CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 SPACECRAFT_NAME = MAGELLAN TARGET_NAME = VENUS OBJECT = TEXT PUBLICATION_DATE = 1992-02-01 BYTES = 80 NOTE = "MAGELLAN ARCDR CD-ROM" END_OBJECT = TEXT END MAGELLAN ARCDR CD-ROM 1. Introduction This CD-ROM contains Altimetry and Radiometry Composite Data Records (ARCDR) and associate documentation relating to a span of 180 orbits of the Magellan spacecraft about the planet Venus. These files are generated at the Massachusetts Institute of Technology and are organized by orbit number and, within each orbit, sequentially by time. They are NOT images. Overall, the collection of Magellan CD-ROMs contains three data sets. One is the ARCDR data set, to which this CD-ROM belongs. Another data set contains the MIT Altimetric and Radiometric Global Data Records: the Global Topography Data Record (GTDR), Global Emissivity Data Record (GEDR), Global Slope Data Record (GSDR), and Global Reflectivity Data Record (GREDR). The third data set consists of the Mosaic Image Data Records (MIDRs) that are generated by the JPL image data processing sub-system (IDPS). All data formats are based on the Planetary Data System document SPIDS 1.1 ("Standards for the Preparation and Interchange of Data Sets", D-4683, JPL, June 28, 1988) and are similar to the formats used in generating the Voyager CD-ROM set ("Voyagers to the Outer Planets", volumes 1-8, Planetary Data System, JPL, 1989). 2. Disk Format The disk has been formatted so that a variety of computer systems (e.g. IBM PC, Macintosh, Sun, VAX) may access the data. Specifically, it is formatted according to the ISO 9660 level 1 Interchange Standard, and file attributes are specified by Extended Attribute Records (XARs). For computer software that fully supports XARs, access to the CD-ROM volume will be straightforward; the disk will appear to the user to be identical to a file system of directories, sub-directories, and data files. Some computer systems that do not support XARs will ignore them; others will append the XAR to the beginning of the file, in which case the user must read past the first 512 bytes of the file. For further information, refer to the ISO 9660 Standard Document: RF# ISO 9660-1988, 15 April 1988. 3. File Formats Each orbit for which ARCDR data exists is represented by up to 4 data files: the Orbit Header File (OHF), NAIF SP-Kernel Ephemeris File (EPF), Altimetry Data File (ADF) and Radiometry Data File (RDF). Each file is accompanied by a detached PDS label file and data files and labels are grouped into sub-directories containing not more than 20 orbits each (i.e. 80 data files and 80 labels). Additional information about each product is found in the LABEL directory. The *.LBL files in that directory contain the PDS catalog information for the Magellan Mission, the spacecraft, the radar instrument, and the data sets. Further information on ARCDR formats and contents can also be obtained from the Magellan Software Interface Specification document MIT-MGN-ARCDR (Project Code SCI-002), Version 2.3, September 12, 1991. A copy of the document is stored on this disk as file ARCDR.TXT in the DOCUMENT directory, although the reader is warned that it describes the magnetic tape product that is generated at MIT, not the CD-ROM itself. Some other documents that will be of use are as follows: [1] JJPL-0006-00-01, JPL SFDU Description and Usage. Issue 5, March 7 1988. [2] SFOC-1-MHR-MGN-SCIEDR, Magellan Software Interface Specification, SAR and Altimeter EDR/TEDR Tapes , J. Springer and B. Wilson, JPL. November 28, 1988. [3] SFOC-2-DPS-CDB-Ephemeris, NAIF Ephemeris File, JPL Navigation Ancillary Information Facility, July 15, 1988. [4] Standards for the Preparation and Interchange of Data Sets, T.Z. Martin et al., DP4683, JPL Planetary Data System, Version 1.1, October 3, 1988. [5] MIT-MGN-SDMP, Magellan Altimetry & Radiometry Data Processing Software and Data Management Plan, MIT Center for Space Research, Revision 5, September 20, 1989. [6] MIT-MGN-SDD, Magellan Altimetry & Radiometry Software Design Document, MIT Center for Space Research, Version 2.0, September 20, 1989. [7] MIT-MGN-GxDR, Magellan Altimetry & Radiometry Global Data Products Software Interface Specification, MIT Center for Space Research, Version 2.1, January 30, 1990. [8] MGN 630-79, Rev. C, Magellan Planetary Constants and Models, D.T. Lyons, Magellan Mission Design, JPL, April 11, 1988. [9] An Introduction to SPICELIB, Volumes I and II, Navigation Ancillary Information Facility, JPL Planetary Data System, September 3, 1988. [10] MIT-MGN-ERR, Magellan Altimetry Error Analysis, MIT Center for Space Research, Version 2, September 20, 1989. [11] NESYS Update, R.E. Thurman, NAIF, JPL Interoffice Memo 314.8-ret.1, June 12, 1989. All document files and detached label files contain 80-byte fixed- length records, with a carriage return character (ASCII 13) in the 79th byte and a line feed character (ASCII 10) in the 80th byte. This allows the files to be read by the MacOS, DOS, Unix, and VMS operating systems. All tabular files are also described by PDS labels, either embedded at the beginning of the file or detached. If detached, the PDS label file has the same name as the data file it describes, with the extension .LBL; for example, the file ACONTENT.TAB is accompanied by the detached label file ACONTENT.LBL in the same directory. PDS labels are object-oriented. The object to which the label refers (e.g. IMAGE, TABLE, etc.) is denoted by a statement of the form: ^object = location in which the carat character (^, also called a pointer in this context) indicates that the object starts at the given location. In an embedded label, the location is an integer representing the starting record number of the object (the first record in the file is record 1). In a detached label, the location denotes the name of the file containing the object, along with the starting record or byte number. For example: ^IMAGE = ("C102.IMG",3) indicates that the IMAGE object begins at record 3 of the file C102.IMG, in the same directory as the detached label file. Below is a list of the possible formats that use the ^object keyword. ^object = n ^object = n ^object = ("filename.ext",n) ^object = ("[dirlist]filename.ext",n) ^object = ("filename.ext",n) ^object = ("[dirlist]filename.ext",n) where n is the starting record or byte number of the object, counting from the beginning of the file (record 1, byte 1). indicates that the number given is in units of bytes. filename is the upper-case file name. ext is the upper-case file extension. dirlist is a period-delimited path-list of parent directories, in upper case, that specifies the object file directory (used only when the object is not in the same directory as the label file). 4. CD-ROM Contents The files on this CD-ROM are organized in one top-level directory with several subdirectories. The following table shows the structure and content of these directories. In the table, directory names are enclosed in square brackets ([]), upper-case letters indicate an actual directory or file name, and lower-case letters indicate the general form of a set of directory or file names. FILE CONTENTS Top-level directory | |- AAREADME.TXT The file you are reading | |- ACUMCOMM.TXT A description of known errors and anomalies in | this and ALL previous Magellan ARCDR CD-ROM | disks. | |- VOLDESC.SFD A description of the contents of this CD-ROM | volume in a format readable by both human and | computers | |- [INDEX] A directory containing index files which describe | | products published so far or on this volume. | | | |- ACUMDIR.TAB A table listing all ARCDR products published so | | so far, including the ARCDRs on this CD-ROM. | | | |- ACUMDIR.LBL A PDS detached label that describes CUMDIR.TAB | | | |- ACONTENT.TAB A tabular listing of each ARCDR file on this | | disk and the directory in which it is located. | | | |- ACONTENT.LBL A PDS detached label that describes ACONTENT.TAB. | |- [SOFTWARE] A directory containing some useful software | | provided (without warranty) by MIT for the | | benefit of users with MS-DOS, UNIX, MaxOS and | | VMS operating systems. Considerable work may | | be needed to adapt this software to run on other | | systems. Read the SOFTWARE.TXT file for details. | | | |- ARCDRLST.C C-language source code for a program that displays | | and copies selected data fields of ARCDR files. | | | |- ARCDRLST.EXE Binary executable version of ARCDRLST.C for MS-DOS | | computers, i.e. IBM-PC's and compatibles. | | | |- ARCDRLST.HQX An archive in BinHex/Stuffit format containing | | an executable version of ARCDRLST for the Apple | | Macintosh, along with MS-WORD documentation and | | copies of ARCDRLST.C and ARCDR.H. | | | |- ARCDRLST.TXT An ASCII file containing instructions for using | | the ARCDRLST command. | | | |- ARCDR.H A C-language header file defining all ARCDR | | binary data structures, used when compiling | | ARCDRLST.C and MGMLIB.C. | | | |- MGMLIB.C C-language routines to assist in reading ARCDR | | data files, to convert binary fields between | | VAX and IEEE format, etc. The routines have been | | tested on a variety of UNIX and VMS systems. See | | SOFTWARE.TXT for details. | | | |- MGMLIB.H A C-language header file used when compiling | | MGMLIB.C. | | | |- MGMLIB.MAN A series of UNIX manual files describing the | | MGMLIB subroutines and data structures. These | | are intended to be used as input to the UNIX | | commands 'nroff', 'troff', and 'man'. If these | | programs are unavailable, read the MGMLIB.TXT | | file instead. Note that, unlike the other files | | on this disk, MGMLIB.MAN is written in STREAM | | format, i.e. its records are of unequal length | | and are delimited by characters. | | | |- MGMLIB.TXT A formatted version of MGMLIB.MAN suitable for | | printing on most output devices or previewing | | with a text editor. | | | |- SOFTWARE.TXT Instructions for compiling and installing the | software contained in this directory. | |- [LABEL] A directory containing catalog information | | describing the ARCDR Magellan data products that | | will be submitted to PDS. The information is in | | the form of catalog templates that will be | | submitted to PDS for loading into the PDS central | | node catalog. | | | |- CATALOG.LBL PDS high-level experiment-description | | templates. | | | |- ARCDRDS.LBL PDS high-level dataset templates for ARCDRs. | | | |- OHFTBL.FMT description of fields in the OHF files. | | | |- ADFTBL.FMT description of fields in the ADF files. | | | |- RDFTBL.FMT description of fields in the RDF files. | |- [DOCUMENT] A directory containing document files relating | | to this disk. | | | |- ARCDR.TXT A machine-readable version of the MIT-MGN-ARCDR | SIS Document describing the format and contents | of the data files. | |- [nnnnmmmm] Directories containing ARCDR data files for | orbits between 'nnnn' and 'mmmm'. | |- OHFnnnnn.v The Orbit Header File for orbit number 'nnnnn', | version 'v' -- a short file that describes the | accompanying ADF and RDF files for this orbit | (see section 5.1, below). | |- OHFnnnnn.LBL PDS label file describing OHFnnnnn.v. | |- EPFnnnnn.v The Ephemeris File, supplied by NAIF, that was | used to process the accompanying ADF file, or | the RDF file if no ADF file exists (see section | 5.2, below). | |- EPFnnnnn.LBL PDS label file describing EPFnnnnn.v. | |- ADFnnnnn.v The Altimetry Data File for this orbit -- the | result of processing data from an ALT-EDR product | at MIT (see section 5.3, below). | |- ADFnnnnn.LBL PDS label file describing ADFnnnnn.v. | |- RDFnnnnn.v The Radiometry Data File for this orbit -- the | result of processing SAR backscatter data at MIT | (see section 5.4, below). | |- RDFnnnnn.LBL PDS label file describing RDFnnnnn.v. 5. Data File Contents The PDS label files and the extended attribute records that accompany all ARCDR data files specify the following format: RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 32500 However, the files really contain a mixture of varying and fixed length structures (SFDU's), which are written contiguously without padding or regard for the 32,500 byte block boundaries implied by the above definition. Carat characters (^) are appended to the file until it is an exact multiple of 32500 bytes in length. Each data file contains a series of Standard Formatted Data Units (SFDU's). Each SFDU begins with a 12-byte type header, followed by an 8-byte length indicator, and a varying-length value field. The ARCDR uses several SFDU types: * Primary Label A string beginning 'CCSD1Z', identifying the data as obeying the conventions of the CCSDS authority. * Catalog/Keyword Label A string beginning 'NJPL1K' that further identifies each data file by a series of 'KEYWORD=VALUE' definitions. * Data Aggregate A string beginning 'NJPL1I' that begins a fixed-length block of data. * Aggregation Marker A pair of strings beginning 'CCSD1R' that sandwiches collections of data whose length is otherwise undefined. The next 4 sections describe the contents of each of these files in detail, starting with a table showing the structure of the ASCII labels that encapsulate the SFDU's, then a description of the keywords used in the catalog labels, then a table of field names and offsets in the binary SFDU's, and finally a description of the binary data fields themselves. The names of binary SFDU aggregates and their fields correspond to the C-language structures in the [SOFTWARE]MGMLIB.H file. When describing the data type of binary fields, the following terms will be used: * sfdu a 20-byte SFDU header label. * uchar an unsigned character, i.e. a single byte to be interpreted as an integer in the range 0-255. * ulong an unsigned 32-bit binary VAX integer. * long a signed 32-bit VAX integer. * float a 32-bit VAX floating point number. * double a 64-bit VAX D-type floating point number. Note that the C-language names of the fields are unique only to ARCDR data structures. The Planetary Data System maintains a set of official names for each of them, and these names are shown in the appropriate [LABEL]*.FMT files, alongside ALIAS names that are identical to the corresponding C-language element names used in [SOFTWARE]MGMLIB.H. 5.1. Orbit Header Record File (OHF) Each Orbit Header Record File (OHF) identifies the orbit number, time frame, and orbital geometry for one Magellan orbit. The OHF data block is depicted in Table 2 and has a fixed length of 112 bytes. The file format is as follows: Table 1 Orbit Header Record SFDU Structure +---+--------------------------------------------+--------------+ | T | CCSD1Z000001 | CCSD label | +---+--------------------------------------------+--------------+ | L | 00000xxx | length | +---+---+----------------------------------------+--------------+ | . | T | NJPL1K00KL00 | Keywd label | +---+---+----------------------------------------+--------------+ | . | L | 00000xxx | length | +---+---+----------------------------------------+--------------+ | . | . | PRODUCT_FILE_NAME=OHFnnnnn.v | | | . | . | PRODUCT_TYPE=ORBIT_HEADER_RECORD | | | . | . | MISSION_ID=4 | | | . | V | MISSION_NAME=MAGELLAN | | | . | A | SPACECRAFT_ID=18 | Keywords | | . | L | SPACECRAFT_NAME=MAGELLAN | and | | . | U | PROCESS_TIME=yyyy-mm-ddThh:mm:ss.fff | Values | | . | E | ORBIT_NUMBER=nnnnn | | | . | . | HARDWARE_VERSION_ID=nn | | | . | . | SOFTWARE_VERSION_ID=nn | | | . | . | DATA_FORMAT_TYPE=VAX | | | . | . | UPLOAD_ID=cccccc | | +---+---+----------------------------------------+--------------+ | . | | Orbit Header | | . | Orbit Header Record SFDU (see Table 2) | Record | | . | | (112 bytes) | +---+--------------------------------------------+--------------+ CCSDS Label 'CCSD1Z000001', the CCSDS primary SFDU label. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the Orbit Header File. Keyword Label 'NJPL1K00KL00', the SFDU Catalog/Keyword label, where '1' indicates that an ASCII length field follows. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the keyword/value field, including two bytes per keyword/value pair for the (unillustrated) carriage return and line feed, and a possible trailing blank if required to make this length an even number. PRODUCT_FILE_NAME= 'OHFnnnnn.v', the external file name of this OHF. 'nnnn' is a 5-digit orbit number and 'v' a decimal version number. PRODUCT_TYPE= The character string 'ORBIT_HEADER_RECORD'. MISSION_ID= The single character '4'. MISSION_NAME= The character string 'MAGELLAN'. SPACECRAFT_ID= For real data, the 2-digit number '18'. For simulated data, the number '28'. SPACECRAFT_NAME= The character string 'MAGELLAN'. PROCESS_TIME= The UTC time at which the Orbit Header Record File was created by the MIT A&R processing system. ORBIT_NUMBER= A 5-digit number, denoting the Magellan orbit number of this and the following three data files. HARDWARE_VERSION_ID= A 2-digit number, 'nn', identifying the hardware version number of the MIT A&R data processing system used to create this file. SOFTWARE_VERSION_ID= A 2-digit number, 'nn', identifying the software version number of the MIT A&R data processing system used to create this file. DATA_FORMAT_TYPE= Either 'VAX' or 'IEEE', depending on the format in which binary fields are represented in the orbit header record. For all ARCDR CD-ROM products, this will be 'VAX'. UPLOAD_ID= 6 characters 'ABBBBC', where 'A' is the mission phase, 'BBBB' is the upload number within each phase, and 'C' is a revision indicator in the range A-Z. Orbit Header Record A structure containing binary data fields, as follows: Table 2 Orbit Header Record Format ----+-----+--------+--------------+-------------------------------------- Off | Len | Type | Field Name | Description ----+-----+--------+--------------+-------------------------------------- +0 | 20 | sfdu | oh_sfdu | SFDU label and length 20 | 4 | ulong | oh_norbit | Orbit number 24 | 4 | ulong | oh_nalt | Number of Altimetry Data Records 28 | 4 | ulong | oh_nrad | Number of Radiometry Data Records 32 | 8 | double | oh_alt_start | First Alt Footprint Time (SCET, TDB) 40 | 8 | double | oh_alt_end | Last Alt Footprint Time (SCET, TDB) 48 | 8 | double | oh_rad_start | First Rad Footprint Time (SCET, TDB) 56 | 8 | double | oh_rad_end | Last Rad Footprint Time (SCET, TDB) 64 | 8 | double | oh_avg.scet | Predicted Periapsis Time (SCET, TDB) 72 | 8 | double | oh_avg.sma | Predicted Semi-Major Axis (km) 80 | 8 | double | oh_avg.ecc | Predicted Eccentricity 88 | 8 | double | oh_avg.incl | Predicted Inclination (deg) 96 | 8 | double | oh_avg.long | Predicted Lon of Ascending Node (deg) 104 | 8 | double | oh_avg.arg | Predicted Argument of Periapsis (deg) 112 | | | | ----+-----+--------+--------------+-------------------------------------- Field Name Type Size Description oh_sfdu sfdu 20 SFDU Label and Length: 'NJPL1I00017800000092'. The number '0178' is registered with the NJPL SFDU authority as the "MIT Orbit Header Record Aggregate". oh_norbit ulong 4 The Magellan Orbit Number corresponding to the following three files (ephemeris, altimetry, and radiometry). An orbit begins at apoapsis, and the number is copied from the orbit header file of the input ALT-EDR tape. oh_nalt ulong 4 Number of Altimetry Data Records -- the number of ar_rec SFDU's in this orbit's altimetry data file. oh_nrad ulong 4 Number of Radiometry Data Records -- the number of rr_rec SFDU's in this orbit's radiometry data file. oh_alt_start double 8 First Altimetry Footprint Time (SCET) -- the S/C ephemeris time (seconds of TDB since J2000) that represents the first altimeter footprint of this orbit. It is equal to the ar_scet value in the first record of this orbit's altimetry data file. oh_alt_end double 8 Last Altimetry Footprint Time (SCET) -- the S/C ephemeris time (seconds of TDB since J2000) that represents the last altimeter footprint of this orbit. It is equal to the ar_scet value in the last record of this orbit's altimetry data file. oh_rad_start double 8 First Radiometer Footprint Time (SCET) -- the S/C ephemeris time (seconds of TDB since J2000) of the first radiometer measurement of this orbit. It is equal to the rr_scet value in the first record of this orbit's radiometry data file. oh_rad_end double 8 Last Radiometer Footprint Time (SCET) -- the S/C ephemeris time (seconds of TDB since J2000) of the last radiometer measurement of this orbit. It is equal to the rr_scet value in the last record of this orbit's radiometry data file. oh_avg.scet double 8 Periapsis Time (SCET) -- the periapsis time (seconds of TDB since J2000) of the predicted orbit. oh_avg.sma double 8 Semi-Major Axis (km) -- the semi-major axis of the predicted orbit. oh_avg.ecc double 8 Eccentricity -- the eccentricity of the predicted orbit. oh_avg.incl double 8 Inclination (deg) -- the inclination of the predicted orbit with respect to the xy-plane of the J2000 coordinate system. oh_avg.long double 8 Longitude of Ascending Node (deg) -- the angle in the xy-plane of the J2000 coordinate system to the ascending node of the predicted orbit. oh_avg.arg double 8 Argument of Periapsis (deg) -- the angle in the plane of the predicted orbit from the ascending node in the xy-plane of the J2000 coordinate system to the periapsis. 5.2. Ephemeris File (EPF) The information recorded in the ephemeris files is in the NAIF S&P Kernel format (SPK), and is therefore not immediately interpretable. The file structure is as follows: Table 3 Ephemeris File SFDU Structure +---+------------------------------------------------+--------------+ | T | CCSD1Z000001 | CCSD label | +---+------------------------------------------------+--------------+ | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | T | NJPL1K00KL00 | Keywd label | +---+---+--------------------------------------------+--------------+ | . | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | . | DATA_OBJECT_TYPE=EPHEMERIS | | | . | . | PRODUCT_VERSION_TYPE=ACTUAL | | | . | . | DATA_SET_NAME=MGNnnnnn.TSP | | | . | . | MISSION_ID=4 | | | . | . | MISSION_NAME=MAGELLAN | | | . | . | SPACECRAFT_NAME=MAGELLAN | | | . | . | SPACECRAFT_ID=18 | | | . | . | PROCESS_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | VERSION_ID=nn | | | . | . | UPLOAD_ID=cnnnnc | | | . | . | ORBIT_NUMBER=nnnnn | | | . | . | OBJECT=ORBIT_TIME_RANGE_GROUP | | | . | . | TIME_RANGE_NUMBER=1 | | | . | . | ORBIT_START_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | ORBIT_STOP_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | END_OBJECT=ORBIT_TIME_RANGE_GROUP | | | . | . | OBJECT=MAPPING_TIME_RANGE_GROUP | | | . | . | TIME_RANGE_NUMBER=1 | | | . | . | MAPPING_START_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | MAPPING_STOP_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | END_OBJECT=MAPPING_TIME_RANGE_GROUP | | | . | . | EFFECTIVE_TIME=yyyy-mm-ddThh:mm:ss.fff | | | . | . | NAV_UNIQUE_ID="cccccccc " | | +---+---+--------------------------------------------+--------------+ | . | T | NJPL1S00KL00 | SFDU label | +---+---+--------------------------------------------+--------------+ | . | L | 00000000 | length | +---+---+--------------------------------------------+--------------+ | . | T | CCSD1S000002 | SFDU label | +---+---+--------------------------------------------+--------------+ | . | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | V | | | | . | A | Comments | ASCII text | | . | L | | | +---+---+--------------------------------------------+--------------+ | . | T | CCSD1R000003 | Start marker | +---+---+--------------------------------------------+--------------+ | . | L | 000000xx | length | +---+---+--------------------------------------------+--------------+ | . | V | DELIMITER=SMARKER | | | . | A | PRODUCT_NAME=NAIF_SPK_FILE | Start value | | . | L | TYPE=NJPL1I000152 | | | | | PROTOCOL=NONE | | +---+---+--------------------------------------------+--------------+ | | | | SPK Ephemeris Data Records | variable | | | | +---+------------------------------------------------+--------------+ | T | CCSD1R000003 | End marker | +---+------------------------------------------------+--------------+ | L | 000000xx | length | +---+------------------------------------------------+--------------+ | V | DELIMITER=EMARKER | End value | | . | PRODUCT_NAME=NAIF_SPK_FILE | | +---+------------------------------------------------+--------------+ The EPF is designed to be accessed by Fortran subroutines distributed by NAIF in its NESYS/SPICELIB system. This is a two-step process: * Convert the EPF to Binary -- The SPICELIB routines expect their input data to be in the form of a binary direct-access file, so the ASCII Ephemeris Data File (as shown in Table 3) must be reformatted. This is performed by first stripping off the SFDU header and trailer labels, and then invoking SEFU -- an interactive program distributed by NAIF that prompts the user to specify the names of the input (ASCII) and output (binary) ephemeris files. * Call the SPICELIB Subroutines -- As an example, a Fortran 77 program that wishes to know the Magellan spacecraft position and velocity vectors relative to the center of Venus at time ScET, might be linked with the SPICELIB library and contain the following code: Parameter (Venus = -18) Parameter (Magellan = 2) Integer*4 Handle Double Precision State(6), Starg(6), ScET Call ClPool () Call LdPool ('LEAPSECONDS') Call LdPool ('CONSTANTS') Call Spklef ('/tmp/spk', Handle) Call Spkssb (Venus, ScET, 'J2000', State) Call Spkapp (Magellan, ScET, 'J2000', State, 'LT+S', Starg, Lt) The required vector will be returned in the Starg array. ScET is expressed in seconds of ephemeris time (TDB) since J2000, and will therefore be a large negative number. The SPICELIB subroutine UTC2ET will convert a UTC date expressed as an ASCII character string into TDB. UTC2ET routine is capable of interpreting a wide variety of UTC character string formats. Character*30 Utc Double Precision ScET Utc = '1991 JUN 21 18:21:33.914' Call Utc2Et (Utc, ScET) 5.3. Altimetry Data File (ADF) Each ADF contains data from a single Magellan orbit. The file begins with the standard keyword label section and then a series of binary Altimetry Data Records, sandwiched between Start and End marker labels. Table 4 Altimetry Data File SFDU Structure +---+------------------------------------------------+--------------+ | T | CCSD1Z000001 | CCSD label | +---+------------------------------------------------+--------------+ | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | T | NJPL1K00KL00 | Keywd label | +---+---+--------------------------------------------+--------------+ | . | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | . | PRODUCT_FILE_NAME=ADFnnnnn.v | | | . | . | PRODUCT_TYPE=ALTIMETRY_FILE | | | . | . | MISSION_ID=4 | | | . | . | SPACECRAFT_NAME=MAGELLAN | | | . | . | SPACECRAFT_ID=18 | | | . | V | MISSION_NAME=MAGELLAN | Keywords | | . | A | PROCESS_TIME=yyyy-mm-ddThh:mm:ss.fff | and | | . | L | ORBIT_NUMBER=nnnnn | Values | | . | U | HARDWARE_VERSION_ID=nn | | | . | E | SOFTWARE_VERSION_ID=nn | | | . | . | TEMPLATE_VERSION_NUMBER=nn | | | . | . | DATA_FORMAT_TYPE=VAX | | | . | . | UPLOAD_ID=cccccc | | | . | . | NAV_UNIQUE_ID="cccccccccc " | | +---+---+--------------------------------------------+--------------+ | . | T | CCSD1R000003 | Start marker | +---+---+--------------------------------------------+--------------+ | . | L | 000000xx | length | +---+---+--------------------------------------------+--------------+ | . | V | DELIMITER=SMARKER | Start value | | . | A | PRODUCT_NAME=ALTIMETRY_DATA_RECORD | | | . | L | TYPE=NJPL1I000177 | | +---+---+--------------------------------------------+--------------+ | | | | Altimetry Data Record SFDUs (ar_rec, see Table 5) | nx1032 bytes | | | | +---+------------------------------------------------+--------------+ | T | CCSD1R000003 | End marker | +---+------------------------------------------------+--------------+ | L | 000000xx | length | +---+------------------------------------------------+--------------+ | V | DELIMITER=EMARKER | End value | | . | PRODUCT_NAME=ALTIMETRY_DATA_RECORD | | +---+------------------------------------------------+--------------+ CCSDS Label 'CCSD1Z000001', the CCSDS primary SFDU label. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the Altimetry Data File header. Keyword Label 'NJPL1K00KL00', the SFDU Catalog/Keyword label, where '1' indicates that an ASCII length field follows. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the keyword/value field, including two bytes per keyword/value pair for the (unillustrated) carriage return and line feed, and a possible trailing blank if required to make this length an even number. PRODUCT_FILE_NAME= 'ADFnnnnn.v', the external file name of this ADF. 'nnnnn' is a 5-digit orbit number and 'v' a decimal version number. PRODUCT_TYPE= The character string 'ALTIMETRY_FILE'. MISSION_ID= The single character '4'. MISSION_NAME= The character string 'MAGELLAN'. SPACECRAFT_ID= For real data, the 2-digit number '18'. For simulated data, the number '28'. SPACECRAFT_NAME= The character string 'MAGELLAN'. PROCESS_TIME= The UTC time at which the Altimetry Data File was created by the MIT A&R processing system. ORBIT_NUMBER= A 5-digit number, denoting the Magellan orbit number of this Altimetry Data File. HARDWARE_VERSION_ID= A 2-digit number, 'nn', identifying the hardware version number of the MIT A&R data processing system used to create this file. SOFTWARE_VERSION_ID= A 2-digit number, 'nn', identifying the software version number of the MIT A&R data processing system used to create this file. TEMPLATE_VERSION_NUMBER= A 2-digit number, 'nn', denoting the version number of the altimetry echo templates used to fit the altimetry profiles and generate this file. DATA_FORMAT_TYPE= Either 'VAX' or 'IEEE', depending on the format in which binary fields are represented in the altimetry data records. For all CD-ROM ARCDR products, this will be 'VAX'. UPLOAD_ID= 6 characters 'ABBBBC', where 'A' is the mission phase, 'BBBB' is the upload number within each phase, and 'C' is a revision indicator in the range A-Z. NAV_UNIQUE_ID= A unique identification string given to this orbital solution by the Magellan navigation team. Start Marker 'CCSD1R000003', the SFDU Aggregate Marker label, indicating the start of a data aggregate of unspecified length. This aggregate consists of a varying number of Altimetry Data Record SFDU's, as shown in Table 5 below. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the aggregate marker SFDU. DELIMITER= The character string 'SMARKER', indicating that this is the start of a data aggregate. PRODUCT_NAME= The character string 'ALTIMETRY_DATA_RECORD'. TYPE= The character string 'NJPL1I000177', where '0177' indicates that the data between the SMARKER and EMARKER labels comprise a registered SFDU aggregate, composed of a set of registered NJPL aggregates. Altimetry Data Record See Table 5 below. End Marker 'CCSD1R000003', the SFDU Aggregate Marker label, indicating the end of a data aggregate of unspecified length. This matches the above "Start Marker". Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the aggregate marker SFDU. DELIMITER= The character string 'EMARKER', indicating that this is the end of a data aggregate. PRODUCT_NAME= The character string 'ALTIMETRY_DATA_RECORD'. Table 5 Altimetry Data File Record Format ----+-----+--------+----------------+-------------------------------------- Off | Len | Type | Field Name | ar_rec Description ----+-----+--------+----------------+-------------------------------------- +0 | 20 | sfdu | ar_sfdu | SFDU header label and length 20 | 4 | long | ar_nfoot | Footprint number 24 | 4 | ulong | ar_flag | Flag fields (see Table 5-7) 28 | 4 | ulong | ar_flag2 | Additional flag fields (unused) 32 | 8 | double | ar_scet | Altimetry Footprint Time (SCET, TDB) 40 | 24 | double | ar_pos[3] | S/C Position Vector (km, J2000) 64 | 24 | double | ar_vel[3] | S/C Velocity Vector (km/sec, J2000) 88 | 4 | float | ar_lon | Footprint Longitude (deg, VBF85) 92 | 4 | float | ar_lat | Footprint Latitude (deg, VBF85) 96 | 4 | float | ar_xfoot | Along-track Alt Footprint Size (km) 100 | 4 | float | ar_yfoot | Cross-track Alt Footprint Size (km) 104 | 4 | float | ar_rcal | Receiver Noise Calibration (km^2) 108 | 4 | float | ar_range | Uncorrected range to nadir (km) 112 | 4 | float | ar_atmos | Atmospheric correction to range (km) 116 | 4 | float | ar_radius | Derived Planetary Radius (km) 120 | 4 | float | ar_slope | Derived RMS Surface Slope (deg) 124 | 4 | float | ar_rho | Derived Fresnel Reflectivity 128 | 4 | float | ar_rhocor | ar_rho corrected for Diffuse Scat. 132 | 12 | float | ar_error[3] | Formal errors in Radius, Slope, Rho 144 | 24 | float | ar_correl[6] | Formal parameter correlations 168 | 4 | float | ar_drad | Ephemeris Radius Correction (km) 172 | 4 | float | ar_dlon | Ephemeris Lon Correction (deg, VBF85) 176 | 4 | float | ar_dlat | Ephemeris Lat Correction (deg, VBF85) 180 | 72 | float | ar_partl[3][6] | Partials of rlon, lat and radius 252 | 4 | float | ar_fit | Non-range-sharpened goodness of fit 256 | 4 | float | ar_scale | Scaling factors for ar_tmpl & ar_prof 260 | 4 | ulong | ar_looks | Number of non-range-sharpened looks 264 | 4 | ulong | ar_nprof0 | ar_prof index matching ar_tmpl[0] 268 | 302 | uchar | ar_prof[302] | Non-range-sharpened Echo Profile 570 | 50 | uchar | ar_tmpl[50] | Best non-range-sharp Model Template 620 | 4 | float | ar_rsfit | Range-sharpened goodness of fit 624 | 4 | float | ar_rsscale | ar_rstmpl & ar_rsprof scaling factors 628 | 4 | ulong | ar_rslooks | Number of range-sharpened looks 632 | 4 | ulong | ar_rsnprof0 | ar_rsprof index matching ar_rstmpl[0] 636 | 302 | uchar | ar_rsprof[302] | Range-sharpened Echo Profile 938 | 50 | uchar | ar_rstmpl[50] | Best range-sharpened Model Template 988 | 4 | float | ar_rhofact | Multi-peak corrn applied to ar_rho 992 | 4 | float | ar_radius2 | Radius from Threshold Detector (km) 996 | 4 | float | ar_sqi | Signal Quality Indicator (dB) 1000 | 4 | ulong | ar_thresh | Threshold Detector Index 1004 | 28 | long | ar_spare[7] | Unused 1032 | | | | ----+-----+--------+----------------+-------------------------------------- Field Name Type Size Description ar_sfdu sfdu 20 SFDU Label and Length: 'NJPL1I00017900001012'. The number '0179' is registered with the NJPL SFDU authority as the "MIT Altimetry Data Record Aggregate". ar_nfoot long 4 The Footprint Number -- a signed integer value. The A&R processing program assigns footprint 0 to that observed at nadir at periapsis. The remaining footprints are located along the S/C nadir track, with a separation that depends on the doppler resolution of the altimeter at the epoch at which that footprint is observed. Pre-periapsis footprints will be assigned negative numbers, post-periapsis footprints will be assigned positive ones. A loss of several consecutive burst records from the ALT-EDR will result in missing footprint numbers. ar_flag ulong 4 Flag fields: Table 6 Altimetry Data Record Flag Values Name | Value | Flag Description -----------+-------+------------------------------------------------- AR_FIT | 1 | Record contains footprint values that have been | | fitted in the A&R MGMTAC processing phase. -----------+-------+------------------------------------------------- AR_EPHC | 2 | Geometry values have been corrected for | | ephemeris errors (MGMORB phase). -----------+-------+------------------------------------------------- AR_RHOC | 4 | Reflectivity correction ar_rhocor has been | | determined from SAR backscatter values | | (MGMORB phase). -----------+-------+------------------------------------------------- AR_RS2 | 8 | Range-sharpened values have passed the 2nd- | | order template fitting criteria (MGMTAC phase). -----------+-------+------------------------------------------------- AR_NRS2 | 16 | Non-range-sharpened values have passed the 2nd- | | order template fitting criteria (MGMTAC phase). -----------+-------+------------------------------------------------- AR_BAD | 32 | Ignore this record entirely. -----------+-------+------------------------------------------------- AR_RBAD | 64 | Ignore the range-sharpened profile ar_rsprof[] | | and the associated ar_radius value. -----------+-------+------------------------------------------------- AR_CBAD | 128 | Ignore the non-range-sharpened profile | | ar_prof[] and the associated ar_slope and | | ar_rho values. -----------+-------+------------------------------------------------- AR_TMARK | 256 | Temporary ar_radius marker flag, used by MGMDQE. -----------+-------+------------------------------------------------- AR_CMARK | 512 | Temporary ar_slope marker flag, used by MGMDQE. -----------+-------+------------------------------------------------- AR_FMARK | 1024 | Temporary ar_rho marker flag, used by MGMDQE. -----------+-------+------------------------------------------------- AR_HAGFORS | 2048 | ar_slope and its errors and correlations are | | expressed as Hagfors' C parameter instead of | | degrees of RMS slope. This flag will not be set | | in any standard ARCDR products. It is solely | | used during some phases of internal MIT | | processing. -----------+-------+------------------------------------------------- AR_BADALTA | 4096 | The altimetry antenna was pointed more than 3 | | degrees from its expected location as given by | | the nominal look-angle profile. -----------+-------+------------------------------------------------- AR_SLOPEBAD| 8192 | The ar_slope parameter value is suspect, and | | ar_prof should also be disregarded. -----------+-------+------------------------------------------------- AR_RHOBAD | 16384 | The ar_rho value is suspect. -----------+-------+------------------------------------------------- AR_RAD2 | 32768 | This record was created under software version | | 2 or higher, in which the data fields ar_rhofact, | | ar_radius2, ar_sqi, & ar_thresh are significant. -----------+-------+------------------------------------------------- AR_RAD2BAD | 65536 | The ar_radius2 value is suspect. -----------+-------+------------------------------------------------- AR_AMBIG |131072 | The value of ar_radius has been shifted by a | | multiple of the range ambiguity (10.02 km) | | during the MGMDQE processing phase. -----------+-------+------------------------------------------------- AR_AMBIG2 |262144 | The value of ar_radius2 has been shifted by a | | multiple of the range ambiguity (10.02 km) | | during the MGMDQE processing phase. -----------+-------+------------------------------------------------- ar_flag2 ulong 4 Unused flag fields. ar_scet double 8 Altimetry Footprint Time (SCET) -- the ephemeris time (seconds of TDB since J2000) at which the S/C passed directly over the center of the footprint. As each footprint is composed of data collected from several altimeter bursts, this epoch doesn't necessarily coincide with a particular burst. ar_pos double 3*8 S/C Position Vector (km, J2000) -- the S/C position at ar_scet, relative to the Venus center of mass, expressed in inertial coordinates. ar_vel double 3*8 S/C Velocity Vector (km sec^1, J2000) -- the S/C velocity at ar_scet, relative to the Venus center of mass, expressed in inertial coordinates. ar_lon float 4 Footprint Longitude (deg, VBF85) -- the crust-fixed longitude of the center of the altimeter footprint, in the range 0E - 360E longitude. Periapsis nadir increases in longitude by about 1.48 degrees per day (about 0.2 degrees per orbit). ar_lat float 4 Footprint Latitude (degrees, VBF85) -- the crust-fixed latitude of the center of the altimeter footprint, in the range of -90 degrees (South Pole) to +90 degrees (North Pole). ar_xfoot float 4 Along-track Altimetry Footprint Size (km) -- the along-track dimension of the Venus surface area whose mean radius, RMS slope, and reflectivity are reported in this data record. The along track dimension is chosen to be the smallest multiple of the doppler resolution of the altimeter (at this point in the S/C orbit) that is greater than 8 km. ar_yfoot float 4 Cross-track Altimetry Footprint Size (km) -- the cross-track footprint dimension is determined solely by the radar baud length and the S/C altitude at this point in the orbit. ar_rcal float 4 Receiver Noise Calibration (km^2) -- a measure of the altimeter noise background, obtained from the pulse-compressed altimeter signals by the MGMTAC phase of the A&R data reduction program. ar_range float 4 Uncorrected range to nadir (km) -- the "raw" measurement of range-to-surface, obtained from the pulse-compressed altimeter signals by the MGMTAC phase of the A&R data reduction program. ar_atmos float 4 Atmospheric correction to range (km) -- the correction applied to ar_radius to allow for the delay of signals passing through the atmosphere, calculated by the MGMOUT phase of the A&R data reduction program. ar_radius float 4 Derived Planetary Radius (km) -- the mean Venus radius for this radar footprint, obtained by subtracting (ar_range - ar_atmos) from the length of the ar_pos vector. ar_slope float 4 Derived RMS Surface Slope (deg) -- the root mean square meter-scale surface slope, averaged over the radar footprint, obtained by fitting the altimeter echo to a suite of theoretical templates derived from the Hagfors scattering model. ar_rho float 4 Derived Fresnel Reflectivity -- the bulk reflectivity of the surface material, averaged over the radar footprint, obtained by fitting the altimeter echo to a suite of theoretical templates derived from the Hagfors scattering model, but ignoring the effect of small-scale surface roughness. ar_rhocor float 4 Rho correction factor for Diffuse Scattering -- a factor that should be added to ar_rho (but only if AR_RHOC is set in ar_flag), to allow for the effect of small- scale surface roughness. ar_error float 3*4 Formal errors in Radius, Slope, Rho -- the 1-sigma statistical errors expected in the determination of ar_radius, ar_slope, and ar_rho, respectively. ar_correl float 6*4 Formal correlations in same -- the formal correlations between ar_radius and ar_slope, between ar_slope and ar_rho, and between ar_rho and ar_radius, respectively. As the profile fitting algorithm is non-linear, the correlations may not be symmetric. ar_drad float 4 Ephemeris Radius Correction (km) -- the correction applied to the length of the ar_pos vector by the post-fitting MGMORB phase of the A&R reduction program. ar_dlon float 4 Ephemeris Longitude Correction (deg. VBF85) -- the correction applied to the footprint longitude by the post-fitting MGMORB phase of the A&R reduction program. ar_dlat float 4 Ephemeris Latitude Correction (deg. VBF85) -- the correction applied to the footprint latitude by the post-fitting MGMORB phase of the A&R reduction program. ar_partl float 18*4 Partials of ar_lon, ar_lat, and ar_radius with respect to ar_pos and ar_vel -- the partial derivatives of the footprint coordinates with respect to changes in the S/C position and velocity. See Appendix B for a discussion of the definition and use of these numbers. ar_fit float 4 Non-range-sharpened "goodness of fit" -- a measure of the correlation between the observed profile ar_prof and the theoretical template ar_tmpl. ar_scale float 4 Scaling factors for ar_tmpl and ar_prof -- the conversion factor that multiplies the integer array elements of ar_tmpl and ar_prof to yield their physical values, expressed as equivalent radar cross-sections in units of km^2. ar_looks ulong 4 Number of non-range-sharpened looks -- the number of statistically independent measurements of echo profile that were summed to produce the profile ar_prof. ar_nprof0 ulong 4 The index of the element in ar_prof that corresponds to the first element in ar_tmpl. The indices start at zero. ar_prof uchar 302*1 Non-range-sharpened Echo Profile -- the power vs. time echo profile, at half-baud (0.21 microsecond) intervals, assembled from up to 16 frequency components, without shifting their time origins (see ar_rsprof, below). This profile yields the best estimate of the time dispersion of the echo, and hence of ar_slope and ar_rho. ar_tmpl uchar 50*1 Best non-range-sharp Model Template -- the theoretical echo profile, at half-baud (0.21 micsec) intervals, that best approximates the peak of the ar_prof array. The optimal fit is made by matching ar_tmpl[i] with ar_prof[i+ar_nprof0], i = 0,49. ar_rsfit float 4 Range-sharpened "goodness of fit" parameter -- a measure of the correlation between the observed profile ar_rsprof and the theoretical template ar_rstmpl. ar_rsscale float 4 Scaling factors for ar_rstmpl and ar_rsprof -- the conversion factor that multiplies the integer array elements ar_rstmpl and ar_rsprof to yield their physical values, expressed as specific radar cross-sections in units of km^2. ar_rslooks ulong 4 Number of equivalent looks -- the number of statistically independent measurements of echo profile that were summed to produce the range- sharpened profile ar_rsprof. ar_rsnprof0 ulong 4 The index of the element in ar_rsprof that corresponds to the first element in ar_rstmpl. The indices start at zero. ar_rsprof uchar 302*1 Range-sharpened Echo Profile -- the power vs. time echo profile, at half-baud (0.21 msec) intervals, assembled from up to 16 frequency components, each shifted in time so as to align their rising edges. ar_rstmpl uchar 50*1 Best range-sharpened Model Template -- the theoretical echo profile, at half-baud (0.21 micsec) intervals, that best approximates the peak of the ar_rsprof array. This profile yields the best estimate of the two-way echo time, and hence of ar_radius. The optimal fit is made by matching ar_rstmpl[i] with ar_rsprof[i+ar_rsnprof0], i = 0,49. ar_rhofact float 4 Multi-peak correction applied to ar_rho -- the raw ar_rho value has been multiplied by a factor (1+ar_rhofact) to allow for multi- peaked echoes. This field is unused in software version 1. ar_radius2 float 4 Radius from Threshold Detector (km) -- the planetary radius derived from threshold detection of the signal in ar_rsprof. This field is unused in software version 1. ar_sqi float 4 Signal Quality Indicator (dB) -- the ratio between the sum of the 10 range bins starting 10 bins after the threshold range bin and the sum of the 10 range bins starting 20 bins before the threshold bin. This field is not used in software version 1. In version 2, it is always recorded in IEEE-754 format, even when the remaining float fields are in VAX format. ar_thresh ulong 4 Threshold Detector Index -- the index in ar_rsprof at which the threshold detector has located the rising signal. This field is not used in software version 1. ar_spare long 7*4 Unused -- reserved for future data fields. 5.4. Radiometry Data File (RDF) Each RDF contains data from a single Magellan orbit. The file begins with the standard keyword label section and then a series of binary Radiometry Data Records, sandwiched between Start and End marker labels. Table 7 Radiometry Data File SFDU Structure +---+------------------------------------------------+--------------+ | T | CCSD1Z000001 | CCSD label | +---+------------------------------------------------+--------------+ | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | T | NJPL1K00KL00 | Keywd label | +---+---+--------------------------------------------+--------------+ | . | L | 00000xxx | length | +---+---+--------------------------------------------+--------------+ | . | . | PRODUCT_FILE_NAME=RDFnnnnn.v | | | . | . | PRODUCT_TYPE=RADIOMETRY_FILE | | | . | . | MISSION_ID=4 | | | . | . | SPACECRAFT_NAME=MAGELLAN | | | . | V | SPACECRAFT_ID=18 | | | . | A | MISSION_NAME=MAGELLAN | Keywords | | . | L | PROCESS_TIME=yyyy-mm-ddThh:mm:ss.fff | and | | . | U | ORBIT_NUMBER=nnnnn | Values | | . | E | HARDWARE_VERSION_ID=nn | | | . | . | SOFTWARE_VERSION_ID=nn | | | . | . | DATA_FORMAT_TYPE=VAX | | | . | . | UPLOAD_ID=cnnnnc | | | . | . | NAV_UNIQUE_ID="cccccccccc " | | +---+---+--------------------------------------------+--------------+ | . | T | CCSD1R000003 | Start marker | +---+---+--------------------------------------------+--------------+ | . | L | 000000xx | length | +---+---+--------------------------------------------+--------------+ | . | V | DELIMITER=SMARKER | Start value | | . | A | PRODUCT_NAME=RADIOMETRY_DATA_RECORD | | | . | L | TYPE=NJPL1I000177 | | +---+---+--------------------------------------------+--------------+ | | | | Radiometry Data Record SFDUs (rr_rec, see Table 8) | nx264 bytes | | | | +---+------------------------------------------------+--------------+ | T | CCSD1R000003 | End marker | +---+------------------------------------------------+--------------+ | L | 000000xx | length | +---+------------------------------------------------+--------------+ | V | DELIMITER=EMARKER | End value | | . | PRODUCT_NAME=RADIOMETRY_DATA_RECORD | | +---+------------------------------------------------+--------------+ CCSDS Label 'CCSD1Z000001', the CCSDS primary SFDU label. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the Radiometry Data File header. Keyword Label 'NJPL1K00KL00', the SFDU Catalog/Keyword label, where '1' indicates that an ASCII length field follows. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the keyword/value field, including two bytes per keyword/value pair for the (unillustrated) carriage return and line feed, and a possible trailing blank if required to make this length an even number. PRODUCT_FILE_NAME= 'RDFnnnnn.v', the external file name of this RDF. 'nnnn' is a 5-digit orbit number and 'v' is a decimal version number. For test RDF files, 'v' consists of the letter 'T' followed by a decimal version number. PRODUCT_TYPE= The character string 'RADIOMETRY_FILE'. MISSION_ID= The single character '4'. MISSION_NAME= The character string 'MAGELLAN'. SPACECRAFT_ID= For real data, the 2-digit number '18'. For simulated data, the number '28'. SPACECRAFT_NAME= The character string 'MAGELLAN'. PROCESS_TIME= The UTC time at which the Radiometry Data File was created by the MIT A&R processing system. ORBIT_NUMBER= A 5-digit number, denoting the Magellan orbit number of this Radiometry Data File. HARDWARE_VERSION_ID= A 2-digit number, 'nn', identifying the hardware version number of the MIT A&R data processing system used to create this file or volume. SOFTWARE_VERSION_ID= A 2-digit number, 'nn', identifying the software version number of the MIT A&R data processing system used to create this file or volume. DATA_FORMAT_TYPE= Either 'VAX' or 'IEEE', depending on the format in which binary fields are represented in the radiometry data records. For all CD-ROM ARCDR products, this will be 'VAX'. UPLOAD_ID= 6 characters 'ABBBBC', where 'A' is the mission phase, 'BBBB' is the upload number within each phase, and 'C' is a revision indicator in the range A-Z. NAV_UNIQUE_ID= A unique identification string given to this orbital solution by the Magellan navigation team. Start Marker 'CCSD1R000003', the SFDU Aggregate Marker label, indicating the start of a data aggregate of unspecified length. This aggregate consists of a varying number of Radiometry Data Record SFDU's (rr_rec), as shown in Table 8 below. Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the aggregate marker SFDU. DELIMITER= The character string 'SMARKER', indicating that this is the start of a data aggregate. PRODUCT_NAME= The character string 'RADIOMETRY_DATA_RECORD'. TYPE= The character string 'NJPL1I000177', where '0177' indicates that the data between the SMARKER and EMARKER labels comprise a registered SFDU aggregate, composed of a set of registered NJPL aggregates. Radiometry Data Record See Table 8 below. End Marker 'CCSD1R000003', the SFDU Aggregate Marker label, indicating the end of a data aggregate of unspecified length. This matches the above "Start Marker". Length Eight bytes, ASCII, with leading zeroes mandatory; the length of the remainder of the aggregate marker SFDU. DELIMITER= The character string 'EMARKER', indicating that this is the end of a data aggregate. PRODUCT_NAME= The character string 'RADIOMETRY_DATA_RECORD'. Table 8 Radiometry Data File Record Format ----+-----+--------+----------------+------------------------------------ Off | Len | Type | Field Name | rr_rec Description ----+-----+--------+----------------+------------------------------------ +0 | 20 | sfdu | rr_sfdu | SFDU header label and length 20 | 4 | long | rr_burst | Radar Burst Number (periapsis=0) 24 | 4 | ulong | rr_flag | Flag fields (see Table 5-9) 28 | 4 | ulong | rr_flag2 | Additional flag fields (unused) 32 | 8 | double | rr_scet | S/C Radiometry Epoch (SCET, TDB) 40 | 24 | double | rr_pos[3] | S/C Position Vector (km, J2000) 64 | 24 | double | rr_vel[3] | S/C Velocity Vector (km/sec, J2000) 88 | 4 | float | rr_lon | Footprint Longitude (deg, VBF85) 92 | 4 | float | rr_lat | Footprint Latitude (deg, VBF85) 96 | 4 | float | rr_xfoot | Along Track Rad Footprint Size (km) 100 | 4 | float | rr_yfoot | Cross Track Rad Footprint Size (km) 104 | 8 | float | rr_sfoot[2] | Footprint Diameters of rr_sar (km) 112 | 8 | float | rr_sar[2] | Average Backscatter Values (dB) 120 | 4 | float | rr_angle | Incidence Angle (deg) 124 | 4 | float | rr_bright | Brightness Temperature (K) 128 | 4 | float | rr_radius | Average Planetary Radius (km) 132 | 4 | float | rr_anttemp | System Temperature of Antenna (K) 136 | 4 | float | rr_skytemp | Assumed Sky Temperature (K) 140 | 4 | float | rr_rcvrtemp | System Temperature of Receiver (K) 144 | 4 | float | rr_surftemp | Physical Surface Temperature (K) 148 | 4 | float | rr_emiss | Surface Emissivity 152 | 72 | float | rr_partl[3][6] | Partials of rlon, lat, and radius 224 | 4 | float | rr_dedrad | Partial of rr_emiss wrt rr_radius 228 | 4 | float | rr_phystemp | Physical Surface Temperature (K) 232 | 4 | float | rr_antval | Radiometer Antenna Value 236 | 4 | float | rr_loadval | Radiometer Load Value 240 | 2 | uchar | rr_askip[2] | Altimeter Skip Factors 242 | 2 | uchar | rr_again[2] | Altimeter Gain Factors 244 | 4 | long | rr_acr | Altimeter Coarse Resolution 248 | 16 | long | rr_spare[4] | Unused 264 | | | | ----+-----+--------+----------------+------------------------------------ Field Name Type Size Description rr_sfdu sfdu 20 SFDU header label 'NJPL1I00018000000244'. The number '0180' is registered with the NJPL SFDU authority as the "MIT Radiometry Data Record Aggregate". rr_burst long 4 SAB Number -- the number assigned by MGMSAR to the burst header that contains the radiometer measurement referenced by this rr_rec. rr_flag ulong 4 Flag fields: Table 9 Radiometry Data Record Flag Values Name | Value | rr_flag field description --------+-------+-------------------------------------------------- RR_GEOC | 1 | Geometry values have been corrected for ephemeris | | errors (MGMORB phase). --------+-------+-------------------------------------------------- RR_RADC | 2 | rr_radius value has been corrected by altimeter | | radius values. Otherwise, its value is taken from | | the Magellan topography model. --------+-------+-------------------------------------------------- RR_NOS1 | 4 | rr_sar[0] value missing. --------+-------+-------------------------------------------------- RR_NOS2 | 8 | rr_sar[1] value missing. --------+-------+-------------------------------------------------- RR_BAD | 16 | The rr_rec fields rr_bright through rr_emiss | | should be ignored. --------+-------+-------------------------------------------------- RR_CAL | 32 | The spacecraft is operating in its "radiometric | | calibration" mode, in which the SAR boresight is | | pointed away from the planet. The rr_lat and | | rr_lon fields contain the boresight latitude and | | longitude in the inertial (J2000) coordinate | | system, not in VBF85. --------+-------+-------------------------------------------------- RR_NRAD | 64 | The rr_radius value could not be estimated from | | the topography model. --------+-------+-------------------------------------------------- RR_RAD2 | 32768 | This record was created under software version 2 | | or higher, in which data fields rr_dedrad through | | rr_acr are significant. --------+-------+-------------------------------------------------- rr_flag2 ulong 4 Additional flag fields (unused). rr_scet double 8 S/C Radiometry Epoch (SCET) -- the ephemeris time (seconds of TDB since J2000) at which the radiometry measurement was made. rr_pos double 3*8 S/C Position Vector (km, J2000) -- the S/C position at rr_scet, relative to the Venus center of mass, expressed in inertial coordinates. rr_vel double 3*8 S/C Velocity Vector (km/sec, J2000) -- the S/C velocity at rr_scet, relative to the Venus center of mass, expressed in inertial coordinates. rr_lon float 4 Footprint Longitude (deg, VBF85) -- the crust-fixed longitude, at rr_scet, of the intersection of the antenna boresight and the planetary surface (a sphere of radius rr_radius). If the RR_CAL flag is set in rr_flag (see Table 9), rr_lon is expressed in inertial (J2000) coordinates. rr_lat float 4 Footprint Latitude (deg, VBF85) -- the crust-fixed latitude, at rr_scet, of the intersection of the antenna boresight and the planetary surface (a sphere of radius rr_radius). If the RR_CAL flag is set in rr_flag (see Table 9), rr_lon is expressed in inertial (J2000) coordinates. rr_xfoot float 4 Along Track Radiometry Footprint Size (km) -- the along track dimension of the intersection of the SAR antenna (3dB one-way attenuation) cone with a sphere of radius rr_radius. rr_yfoot float 4 Cross Track Radiometry Footprint Size (km) -- the cross track dimension of the intersection of the SAR antenna (3dB one-way attenuation) cone with a sphere of radius rr_radius. rr_sfoot float 2*4 SAR Footprint Diameters (km) -- the approximate dimension of the surface areas represented by the pair of SAR backscatter values, rr_sar. rr_sar float 2*4 SAR Average Backscatter Values (dB) -- a pair of running averages of SAR image pixel values, rr_sar[0] taken from pixels lying westward of the antenna boresight, and rr_sar[1] taken from pixels lying to the east of it. rr_angle float 4 Incidence Angle (deg) -- the angle between the local vertical and the S/C direction, measured at the center of the radiometer footprint at rr_scet. rr_bright float 4 Brightness Temperature (K) -- the planet brightness temperature, derived from rr_anttemp after correcting for antenna efficiency and side-lobe gain. rr_radius float 4 Average Planetary Radius (km) -- the planetary radius of the radiometer footprint, used to compute rr_lon and rr_lat, and also rr_surftemp and atmospheric corrections to rr_emiss. rr_anttemp float 4 System Temperature of the SAR Antenna (K) -- the rr_rcvrtemp value compensated for cable noise and losses. rr_skytemp float 4 Sky Temperature (K) -- the temperature assumed for the dominant portion of "sky" reflected in the radiometer footprint, including atmospheric absorption and emission. rr_rcvrtemp float 4 System Temperature of the receiver input (K) -- the difference between rr_antval and rr_loadval, converted to equivalent noise temperature, and compensated for receiver gain and temperature. rr_surftemp float 4 Radiometric Emission Temperature (K) -- the emission temperature of the planetary surface covered by the radiometer footprint, derived by correcting rr_bright for atmospheric emission and absorption. rr_emiss float 4 Surface Emissivity -- defined by the following expression: rr_surftemp - rr_skytemp ------------------------ rr_phystemp - rr_skytemp rr_partl float 18*4 Partials of rr_lat, rr_lon, and rr_radius with respect to rr_pos and rr_vel. rr_dedrad float 4 Partial of rr_emiss with respect to rr_radius -- obtained by numerical differentiation. This may be used to correct the rr_emiss value when a more accurate value of rr_radius becomes available. rr_phystemp float 4 Physical Surface Temperature (K) -- the temperature of the atmosphere in contact with the surface at a radius of rr_radius. rr_antval float 4 Radiometer Antenna Value -- the raw radiometer reading when detecting a signal from the antenna, corrected for altimeter leakage. rr_loadval float 4 Radiometer Load Value -- the raw radiometer reading when detecting a signal from the load, corrected for altimeter leakage. rr_askip uchar 2 Altimeter Skip Factors -- the two skip factors taken from the SAB header during the bursts in which the antenna and load signals were measured. rr_again uchar 2 Altimeter Gain Factors -- the two gain factors taken from the SAB header during the bursts in which the antenna and load signals were measured. rr_acr long 4 Altimeter Coarse Resolution -- the coarse range index taken from the SAB header during the burst in which the antenna signal was measured. rr_spare long 4*4 Unused -- reserved for future data fields. 6. Recommended CD-ROM Drives and Driver Software VAX/VMS Drive: Digital Equipment Corporation (DEC) RRD40 or RRD50 Driver: DEC VFS CD-ROM driver V4.7 or V5.2 and up. Note: The driver software may be obtained from Jason Hyon at JPL. It is necessary to use this driver to access the XARs on the CD-ROM. VAX/Ultrix Drive: DEC RRD40 or RRD50 Driver: Supplied with Ultrix 3.1 Note: Internet users can obtain a copy of the "cdio" software package via anonymous ftp from the "space.mit.edu" server in the file named "src/cdio.shar". Contact Peter Ford for details (see below). IBM PC Drive: Toshiba, Hitachi, Sony, or compatible. Driver: Microsoft MSCDEX version 2.2. Note: The newest version of MSCDEX (released in February 1990) is generally available. Contact Jason Hyon for assistance in locating a copy. Apple Macintosh Drive: Apple CD SC (Sony) or Toshiba Driver: Apple CD-ROM driver Note: The Toshiba drive requires a separate driver, which may be obtained from Toshiba. Sun Micro (SunOS 4.0.x and earlier) Drive: Delta Microsystems SS-660 (Sony) Driver: Delta Microsystems driver or SUN CD-ROM Driver Note: For questions concerning this driver, contact Denis Down at Delta Microsystems, 415-449-6881. Sun Micro (SunOS 4.0.x and later) Drive: Sun Microsystems Driver: SunOS sr.o driver Note: A patch must be made to SunOS before the Sun driver can access any CD-ROM files containing Extended Attribute Records, e.g. most of the files on this disk. A copy of this patch is available to Internet users via anonymous ftp from the "space.mit.edu" server in the file named "src/SunOS.4.x.CD-ROM.patch". 7. Whom to Contact for Information For questions about how to read the CD-ROM: Jason J. Hyon MS 525-3610 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 818-306-6054 Electronic mail addresses: Internet: jjh345@mipl3.jpl.nasa.gov NASAmail: JHYON SPAN: MIPL3::JJH345 X.400: (ID:JHYON,PRMD:NASAMAIL,ADMD:TELEMAIL,C:USA) For questions concerning the MIT products and documentation: Peter G. Ford Center for Space Research Building 37-601 Massachusetts Institute of Technology Cambridge, MA 02139 617-253-6485 Electronic mail addresses: Internet: pgf@space.mit.edu NASAmail: PFORD SPAN: JPLPDS::PFORD X.400: (ID:PFORD,PRMD:NASAMAIL,ADMD:TELEMAIL,C:USA) NOTE: there exists a public domain software package called MGMDQE that displays ARCDR data files on Sun SPARCstations using the SunView interface. There are NO plans to port this code to the X Window system. Internet users can copy it via anonymous ftp from the "delcano.mit.edu" server [18.75.0.80] in the file named "mgmdqe.vvvv.sparc.tar.Z", where "vvvv" represents the latest version number. This file should be copied in BINARY mode. Users without Internet access should contact Peter Ford at the above address. 8. Cognizant Persons Mike Martin (JPL), Gail Woodward (JPL), Peter Ford (MIT), Robert Mehlman (UCLA), and Jason Hyon (JPL) designed the PDS labels and the tables. Florence Moss (JPL) and Jason Hyon developed the software to generate the PDS labels and tables. Raymond Arvidson and Gail Woodward created the catalog templates, with help from Pam Woncik (JPL), Mary Dale-Bannister (Washington University), and Susan Slavney (Washington University). The data and documentation were generated at MIT by Peter Ford, Gordon Pettengill, Fang Liu, and Joan Quigley from data supplied by the Magellan Project. Judy Mankin and Bob Canada at DADC designed the cover of this CD-ROM. This disk was produced by Jason Hyon.