MESSENGER MASCS VIRS Calibrated Data Record, Derived Data Record, and Derived Analysis Product Software Interface Specification Version 5.4 April 11, 2017 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, Table 3, Section 6.3, Appendix A, B 1. Replaced sample PDS labels with new versions containing PRODUCT_VERSION_ID. 2. Added PRODUCT_VERSION_ID to VICINDEX.TAB column list. 3. Updated VIRSNC.FMT and VIRSVC.FMT columns to match files delivered in PDS Release 5. 1.7 9/15/10 J. Ward, GEO 6.1.3, 6.1.4 1. Added EXTRAS directory tables. 2. Updated DATA directory structure. 1.8 5/5/11 J. Ward, GEO 6.1.3, 6.1.4 Updated to reflect new data directory structure. 1.9 6/10/11 J. Ward, GEO Table 2, Figure 4, 6.1.4, 6.3.3, Appendix A, B 1. Added "temperature-corrected" to Table 2. 2. Fixed labeling in Figure 4. 3. Updated EXTRAS directory contents. 4. Revised column 34 & 35 format file descriptions. 2.0 6/14/11 S. Ensor, SOC Document Review Replaced signature page with Document Review information. 2.1 6/17/11 J. Ward, GEO 6.1.4 Renamed SUPERTABLE.XLS TO MASTER_CRUISE_TABLE.XLS. 2.2 1/24/12 N. Izenberg, MASCS; J. Ward, GEO 2, 6.3.2, 6.1.4, Appendix A, B 1. Added refs to calibration updates: Dark current calibration improvement; Noise spectrum definition revision. 2. Added new documents to DOCUMENT and EXTRAS directory contents. 3. Revised descriptions for columns 23 & 24 in VIRSNC.FMT & VIRSVC.FMT. 2.3 4/6/12 N. Izenberg, MASCS; J. Ward, GEO All 1. Deleted J2000 geometry fields from CDR records. 2. Added SITE_ID keyword to CDR labels. 3. Added new DDR data product. 2.4 4/10/12 J. Ward, GEO 5.3.4.1-5.3.4.4, Appendix B 1. Revised SITE_ID in sample CDR labels. 2. Fixed START_BYTE error in Appendix B. 2.5 4/13/12 J. Ward, GEO Section 7 Removed Section 7 Archive Release schedule. 2.6 4/30/12 J. Ward, GEO Fig. 4, Tables 3a-3b, Section 6.1.4 Revised directory structure. 2.7 5/4/12 J. Ward, GEO Section 6.3.2, Appendix C, D Revised DDR format files. 2.8 5/14/12 J. Ward, GEO Appendix B Fixed typo in VIRSVC.FMT, column 44. 2.9 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. 3.0 5/18/12 J. Ward, GEO 6.1.4, Figure 4, Tables 3a-3b 1. Edited catalog directory contents. 2. Minor edits to directory structure. 3. Removed length column from index table contents table. 3.1 5/22/12 J. Ward, GEO 5.3.4.4, Table 3b, Appendix C, D 1. Fixed typos in DDR format files and sample labels. 2. Removed "ANY_LAMP_ON" column from DDR index table. 3.2 7/17/12 J. Ward, GEO 6.1.4 Updated EXTRAS directory contents. 3.3 12/13/12 N. Izenberg, MASCS; J. Ward, GEO 6.1.4, 6.3.1.2, Appendices A-D Calibration update (added to list in section2), DQI revision (updated format files). Updated DOCUMENT and EXTRAS directory contents. 3.4 4/22/13 P. Bedini, SOC; J. Ward, GEO All Editorial changes. 3.5 4/25/13 J. Ward, GEO All Added new Derived Analysis Product (DAP). 3.6 6/5/13 N. Izenberg 5.23, 5.3.4.5 Sections on DAP details. 3.7 6/13/13 J. Ward, GEO All Additional edits. 3.8 6/17/13 N. Izenberg 5.2.3 Additional edits. Version submitted for PDS peer review. 3.9 12/4/13 J. Ward, GEO 2, 6.1.4 Added Applicable Document. Updated DOCUMENT and EXTRAS directory contents. 4.0 12/6/13 J. Ward, GEO 6.1.4 Minor edit. 4.1 1/10/14 J. Ward, GEO, N. Izenberg 5.2.1, 5.2.2, 6.1.2, 6.1.4 Minor edits. 4.2 1/16/14 J. Ward, GEO 6.1.4 Minor typo. 4.3 2/18/14 J. Ward, GEO 6.1.4 Added Ca Chamberlain model document. 4.4 7/8/14 N. Izenberg 5.4.2, 6.3.1, 5.5 Various MET/UT fixes, standardization between products. Invalid number adjustments. Minor edits. 4.5 7/10/14 J. Ward, GEO Appendices A-D Added INVALID_CONSTANT keyword to VIRS format files 4.6 1/14/16 S. Ensor, SOC All Final mission edits. 4.7 1/21/16 J. Ward, GEO All Additional minor edits. 4.8 1/27/16 J. Ward, GEO 6.1.4 Additional minor edits. 4.9 2/22/16 J. Ward, GEO 5.1, 6.1.4, Appendices A-D Additional minor edits. 5.0 8/22/16 J. Ward, GEO 5.2.2, 5.3.4, 6.1.2-6.1.4, 6.3 Added applicable information for new data products, UVVS+VIRS Combined DDR and UVVS Atmosphere Summary DDR, UVVS FUV Surface DDR. 5.1 1/23/17 J. Ward, GEO Appendix I Added Appendix I. 5.2 3/30/17 N. Izenberg, D. Domingue, R. Klima, J, Ward, GEO 5.2.1.1, 5.2.2, 5.2.3, 6.3.2.2 1. Added photometric normalization description for V1 and V2. 2. Added flat-field analysis information. 3. Updated for version 2 of the VIRS DDR and DAP datasets. 4. Additional minor edits. 5.3 4/7/17 J, Ward, GEO 6.1.4 Additional minor edits. 5.4 4/11/17 J, Ward, GEO 6.1.4 Additional minor edits. 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) 5.2.1.1 MASCS Lamp-Based Flat-field 5.2.2 Derived Data Records (DDRs) 5.2.3 Derived Data Products (DAPs) 5.3 Data Processing 5.3.1 Data Processing Level 5.3.2 Data Product Generation 1 5.3.3 Data Flow 5.3.4 Labeling and Identification 5.3.4.1 Example PDS Label for the VIRS NIR CDR Data Products 5.3.4.2 Example PDS Label for the VIRS VIS CDR Data Products 5.3.4.3 Example PDS Label for the VIRS NIR DDR Data Products 5.3.4.4 Example PDS Label for the VIRS VIS DDR Data Products 5.3.4.5 Example PDS Label for the VIRS DAP Data Product 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 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 Obtained from Experiment Data Record (EDR) 6.3.1.2 Calibrated Items and Additional Metadata 6.3.1.3 SPICE Derived Geometry Values 6.3.1.4 SPARE Columns 6.3.2 DDR Column Descriptions 6.3.2.1 Fields Obtained from Experiment Data Record (EDR) 6.3.2.2 Derived Items and Additional Metadata 6.3.2.3 SPICE Derived Geometry Values 6.3.2.4 SPARE Columns 7. Appendices APPENDIX A- VIRSNC.FMT FILE APPENDIX B- VIRSVC.FMT FILE APPENDIX C- VIRSND.FMT FILE APPENDIX D- VIRSVD.FMT FILE APPENDIX E- SPICE Kernel Files Used In Messenger Data Products APPENDIX F- CODMAC/NASA Definition of Processing Levels for Science Data Sets APPENDIX G- ACRONYMS APPENDIX H- MASCS Instrument Overview APPENDIX I- MASCS Data Product Summary 1. Purpose and Scope of Document 1.1 Purpose This document provides users of the MESSENGER Visible and Infrared Spectrograph (VIRS) data products with a detailed description of the instrument (Figure 1), as well as Calibrated Data Record (CDR), Derived Data Record (DDR), and Derived Analysis Product (DAP) generation and storage. The VIRS 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/DAP data product SIS and a CDR/DDR/DAP archive volume SIS. Figure 1: MASCS Instrument, VIRS 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 VIRS CDRs, DDRs, and DAPs. Typically, these individuals include software engineers, data analysts, and planetary scientists. The SIS applies to the CDR/DDR/DAP data products produced during the course of MESSENGER mission operations. Experiment data records (EDRs), the raw, uncalibrated data from MASCS VIRS, are addressed in the VIRS EDR SIS (Applicable Document 8). EDR data products are archived in a separate PDS archive volume. This document has been updated for version 2 of the VIRS DDR and DAP data sets (MESS-E/V/H-MASCS-4-VIRS-DDR-V2.0 and MESS-E/V/H-MASCS-5-VIRS-DAP-V2.0). 2. Applicable Documents The MESSENGER MASCS VIRS CDR/DDR/DAP 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/VIRS EDR SIS: APL doc no. SIE-06-045 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. VIRS IR Dark Analysis Report 1: Operational Changes: R. Klima & MASCS Team, SRE-01-11. 12. VIRS IR Dark Analysis Report 2: Calibration Changes: R. Klima & MASCS Team, SRE-02-11. 13. VIRS Calibration Changes for PDS Delivery 9: R. Klima and the MASCS Team. SRE-05-12. 14. VIRS Calibration Changes for PDS Delivery 11: MASCS/VIRS Instrument Team. SRE-01-13. 15. Hillier, J., Buratti, B., Hill, K., 1999. Multispectral photometry of the Moon and absolute calibration of the Clementine UV/VIS camera. Icarus 141, 205-225. 16. Domingue, D.L., Denevi, B.W., Murchie, S.L., Hash, C.D., 2016. Application of multiple photometric models to disk-resolved measurements of Mercury's surface: Insights into Mercury's regolith characteristics. Icarus 268, 172-203. 17. Domingue, D.L, D'Amore, M., Ferrari, S., Helvert, J., Izenberg, N., 2017. Analysis of the MESSENGER MASCS Photometric Targets Part I: Photometric Standardization for Examining Spectral Variability Across Mercury's Surface. In prep. 18. Kaasalainen, M., J. Torppa, K. Muinonen, 2001. Optimization Methods for Asteroid Lightcurve Inversion II. The Complete Inverse Problem. Icarus 153, 37-51. 19. Shkuratov Y., Kaydash, V., Korokhin, V., Velikodsky, Y., Opanasenko, N., Videen, G., 2011. Optical measurements of the Moon as a tool to study its surface. Planet. Space Sci. 59, 1326-1371. 20. MASCS/VIRS Lamp-Based Flat Field Report: R. Klima, G. Holsclaw & the MASCS team, 2017. 3. Relationships with other Interfaces The VIRS 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 VIRS and UVVS CDRs, DDRs, and DAPs have 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, the 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 fed 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 (115-190 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, Na, and Ca) and from newly discovered species (Mg, Al, Mn, and Ca+). In addition to determining the composition and structure of the exosphere, these confirmed detections provide the basis for determining exospheric processes, studying the relationship between surface and exospheric composition, and studying surface-exosphere-magnetosphere interactions. Searches were made for numerous additional predicted species (e.g. S, C, Si, Fe, OH, and Mg+). Observations were also acquired that covered emissions from O, which may or may not have been detected by Mariner 10, and K, which is known from ground-based observations but which was difficult for UVVS given that the strongest resonance line was outside the UVVS wavelength range. These searches are still undergoing analysis and will provide stringent upper limits even if no detections are found through detailed analysis. 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 UVVS data products are described in a separate UVVS data product SIS. The VIRS data products are described below. Table 1: MASCS Instrument Overview. See PDF version of document for table. Please see Applicable Document 9 and Appendix H for additional details about the MASCS instrument. 5.2 Data Product Overview Please see Appendix I for a summary table of all MASCS data products. 5.2.1 Calibrated Data Records (CDRs) The VIRS CDRs consist of calibrated data derived from MASCS VIRS Experiment Data Records (EDRs). The EDRs are the raw data records used to derive surface reflectance data used for scientific analysis. The science EDRs contain raw counts of the VIRS detectors for the assigned integration times and pointing orientations. The VIRS instrument shutter can be closed for on-board dark observations, or the instrument can be pointed to empty space for space-darks. Additionally there are two on-board "grain-of-wheat" size lamps that are periodically used to illuminate the detectors to acquire "flat-field" observations. Wavelength range and sensitivity of each detector are 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 values 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 which are stored in CDRs. There are two EDR data products produced by the VIRS instrument, one for each detector (VIS and NIR). These are identified in the EDR PDS labels as "VIRSVIS" and "VIRSNIR" standard data products, respectively. There is also a MASCS housekeeping EDR data product generated by the MASCS instrument. This is identified in the EDR PDS labels as the "MASCSHK" standard data product. There is one CDR product derived for each detector (VIS and NIR) using the EDR and associated housekeeping data from the HK EDR. The housekeeping EDR is defined in both the UVVS and the VIRS EDR SISs. VIRS and Housekeeping data are input into the VIRS calibration pipeline to derive Calibrated Data Records, which are identified as "VIRSCVIS" and "VIRSCNIR" CDRs. For the VIRS CDR data products, one CDR contains all the calibrated data from one observation. However, one observation generated a variable number of spectra and a variable number of CCSDS (Consultative Committee for Space Data Systems) -standard packets. Thus, there is not a one-to-one correspondence between CCSDS packets and VIRS EDRs or CDRs, but there should be a correspondence between VIRS EDRs and CDRs modulated by dark spectra taken by VIRS used as part of calibration data. Each CDR data product consists of two files. One file contains the data itself, arranged in a PDS binary table format. The other file is a detached PDS label, which describes the content of the data file. The label defines the start time and end of the observation, product creation time, etc. The label points to an associated format file that defines the columns of the binary table contained within the data file. At high instrument temperatures, NIR pixels begin to saturate due to elevated background noise. Saturated pixel values are denoted in the CDR by NaN or other invalid indicators. There are four types of spectra stored in each CDR data file: RAW_SPECTRUM_DATA (table column 20), CORRECTED_COUNTS_SPECTRUM_DATA (table column 22), CALIBRATED_RADIANCE_SPECTRUM_DATA (table column 23), and NOISE_SPECTRUM_DATA (table column 24). Please see the table column definitions in section 6.3 for detailed descriptions of these columns. 5.2.1.1 MASCS Lamp-Based Flat-field VIRS contained internal stimulus lamps that illuminated both detector channels. During the orbital mission, calibration sequences were conducted to monitor time- or temperature-dependent changes in the pixel-to-pixel sensitivity in both the Si and InGaAs detectors. Due to high temperatures and corresponding high dark current, the InGaAs detector was saturated during almost all lamp observations. The Si detector, however, was unsaturated for most temperatures. We examined these data in an effort to derive a flat-field correction from the lamp data. However, efforts to normalize the variable lamp signal and model changes in the flat-field as a function of temperature were found not to improve the data beyond the existing lab-based calibration, and thus have not been applied to the PDS data. See VIRS_FLATFIELD_REPORT.PDF in the DOCUMENT directory for the flat-field derivation and additional information. 5.2.2 Derived Data Records (DDRs) For the VIRS DDR data products, one DDR contains all the derived reflectance data from one observation. Not all CDRs were converted to DDRs; lamp calibrations, dark calibrations, data looking solely out into space, and star calibrations do not provide meaningful reflectance information. Thus, there is not a one-to-one correspondence between VIRS CDRs and DDRs, but there should be a correspondence between VIRS CDRs and DDRs that target the surface of planets (Earth, Moon, Venus, Mercury). 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 adjustment was then applied to Mercury reflectance data to normalize viewing geometry to a uniform set of incidence, emission, and phase angles (45, 45, and 90 deg., respectively). At high temperatures in the extended mission, the VIRS shutter sometimes failed to operate, resulting in bad interleaved dark corrections. Observations with frozen shutter anomalies have not been processed to DDR. Each DDR data product consists of two files, following the same divisions as the CDR: data and label files. There are four types of spectra stored in each DDR data file: IOF_SPECTRUM_DATA (table column 14), PHOTOM_IOF_SPECTRUM_DATA (table column 15), IOF_NOISE_SPECTRUM_DATA (table column 16), and PHOTOM_IOF_NOISE_SPECTRUM_DATA (table column 17). Table 2 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. The UVVS+VIRS Combined DDRs are described in a separate specification document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory of this volume. 5.2.3 Derived Data Products (DAPs) For the VIRS DAP data products, one DAP contains a 500 meter per pixel mosaic map of 1 wavelength (750 nm) of VIRS spectral data for footprints covering the whole planet. MASCS/VIRS mosaics include MASCS/VIRS footprints collected after orbit insertion. A metric defined as M = footprint_area / (cos(e)*cos(i)) was computed for each footprint of each observation. In the case of individual spectra that cover the same location, spectra with the lowest metric value were stacked on top, and are the only ones captured in the final map layer. The spectra examined for inclusion in the mosaic come from CDRs converted to photometrically normalized reflectance using the same method as the VIRS Version 2 DDRs. Mosaicked spectra must have M > 0, emission angle < 80 degrees and incidence angle < 70 degrees for footprints with latitude in [-65,65] or incidence angle < footprint's latitude + 5 degrees for other footprints. The mosaic product has nine layers. Each layer information is derived from the CDR and the spectrum of the topmost spectrum at a given map location. 1) Reflectance @750 nm, taken from DDR for spectrum with maximum M value 2) Interpolated reflectance @750nm derived from layer 1 using a spatial interpolation algorithm 3) Incidence angle (of maximum M value spectrum), taken from CDR 4) Emission angle (of maximum M value spectrum), taken from CDR 5) Phase angle (of maximum M value spectrum), taken from CDR 6) Observation area (of maximum M value spectrum), derived from footprint dimension from CDR 7) Observations, CDR date (of maximum M value spectrum) 8) Observations, CDR time (of maximum M value spectrum) 9) Observations Spectrum number, taken from CDR (of maximum M value spectrum) Table 2: VIRS EDR to CDR to DDR to DAP Processing Steps. See PDF version of document for table. 5.3 Data Processing 5.3.1 Data Processing Level The CDR/DDR/DAP archive includes level 3 (CDR), level 4 (DDR), and level 5 (DAP) data as defined by the Committee on Data Management and Computation (CODMAC, Appendix F). 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 VIRS CDR/DDR/DAP files were produced by the MESSENGER Science Operations Center (SOC), operated jointly by APL and ACT. The 'PIPE-MASCS2CDR', 'PIPE-MASCS2DDR', and 'PIPE_VIRS_CREATE_PDS_DAP' 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 used for producing the CDRs and DDRs are included in the archive. The CDR/DDR/DAP 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 transfer to the Geosciences and Atmospheres Nodes. The transfer 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 VIRS are located in the CALIB directory. Calibration and data reduction details and tables are described in the VIRS_EDR2CDR.TXT, VIRS_CDR2DDR.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 2). The SOC was located at 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 VIRS and UVVS 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 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 provides an independent method of verifying the integrity of the archive after it has been 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 is expected that the Nodes would 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/DAPs. Regenerated data were included in the next scheduled delivery. 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. For every CDR/DDR/DAP data file there exists a PDS label file. The following are examples of PDS labels, one each for the two CDR standard data products, "VIRSCNIR" and "VIRSCVIS", the two DDR standard data products, "VIRSDNIR" and "VIRSDVIS", and the one DAP special data product, "VIRSDAP" (section 5.2). Details about the label format are specified in section 6.3. The UVVS+VIRS Combined DDR label and format are described in a separate specification document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory of this volume. 5.3.4.1 Example PDS Label for the VIRS NIR CDR Data Products PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 5050 FILE_RECORDS = 20 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "VIRSNC_MF3_09285_004616_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2009-12-04T21:12:48 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 = "VIRS" DATA_SET_ID = "MESS-E/V/H-MASCS-3-VIRS-CDR-CALDATA-V1.0" STANDARD_DATA_PRODUCT_ID = "VIRSCNIR" MISSION_PHASE_NAME = "MERCURY 3 FLYBY" TARGET_NAME = "MERCURY" SITE_ID = {"1234", "5678"} START_TIME = 2009-10-12T00:46:17 STOP_TIME = 2009-10-12T00:47:00 SPACECRAFT_CLOCK_START_COUNT = "163795843.705" SPACECRAFT_CLOCK_STOP_COUNT = "163795886.455" ^TABLE = "VIRSNC_MF3_09285_004616.DAT" OBJECT = TABLE COLUMNS = 62 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 5050 ROWS = 20 DESCRIPTION = " This table contains MESSENGER VIRS spectra collected in the near Infrared wavelength as well as 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: msgr20091011.bc msgr20091012.bc msgr20091013.bc msgr_dyn_v600.tf msgr_v200.tf msgr_mascs_v011.ti naif0009.tls pck00008.tpc pck00008_MSGR.tpc messenger_0793.tsc de405.bsp msgr_20040803_20120401_od170sc.bsp " ^STRUCTURE = "VIRSNC.FMT" END_OBJECT = TABLE END 5.3.4.2 Example PDS Label for the VIRS VIS CDR Data Products PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 9658 FILE_RECORDS = 20 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "VIRSVC_MF3_09285_004616_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2009-12-04T21:14:22 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 = "VIRS" DATA_SET_ID = "MESS-E/V/H-MASCS-3-VIRS-CDR-CALDATA-V1.0" STANDARD_DATA_PRODUCT_ID = "VIRSCVIS" MISSION_PHASE_NAME = "MERCURY 3 FLYBY" TARGET_NAME = "MERCURY" SITE_ID = {"1234", "5678"} START_TIME = 2009-10-12T00:46:17 STOP_TIME = 2009-10-12T00:47:00 SPACECRAFT_CLOCK_START_COUNT = "163795843.705" SPACECRAFT_CLOCK_STOP_COUNT = "163795886.455" ^TABLE = "VIRSVC_MF3_09285_004616.DAT" OBJECT = TABLE COLUMNS = 62 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 9658 ROWS = 20 DESCRIPTION = " This table contains MESSENGER VIRS spectra collected in the visible wavelength as well as 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: msgr20091011.bc msgr20091012.bc msgr20091013.bc msgr_dyn_v600.tf msgr_v200.tf msgr_mascs_v011.ti naif0009.tls pck00008.tpc pck00008_MSGR.tpc messenger_0793.tsc de405.bsp msgr_20040803_20120401_od170sc.bsp " ^STRUCTURE = "VIRSVC.FMT" END_OBJECT = TABLE END 5.3.4.3 Example PDS Label for the VIRS NIR DDR Data Products PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 5338 FILE_RECORDS = 20 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "VIRSND_MF3_09285_004616_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2013-12-04T21:12:48 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 = "VIRS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-VIRS-DDR-V2.0" STANDARD_DATA_PRODUCT_ID = "VIRSDNIR" MISSION_PHASE_NAME = "MERCURY 3 FLYBY" TARGET_NAME = "MERCURY" SITE_ID = {"1234", "5678"} START_TIME = 2012-10-12T00:46:17 STOP_TIME = 2012-10-12T00:47:00 SPACECRAFT_CLOCK_START_COUNT = "163795843.705" SPACECRAFT_CLOCK_STOP_COUNT = "163795886.455" ^TABLE = "VIRSND_MF3_09285_004616.DAT" OBJECT = TABLE COLUMNS = 62 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 5338 ROWS = 20 DESCRIPTION = " This table contains MESSENGER VIRS spectra collected in the near Infrared wavelength, converted to reflectance and photometrically normalized, as well as 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: msgr20091011.bc msgr20091012.bc msgr20091013.bc msgr_dyn_v600.tf msgr_v200.tf msgr_mascs_v011.ti naif0009.tls pck00008.tpc pck00008_MSGR.tpc messenger_0793.tsc de405.bsp msgr_20040803_20120401_od170sc.bsp " ^STRUCTURE = "VIRSND.FMT" END_OBJECT = TABLE END 5.3.4.4 Example PDS Label for the VIRS VIS DDR Data Products PDS_VERSION_ID = "PDS3" /*** FILE FORMAT ***/ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 10458 FILE_RECORDS = 20 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ PRODUCT_ID = "VIRSVD_MF3_09285_004616_DAT" PRODUCT_VERSION_ID = "V1 " PRODUCT_CREATION_TIME = 2013-12-04T21:14:22 PRODUCT_TYPE = "DDR" SOFTWARE_NAME = "PIPE-MASCS2DDR" SOFTWARE_VERSION_ID = "2.0" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "VIRS" DATA_SET_ID = "MESS-E/V/H-MASCS-4-VIRS-DDR-V2.0" STANDARD_DATA_PRODUCT_ID = "VIRSDVIS" MISSION_PHASE_NAME = "MERCURY 3 FLYBY" TARGET_NAME = "MERCURY" SITE_ID = {"1234", "5678"} START_TIME = 2012-10-12T00:46:17 STOP_TIME = 2012-10-12T00:47:00 SPACECRAFT_CLOCK_START_COUNT = "163795843.705" SPACECRAFT_CLOCK_STOP_COUNT = "163795886.455" ^TABLE = "VIRSVD_MF3_09285_004616.DAT" OBJECT = TABLE COLUMNS = 62 INTERCHANGE_FORMAT = BINARY ROW_BYTES = 10458 ROWS = 20 DESCRIPTION = " This table contains MESSENGER VIRS spectra collected in the visible wavelength, converted to reflectance and photometrically normalized as well as 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: msgr20091011.bc msgr20091012.bc msgr20091013.bc msgr_dyn_v600.tf msgr_v200.tf msgr_mascs_v011.ti naif0009.tls pck00008.tpc pck00008_MSGR.tpc messenger_0793.tsc de405.bsp msgr_20040803_20120401_od170sc.bsp " ^STRUCTURE = "VIRSVD.FMT" END_OBJECT = TABLE END 5.3.4.5 Example PDS Label for the VIRS DAP Data Product PDS_VERSION_ID = PDS3 /*** FILE FORMAT ***/ RECORD_TYPE = UNDEFINED /* Derived Analysis Product Identification */ DATA_SET_ID = "MESS-E/V/H-MASCS-5-VIRS-DAP-V2.0" PRODUCT_ID = "VIRS_DAP_500MPP_V01" INSTRUMENT_HOST_NAME = "MESSENGER" INSTRUMENT_NAME = " MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER" INSTRUMENT_ID = "MASCS" DETECTOR_ID = "VIRS" TARGET_NAME = "MERCURY" PRODUCT_TYPE = "DAP" PRODUCT_CREATION_TIME = 2013-05-09T14:57:48 START_TIME = 2011-03-29T02:02:40 STOP_TIME = 2013-03-17T22:55:43 SPACECRAFT_CLOCK_START_COUNT = "1/209851629.245" SPACECRAFT_CLOCK_STOP_COUNT = "2/5884942.235" PRODUCT_VERSION_ID = "V1" PRODUCER_INSTITUTION_NAME = "APPLIED COHERENT TECHNOLOGY CORPORATION" SOFTWARE_NAME = "ACT_PIPE_virs_create_pds_DAP" SOFTWARE_VERSION_ID = "1.0" NOTE = "This label describes nine data files: 1. An image file containing the mosaic of MASCS/VIRS reflectance @750nm, 2. An image file containing the interpolated mosaic of MASCS/VIRS reflectance @750nm, 3. An image file containing the incidence angle of MASCS/VIRS observations used in mosaic, 4. An image file containing the emission angle of MASCS/VIRS observations used in mosaic, 5. An image file containing the phase angle of MASCS/VIRS observations used in mosaic, 6. An image file containing the area of MASCS/VIRS observations used in mosaic, 7. An image file containing the CDR Date of MASCS/VIRS observations used in mosaic, 8. An image file containing the CDR Time of MASCS/VIRS observations used in mosaic, 9. An image file containing the spectrum number of MASCS/VIRS observations used in mosaic. The CDR date, CDR time can be used to find the CDR where the observation source data is stored, while the spectrum number can be used to find the CDR record associated to the observation." /* Description of Reflectance image file */ OBJECT = RFL_FILE ^RFL_IMAGE = "VIRS_DAP_500MPP_V01_RFL.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = RFL_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Reflectance" BANDS = 1 BAND_NAME = "REFLECTANCE 750NM" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = RFL_IMAGE END_OBJECT = RFL_FILE /* Description of interpolated Reflectance image file */ OBJECT = INTRFL_FILE ^INTRFL_IMAGE = "VIRS_DAP_500MPP_V01_INTRFL.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = INTRFL_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Reflectance" BANDS = 1 BAND_NAME = "INTERPOLATED REFLECTANCE 750NM" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = INTRFL_IMAGE END_OBJECT = INTRFL_FILE /* Description of incidence angle image file */ OBJECT = INC_FILE ^INC_IMAGE = "VIRS_DAP_500MPP_V01_INC.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = INC_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Deg" BANDS = 1 BAND_NAME = "INCIDENCE ANGLE" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = INC_IMAGE END_OBJECT = INC_FILE /* Description of emission angle image file */ OBJECT = EMI_FILE ^EMI_IMAGE = "VIRS_DAP_500MPP_V01_EMI.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = EMI_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Deg" BANDS = 1 BAND_NAME = "EMISSION ANGLE" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = EMI_IMAGE END_OBJECT = EMI_FILE /* Description of phase angle image file */ OBJECT = PHA_FILE ^PHA_IMAGE = "VIRS_DAP_500MPP_V01_PHA.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = PHA_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Deg" BANDS = 1 BAND_NAME = "PHASE ANGLE" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = PHA_IMAGE END_OBJECT = PHA_FILE /* Description of observations area image file */ OBJECT = AREA_FILE ^AREA_IMAGE = "VIRS_DAP_500MPP_V01_AREA.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = AREA_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = PC_REAL SAMPLE_BITS = 32 UNIT = "Km^2" BANDS = 1 BAND_NAME = "OBSERVATION AREA" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999.0 END_OBJECT = AREA_IMAGE END_OBJECT = AREA_FILE /* Description of observations CDR Date image file */ OBJECT = CDRDATE_FILE ^CDRDATE_IMAGE = "VIRS_DAP_500MPP_V01_CDRDATE.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = CDRDATE_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = LSB_INTEGER SAMPLE_BITS = 32 BANDS = 1 BAND_NAME = "CDR DATE" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999 DESCRIPTION = "Obervation CDR date in the form YYDOY" END_OBJECT = CDRDATE_IMAGE END_OBJECT = CDRDATE_FILE /* Description of observations CDR Time image file */ OBJECT = CDRTIME_FILE ^CDRTIME_IMAGE = "VIRS_DAP_500MPP_V01_CDRTIME.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = CDRTIME_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = LSB_INTEGER SAMPLE_BITS = 32 BANDS = 1 BAND_NAME = "CDR TIME" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999 DESCRIPTION = "Obervation CDR time in the form HHMMSS. In case the number has only 5 digits then prepend a 0 to it" END_OBJECT = CDRTIME_IMAGE END_OBJECT = CDRTIME_FILE /* Description of observations spectrum number image file */ OBJECT = SPENUM_FILE ^SPENUM_IMAGE = "VIRS_DAP_500MPP_V01_SPENUM.IMG" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122648 FILE_RECORDS = 15331 OBJECT = SPENUM_IMAGE LINES = 15331 LINE_SAMPLES = 30662 SAMPLE_TYPE = LSB_INTEGER SAMPLE_BITS = 32 BANDS = 1 BAND_NAME = "SPECTRUM NUMBER" BAND_STORAGE_TYPE = BAND_SEQUENTIAL MISSING_CONSTANT = -999 END_OBJECT = SPENUM_IMAGE END_OBJECT = SPENUM_FILE /* Map projection information about this DAP is in the */ /* IMAGE_MAP_PROJECTION object below. */ OBJECT = IMAGE_MAP_PROJECTION ^DATA_SET_MAP_PROJECTION = "DAP_MAP.CAT" MAP_PROJECTION_TYPE = "EQUIRECTANGULAR" A_AXIS_RADIUS = 2439.4 B_AXIS_RADIUS = 2439.4 C_AXIS_RADIUS = 2439.4 FIRST_STANDARD_PARALLEL = "N/A" SECOND_STANDARD_PARALLEL = "N/A" POSITIVE_LONGITUDE_DIRECTION = "EAST" CENTER_LATITUDE = 0.0 CENTER_LONGITUDE = 0.0 LINE_FIRST_PIXEL = 1 LINE_LAST_PIXEL = 15331 SAMPLE_FIRST_PIXEL = 1 SAMPLE_LAST_PIXEL = 30662 MAP_PROJECTION_ROTATION = 0.0 MAP_RESOLUTION = 85.172067 MAP_SCALE = 500 MAXIMUM_LATITUDE = 90 MINIMUM_LATITUDE = -90 WESTERNMOST_LONGITUDE = -180 EASTERNMOST_LONGITUDE = -179.999346 LINE_PROJECTION_OFFSET = 7665.986075 SAMPLE_PROJECTION_OFFSET = 15331.472150 COORDINATE_SYSTEM_TYPE = "BODY-FIXED ROTATING" COORDINATE_SYSTEM_NAME = "PLANETOCENTRIC" END_OBJECT = IMAGE_MAP_PROJECTION END 5.4 Standards Used in Generating Data Products 5.4.1 PDS Standards The VIRS CDR/DDR/DAP 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. In the PDS standard, the VIRS CDR and DDR data are grouped into pairs; one file is a table of binary data and the other is a detached PDS label describing the data. The detached label file contains a pointer to the binary table file, which stores the housekeeping data, derived pointing data, and the spectra. Each DAP image plane is an .IMG file in the standard PDS format. The 9 images planes are described by a detached PDS label. 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 E) 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 E- 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 VIRS CDR/DDR/DAP data products are validated by the VIRS Instrument Scientist for science content and for compliance with PDS archive standards and the MESSENGER Data Management and Archiving Plan [Applicable Document 4]. "Invalid" data includes detector pixels that are saturated, detector pixels that receive no light, and photometric fields such as incidence, emission, and phase angles, and coordinate fields such as solar distance, where the MASCS footprint does not fall on the surface of Mercury. Invalid data in CDRs and advanced products is assigned a value of 1.e32. 6. Detailed Data Product Specifications 6.1 Data Archive Structure and Organization The VIRS EDR data set is a static dataset. Static data sets, once produced and validated, are not subject to update or modification. The VIRS CDR/DDR/DAP 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 were 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 data products that are revised during the course of the mission. Revised data products or data products 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 then replaced the outdated files with the revised files in the data directories of the archive volume. MASCS followed similar procedures as other instruments have historically. The CONFIDENCE_LEVEL_NOTE in the virs_*_ds.cat files located in the CATALOG directory was updated with each regeneration, and CDR/DDR/DAP 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/DAP geometry fields of all CDRs/DDRs/DAPs. 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 base file name for the VIRS CDR and DDR data products is "VIRSdL_mmm_YYDDD_HHMMSS" where: VIRS: instrument name d: detector identifier. N = NIR, 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 MC2 = 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) YY: the last two digits of the year in which the data was acquired DDD: The three digit day of year in which the data was acquired. HHMMSS: Is the 6 digit hour, minute, second of the start of the observation. The general form of the base file name for the VIRS DAP data product is "VIRS_DAP_500MPP_VXX_AAAAAAA" where: VIRS: instrument name DAP: derived analysis product (DAP) MPP: meters per pixel (map scale, 500 mpp) VXX: version number. AAAAAAA: map layer type. RFL = reflectance at 750 nm at given coordinate INTRFL = interpolated reflectance at given coordinate INC = incidence angle at given coordinate EMI = emission angle at given coordinate PHA = phase angle at given coordinate AREA = footprint area at given coordinate CDRDATE = date of acquisition of the footprint at given coordinate CDRTIME = time of acquisition of that footprint at given coordinate SPENUM = spectrum number within the CDR of that footprint at given coordinate The file naming convention of the UVVS+VIRS Combined DDR products are described in a separate specification document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory of this volume. 6.1.3 Directory Structure for MASCS CDR/DDR/DAP Archive Volume The following illustrations (Figures 3a-3c) show the directory structure 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 UVVS CDRs/DDRs are contained in the document UVVS_CDR_DDR_SIS.PDF, and details for the UVVS+VIRS Combined DDR are contained in the document UVVS_VIRS_COMBINED_DDR_SPEC.PDF, both located in the DOCUMENT directory. This archive volume is stored at both the Atmospheres and Geosciences PDS Nodes. Figure 3a: Directory Structure Overview. _________________________________________|___________________________ | | | | | | | | |