VEX-VMC To Planetary Science Archive Interface Control Document (EAICD) Prepared by Dr. Th. Roatsch Release Dr. W. Markiewicz ( VMC Principal Investigator ) Distribution List: x Dr. Markiewicz, MPS Lindau x K.-D. Matz, DLR x Dr. Jaumann, DLR Berlin x Dr. Svedham, ESTEC x D. Heather, ESAC Document Change Record Issue Date Document No. Affected Pages 001 27-Oct-2006 VMC-DLR-TN-002,Issue 001 Original 002 9-Apr-2008 VMC-DLR-TN-002,Issue 002 all 003 25-Mar-2009 VMC-DLR-TN-002,Issue 003 all 004 15-May-2013 VMC-DLR-TN-002,Issue 004 all 005 1-Jun-2015 VMC-DLR-TN-002,Issue 005 11,14 Table Of Contents 1 Introduction 6 1.1Purpose and Scope 6 1.2 Archiving Authorities 6 1.3 Contents 6 1.4 Intended Readership 6 1.5 Applicable Documents 6 1.6 Relationships to Other Interfaces 7 1.7 Acronyms and Abbreviations 7 1.7 Contact Names and Addresses 8 2 Overview of Instrument Design, Data Handling Process and Product Generation 8 2.1 Instrument Design Overview 8 2.2 Data Handling Process 9 2.3 Product Generation 10 3 Archive Format and Content 10 3.1 Format and Conventions 10 3.1.1 Deliveries and Archive Volume Format 10 3.1.2 Data Set ID Formation 11 3.1.3 Data Directory Naming Convention 11 3.1.4 Filenaming Convention 12 3.2 Standards Used in Data Product Generation 12 3.2.1 PDS Standards 12 3.2.2 Time Standards 12 3.2.2.1 START_TIME and STOP_TIME Formation 12 3.2.2.2 SPACECRAFT_CLOCK_START_COUNT and SPACECRAFT_STOP_CLOCK_COUNT 12 3.2.3 Reference Systems 12 3.2.4 Other Applicable Standards 13 3.3 Data Validation 13 3.4 Content 14 3.4.1 Volume Set 14 3.4.2 Data Set 14 3.4.3 Directories 14 3.4.3.1 Root Directory 14 3.4.3.2 Calibration Directory 14 3.4.3.3 Catalog Directory 15 3.4.3.4 Index Directory 15 3.4.3.4.1 Dataset Index File, index.lbl and index.tab 15 3.4.3.4.2 Geometric Index File, geoindex.lbl and geoindex.tab 15 3.4.3.4.3 Other Index Files 15 3.4.3.5 Browse Directory and Browse Files 15 3.4.3.5 Geometry Directory 15 3.4.3.6 Software Directory 16 3.4.3.7 Gazetter Directory 16 3.4.3.8 Label Directory 16 3.4.3.9 Document Directory 16 3.4.3.10 Extras Directory 16 3.4.3.11 Data Directory 16 3.4.4 Other Data Products 16 3.4.5 In-Flight Data Products 17 3.4.6 Software 17 3.4.7 Documentation 17 3.4.8 Derived and other Data Products 17 4. Detailed Interface Specifications 17 4.1 Data Product Structure 18 4.2 Label and Header Description 18 4.2.1 PDS Label 18 4.2.2 PDS Image Object 18 4.2.3 Keyword Length Limits 19 4.2.4 Data Type Restrictions 19 4.2.5 Interpretation of N/A, UNK and NULL 19 4.2.6 VICAR Label 20 4.2.7 VICAR Format 20 4.3 Binary Data Storage Conventions 21 4.4 PDS Keyword Table 21 4.4 Example PDS Product Label 27 1 INTRODUCTION 1.1 Purpose and Scope The purpose of this EAICD (Experimenter to (Science) Archive Interface Control Document) is two fold. First it provides users of the VMC instrument with detailed description of the product and a description of how it was generated, including data sources and destinations. Secondly, it is the official interface between the VMC team and the Planetary Science Archive. 1.2 Archiving Authorities The ESA Planetary Science Archive is the official archive authority of the Venus Express Mission. 1.3 Contents This document describes the data flow of the VMC instrument on VenusExpress from the s/c until the insertion into the PSA for ESA. It includes information on how data were processed, formatted, labeled and uniquely identified. The document discusses general naming schemes for data volumes, data sets, data and label files. Standards used to generate the product are explained. Software that may be used to access the product is explained furtheron. The design of the data set structure and the data product is given. Examples of these are given in the appendix. 1.4 Intended Readership The staff of the archiving authority (Planetary Science Archive, ESA, RSSD, design team) and any potential user of the VMC data. 1.5 Applicable Documents 1. Planetary Data System Preparation Workbook, February 1, 1995, Version 3.1, JPL, D-7669, Part1 2. Planetary Data System Standards Reference, August 1, 2003, Version 3.6, JPL, D-7669, Part 2 3. VenusExpress Archive Generation, Validation and Transfer Plan, J. Zender, , ESA-VEX-PL-001, Version 1.1, 7. June 2004. 4. Venus Monitoring Camera Flight User Manual, Issue 1,VMC-IDA-MA-SF000-001_1, 26.05.2004, Prepared by Björn Fiethe 5. Venus Express VMC Data Products Naming Convention, T. Roatsch, VMC-DLR-TN-001, Issue 001, 20-February-2006. 6. PDS Standards Reference , http://pds.jpl.nasa.gov/documents/sr/index.html 7. Planetary Science Data Archive Technical Note – Geometry and Position Information, Issue 3, Revision 4, J. Diaz del Rio, ESA RSSD Planetary Missions Division, SOP-RSSD-TN-010, 09-November-2004. 8. VenusExpress - VMC Level-1 Product Description, T. Roatsch, VMC-DLR-TN-002, Issue 001, 20-February-2006. 9. VenusExpress - VMC Level-2 Product Description, T. Roatsch, VMC-DLR-TN-003, Issue 001, 20-February-2006. 11. The VICAR Image Processing System, http://www-mipl.jpl.nasa.gov/external/vicar.html 12. Navigation and Ancillary Information Facility (NAIF), http://pds-naif.jpl.nasa.gov/ 13. Planetary Science Archive PVV User Manual, D. Heather, A. Venet, J, Vazquez, SOP-RSSD-UM-004, Issue 2.6, 21-October-2004 14. Planetary Science Archive Experiment Data Release Concept Technical Proposal, J. Zender, SOP-RSSD-TN-015 Issue 1.14 22 October 2004 1.6 Relationships to Other Interfaces This document is in close relationship to - VenusExpress - VMC Data Products Naming Convention [5] - VenusExpress - VMC Level-1 Product Description [8] - VenusExpress - VMC Level-2 Product Description [9] The contents of these documents is summarized in this document for easier use. 1.7 Acronyms and Abbreviations CoI Co-Investigator DLR Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Center) ESOC European Space Operation Center ESTEC European Space Research and Technology Center IDA Institute of Computer and Communication Network Engineering, Braunschweig, Germany JPL NASA Jet Propulsion Laboratory MPS Max-Planck-Institute for Solar System Exploration, Lindau PI Principal Investigator PSA Planetary Science Archive PVV PSA Volume Verifier VICAR Video Image Communication and Retrieval VMC Venus Monitoring Camera 1.8 Contact Names and Addresses Archive generation software Klaus-Dieter Matz, DLR Archive distribution Thomas Roatsch, DLR Levels 1 generation software cognizant engineer Thomas Roatsch, DLR Calibration software and procedures Klaus-Dieter Matz, DLR VICAR software cognizant Engineer Robert G. Deen, JPL 2 OVERVIEW OF INSTRUMENT DESIGN, DATA HANDLING PROCESS AND PRODUCT GENERATION 2.1 Instrument Design Overview The VMC camera consists of one unit that houses the optics, CCD and readout electronics (CRE), digital processing unit (DPU), and power converter (POC). Figure.1 shows the sketch of the VMC camera. The experiment consists of one unit with optics and focal plane mounted to the upper cover and a stack of electronic boards occupying the rest of the box. The size of PCBs is 80x80 mm. The walls of the camera are 3 mm thick to provide sufficient stiffness and radiation protection. Additional radiation shielding will be provided in the vicinity of the CCD. The current baseline is to mount the camera on the +Y wall inside the spacecraft. Red dots on the +Y wall in the VMC sketch mark the mounting points of the camera. A Peltier cooler is attached to the CCD bottom. A thermal strap will take heat from the CCD to the spacecraft wall. The red star shows the thermal reference point (TRP), specified for the CCD and the electronics. In order to avoid moving parts (filter wheel) the camera is designed so that four objectives (channels) share a single CCD. The stray light protection is provided by external and internal baffles. The latter are also used to prevent optical cross-talk between the channels. Figure.1: VMC sketch Further information about the insturment and its operation can be found in [4]. 2.2 Data Handling Process All VMC data are processed at IDA, Braunschweig and DLR in Berlin, Germany. The data processing consists of the following steps: - transfer of data from ESOC to IDA - remove all transmission headers to get the original camera data - decompress the data - transfer data to DLR - convert data into VICAR file format - split data from different sensors to generate Level-1 files - radiometric calibration of the data - calculate footprints of every image file and get Level-2 files The formats of the data levels 1 and 2 are described in [8] and [9], respectively. All data processing steps at DLR are performed in the VICAR environment [11], a software package developed and maintained by JPL and used for the data processing of many planetary missions. DLR developed specific VICAR modules for every processing step. The cognizitant persons for the specific task are listed in chapter 1.8. Please, adress all questions and comments through the Data Processing Manager (thomas.roatsch@dlr.de). 2.3 Product Generation The VMC data are processed at IDA and DLR when they become available at ESOC. Both level-1 and level-2 data are sent to the PI and distributed to the CoI team. The data will be checked by the team and improved versions of the data will be calculated if necessary. Another reason for new image version are improved SPICE kernels.. The final step of the product generation is the conversion from the VICAR format to PDS format and the generation of the complete data sets. This step is also performed at DLR in Berlin about a month before the final delivery to PSA. The final products will be sent to the PI and the CoIs who are in charge for the data validation. The data will be send from DLR to PSA after succesful validation and PI approval. 3 ARCHIVE FORMAT AND CONTENT 3.1 Format and Conventions 3.1.1 Deliveries and Archive Volume Format The VMC data will be delivered to PSA every 6 months. Every delivery contains the data taken during a time period of 6 months. The delivery will be performed only via file transfer, no storage media like CD or DVD will be used. The Planetary Science Archive of ESA implemented the “Release” concept [14]: data is delivered as units (releases), which can be updated (revision). Two specific data elements are included to handle the release concept: RELEASE_ID REVISION_ID RELEASE_ID defines the release number and REVISION_ID defines the revision number. The data will be split in a couple of different releases to avoid file transfer problems with very huge files. The releases will also be compressed (using bzip2) to minimize the file transfer time. Every release will be packed to one single file (only for the file transfer from DLR to PSA) using the UNIX tar command with the following options: tar cfv. The following file naming scheme (including release and revision number) will be used for the file transfer ot the releases: VMC_rel001rev000.tar.bz2 The VMC team delivers only radiometrically calibrated data since raw data are useless for the general public due to a couple of camera problems. The uncalibrated (raw) data will be delivered to ESTEC in VICAR format six months after the end of the nominal mission together with the radiometric calibration software. No special documentation will be written for these data and the software. 3.1.2 Data Set ID Formation The data from the nominal mission belong to this dataset: VEX-V-VMC-3-RDR-V3.0 The data from the first mission extension (starting with orbit 550) belong to this dataset: VEX-V-VMC-3-RDR-EXT1-V3.0 The data from the second mission extension (starting with orbit 550) belong to this dataset: VEX-V-VMC-3-RDR-EXT2-V3.0 The data from the third mission extension (starting with orbit 550) belong to this dataset: VEX-V-VMC-3-RDR-EXT3-V3.0 The data from the fourth mission extension (starting with orbit 550) belong to this dataset: VEX-V-VMC-3-RDR-EXT4-V2.0 This name follows the standard PDS rules and contains the mission name, the instrument name, describes the level of processing (REDR) and the version number. It is currently not planned to deliver different versions. The DATA_SET_ID must be changed whenever it will become necessary to deliver different versions. 3.1.3 Data Directory Naming Convention The VMC data are sorted by orbit in the DATA directory, each sub-directory will have the name oooo where oooo is the number of the orbit in which the data were taken. 3.1.4 Filenaming Convention The file naming convention is described in detail in [5]. The image files in the DATA directories follow this convention: VOOOO_MMM_DD2.IMG where OOOO 4 digit orbit number MMM number of the image in this orbit DD sensor name (can be N1, N2, VI, UV) The ‘2’ indicates the level of processing which is archived in PSA/PDS. Please, note that all sensor data which were taken together will get the same image number. 3.2 Standards Used in Data Product Generation 3.2.1 PDS Standards All data apply to version 3.6 of the PDS Standards Reference, please see [1], [6] for details. 3.2.2 Time Standards All time information in the data follows the SPICE time standards. Please, see [12] for details. Within the data products themselves, the time standard used is ET (Ephemeris Time), which is a double precision number of seconds.  The starting point for this time is the J2000 epoch. This epoch is Greenwich noon on January 1, 2000 Barycentric Dynamical Time. This ephemeris time is calculated from the Spacecraft Onboard Time using the appropriate SPICE routines and the time correlation packages which are provided by ESTEC as a SPICE Clock Kernel. Outside of the products themselves, there are a few instances in the VMC data sets where time flags are provided.  The main time values are provided in the data product labels, which provide a start and stop time for the measurement, and a corresponding clock count from the spacecraft.  Below, the standards used to define these values are described. 3.2.2.1     START_TIME and STOP_TIME Formation The PDS formation rule for dates and time in UTC is: YYYY-MM-DDThh:mm:ss.fff   YYYY      year (0000-9999)   MM        month (01-12)   DD      day of month (01-31)   T        date/time separator   hh       hour (00-23)   mm        minute (00-59)   ss       second (00-59)   fff      fractions of second (000-999) (restricted to 3 digits) This standard is followed for all START_TIME and STOP_TIME values in the products included in the VMC data sets.  3.2.2.2   SPACECRAFT_CLOCK_START_COUNT and SPACECRAFT_CLOCK_STOP_COUNT The SPACECRAFT_CLOCK_START_COUNT and SPACECRAFT_CLOCK_STOP_COUNT values represent the on-board time counters (OBT) of the spacecraft and instrument computers.  This OBT counter is given in the headers of the experiment telemetry source packets.  It contains the data acquisition start time as 32-bit of unit seconds followed by 16-bit of fractional seconds.  The time resolution of the fractional part is 2^-16 = 1.52×10^-5 seconds.  Thus, the OBT is represented as a decimal real number in floating-point notation with 5 digits after the decimal point. A reset of the spacecraft clock is represented by an integer number followed by a slash, e.g. "1/" or "2/". Example: SPACECRAFT_CLOCK_START_COUNT = "1/21983325.39258"   3.2.3 Reference Systems The reference systems used for orbit, attitude, and target body follow the SPICE standards and are defined in the different SPICE kernels. Please, see [3], and [12] for details. All latitudes and longitudes are given in degrees, latitudes are planetocentric. 3.2.4 Other Applicable Standards No other standards are used. 3.3 Data Validation The validation of these volumes is divided into two processes: The first process is to check that the volumes are technically correct: - Insure that the volume is complete, and has correct structure as defined in this document. - Insure that dynamically generated file, such as index and catalog files are correct and complete. - Insure that structure of each generated volume is PDS compliant These steps will be performed using PVV, the PSA Validation and Verification Tool developed by ESTEC [13]. The second process is to check that the image data contained in the data volumes are correct. This will be done by visual inspection by the PI and the CoIs (tbd). Specific tools for automated checks may be developed by the teams in charge for this step. 3.4 Content 3.4.1 Volume Set There are no volume sets since the data will be delivered electronically. It is not planned to generate archives on any medium (like CD-ROM or DVD). 3.4.2 Data Set There are five datasets, one contains the data from the nominal mission, the second one (starting at orbit 550) contains the data from the first mission extension, the third one contains the data from the second mission extension, the fourth one contains the data from the third mission extension, and te fivth one contains the data from the fourth mission extension. 3.4.3 Directories 3.4.3.1 Root Directory The Root Directory contains the following standard PDS files: AAREADME.TXT ERRATA.TXT VOLDESC.CAT 3.4.3.2 Calibration Directory There is no calibration directory for the data set VEX-V-VMC-3-RDR-V1.0, the data are already radiometrically calibrated. Information about the calibration can be found in VMC_CALIBRATION_REPORT.PDF and VMC_INLIGHT_CALIBRATION_REPORT.TXT in the DOCUMENT directory. Information about the geometric calibration can be found in the SPICE instrument kernel which is distributed seperately by PSA. 3.4.3.3 Catalog Directory The Catalog Directory contains the following standard PDS files: CATINFO.TXT DATASET.CAT INST.CAT INSTHOST.CAT MISSION.CAT PERSON.CAT REF.CAT This directory also contains the file RELEASE.CAT as described in [14]. This file is necessary to use the release concept developed by PSA. 3.4.3.4 Index Directory 3.4.3.4.1 Dataset Index File, index.lbl and index.tab The Index Directory contains the required PDS index files which are generated by PVV [13]. 3.4.3.4.2 Geometric Index File, geoindex.lbl and geoindex.tab The Index Directory also contains the Geometric Index File as defined in [7]. The geometry index files contains the information for 100 points in the VMC image when at least a part of Venus is visible in the image. These 100 points are the same as in the label entries FOOTPRINT_POINT_LATITUDE and FOOTPRINT_POINT_LONGITUDE which describe the footprint of the image. 3.4.3.4.3 Other Index Files The data set also contains browse index files which are generated using PVV [13]. Browse images are still tbd, please see 3.4.3.5 3.4.3.5 Browse Directory and Browse Files It is still tbd if browse image are necssary. The original images data are already very small (512x512). This will be decided when a sufficient set of Venus data will be available. 3.4.3.6 Geometry Directory This directory has the same structure as the DATA directory, the files are sorted by orbit number. The geometry files have the same filename as the image files, only the extension is changed to GEO. Each geometry file has five bands: INCIDENCE ANGLE, EMISSION ANGLE, PHASE ANGLE, LATITUDE, and LONGITUDE The unit for all five bands is DEGREE. All external geometry information (orbit data, attitude data, etc.) can be found in the Venus Express SPICE data set. The SPICE data are released as seperate data sets and are necessary for the generation of higher data levels, SPICE kernels will not be available as separate release at the time of the first VMC data release, unfortunately. The user of the VMC data has to get the SPICE kernels from the ftp server at ESTEC ftp:// ssols01.esac.esa.int/pub/projects/vex/data/spice/kernels/ or from the ftp mirror at NAIF ftp://naif.jpl.nasa.gov/pub/naif/VEX/kernels/ 3.4.3.7 Software Directory No software will be delivered. Software to read the images and the geometry files is available at different locations, e.g.: - IDL PDS Reader Library http://pds-smallbodies.astro.umd.edu/tools/tools_readPDS.shtml - PDS Image Readers http://www.planetary.org/explore/space-topics/space-imaging/data.html http://www.mmedia.is/bjj/utils/img2png/ - GIMP and Plug-in to load PDS images into GIMP http://www.gimp.org/ http://registry.gimp.org/node/1627 3.4.3.8 Gazetter Directory There is no Gazetter Directory. 3.4.3.9 Label Directory There is no Label directory. 3.4.3.10 Document Directory This directory contains the documentation for the VMC data sets. The content is: - DOCINFO.TXT the standard PDS info file. - VMC_EAICD.LBL the label for the Experimenter to Archive ICD - VMC_EAICD.PDF the Adobe PDF file of the Experimenter to Archive ICD - VMC_EAICD.TXT the Text file of the Experimenter to Archive ICD - VMC_ESA_SP.LBL the label for the VMC Instrument Description published in the ESA SP-13 - VMC_ESA_SP.PDF the Adobe PDF file of the ESA SP-1325 - VMC_LABEL.LBL the label for VMC_LABEL.PDF - VMC_LABEL.PDF a table summarizing the PDS label - VMC_NATURE.LBL the label for VMC_NATURE.PDF - VMC_NATURE.PDF an article from Nature summarizing the first scientific results from VMC - VICAR2.LBL the Label for the description of the VICAR labels - VICAR2.TXT Text file describing the VICAR label. 3.4.3.11 Extras Directory There is no Extras Directory. 3.4.3.12 Data Directory The Data Directory contains sub-directories for every orbit which is part of the data set, the directory names are the four digits orbit number. The contents of these sub-directories is described in 3.4.8. 3.4.4 Other Data Products No Pre-Flight Data Products, Sub-System test data, and instrument calibration data will be delivered to PSA/PDS. 3.4.5 In-Flight Data Products The VMC data archive contains all data which were taken in Venus orbit. 3.4.6 Software The VMC processing software was developed in the VICAR environment [11]. VICAR was developed by NASA/JPL and was used for the processing of camera data from many planetary missions (e.g. Viking, Galeileo). The data processing team at DLR in Berlin developed specific modules to process the VMC data. These modules perform the following steps: - remove all telemetry headers from the data - sort the data by sensor and combine the image data with the housekeeping data - decompression of the data - radiometric calibration of the data - apply additonal orbit dependent calibration files to reduce the data artefacts - calculation of the footprints for every image 3.4.7 Documentation The contents of the documentation directory is described in 3.4.3.10. 3.4.8 Derived and other Data Products There are currently no plans to deliver derived and other data products. Also, no data based on the cooperation with other Venus Express teams will be delivered. 4. DETAILED INTERFACE SPECIFICATIONS 4.1. Data Product Structure The data structure consists of an ASCII PDS label, followed by an embedded ASCII VICAR label, followed by a block of binary image data. Inherent to the VICAR label is the possibility of an ASCII EOL label being appended after the binary data in order to handle label modifications. This EOL label is simply a continuation field for the main VICAR label, when there is no more space for expansion before the image data. 4.2 Label and Header Descriptions 4.2.1 PDS Label VMC data have an attached PDS label. A PDS label is object-oriented and describes the objects in the data file. The PDS label contains keywords for product identification. The label also contains descriptive information needed to interpret or process the data in the file. PDS labels are written in Object Description Language (ODL [1]. PDS label statements have the form of "keyword = value". Each label statement is terminated with a carriage return character (ASCII 13) and a line feed character (ASCII 10) sequence to allow the label to be read by many operating systems. Pointer statements with the following format are used to indicate the location of data objects in the file: ^object = location where the carat character (^, also called a pointer) is followed by the name of the specific data object. The location is the 1-based starting record number for the data object within the file. 4.2.2 PDS Image Object An IMAGE object is a two-dimensional array of values, all of the same type, each of which is referred to as a sample. IMAGE objects are normally processed with special display tools to produce a visual representation of the samples by assigning brightness levels or display colors to the values. An IMAGE consists of a series of lines, each containing the same number of samples. The required IMAGE keywords define the parameters for simple IMAGE objects: * LINES is the number of lines in the image. * LINE_SAMPLES is the number of samples in each line. * SAMPLE_BITS is the number of bits in each individual sample. * SAMPLE_TYPE defines the sample data type. The IMAGE object has a number of keywords relating to image statistics. These keywords will be present in all data, the statistics keywords are: * MEAN * MEDIAN * MAXIMUM * MINIMUM * STANDARD_DEVIATION Many variations on the basic IMAGE object are possible with the addition of optional keywords and/or objects. The “^IMAGE” keyword identifies the start of the image data and will skip over the VICAR label. 4.2.3 Keyword Length Limits All PDS keywords are limited to 30 characters in length (Section 12.7.3 in PDS Standards Reference). Therefore, software that reads VMC PDS labels must be able to ingest keywords up to 30 characters in length. 4.2.4 Data Type Restrictions In order to accomodate VICAR dual-labeled files, 16-bit data must be stored as signed data. Unsigned 16-bit data is not supported. 4.2.5 Interpretation of N/A, UNK, and NULL During the completion of data product labels or catalog files, one or more values may not be available for some set of required data elements. In this case PDS provides the symbolic literals “N/A”, “UNK”, and “NULL”, each of which is appropriate under different circumstances. * “N/A” (“Not Applicable”) indicates that the values within the domain of this data element are not applicable in this instance. * “UNK” (“Unknown”) indicates that the value for the data element is not known and never will be. * “NULL” is used to flag values that are temporarily unknown. It indicates that the data preparer recognizes that a specific value should be applied, but that the true value was not readily available. “NULL” is a placeholder The following values are used for N/A and UNK in the image labels (as described in chapter 17 of the PDS standards reference [6]): Signed Integer (4 byte) Real N/A -2147483648 -1.E32 UNK 2147483647 1.E332 4.2.6 VICAR Label For all data products, an embedded VICAR label follows the PDS label and is pointed to by the PDS pointer “^IMAGE_HEADER”. The VICAR label is also organized in an ASCII, “keyword = value” format, although there are only spaces between keywords (no carriage return/line feeds as in PDS). The information in the VICAR label is an exact copy of the information in the PDS label as defined in the next section. The VICAR label is not intended for the data user, it is only used DLR internal during the processing pipeline. 4.2.7 VICAR Format The reader is referred to the VICAR File Format document for details of the format, which is available at the URL “http://www-mipl.jpl.nasa.gov/vicar/vic_file_fmt.html”. The following text is an excerpt which describes the basic structure: A VICAR file consists of two major parts: the labels, which describe what the file is, and the image area, which contains the actual image. The labels are potentially split into two parts, one at the beginning of the file, and one at the end. Normally, only the labels at the front of the file will be present. However, of the EOL keyword in the system label (described below) is equal to 1, then the EOL labels (End Of file Labels) are present. This happens if the labels expand beyond the space allocated for them. The VICAR file is treated as a series of fixed-length records, of size RECSIZE (see below). The image area always starts at a record boundary, so there may be unused space at the end of the label, before the actual image data starts. The label consists of a sequence of "keyword=value" pairs that describe the image, and is made up entirely of ASCII characters. Each keyword-value pair is separated by spaces. Keywords are strings, up to 32 characters in length, and consist of uppercase characters, underscores (“_”), and numbers (but should start with a letter). Values may be integer, real, or strings, and may be multiple (e.g. an array of 5 integers, but types cannot be mixed in a single value). Spaces may appear on either side of the equals character (=), but are not normally present. The first keyword is always LBLSIZE, which specifies the size of the label area in bytes. LBLSIZE is always a multiple of RECSIZE, even if the labels don't fill up the record. If the labels end before LBLSIZE is reached (the normal case), then a 0 byte terminates the label string. If the labels are exactly LBLSIZE bytes long, a null terminator is not necessarily present. The size of the label string is determined by the occurrence of the first 0 byte, or LBLSIZE bytes, whichever is smaller. If the system keyword EOL has the value 1, then End-Of-file Labels exist at the end of the image area (see above). The EOL labels, if present, start with another LBLSIZE keyword, which is treated exactly the same as the main LBLSIZE keyword. The length of the EOL labels is the smaller of the length to the first 0 byte or the EOL's LBLSIZE. Note that the main LBLSIZE does not include the size of the EOL labels. In order to read in the full label string, simply read in the EOL labels, strip off the LBLSIZE keyword, and append the rest to the end of the main label string. 4.3 Binary Data Storage Conventions VMC data are stored as binary data. The data are stored in signed 16-bit integers. The PDS and VICAR labels are stored as ASCII text. The ordering of bits and bytes is only significant for pixel data; all other labeling information is in ASCII. All data are stored as Most Significant Byte first ("big-endian", as used by e.g. Sun computers and Java) 4.4 PDS keyword table The same keywords are used for all data. These keywords are described in the following table. Please, note that more keywords could become necessary if advanced onboard processing will be used. The decision about advanced onboard processing is delayed until arrival at Venus. Aditional geometry keywords, e.g. SPACECRAFT_ALTITUDE, can be calculated by the user using the SPICE kernels from the PSA web page ftp://ssols01.esac.esa.int/pub//data/SPICE/VEX/kernels/. The SPICE tutorials from the NAIF web page ftp://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/ contain detailed examples in different programming languages how to calculate these values. FILE_NAME usual default name of the output file; this entry allows the user to check for accidental renaming of files, filename without path   string   DATA_SET_ID The data_set_id element is a unique alphanumeric identifier for a data set or a data product.   string VEX-V-VMC-2-EDR-V1.0 VEX-V-VMC-3-RDR-V1.0 DATA_SET_NAME The data_set_name element provides the full name given to a data set or a data product. string PRODUCER_ID The producer_id element provides a short name or acronym for the producer or producing team/group of a dataset. string PRODUCER_FULL_NAME The producer_full_name element provides the full_name of the individual mainly responsible for the production of a data set. string PRODUCER_INSTITUTION_NAME The producer_institution_name element identifies a university, research center, NASA center or other institution associated with the production of a data set. string DETECTOR_ID identifies which of the ten CCD detectors was used for this particular image.   string VEX_VMC_NIR-1, VEX_VMC_NIR-2, VEX_VMC_VIS, VEX_VMC_UV INSTRUMENT_HOST_ID The instrument_host_id element provides a unique identifier for the host where an instrument is located.   string VEX INSTRUMENT_HOST_ NAME full name of the spacecraft   string VENUS_EXPRESS INSTRUMENT_ID The instrument_id element provides an abbreviated name or acronym which identifies an instrument.   string VMC INSTRUMENT_NAME full name of an instrument   string VENUS MONITORING CAMERA INSTRUMENT_TYPE The instrument_type element identifies the type of an instrument. string FRAMING CAMERA MISSION_NAME full name of mission   string VENUS_EXPRESS MISSION_ID The mission_id element provides a synonym or mnemonic for the mission_name element. string VEX MISSION_PHASE_NAME The mission_phase_name element provides the commonly-used identifier of a mission phase.   string   PROCESSING_LEVEL_ID identifies the processing level of a data set; parameter must be updated after each processing step according to the program specification , DLR-Levels   int 1 or 2 PRODUCT_CREATION_ TIME The product_creation_time element defines the UTC system format time when a product was created.   string   PRODUCT_ID The product_id data element represents a permanent, unique identifier assigned to a data product by its producer.   string   PRODUCT_TYPE The PRODUCT_TYPE data element identifies the type or category of a product within a data set. string RELEASE_ID Number of the data release int REVISION_ID Number of the revision in a release int VEX:SCIENCE_CASE_ID Tbd int {1, 2, …, 9, 10} OBSERVATION_TYPE Type of the observation this image belongs to. string { tbd } SPACECRAFT_CLOCK_ START_COUNT Provides the value of the spacecraft clock at the beginning of a time period of interest.   String   SPACECRAFT_CLOCK_ STOP_COUNT Provides the value of the spacecraft clock at the end of a time period of interest.   string   IMAGE_TIME Date and time of the middle of the image acquisition in UTC format "YYYY-MM-DDTHH:MM:SS.MMMZ" START_TIME Date and time of the start of the image acquisition in UTC format "YYYY-MM-DDTHH:MM:SS.MMMZ"   string   STOP_TIME Date and time of the end of the image acquisition in UTC format "YYYY-MM-DDTHH:MM:SS.MMMZ"   string   ASCENDING_NODE_ LONGITUDE value of the angle of the xy-plane of the J2000 coordinate system to the ascending node computed from the spacecraft's position- and velocity vector at periapsis (not to be used during test and cruise) deg real   MAXIMUM_RESOLUTION highest resolution in an image m/pixel real FOOTPRINT_POINT_ LATITUDE The footprint_point_latitude element provides the latitude of a point within an array of points along the border of a footprint, described as a polygon, outlining an imaged area on the planet's surface. Latitude values are planetocentric. deg real (100)   FOOTPRINT_POINT_ LONGITUDE The footprint_point_longitude element provides the longitude of a point within an array of points along the border of a footprint, described as a polygon, outlining an imaged area on the planet's surface. Longitude values are planetocentric. deg real (100)   ORBIT_NUMBER number of the orbital revolution of the s/c around the target body (not to be used during test and cruise)   int   ORBITAL_ECCENTRICITY value of orbit eccentricity computed from the spacecraft's position- and velocity vector at periapsis (not to be used during test and cruise)   real   ORBITAL_INCLINATION value of the angle of inclination with respect to the xy-plane computed from the spacecraft's position- and velocity vector at periapsis   real   ORBITAL_SEMIMAJOR_ AXIS value of orbit semi-major axis computed from spacecraft's position- and velocity vector at periapsis (not to be used during test and cruise) km real   PERIAPSIS_ALTITUDE The PERIAPSIS_ALTITUDE element provides the distance between the spacecraft and the target body at periapsis. Periapsis is the closest approach point of the spacecraft to the target body in its orbit around the target body. km real   PERIAPSIS_ARGUMENT_ ANGLE angle in the xy-plane of the J2000 coordinate system from the ascending node to periapsis (not to be used during test and cruise) deg real   PERIAPSIS_TIME The PERIAPSIS_TIME element is the time, in UTC format "YYYY-MM-DDThh:mm:ss[.fff]Z", when the spacecraft passes through periapsis. Periapsis is the closest approach point of the spacecraft to the target body in its orbit around the target body. (not to be time string   SPACECRAFT_ ORIENTATION The spacecraft orientation element provides the orientation of a spacecraft in orbit or cruise in respect to a given frame. E.g. a non-spinning spacecraft might be flown in +Y or -Y direction in respect to the spacecraft mechanical build frame. This element shall be used in combination with the keyword spacecraft_orientation_desc that describes the convention used to describe the spacecraft orientation. The spacecraft orientation shall be given as a 3-tuple, one value for the x,y and z axes   real SPACECRAFT_POINTING_ MODE The spacecraft pointing element provides information on the pointing mode of the spacecraft. The definition of the modes and the standard values are given in the s/c pointing mode description element, that shall always accompany the keyword   string {"NADIR", "ALONGTRACK", "ACROSSTRACK", “INERT”} RIGHT_ASCENSION The right_ascension element provides the right ascension value. Right_ascension is defined as the arc of the celestial equator between the vernal equinox and the point where the hour circle through the given body intersects the Earth's mean equator (reckoned eastward). degree real DECLINATION The declination element provides the value of an angle, corresponding to latitude, used to fix position on the celestial sphere. Declination is measured positive north and negative south of the celestial equator, and is defined relative to a specified reference period or epoch. degree real SPACECRAFT_SOLAR_ DISTANCE the spacecraft's distance to the Sun measured from its position vector at periapsis (not to be used during test and cruise) km real   TARGET_NAME name of the target body   string VENUS, SKY TARGET_TYPE The target_type element identifies the type of a named target. string PLANET, STAR, SUN, COMET DETECTOR_ TEMPERATURE Detector temperature Celsius real   INST_CMPRS_NAME flag indicating whether spacecraft on-board compression has been bypassed, in which case, the received data were uncompressed   string NONE, tbd INST_CMPRS_QUALITY The compression index. A higher value means more compression   int INST_CMPRS_RATIO mean compression rate for the entire image data represented in the file, this number is =1 for data collected in the bypass mode.   real   BANDWIDTH The bandwidth element provides a measure of the spectral width of a filter or channel. For a root-mean-square detector this is the effective bandwidth of the filter i.e., the full width having a flat response over the bandwidth and zero response elsewhere. For VMC this value is for the whole sensor (CCD+Optics). nm real   CENTER_FILTER_ WAVELENGTH The center_filter_wavelength element provides the mid_point wavelength value between the minimum and maximum instrument filter wavelength values. For VMC this value is for the whole sensor (CCD+Optics). nm real   EXPOSURE_DURATION Integration time of the instruments CCD. ms real MACROPIXEL_SIZE The MACROPIXEL_SIZE element provides the sampling array size (e.g., 2x2, 4x4, 8x8), in pixels, that is used to reduce the amount of data an image contains by summing the values of the pixels, along the lines of the image. int LINE_FIRST_PIXEL The line_first_pixel element provides the line index for the first pixel that was physically recorded at the beginning of the image array. int SAMPLE_FIRST_PIXEL The sample_first_pixel element provides the sample index for the first pixel that was physically recorded at the beginning of the image array. int RADIANCE_OFFSET The radiance_offset element provides the constant value by which a stored radiance is added. Note: Expressed as an equation: true_radiance_value = radiance_offset + radiance_scaling_factor * stored_DN_value. W/m3/steradian real   RADIANCE_ SCALING_FACTOR The radiance_scaling_factor element provides the constant value by which a stored radiance is multiplied. Note: Expressed as an equation: true_radiance_value = radiance_offset + radiance_scaling_factor * stored_DN_value W/m3/steradian real   4.5. Example PDS Product Label PDS_VERSION_ID = PDS3 /* FILE DATA ELEMENTS */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 1024 FILE_RECORDS = 528 LABEL_RECORDS = 9 /* POINTERS TO DATA OBJECTS */ ^IMAGE_HEADER = 10 ^IMAGE = 17 /* PRODUCER IDENTIFICATION */ PRODUCT_CREATION_TIME = 2006-11-01T12:42:09.000Z PRODUCER_FULL_NAME = "THOMAS ROATSCH" PRODUCER_ID = DLR PRODUCER_INSTITUTION_NAME = "DEUTSCHES ZENTRUM FUER LUFT- UND RAUMFAHRT" /* DATA DESCRIPTION AND IDENTIFICATION */ DATA_SET_ID = "VEX-V-VMC-3-RDR-V1.0" DATA_SET_NAME = "VENUS EXPRESS VENUS VMC 3 V1.0" DETECTOR_ID = "VEX_VMC_NIR-1" FILE_NAME = "V0025_0000_N12.IMG" INSTRUMENT_HOST_ID = VEX INSTRUMENT_HOST_NAME = "VENUS EXPRESS" INSTRUMENT_ID = VMC INSTRUMENT_NAME = "VENUS MONITORING CAMERA" INSTRUMENT_TYPE = "FRAMING CAMERA" ^INSTRUMENT_DESC = "INSTRUMENT_DESC.TXT" MISSION_ID = VEX MISSION_NAME = "VENUS EXPRESS" MISSION_PHASE_NAME = PHASE_0 PROCESSING_LEVEL_ID = 2 PRODUCT_ID = "V0025_0000_N12.IMG" PRODUCT_TYPE = RDR RELEASE_ID = 0001 REVISION_ID = 0000 /* TIME RELATED INFORMATION */ SPACECRAFT_CLOCK_START_COUNT = "1/0038065833.64010" SPACECRAFT_CLOCK_STOP_COUNT = "1/0038065833.64207" IMAGE_TIME = 2006-05-15T13:50:34.000Z START_TIME = 2006-05-15T13:50:33.998Z STOP_TIME = 2006-05-15T13:50:34.001Z /* ORBITAL INFORMATION */ ASCENDING_NODE_LONGITUDE = 107.3 ORBIT_NUMBER = 25 ORBITAL_ECCENTRICITY = 0.84 ORBITAL_INCLINATION = 89.94 ORBITAL_SEMIMAJOR_AXIS = 39468.3 PERIAPSIS_ALTITUDE = 269.17 PERIAPSIS_ARGUMENT_ANGLE = 101.25 PERIAPSIS_TIME = 2006-05-16T01:34:46.000Z MAXIMUM_RESOLUTION = 46063.6 FOOTPRINT_POINT_LATITUDE = (-11.8599,-12.397,-12.8521,-13.242, -13.5773,-13.8648,-14.1092,-14.4806, -14.7057,-14.7646,-14.7869,-14.7714, -14.7159,-14.617,-14.4702,-13.6511, -11.5284,-18.7065,-18.0101,-17.4004, -22.4778,-21.6752,-23.0756,-23.2093, -17.2483,-23.646,-22.0455,-23.5859, -17.0539,-22.5451,-19.6774,-21.3421, -21.6056,-20.8355,-18.4799,-21.8812, -20.7332,-18.4333,-19.8844,-16.3322, -17.3995,-14.1295,-15.0577,-13.4548, -14.3536,-12.5112,-11.9466,-11.673, -4.48951,-6.52847,-6.90381,-7.43973, -7.76693,-7.86837,-7.93341,-7.96459, -7.87035,-7.50725,-7.32558,-7.11188, -6.86434,-6.25669,-5.8883,-4.42895, -3.76713,-2.94906,-1.83265,-0.525568, -1.46103,4.4672,0.757054,1.83794, 1.49245,4.26984,0.564325,4.19422, 4.66562,1.01102,4.67885,3.89761,5.66783 ,-0.081147,5.52245,0.597961,3.24192, 0.851394,1.33399,3.52298,-1.2659, -0.721338,1.27833,-1.6656,1.16806, -1.16743,-1.3162,-4.28845,-1.15241, -5.16394,-0.740856,-11.8599) FOOTPRINT_POINT_LONGITUDE = (256.244,256.856,258.482,260.324, 262.348,264.077,285.237,289.763,302.474 ,305.836,309.461,312.541,315.801, 318.568,321.472,324.429,327.06,329.763, 332.482,335.173,337.754,340.289,342.782, 345.456,347.873,350.468,353.01,355.484 ,357.849,359.915,2.6989,5.2615,7.66938, 9.69767,12.8128,15.5552,18.1162,20.4181 ,23.5341,26.3797,28.9658,32.2748, 35.2849,37.9259,41.2141,45.1023,48.381, 53.0852,56.714,78.584,80.3664,82.3779, 84.2168,85.898,86.6523,87.2512,101.076, 107.129,112.31,124.06,127.438,130.541, 133.596,136.433,139.285,141.989,144.629 ,147.178,149.673,152.157,154.65,156.975 ,159.308,161.66,164.047,166.526,168.712 ,170.976,173.303,175.726,177.84,180.49, 182.759,185.221,187.243,189.942,192.263 ,194.786,197.679,199.874,202.486, 205.377,207.992,210.947,214.316,217.572 ,220.82,224.851,228.694,256.244) SPACECRAFT_ORIENTATION = (0.945199,-0.324269,0.0380489) ^SPACECRAFT_ORIENTATION_DESC = "SPACECRAFT_ORIENTATION_DESC.TXT" SPACECRAFT_POINTING_MODE = "NULL" ^SPACECRAFT_POINTING_MODE_DESC = "SPACECRAFT_POINTING_MODE_DESC.TXT" /* TARGET IDENTIFICATION */ TARGET_TYPE = PLANET TARGET_NAME = VENUS RIGHT_ASCENSION = -1e+32 DECLINATION = -1e+32 SPACECRAFT_SOLAR_DISTANCE = 1.0894e+08 /* SCIENCE OPERATIONS INFORMATION */ VEX:SCIENCE_CASE_ID = -2147483647 VEX:^SCIENCE_CASE_ID_DESC = "VEX_SCIENCE_CASE_ID_DESC.TXT" OBSERVATION_TYPE = "NULL" ^OBSERVATION_TYPE_DESC = "OBSERVATION_TYPE_DESC.TXT" /* INSTRUMENT INFORMATION */ EXPOSURE_DURATION = 3.0 INST_CMPRS_NAME = NONE INST_CMPRS_RATIO = 1.0 INST_CMPRS_QUALITY = 0 MACROPIXEL_SIZE = 1 LINE_FIRST_PIXEL = 1 SAMPLE_FIRST_PIXEL = 1 DETECTOR_TEMPERATURE = 3.4 /* RADIOMETRIC DATA INFORMATION */ RADIANCE_OFFSET = 0.0 RADIANCE_SCALING_FACTOR = 378966.0 /* DATA OBJECT DEFINITIONS */ OBJECT = IMAGE INTERCHANGE_FORMAT = BINARY LINES = 512 LINE_SAMPLES = 512 SAMPLE_TYPE = MSB_INTEGER SAMPLE_BITS = 16 BANDS = 1 BAND_STORAGE_TYPE = BAND_SEQUENTIAL MAXIMUM = 662 MEAN = 32.1774 MINIMUM = 0 STANDARD_DEVIATION = 101.901 END_OBJECT = IMAGE DLR Institut für Planetenforschung VMC on VenusExpress Doc.-No. : VMC-DLR-TN-002 Issue : 005 Date : 1-Jun-2015 Page : 1 DLR Institut für Planetenforschung VMC on VenussExpress Doc.-No. : VMC-DLR-TN-002 VEX-VMC to Planetary Science Archive Issue : 005 Interface Control Document (EAICD) Date : 1-Jun-2015 Page : 2 of 29