/12 J. Ward, GEO 6.1.4 EXTRAS directory contents. 3.6 12/13/12 J. Ward, GEO 6.1.4 DOCUMENT and EXTRAS directory contents. 3.7 4/22/13 P. Bedini, SOC, J. Ward, GEO All Editorial changes. 3.8 4/25/13 J. Ward, GEO All Added new surface reflectance and atmosphere surface density data products. Draft version. 3.9 6/5/13 N. Izenberg, MASCS All Added Surface DDR information. 4.0 6/13/13 J. Ward, GEO All Additional edits. 4.1 6/19/13 R. Vervack, MASCS, J. Ward, GEO 5.2.2.3, 5.3.4, 6.1.2, 6.3.4 Added Atmospheric Model DDR information. 4.2 10/10/13 J. Ward, GEO 6.3.2.2, Table 3c DDR-DAP peer review revisions. 4.3 12/4/13 J. Ward, GEO 2, 6.1.4 Added Applicable Document. Updated DOCUMENT and EXTRAS directory contents. 4.4 12/6/13 J. Ward, GEO 2, 6.1.4 Minor edit. 4.5 1/10/14 J. Ward, GEO 6.1.2, 6.1.4 Minor edits. 4.6 1/16/14 J. Ward, GEO 6.1.4 Minor typo. 4.7 2/18/14 J. Ward, GEO 5.2.2.3, 5.3.4.6, 6.1.4 1. Added Ca Chamberlain model document. 2. Updated Na atmospheric model sample label. 4.8 7/9/14 N. Izenberg 5.4.2, Various MET/UT fixes, standardization between products, minor edits. 4.9 1/20/16 S. Ensor All Final mission edits. Reflect use of DEM in final surface pointing parameters. 5.0 1/21/16 J. Ward, GEO All Additional minor edits. 5.1 1/27/16 J. Ward, GEO 6.1.4 Additional minor edits. 5.2 2/22/16 R. Vervack, MASCS, J. Ward, GEO All Additional edits from Vervack for final release. Table of Contents 1. Purpose and Scope of Document 1.1 Purpose 1.2 Scope 2. Applicable Documents 3. Relationships with other Interfaces 4. Roles and Responsibilities 5. Data Product Characteristics and Environment 5.1 Instrument Overview 5.2 Data Product Overview 5.2.1 Calibrated Data Records (CDRs) 5.2.2 Derived Data Records (DDRs) 5.2.2.1 Surface DDRs 5.2.2.2 Atmosphere DDRs 5.2.2.3 Atmospheric Model DDRs 5.3 Data Processing 5.3.1 Data Processing Level 5.3.2 Data Product Generation 5.3.3 Data Flow 5.3.4 Labeling and Identification 5.3.4.1 Example PDS Label for the UVVS Science Header CDR 5.3.4.2 Example PDS Label for the UVVS Science CDR 5.3.4.3 Example PDS Label for the UVVS Surface Header DDR 5.3.4.4 Example PDS Label for the UVVS Surface Science DDR 5.3.4.5 Example PDS Label for the UVVS Atmosphere DDR 5.3.4.6 Example PDS Label for the UVVS Atmospheric Model DDR 5.4 Standards Used in Generating Data Products 5.4.1 PDS Standards 5.4.2 Time Standards 5.4.3 Coordinate Systems 5.4.4 Data Storage Conventions 5.5 Data Validation 6. Detailed Data Product Specifications 6.1 Data Archive Structure and Organization 6.1.1 Handling Errors 6.1.2 File Naming Conventions 6.1.3 Directory Structure and Contents for MASCS CDR/DDR/DAP Archive Volume 6.1.4 Directory Contents 6.2 Data Format Description 6.3 Label and Header Descriptions 6.3.1 CDR Column Descriptions 6.3.1.1 Fields in Science Header CDR Format File (UVVSHDRC.FMT) 6.3.1.2 Fields in Science Data CDR Format File (UVVSSCIC.FMT) 6.3.2 Surface DDR Column Descriptions 6.3.2.1 Fields in Surface HDR DDR Format File (UVVSHDRD_SUR.FMT) 6.3.2.2 Fields in Surface SCI DDR Format File (UVVSSCID_SUR.FMT) 6.3.3 Atmosphere DDR Column Descriptions 6.3.2.1 Fields in Atmosphere DDR Format File (UVVSSCID.FMT) 6.3.4 Atmospheric Model DDR Column Descriptions 7. Appendices APPENDIX A- UVVSHDRC.FMT FILE APPENDIX B- UVVSSCIC.FMT FILE APPENDIX C- UVVSHDRD_SUR.FMT FILE APPENDIX D- UVVSSCID_SUR.FMT FILE APPENDIX E- UVVSSCID.FMT FILE APPENDIX F- SPICE Kernel Files Used In Messenger Data Products APPENDIX G- CODMAC/NASA Definition of Processing Levels for Science Data Sets APPENDIX H- ACRONYMS APPENDIX I- MASCS Instrument Overview 1. Purpose and Scope of Document 1.1 Purpose This document provides users of the MESSENGER Ultraviolet and Visible Spectrometer (UVVS) data products with a detailed description of the instrument (Figure 1), as well as Calibration Data Record (CDR) and Derived Data Record (DDR) generation and storage. The UVVS data products are deliverables to the Planetary Data System (PDS) and the scientific community that it supports. All data formats are compliant with PDS standards. In addition, this Software Interface Specification (SIS) documents the format and content of the MESSENGER MASCS CDR/DDR/DAP PDS archive volume. This document is both a CDR/DDR data product SIS and a CDR/DDR/DAP archive volume SIS. Figure 1: MASCS Instrument, UVVS Subsystem. See PDF version of document for figure. 1.2 Scope This specification is useful to those who wish to understand the format and content of the UVVS CDR and DDR data products. Typically, these individuals include software engineers, data analysts, and planetary scientists. The SIS applies to CDR/DDR data products produced during the course of MESSENGER mission operations. Experiment Data Records (EDRs), the raw, uncalibrated data from MASCS UVVS, are addressed in the UVVS EDR SIS (Applicable Document 8). EDR data products are archived in a separate PDS archive volume. 2. Applicable Documents This SIS references the following documents: 1. 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. 2. Planetary Data System Archive Preparation Guide, NASA/JPL, August 29, 2006, Version 1.1, JPL D-31224. 3. Planetary Data System Standards Reference, NASA/JPL, March 20, 2006, Version 3.7, JPL D-7669, Part-2. 4. MESSENGER Data Management and Archiving Plan. The Johns Hopkins University, APL. Document ID number 7384-9019. 5. [PLR] Appendix 7 to the discovery program Plan; Program Level Requirement for the MESSENGER Discovery project; June 20, 2001. 6. MASCS Users Guide. Laboratory for Atmospheric and Space Physics, University of Colorado. Document ID number 20580-T5-5103. 7. Instrument Calibration Report. Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the Mercury: Surface, Space Environment, Geochemistry, Ranging (MESSENGER) Mission. LASP/CU Document Number 20580-T6-7915. 8. MESSENGER MASCS/UVVS EDR SIS: APL doc no. SIE-06-044 D. 9. MASCS Instrument Paper: W. E. McClintock and M. R. Lankton (2007) Space Sci. Rev. 131, 481-522. 10. MASCS Calibration Release Notes: W. E. McClintock and G. M. Holsclaw. APL document ID number: TSSD-19929. 11. UVVS Calibration Changes for PDS Delivery 7: Aimee Merkel, Ron Vervack, Noam Izenberg and the MASCS Team, APL Doc. No. SRE-02-12. 12. MESSENGER MASCS UVVS Calibration Update - PDS 11: Aimee Merkel and the MASCS Team, APL Doc. No. SRE-02-13, December 5, 2013. 3. Relationships with other Interfaces The UVVS 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 are electronically transferred to the PDS Geosciences and Atmospheres Nodes according to the delivery schedule in the MESSENGER Data Management and Archiving Plan [Applicable Document 4]. The UVVS and VIRS CDRs, DDRs, and DAPs contain some data that are useful in cross-comparison, therefore both the UVVS and VIRS CDRs/DDRs/DAPs are grouped together in the MASCS CDR/DDR/DAP archive volume stored at both PDS nodes. 4. Roles and Responsibilities The roles and responsibilities of the instrument teams, Applied Physics Laboratory (APL), Applied Coherent Technology Corporation (ACT), and the PDS are defined in the MESSENGER Data Management and Archiving Plan [Applicable Document 4]. 5. Data Product Characteristics and Environment 5.1 Instrument Overview The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) was comprised of a small Cassegrain telescope with a 257-mm effective focal length and a 50-mm aperture that simultaneously feeds both an UltraViolet and Visible Spectrometer (UVVS) and a Visible and InfraRed Spectrograph (VIRS). MASCS investigated Mercury's exosphere by measuring altitude profiles of known species as well as searching for previously undetected species. MASCS investigated the mineralogical composition of the surface of Mercury by obtaining maps of surface reflectance spectra on spatial scales of 5 km. UVVS was a scanning grating, Ebert-Fastie monochromator with a focal length of 125 mm and equipped with three photomultiplier tube detectors (see Table 1). The three detectors covered the wavelength ranges of the far ultraviolet (115-180 nm), middle ultraviolet (160-320 nm), and visible (250-600 nm) with an average spectral resolution of 0.6 nm. The UVVS detector helped determine the global composition and spatial structure of Mercury's exosphere by measuring emission from known species (H, O, Na, K, and Ca) as well as previously undetected but predicted species (e.g. S, Si, Al, Mg, Fe, and OH). In addition to determining the composition and structure of the exosphere, these data provide the basis for determining exospheric processes, studying the relationship between surface and exospheric composition, and studying surface-exosphere-magnetosphere interactions. VIRS was a fixed concave grating spectrograph with a 210-mm focal length (see Table 1). A beam splitter simultaneously dispersed the spectrum onto two solid-state array detectors: a 512-element silicon photodiode array, with a sensitivity to visible wavelengths (300-1050 nm), and a 256-element indium-gallium-arsenide photodiode array, to measure near infrared wavelengths (850-1450 nm). It was optimized to measure visible and near infrared surface reflectance, and VIRS obtained data with a resolution of 5 nm. Together, the VIRS and UVVS detectors measured surface reflectance at middle ultraviolet to visible to near infrared wavelengths to search for ferrous bearing minerals, Fe-Ti bearing phases, and ferrous iron. These measurements were made with a spatial resolution of 5 km or better. The VIRS data products are described in a separate VIRS data product SIS. The UVVS data products are described below. Table 1: MASCS Instrument Overview. See PDF version of document for table. Please see Applicable Document 9 and Appendix I for additional details about the MASCS instrument. 5.2 Data Product Overview 5.2.1 Calibrated Data Records (CDRs) The UVVS CDRs consist of calibrated data derived from MASCS UVVS EDRs. The Science EDRs are the raw data records used to derive emission and reflectance data used for scientific analysis. The Science EDRs contain raw counts of the UVVS photomultiplier tubes (PMT) at the commanded step of the UVVS grating, which correspond to a specific wavelength of light. Wavelength range and sensitivity of each PMT at each grating step vary, as documented in the MASCS Calibration Report, MASCS_CAL_RPT.PDF, provided in the DOCUMENT directory. Before the science data can be used for scientific analysis, the count rates in the EDRs must be converted to physical units and the data must be transformed into meaningful physical reference systems. This conversion yields calibrated data that are stored in CDRs. Table 2a lists the processing steps from the EDR to the CDR level, along with the corresponding CDR table column names and numbers. The *.FMT files and their columns are fully described in section 6.3. The algorithms and tables used to convert raw, uncalibrated data to calibrated radiance at the sensor can be found in the CALIB and DOCUMENT directories of this archive volume. Table 2a: UVVS EDR to CDR to Surface DDR Processing Steps. See PDF version of document for table. The UVVS CDR data product contains all the data from one observation set. An observation set is defined in three ways. 1) Before adoption of macro-based commanding on the spacecraft, one observation set contains all the CCSDS (Consultative Committee for Space Data Systems) packets generated by one photomultiplier tube in a given hour of operation. UVVS produces one CCSDS packet per scan of the instrument grating (one scan may have repeated passes and/or a zigzag across a defined number of steps). 2) After macro-based commanding of the instrument commenced, an observation set consists of the all scans and packets produced by a single macro call. The exception to this is case 3) for very long executions of high-data rate macros that produce hundreds of megabytes of calibrated data. These "fat" macros are subdivided into several hour chunks. A variable number of CDR products are generated each day depending on the UVVS observation plan. One observation set is associated with two CDR data products: a science header table (HDR), showing the instrument command parameters for a given observation, and a science data table (SCI), showing counts, derived science data, and pointing information for each step of an observation. The CDRs are in binary table format, and each is described by a detached PDS label. The label files define the start and end time of the observation, product creation time, etc. The label points to an associated format file that defines the fields of the binary table contained within the data file. The UVVS macro-based science header (HDR) CDR (case 2) contains engineering data that does not change over the entire packet. It has N records, where N is the same number as in the corresponding EDR, and there is 1 record per packet. Thus, there is a 1-1 correspondence between the science header CDR and the corresponding EDR. The UVVS macro-based science (SCI) CDR contains per step data. 1 record = 1 step. The file contains N * f(N) records, where N is the number of records in the corresponding EDR and f(N) is a function of how many steps are extracted from a given packet in the EDR. Thus, the records f(N) in the macro science CDR correspond to record N in the macro science header CDR, which corresponds to record N in the EDR. There are three EDR data products produced by the UVVS instrument, one for each detector (FUV, MUV, VIS). The detectors are also referred to as the Photomultiplier Tube detectors (FUV PMT, MUV PMT, VIS PMT). These are identified in the EDR PDS label as the "UVVSFUV," "UVVSMUV," and "UVVSVIS" standard data products, respectively. There is also a MASCS housekeeping EDR data product generated by the MASCS instrument. This is identified in the PDS label as the "MASCSHK" standard data product. The housekeeping EDR is defined in both the UVVS and the VIRS EDR SISs. UVVS EDR and associated housekeeping data are input into the UVVS calibration pipeline to derive Calibrated Data Records (CDRs). The CDR archive consists of 6 standard data products, 2 for each detector (FUV, MUV, VIS). These are identified as "UVVSCFUVHDR," "UVVSCFUVSCI," "UVVSCMUVHDR," "UVVSCMUVSCI," "UVVSCVISHDR," and "UVVSCVISSCI" CDRs. There are three types of data stored in each data file: RAW_STEP_DATA (SCI table column 39), count rates (SCI table columns 40-44), and STEP_RADIANCE (_KR & _W, SCI table columns 46 & 47, respectively). Please see the table column definitions in section 6.3 for detailed descriptions of these columns. 5.2.2 Derived Data Records (DDRs) 5.2.2.1 Surface DDRs For the UVVS surface DDR data products, one DDR contains all the derived reflectance data from one MUV surface observation. Not all surface CDRs are converted to DDRs; only targeted surface observations of the MUV PMT from Mercury orbit were processed to a DDR. Thus, there are only a few thousand total UVVS DDRs. CDRs were converted to DDRs by first filtering out non-planet-targeted observations, then converting to reflectance by dividing the solar irradiance spectrum out of the MASCS radiance data. A photometric correction was then applied to the reflectance data for corrected data. Bins of approximately 1 nm bandwidth (~5 UVVS steps) were created by coadding the signal in each step of the bin. In a 660 step scan of the standard UVVS surface observation, this results in a single UVVS spectrum of about 132 bins. One observation set is associated with two surface DDR data products: a science header table, showing the instrument command parameters for a given observation, and a science data table, showing counts, derived science data, and pointing information for each bin of 5 steps of an observation. The surface DDRs are in binary table format, and each is described by a detached PDS label. The label points to an associated format file that defines the fields of the binary table contained within the data file. There are four types of spectra stored in each surface DDR science data file: IOF_BIN_DATA (table column 14), PHOTOM_IOF_BIN_DATA (table column 15), IOF_ BIN_NOISE_DATA (table column 16), and PHOTOM_IOF_ BIN_NOISE_DATA (table column 17). Table 2a lists the processing steps from the EDR to the CDR and DDR levels, along with the corresponding CDR and DDR table column names and numbers. The *.FMT files and their columns are fully described in section 6.3. The *algorithms and tables used to convert EDRs to CDRs and DDRs can be found in *the CALIB and DOCUMENT directories of this archive volume. 5.2.2.2 Atmosphere DDRs The UVVS Atmosphere Derived Data Records consist of time ordered sequences of radiance values that are measured along lines of sight perpendicular to Mercury radius vectors. The viewing direction for each measurement is determined by specifying the latitude, longitude, and altitude of the spacecraft and the latitude, longitude, and altitude of the minimum ray (Figure 5a). Figures 2a-2c illustrate the three general geometry-based classifications of Atmosphere DDRs. These are dayside limb scans (LS), which are acquired as sets of limb altitude profiles at specific local times, dayside and nightside limb drift profiles (LD), which are acquired in a more random fashion, and nightside tail sweeps (NS), which are sets of back-and-forth sweeps of the UVVS line of sight across the nightside exosphere. Each of these products is generated for the three major exosphere species that were regularly observed by the UVVS: sodium (Na), magnesium (Mg), and calcium (Ca). The Mg data in the DDRs are observations of the emission line at 285.3 nm, the Ca data are observations of the emission line at 422.8 nm, and the Na data are observations of the doublet emission lines at 589.2 nm (D2) and 589.8 nm (D1). All wavelengths are specified in vacuum. The total radiance calculated for Na pertains to the sum of the D1 and D2 lines, which overlap to some extent at the spectral resolution of the UVVS. A single Atmosphere DDR contains all of the observations for a given species and classification that were acquired during a single Mercury year. "Mercury year" is defined as the time to cover the full 360 degrees of Mercury's orbit around the Sun, with the starting point being at 0 degrees true anomaly. Because MESSENGER orbit insertion and the start of science data acquisition occurred at 73 degrees true anomaly, the first Mercury year only covered a range from 73 degrees to 360 degrees. The final Mercury year was also a partial year, covering true anomalies from 0 to 64 degrees at mission end. Table 2b summarizes the processing of the Atmosphere DDR products. They were assembled from the CDRs by filtering each species to identify the particular geometry classification and eliminating observations of marginal to no use (e.g., saturated spectra, slit half-on/half-off the planet). Each Atmosphere DDR product consists of time-ordered sequences of spectra (wavelength versus radiance value), total radiance (total column emission rate), and pointing information for each minimum ray altitude within the given Mercury year. Figure 2a. Dayside limb scan implementation. See PDF version of document for figure. The nominal seven-scan scenario with full local-time coverage is shown at the left. The maximum altitude of each scan was fixed at 4000 km, or at whatever maximum altitude was achievable within spacecraft pointing constraints. The scans took 9 minutes each. The numbers indicate the order in which the scans occured, the back-and-forth step-like nature across the planet being necessary to keep the particular local times within the allowed pointing window as the spacecraft moved in its orbit. This nominal seven-scan scenario covers the majority of the limb scans. The thirteen-scan scenario (middle panel) covers some cases from early in the orbital phase (mostly Mercury years 1-5) and occured when spacecraft pointing constraints did not allow for higher altitudes to be reached. To offset the lower altitude ranges (up to 2500 km maximum) the number of local times was increased. The time per scan in this case was reduced to 4 minutes per scan. The four-scan scenario (right panel) occured when full local-time coverage was not possible within the spacecraft pointing constraints. Instead, four scans were conducted, two at dawn and two at dusk, to study the important dawn-dusk asymmetries. These scans could reach 4000 km altitude maximum and take 9 minutes each. In all cases, A and B indicate a particular macro. A and B may be the same, but having different macros on the interleaved scans allows for multiple species to be observed in a given sequence. A and B may also indicate a change in the maximum altitude, with the A (or B) scans having a higher maximum altitude relative to the B (or A) scans. This option was employed in various ways throughout the orbital phase to provide a mix of spatial resolutions during any given sequence. The most common combination was A scans with maximum altitude of 4000 km and B scans with maximum altitude of 2500 km. Figure 2b. Example limb drift observations. See PDF version of document for figure. These drift observations were serendipitous exospheric limb profile measurements during ride-alongs with other instruments. They occurred anywhere in the orbit as long as the UVVS line of sight observed off the planetary limb. As ride-along observations, the pointing was dictated by the other instruments; thus, the UVVS pointing may have varied during any given drift observation, and the altitudes covered ranged from as few as a hundred kilometers to as many as several thousand kilometers. Figure 2c. Two end-member examples of the exosphere mapping scans (tail sweeps). See PDF version of document for figure. The left two illustrations show the noon-midnight/nightside apoapse case and the right two illustrations show the dawn-dusk/dawn side apoapse case. As indicated in the illustrations, the exosphere mapping scans proceeded by rocking the spacecraft back and forth about the line from the spacecraft to the Sun-Mercury line. The angle of the rocking was adjustable, generally smaller near apoapse, and the resulting observational sequence was a series of "fans" stacked one after the other. The Atmosphere DDRs are in binary format and each is described by a detached PDS label. The label files define the start and end time, creation date, etc. The label points to an associated format file that defines the fields of the binary table contained within the data file. The UVVS Atmosphere DDR file contains pointing data and N records, where N is the number of sequential spectra recovered from the filtering process. There are nine Atmosphere DDR standard data products produced from the CDRs, three for each species. These are identified as "UVVSDNALS," "UVVSDNALD," and "UVVSDNANS" for sodium. Names for Mg and Ca are produced by replacing 'NA' with 'MG' and 'CA', respectively. There are two types of data stored in each science file: RADIANCE versus WAVELENGTH (spectra, table column 23) and TOTAL_RADIANCE in each observed emission line (total radiance measured at each altitude (pointing), table column 25). Data Product Processing Step Description Dayside limb altitude profiles (LS) 1. Filter CDRs for a specified species and spacecraft orbit 2. Order as a time series, which keeps individual altitude profiles together Dayside altitude limb scans for Na, Ca, and Mg each consisting of a sequential list of altitude scans with radiance values and spectra including appropriate geometry fields. Dayside and nightside limb drift profiles (LD) 1. Filter CDRs for a specified species and spacecraft orbit 2. Order as a time series Dayside and nightside limb drift profiles for Na, Ca, and Mg each consisting of a sequential list of altitude scans with radiance values and spectra including appropriate geometry fields. Night side tail sweep profiles (NS) 1. Filter CDRs for a specified species and spacecraft orbit 2. Order as a time series Night side sweep scans for Na, Ca, and Mg provides a sequential list of sweep scans with radiance values and spectra including appropriate geometry fields. Table 2b: UVVS CDR to Atmosphere DDR Processing Steps. 5.2.2.3 Atmospheric Model DDRs The UVVS Atmospheric Model Derived Data Records consist of a series of model fits to data averaged over specific Mercury true anomalies and local times. These model fits, and the parameters provided in the DDRs, are described below. The description is given for Na, but Ca and Mg are similarly fitted. For a full description of the Ca model, please see CALCIUM_CHAMBERLAIN_MODELS.PDF in the document directory. It should be noted that these models are intended only as a first-order approximation of the average atmospheric state on the dayside using a well-known and accepted model (the Chamberlain model). However, such models lack some of the relevant physics that are pertinent to the Mercury exosphere. As such, they are excellent starting points for more detailed models but should not be interpreted as a true representation of the actual exosphere. More detailed models are too complicated to provide in any meaningful way. The model employed is adapted from the model developed by Chamberlain (1963). The temperature and density of the dayside sodium exosphere were found by fitting the estimated column densities from individual limb scans. The fit applies only to the lower 700-1000 km of the exosphere, which is relatively cold and dense compared to the exosphere at higher altitudes. The DDRs give the averages of these fits as a function of true anomaly in 5 degree increments. The column density N (cm^-2) is derived from radiance I (kR) using N=I/(g 10^6) (1) The g-value is the rate (s^-1) at which an atom scatters sodium D1 and D2 solar photons. It depends on distance from, and radial velocity relative to, the sun. The sodium atoms have a distribution of speeds, but because this distribution is relatively narrow for the low-altitude, low-temperature portion of the exosphere described in this data product, we use Mercury's radial velocity and distance from the sun to calculate g. The exospheric column density is related to the density via N=KHn (2) where n is the density of the exosphere at the line-of-sight tangent point, H is the scale height of the exosphere, and K is the ratio between the line-of-sight column density and the vertical column density (~Hn) and given, approximately, by [pi*r/(2H)]^(1/2). These formulas come from Chamberlain (1963). The density is approximated by n=n0e^-(U/kT) (3) where U is the gravitational potential energy due to gravity and photon acceleration, T the temperature, and n0 the surface density (see Feynman (1963) for a general discussion of this formula). The temperature and surface density are the free parameters of our fits to the limb scans and are provided in the DDR. Photon acceleration (also called photon pressure or radiation pressure) is an antisunward acceleration due to the resonant scattering of sunlight. It is directly proportional to the g-value. At Mercury, for sodium, it can be nearly half as large as surface gravity (e.g., Wang and Ip, 2011). For that reason we included it along with the gravitational potential term in Eq. (1), so that the potential energy is written as U=GMm/r + mbrcos(theta) (4) as described in Bishop (1985), where b is the photon acceleration, theta is the angle between the local radial vector and the Mercury-sun axis, G is the gravitational constant, M is the mass of Mercury, m is the mass of a sodium atom, and r is the distance from Mercury's center. For each limbscan, because they all have line-of-sight tangent points near the equator, theta is derived, approximately, by the angular distance from noon as measured by the local time provided in the DDR. The scale height, used in the formulas above and provided in the data product, is defined by H = n/(dn/dr) = kT/( GMm/r^2 + mbcos(theta) ). (5) Note that in the absence of photon pressure and ignoring the radial variation in gravity, this definition reduces to the classic kT/ma, where a is gravitational acceleration. Alternately, we can write H as kT/m(a + bcos(theta) ) (6) where the parenthetical term in the denominator can be seen as a sum of two terms, the gravitational term and the radial component of the photon pressure. This scale height (measured in km) is also provided in the DDR. Bishop, J., 1985. Geocoronal structure - The effects of solar radiation pressure and the plasmasphere interaction. Journal of Geophysical Research 90, 5235-5245. Chamberlain, J. W., 1963. Planetary coronae and atmospheric evaporation. Planetary and Space Science 11, 901. Feynman, R. P., 1963. Feynman lectures on physics - Volume 1, Chapter 40. Reading, Ma.: Addison-Wesley, 1963, edited by Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew. Wang, Y. C. and W. H. Ip, 2011. Source dependency of exospheric sodium on Mercury. Icarus 216, 387-402. 5.3 Data Processing 5.3.1 Data Processing Level The CDR/DDR archive includes level 3 (CDR) and level 4 (DDR) data as defined by the Committee on Data Management and Computation (CODMAC, Appendix G). The archive also contains calibration information, a description of the SPICE kernels that are needed to generate viewing geometry, and documentation describing the characteristics and generation of the data products. Each product has a unique file name across all MASCS data products, see section 6.1.2. 5.3.2 Data Product Generation The UVVS CDR/DDR files were produced by the MESSENGER Science Operations Center (SOC), operated jointly by APL and ACT. The 'PIPE-MASCS2CDR' and 'PIPE-MASCS2DDR' software, derived from MASCS-team produced calibration algorithms, converted the data to the proper PDS labeled format. These software were not supported products deliverable to the PDS; however the algorithms and tables are included in the archive. The CDR/DDR data products were made available to the MESSENGER Science Team during the mission for initial evaluation and validation. At the end of the evaluation and validation period, the data were organized and stored in the directory structure described in section 6.1.3 for transmittal to the Geosciences and Atmospheres Nodes. The transmittal process is described in the following section, Data Flow. PDS provides public access to the data products through its online data distribution system. These products are used for engineering support, direct science analysis, and construction of other science products. Although there is enough information in the header to perform some processing, for more sophisticated processing, ancillary data are required. Examples of ancillary data include calibration files and viewing geometry files (SPICE kernels). Calibration files for UVVS are located in the CALIB directory. Calibration and data reduction details and tables are described in the UVVS_EDR2CDR.TXT, UVVS_CDR2DDR.TXT, UVVS_CDR2DDR_SUR.TXT, and MASCS_CAL_RPT.TXT documents, located in the DOCUMENT directory. The geometry.txt file located in the GEOMETRY directory (section 6.1.4) contains a listing of the SPICE kernel types that are needed by a user to generate viewing geometry. The SPICE kernel files are archived with the PDS NAIF Node. 5.3.3 Data Flow The MESSENGER SOC operated under the auspices of the MESSENGER Project Scientist to plan data acquisition and generate and validate data archives. The SOC supported and worked with the Mission Operations Center (MOC), the Science Team, instrument scientists, and the PDS (Figure 3). The SOC was located at the Johns Hopkins University Applied Physics Lab (JHU/APL). During the mission operations phase, the SOC produced early versions of products to be used by the science and instrument teams. The MESSENGER SOC delivered data to both the PDS Geosciences and Atmospheres Nodes in standard product packages according to the schedule outlined in the MESSENGER Data Management and Archiving Plan [Applicable Document 4]. The UVVS and VIRS data sets are archived at both Nodes. Each package comprises both data and ancillary data files, organized into directory structures consistent with the volume design described in Section 6.1.3. In preparation for the delivery, the directory structure was copied onto hard disk and mailed to the Geosciences and Atmospheres PDS nodes. Also transferred was a checksum file created using the MD5 algorithm. This provided an independent method of verifying the integrity of the archive after it was transferred to disk. Within several days of delivery, the PDS Node acknowledged receipt of the archive and checksum file. If acknowledgement was not received, or if problems were reported, the MESSENGER SOC immediately took corrective action. After receipt of the hard disk, the PDS Nodes transferred the archive files to their local archive staging areas and checked for data integrity using the checksum file. The Nodes performed any additional verification and validation of the data provided and reported any discrepancies or problems to the MESSENGER SOC. It was expected that the Nodes perform these checks in about two weeks. After inspection was completed to the satisfaction of the PDS Nodes, the Nodes issued to the MESSENGER SOC acknowledgement of successful receipt of the data. Following receipt of a data delivery, each Node organized the data into PDS archive volume structure within its online data system. The Science Team generated all of the required files associated with a PDS archive volume (index file, readme files, etc.) as part of its routine processing of incoming MASCS data. Newly delivered data were made available publicly from PDS once accompanying labels and other documentation were validated. Changes and/or updates in instrument calibration resulted in an incremented calibration version number and regeneration of CDRs/DDRs. Regenerated data were included in the next scheduled delivery, as appropriate. 5.3.4 Labeling and Identification The PDS label conforms to the PDS version 3 standards. For more information on this standard consult the PDS Standards Reference JPL D-7669 Document [Applicable Document 3]. The purpose of the PDS label is to describe the data product and provide ancillary information about the data product. One observation is associated with two CDR data products: a science header table (HDR), showing the instrument command parameters for a given observation, and a science data table (SCI), showing counts, derived science data, and pointing information for each step of an observation. The CDRs are in binary table format, and each is described by a detached PDS label. There are six standard data products, "UVVSCFUVHDR," "UVVSCFUVSCI," "UVVSCMUVHDR," "UVVSCMUVSCI," "UVVSCVISHDR," and "UVVSCVISSCI" (Section 5.2). UVVS Surface DDRs consist of individual surface scans of the MUV PMT on point targets to keep the FOV on the same spot during the entire grating scan. There is one pair of surface DDRs: "UVVSDMUVHDR" and "UVVSDMUVSCI". The UVVS Atmosphere DDRs consist of time-ordered sequences of calibrated spectra and radiance values that are measured along lines of sight perpendicular to Mercury radius vectors. There are three defined geometry classifications: dayside limb scans, dayside and nightside limb drift profiles, and nightside tail sweeps. The Atmosphere DDRs are in binary format and each is described by a detached PDS label. Each file contains N records where N is the number of sequential steps recovered from the filtering process. There are nine standard Atmosphere DDRs produced from the CDRs. These are identified as "UVVSDNALS," "UVVSDNALD," and "UVVSDNANS" for sodium. Names for Mg and Ca are produced by replacing 'NA' with 'MG' and 'CA', respectively. The UVVS Atmospheric Model DDRs consist of average fits to observations at a series of Mercury true anomaly and local times. The model parameters near-surface density, temperature, and scale height are provided. The data are provided in an ASCII table format. There are 3 atmospheric model DDRs, identified as "UVVSDNAMOD", "UVVSDMGMOD", and "UVVSDCAMOD" for the sodium, magnesium, and calcium models, respectively. The following are examples of UVVS PDS labels for the "UVVSFUVHDR" and "UVVSFUVSCI" CDR data products and the "UVVSDMUVHDR", "UVVSDMUVSCI", "UVVSDNALS", and "UVVSDNAMOD" DDR data products, respectively. Details about the label format are specified in section 6.3. 5.3.4.1 Example PDS Label for the UVVS Science Header CDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 50 FILE_RECORDS = 480 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UFC_MC4_07_09343_064005_HDR_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2010-07-28T19:53:37 PRODUCT_TYPE = "CDR" SOFTWARE_NAME = "PIPE-MASCS2CDR" SOFTWARE_VERSION_ID = "2.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-3-UVVS-CDR-CALDATA-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSCFUVHDR" MISSION_PHASE_NAME = "MERCURY 4 CRUISE" TARGET_NAME = "VENUS" TARGET_DESC = "Venus-As-Star Cal" START_TIME = 2009-12-09T06:40:05 STOP_TIME = 2009-12-09T10:08:02 SPACECRAFT_CLOCK_START_COUNT = "168828279.009" SPACECRAFT_CLOCK_STOP_COUNT = "168840756.989" ^TABLE = "UFC_MC4_07_09343_064005_HDR.DAT" OBJECT = TABLE COLUMNS = 23 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 50 ROWS = 480 DESCRIPTION = " This table contains instrument engineering data collected by the FUV detector. Detailed descriptions for the parameters defined below are contained in the CDR SIS document. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. " ^STRUCTURE = "UVVSHDRC.FMT" END_OBJECT = TABLE END 5.3.4.2 Example PDS Label for the UVVS Science CDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 752 FILE_RECORDS = 1216 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UFC_ORB_29_12056_051641_SCI_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2012-03-26T18:13:40 PRODUCT_TYPE = "CDR" SOFTWARE_NAME = "PIPE-MASCS2CDR" SOFTWARE_VERSION_ID = "9.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-3-UVVS-CDR-CALDATA-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSCFUVSCI" MISSION_PHASE_NAME = "MERCURY ORBIT" TARGET_NAME = "MERCURY" OBSERVATION_TYPE = {"LimbOpp","ExoScan"} START_TIME = 2012-02-25T05:16:41 STOP_TIME = 2012-02-25T05:22:26 SPACECRAFT_CLOCK_START_COUNT = "238634468.125" SPACECRAFT_CLOCK_STOP_COUNT = "238634813.953" ^TABLE = "UFC_ORB_29_12056_051641_SCI.DAT" OBJECT = TABLE COLUMNS = 63 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 752 ROWS = 1216 DESCRIPTION = " This table contains MESSENGER UVVS spectra collected by the FUV detector and instrument engineering data. Detailed descriptions for the parameters defined below are contained in the CDR SIS document. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. " NOTE = " SPICE Kernels: msgr20120224.bc msgr20120225.bc msgr20120226.bc msgr_dyn_v600.tf msgr_v210.tf msgr_mascs_v100.ti naif0010.tls pck00009_MSGR_v10.tpc messenger_1444.tsc msgr_de405_de423s.bsp msgr_20040803_20140820_od259sc_0.bsp " ^STRUCTURE = "UVVSSCIC.FMT" END_OBJECT = TABLE END 5.3.4.3 Example PDS Label for the UVVS Surface Header DDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 36 FILE_RECORDS = 1 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UMD_ORB_48_11112_111324_HDR_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2013-05-31T19:53:37 PRODUCT_TYPE = "DDR" SOFTWARE_NAME = "PIPE-MASCS2DDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSDMUVHDR" MISSION_PHASE_NAME = "MERCURY ORBIT" TARGET_NAME = "MERCURY" TARGET_DESC = "UVVS SURFACE OBSERVATION" START_TIME = 2011-04-22T11:13:26 STOP_TIME = 2011-04-22T11:13:31 SPACECRAFT_CLOCK_START_COUNT = "1/211958275" SPACECRAFT_CLOCK_STOP_COUNT = "1/211958280" ^TABLE = "UMD_ORB_48_11112_111324_HDR.DAT" OBJECT = TABLE COLUMNS = 16 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 36 ROWS = 1 DESCRIPTION = " This table contains instrument engineering data collected by the MUV detector. Each record contains the values over a single UVVS observation. A UVVS observation is defined as all the scan data contained within one UVVS science packet. Detailed descriptions for the parameters defined below are contained in the CDR-DDR SIS document. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. " ^STRUCTURE = "UVVSHDRD_SUR.FMT" END_OBJECT = TABLE END 5.3.4.4 Example PDS Label for the UVVS Surface Science DDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 270 FILE_RECORDS = 46 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UMD_ORB_48_11112_111324_SCI_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2012-03-26T18:13:40 PRODUCT_TYPE = "DDR" SOFTWARE_NAME = "PIPE-MASCS2DDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSDMUVSCI" MISSION_PHASE_NAME = "MERCURY ORBIT" TARGET_NAME = "MERCURY" OBSERVATION_TYPE = "UVVSPhotometry" START_TIME = 2011-04-22T11:13:26 STOP_TIME = 2011-04-22T11:13:31 SPACECRAFT_CLOCK_START_COUNT = "1/211958275" SPACECRAFT_CLOCK_STOP_COUNT = "1/211958280" ^TABLE = "UMD_ORB_48_11112_111324_SCI.DAT" OBJECT = TABLE COLUMNS = 25 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 270 ROWS = 46 DESCRIPTION = " This table contains MESSENGER UVVS spectra collected by the MUV detector and instrument engineering data. Detailed descriptions for the parameters defined below are contained in the CDR-DDR SIS document. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. " NOTE = " SPICE Kernels: msgr20110421.bc msgr20110422.bc msgr20110423.bc msgr_dyn_v600.tf msgr_v220.tf msgr_mascs_v100.ti naif0010.tls pck00010_MSGR_v10.tpc messenger_1728.tsc msgr_de405_de423s.bsp msgr_20040803_20140822_od301sc_0.bsp " ^STRUCTURE = "UVVSSCID_SUR.FMT" END_OBJECT = TABLE END 5.3.4.5 Example PDS Label for the UVVS Atmosphere DDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 906 FILE_RECORDS = 1234 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UD_05_LS_NA_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2013-01-14T15:02:30 PRODUCT_TYPE = "DDR" SOFTWARE_NAME = "PIPE-MASCS2DDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSDNALS" MISSION_PHASE_NAME = "MERCURY ORBIT YEAR 2" TARGET_NAME = "MERCURY" OBSERVATION_TYPE = "LimbScan" START_TIME = 2013-12-09T06:40:05 STOP_TIME = 2013-12-09T10:08:02 SPACECRAFT_CLOCK_START_COUNT = "268828279.009" SPACECRAFT_CLOCK_STOP_COUNT = "268840756.989" ^TABLE = "UD_05_LS_NA.DAT" OBJECT = TABLE COLUMNS = 30 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 906 ROWS = 1234 DESCRIPTION = " This table contains dayside limb scan data collected by the UVVS for a given Mercury year. Detailed descriptions for the parameters defined below are contained in the CDR/DDR SIS document. The complete column definitions are contained in an external file found in the LABEL directory of the archive volume. " ^STRUCTURE = "UVVSSCID.FMT" END_OBJECT = TABLE END 5.3.4.6 Example PDS Label for the UVVS Atmospheric Model DDR PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 128 FILE_RECORDS = 504 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "UD_NA_MOD_TAB" PRODUCT_VERSION_ID = "V1" PRODUCT_CREATION_TIME = 2014-02-18T16:23:13 PRODUCT_TYPE = "DDR" SOFTWARE_NAME = "PIPE-MASCS2DDR" SOFTWARE_VERSION_ID = "1.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "UVVS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0" STANDARD_DATA_PRODUCT_ID = "UVVSDNAMOD" MISSION_PHASE_NAME = "MERCURY ORBIT" TARGET_NAME = "MERCURY" START_TIME = 2011-04-04T21:02:28 STOP_TIME = 2013-03-17T23:51:20 SPACECRAFT_CLOCK_START_COUNT = "1/210438416.311" SPACECRAFT_CLOCK_STOP_COUNT = "2/005888279.695" ^TABLE = "UD_NA_MOD.TAB" OBJECT = TABLE COLUMNS = 9 INTERCHANGE_FORMAT = ASCII ROW_BYTES = 128 ROWS = 504 DESCRIPTION = " The table contains the series of model fits to data averaged over specific Mercury true anomalies and local times for Sodium. The table contains data processed from UVVS CDRs for the time period specified by START_TIME and END_TIME in the PDS label. " OBJECT = COLUMN NAME = TRUE_ANOMALY COLUMN_NUMBER = 1 START_BYTE = 1 BYTES = 7 DATA_TYPE = ASCII_REAL FORMAT = "F7.3" DESCRIPTION = "Mercury orbital position in degrees. Fit parameters are provided as averages over 5 degree increments, the middle of that 5 degree increment is listed in the file (e.g. 2.5 degrees for the 0-5 degree bin)." END_OBJECT = COLUMN OBJECT = COLUMN NAME = LOCAL_TIME COLUMN_NUMBER = 2 START_BYTE = 9 BYTES = 6 DATA_TYPE = ASCII_REAL FORMAT = "F6.3" DESCRIPTION = "Local time of the model fit. Only limb scans taken within half an hour of the given local time are included in the average." END_OBJECT = COLUMN OBJECT = COLUMN NAME = NEAR_SURFACE_DENSITY COLUMN_NUMBER = 3 START_BYTE = 16 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Average near-surface density from modified Chamberlain model fits. A value of -1 indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of cm-3." END_OBJECT = COLUMN OBJECT = COLUMN NAME = NEAR_SURFACE_DENSITY_UNCERTAINTY COLUMN_NUMBER = 4 START_BYTE = 32 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Average one-sigma standard deviation of the fit to near-surface density. A value of -1 indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of cm-3." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TEMPERATURE COLUMN_NUMBER = 5 START_BYTE = 48 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Average temperature modified from Chamberlain model fits. A value of -1 indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of K." END_OBJECT = COLUMN OBJECT = COLUMN NAME = TEMPERATURE_UNCERTAINTY COLUMN_NUMBER = 6 START_BYTE = 64 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Average one-sigma standard deviation of the fit to temperature. A value of -1 indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of K." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SCALE_HEIGHT COLUMN_NUMBER = 7 START_BYTE = 80 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Scale height corresponding to the model fit. A value of -1 indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of km." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SPARE_1 COLUMN_NUMBER = 8 START_BYTE = 96 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Spare column, placeholder for future parameter. Default to spare value of 0.000000." END_OBJECT = COLUMN OBJECT = COLUMN NAME = SPARE_2 COLUMN_NUMBER = 9 START_BYTE = 112 BYTES = 15 DATA_TYPE = ASCII_REAL FORMAT = "F15.6" DESCRIPTION = "Spare column, placeholder for future parameter. Default to spare value of 0.000000." END_OBJECT = COLUMN END_OBJECT = TABLE END 5.4 Standards Used in Generating Data Products 5.4.1 PDS Standards The UVVS CDR/DDR data products were constructed according to the data object concepts developed by the PDS. By adopting the PDS standards, the data products are consistent in content and organization with other planetary data collections. The UVVS CDR data are grouped into fours: a binary table of science data, a binary table of science header information, and detached PDS labels describing each of the binary tables. The UVVS Atmosphere and Surface DDR data are grouped into pairs: a table of binary data and a detached PDS label describing the data. The UVVS Atmospheric Model data are provided as ASCII tables (*.TAB) with detached PDS labels. 5.4.2 Time Standards The SC_TIME field matches the spacecraft time in integer seconds that is transmitted to MESSENGER subsystems by the Integrated Electronics Module (IEM). It is intended to be the Mission Elapsed Time (MET). MET = 0 is August 3, 2004, at 05:59:16UTC, 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 reset in early 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/). The SPICE spacecraft clock coefficients file (see Appendix F) should be used to calculate the conversion between MET and UTC. Product label files express MET in /. format (note: MET milliseconds are only used in CDR and DDR product labels). UTC times in some products had a 1-second quantization issue before PDS Delivery 12 that has been solved (and the affected products redelivered). 5.4.3 Coordinate Systems The computational assumptions for the geometric and viewing data provided in the PDS label are listed below. There are two coordinate systems in use: 1) the celestial reference system used for target and spacecraft position and velocity vectors; and 2) the planetary coordinate system for geometry vectors and target location. The celestial coordinate system is J2000 (Mean of Earth equator and equinox of J2000). The planetary coordinate system is planetocentric. * For individual spectra in VIRS and individual steps in UVVS, the midpoint of the observation is used for determination of most geometric elements (such as center of observation, subspacecraft latitude/longitude/altitude, etc.). For VIRS, the "leading" and "trailing" point of the footprint smear use interpolation of the start and end time of the observation. * Label parameters reflect observed, not true, geometry. Therefore, light-time and stellar aberration corrections are used as appropriate. * The inertial reference frame is J2000 (also called EME2000). * Latitudes and longitudes are planetocentric. * The "sub-point" of a body on a target is defined by the surface intercept of the body-to-target-center vector. This is not the closest point on the body to the observer. * Distances are in km, speeds in km/sec, angles in degrees, angular rates in degrees/sec, unless otherwise noted. * Angle ranges are 0 to 360 degrees for azimuths and local hour angle. Longitudes range from 0 to 360 degrees (positive to the East). Latitudes range from -90 to 90 degrees. * SPICE kernel files used in the geometric parameters are outlined in APPENDIX F- SPICE Kernel Files Used in MESSENGER Data Products. 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 transfers data to PDS via electronic transfer and delivery methods as detailed in section 5.3.3. After verification of the data transfer, PDS provides public access to MESSENGER science data products through its online data distribution system. Data are stored under a unique file name as defined in section 6.1.2. 5.5 Data Validation The UVVS CDR/DDR data products are validated by the UVVS Instrument Scientist for science content and for compliance with PDS archive standards and the MESSENGER Data Management and Archiving Plan [Applicable Document 4]. 6. Detailed Data Product Specifications 6.1 Data Archive Structure and Organization The UVVS EDR data set is a static dataset. Static data sets, once produced and validated, are not subject to update or modification. The UVVS CDR/DDR data set is a dynamic dataset. Dynamic data sets have the inherent property that they continue to evolve and improve as the knowledge of the mission parameters improve. These data sets are periodically updated or replaced with new versions, and are likely to be updated by post-mission data analysis programs. As an example, the calibration files continue to evolve as knowledge of the MASCS sensor, as well as of the pointing accuracy of the MESSENGER spacecraft improves. 6.1.1 Handling Errors It is inevitable that errors are introduced into the archive even with data validation procedures applied to the volumes. As errors were discovered, they are reported to the MESSENGER SOC. An errata report file (ERRATA.TXT), located in the ROOT directory, was maintained to track and document all discovered errors during the mission, including any CDRs/DDRs that were revised during the course of the mission. Revised CDRs/DDRs or CDRs/DDRs that were missing from a previous PDS delivery were provided at the next scheduled PDS delivery or at the final PDS delivery as needed. PDS replaces the outdated files with the revised files when provided in the data directories of the archive volume. MASCS followed similar procedures as other instruments have historically. The CONFIDENCE_LEVEL_NOTE in the uvvs_cdr/ddr_ds.cat files located in the CATALOG directory was updated with each regeneration, and CDR/DDR regenerations were delivered at normal periodic delivery times. Redeliveries followed the same pattern as standard deliveries. As SPICE kernels were updated periodically, updated pointing information flowed down to CDR/DDR geometry fields of all CDRs/DDRs. File delivery manifests were provided with deliveries, including MD5 checksums. 6.1.2 File Naming Conventions The file names developed for PDS data volumes are restricted to a 36-character file name and a 3-character extension name with a period separating the file and extension names. The general form of the UVVS CDR and Surface DDR file name is "UdL_mmm_XX_YYDDD_HHMMSS_xxx" where: U: UVVS d: detector. F = FUV, M = MUV, V = VIS L: data-level. E = EDR, C = CDR, D = DDR mmm: mission phase EAC = Earth cruise to Earth flyby EAF = Earth flyby VC1 = cruise, post Earth flyby to pre-Venus 1 flyby VF1 = Venus 1 flyby VC2 = cruise, post Venus 1 to pre-Venus 2 flyby VF2 = Venus 2 flyby MC1 = cruise, post Venus 2 to pre-Mercury 1 flyby MF1 = Mercury 1 flyby MC1 = cruise, post Mercury 1 to pre-Mercury 2 flyby MF2 = Mercury 2 flyby MC3 = cruise, post Mercury 2 to pre-Mercury 3 flyby MF3 = Mercury 3 flyby MC4 = cruise, post Mercury 3 to pre-orbit insertion ORB = Orbit insertion until end of nominal orbit mission OB2 = Extended mission (orbit year 2) OB3 = Extended mission (orbit year 3) OB4 = Extended mission (orbit year 4) OB5 = Extended mission (orbit year 5) XX: two digit macro id. Valuebe 00 for data created prior to the existence of UVVS macros or when PIPE cannot determine the macro id used. Value 48 or 49 for surface observations. YY: The last two digits of the year in which the data were acquired. DDD: The three digit day of year in which the data were acquired. HHMMSS: The 6 digit hour, minute, second of the start of the observation. xxx: data-type. HDR = per observation (science header) data, SCI = per step (science CDR) or per bin (surface science DDR) data. The general form of the UVVS Atmosphere DDR file name is "UL_mm_XX_ss" where: U: UVVS L: data-level. D = DDR mm: mercury year 01-04 = Primary mission 05-09 = Extended mission (orbit year 2) 10-13 = Extended mission (orbit year 3) 14-17 = Extended mission (orbit year 4) 18 = Extended mission (orbit year 5) XX: the record category LS = Dayside Limb Scan LD = Dayside and Nightside Limb Drift NS = Nightside Sweep ss: species. NA = sodium, MG = magnesium, CA = calcium The general form of the UVVS Atmospheric Model DDR file name is "UL_ss_XXX" where: U: UVVS L: data-level. D = DDR ss: species. NA = sodium, MG = magnesium, CA = calcium XXX: MOD = model 6.1.3 Directory Structure and Contents for MASCS CDR/DDR/DAP Archive Volume The following illustrations (Figures 4a-4c) show the directory structure overview for the MASCS CDR/DDR/DAP archive volume. A detailed description of the directory tree is provided in section 6.1.4. Empty directories are not included on the volume. Note that the volume contains both UVVS and VIRS CDRs/DDRs/DAPs. Details for the VIRS CDRs/DDRs/DAPs are contained in a separate VIRS SIS document. This archive volume is stored at both the Atmospheres and Geosciences PDS Nodes. Figure 4a: Directory Structure Overview. _________________________________________|___________________________ | | | | | | | | |