PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 1996-12-23 NOTE = "N/A" END_OBJECT = TEXT END Magellan Bistatic Radar Raw Data Archive (MGN-V-RSS-1-BSR-V1.0) AAREADME.TXT 23 December 1996 R.A. Simpson Stanford University ============================================================================== INTRODUCTION ============================================================================== This compact disc contains archival raw and partially processed data acquired during bistatic radar observations of Venus. The experiments were carried out using the Magellan spacecraft and Earth-based receiving stations of the NASA Deep Space Network (DSN). The observations were designed to probe scattering behavior of the Venus surface using geometries that are impossible with spacecraft or Earth-based radar systems alone. For a report on early results, see Pettengill et al., Electrical properties of the Venus surface from bistatic radar observations, SCIENCE, 272, 1628-1631, 1996. Each disc in the volume set contains data from a limited number of bistatic radar observations. The following table lists the individual volumes (CDs) and their respective observation times. VOLUME_ID Start Date/Time End Date/Time DSS ORBITS --------- ------------------------- ------------------------- ----- --------- MG_2301 06 October 1993 13:24:14 06 October 1993 13:43:35 14 9331 06 October 1993 19:42:46 06 October 1993 21:33:20 43 9335-6 MG_2302 09 November 1993 09:17:32 09 November 1993 10:17:41 63 9846 MG_2303 09 November 1993 10:51:41 09 November 1993 11:31:08 63 9847 MG_2304 09 November 1993 11:31:09 09 November 1993 12:50:11 63 9847-8 MG_2305 09 November 1993 12:50:12 09 November 1993 13:27:02 63 9848 MG_2306 31 May 1994 11:31:38 31 May 1994 12:54:58 63 12955 MG_2307 31 May 1994 12:55:31 31 May 1994 14:35:53 63 12955-6 MG_2308 31 May 1994 15:25:10 31 May 1994 17:45:57 63 12957-8 MG_2309 05 June 1994 13:09:31 05 June 1994 15:13:08 63 13032-4 MG_2310 05 June 1994 15:13:09 05 June 1994 17:47:11 63 13034-5 MG_2311 05 June 1994 17:47:12 05 June 1994 20:00:23 63 13035-7 MG_2312 05 June 1994 20:37:11 05 June 1994 21:21:07 63 13037-8 05 June 1994 18:52:34 05 June 1994 20:52:09 14 13037 MG_2313 05 June 1994 20:55:54 06 June 1994 00:27:37 14 13037-40 Experiments conducted on 6 October 1993 and 31 May 1994 were in 'spotlight' mode, where a single target was illuminated at many different angles; targets were Gula Mons and Maxwell Montes, respectively. Experiments conducted on 9 November 1993 and 5 June 1994 were in the 'quasi-specular' mode; the ground track on 5 June was intended to pass very near (if not directly over) the spotlight target in Maxwell Montes, used six days earlier. ============================================================================== VOLUME SET INFORMATION ============================================================================== This disc is one of 13 which contain raw bistatic radar data from the Magellan Mission at Venus. Each archive volume has the structure illustrated in the diagram below. Not all directories or file types will be populated on every disc; for example, only some volumes contain Archival Tracking Data Files (TDF directory). In cases where the directory contains no files, the directory itself has been omitted from the CD-WO volume. The primary data type for these volumes is the DSN Original Data Record (ODR). ODR files are stored in the ODR directory; they are organized chronologically within the volume set with the earliest ODRs appearing on the first CD-WO volume. Archival Tracking Data Files (ATDFs or TDFs) are considered backup data to the ODR; they also appear chronologically on the volume set, synchronized with ODRs. Each ODR and TDF file appears only once in the volume set. Each ODR is accompanied by a number of ancillary files in the CALIB and GEOMETRY directories. Documentation is in the DOCUMENT directory. Ancillary and document files appear on every volume where they could be useful in analyzing the corresponding ODRs. TDFs also serve in an ancillary role; as noted above and because of their volume, TDFs are not repeated, however. A BROWSE directory appears on each volume. It contains PostScript plot files which summarize the contents of each ODR file. Each file is a set of three 'landscape' plots arranged for printing on a single 8-1/2 x 11 inch page. Each page includes a histogram of data samples, a plot of 60-second averaged power spectra, and a plot of 1-second averages of sample power versus time for each receiver channel recorded. In a small number of cases (when the ODR file was corrupted, as in 32791324.ODR) these nominal plotting parameters were modified. PostScript files were created using MATLAB 4.2c routines running under SunOS 4.1.3 on a SPARC-2 UNIX workstation. Individual plot files were combined using the utility 'psmulti', a PERL script written by D. Murray Laing. Filenames within the BROWSE directory have the form ydddhhmm.PSc where y is the least significant digit of the data acquisition year, ddd is the 3-digit day-of-year, hh is the 2-digit hour, and mm is the 2-digit minute. The suffix character 'c' denotes the receiver channel in the corresponding ydddhhmm.ODR raw sample file from which the plot data were derived; 'c' is a digit in the range 1-4. root | |- AAREADME.TXT |- ERRATA.TXT |- VOLDESC.CAT | |- CALIB | | | |- CALINFO.TXT Overview of directory | |- 018aaddd.LMC LMC log for DSN station aa on day ddd | |- HGA_DOC.ASC HGA antenna pattern description, | |- ... appendices, and figures | |- *.LBL Detached PDS labels | |- CATALOG | | | |- CATINFO.TXT Streamlined PDS templates | |- MISSION.CAT for mission, host, | |- INSTHOST.CAT instrument, references, | |- INST.CAT personnel, and data set. | |- REF.CAT | |- PERSON.CAT | |- DATASET.CAT | |- DOCUMENT | | | |- DOCINFO.TXT Overview of directory | |- DESC_AAA.LBL Experiment Description (label) | |- DESC_TXT.ASC Experiment Description (ASCII body) | |- DESC_FGn.EPS Figure n in Encapsulated PostScript | |- DESC_FGn.PS Figure n in PostScript Version 1 format | |- yydddAAA.LBL Experiment Report, date yy-ddd (label) | |- yydddXXX.ASC Experiment Report (ASCII part XXX) | |- yydddXXX.EPS Experiment Report (EPS part XXX) | |- yydddXXX.PS Experiment Report (PostScript part XXX) | |- FILELIST.TAB Table of file inter-relationships | |- LMC.TXT Link Monitor and Control file description | |- QTERNION.TXT Quaternion file description | |- MGBSRSIS.TXT SIS document for this data set | |- RSC11_11.TXT ODR SIS document | |- TK_FTP.TXT Ephemeris documentation | |- TK_DESCR.TXT | |- TK_INSTL.TXT | |- TRK_2_25.TXT TDF SIS document | |- *.LBL Detached PDS labels | |- GEOMETRY | | | |- GEOMINFO.TXT Overview of directory | |- MGNnnnnn.TSP Text format SPK file (ephemerides) | |- xxxxxxxx.XSP Transfer format SPK file (ephemerides) | |- KEPELEMS.TAB Magellan Keplerian orbital elements | |- yydddeee.QPC Quaternion file for days ddd to eee | |- *.LBL Detached PDS labels | |- INDEX | | | |- INDXINFO.TXT Overview of directory | |- INDEX.LBL Label to INDEX.TAB | |- INDEX.TAB List of data file contents, this volume | |- CUMINDEX.LBL Label to CUMINDEX.TAB | |- CUMINDEX.TAB List of data file contents, all volumes | |- ODR Data directory (ODR files) |- TDF Data directory (TDF files) | |- BROWSE | |- ydddhhmm.PS1 Summary plots in PostScript format |- ydddhhmm.PS2 |- ydddhhnn.PS1 |- ... ============================================================================== ERRATA ============================================================================== A cumulative list of errors and changes is maintained in the file ERRATA.TXT at the root level of each volume. ERRATA.TXT in higher numbered volumes (or higher version numbers) will have errors for earlier volumes. ============================================================================== DISC FORMAT ============================================================================== The disc is organized according to the PDS standard for "one data set, many volumes." This file (AAREADME.TXT), a PDS volume object definition (VOLDESC.CAT), and the listing of errors and changes (ERRATA.TXT) are included at the root level. The following directories of descriptive material are also at the root level: CALIB contains LMC logs and reports on measurement of high-gain antenna patterns. CATALOG contains descriptive files for cataloging each of the data types included in this disc. DOCUMENT contains a plain text Software Interface Specification (SIS) for each data type (if available), a text description of the goals and procedures, experimenter notes, and other documentation. GEOMETRY contains files giving ephemerides or orbital elements so that observing geometry can be reconstructed; contains quaternion coefficients and fixed values so that spacecraft attitude can be reconstructed. INDEX contains index information on each of the data files included in this disc; it also includes a cumulative index to all files in this volume set. BROWSE contains PostScript files which provide an overview of each ODR. The remaining directories at the root level (ODR and TDF) contain data files and detached PDS labels. ============================================================================== FILE FORMAT ============================================================================== All data files (ODRs and TDFs) on the disc are accompanied by detached PDS labels, which describe their contents. Ancillary files also have PDS labels, most of which are detached. PDS TEXT objects have attached labels. Detached labels have the same file name as the data file except that the label name has the suffix "LBL". Detached PDS labels for multi-file documents have distinctive file names ending with ".LBL". Detailed documentation on file structure is available for ODR and TDF file types in Software Interface Specifications in the DOCUMENT directory. For other file types, where no electronic version of the SIS was available, the PDS label provides a reference to a hard copy document. See the DESCRIPTION keyword in each PDS label. NB: A 32-byte label record at the beginning of each ODR tape (see Section D1 in RSC11_11.TXT, DOCUMENT directory) has been preserved in the PDS label for each ODR. It is NOT retained in the data file. This allows the user to treat the data file as having an integral number of fixed length records. Text files, including data files of ASCII text and all labels (*.LBL files) and tables (*.TAB files), are delimited with carriage-return (ASCII 13) line-feed (ASCII 10) pairs at the end of each line. Detached labels, catalog files (*.CAT files), and text files (*.TXT or *.ASC file names) have fixed length records of 80 bytes to facilitate their use as either fixed-length record files or as stream files with carriage-return line-feed delimiters. ============================================================================== SOFTWARE ============================================================================== Software for parsing 8- and 12-bit samples from ODR data records has been developed at several institutions to support NASA flight projects. Because parsing must be done at the bit level and the code is usually written for a narrow platform-specific application, no software has been included as part of this archival product. ============================================================================== RELATED PDS PRODUCTS ============================================================================== Planned for archive later are partially processed data from these experiments as described in the paper by Pettengill et al. (SCIENCE, 272, 1628-1631, 1996). Bistatic radar data acquired using the Clementine spacecraft while it was in lunar orbit have been archived with the Planetary Data System under DATA_SET_ID = "CLEM1-L-RSS-1-BSR-V1.0" VOLUME_SET_ID = USA_NASA_PDS_CL_20XX VOLUME_ID = {CL_2001, ... , CL_2013} The Clementine and Magellan bistatic radar data were obtained using essentially the same ground system; the only difference was a conversion of the Clementine S-band signal to the X-band IF amplification chain because the Clementine RF carrier frequency was too low for standard S-band downconversion. Magellan Venus radio occultation data were also acquired during 1991- 1994; they have been archived by PDS under DATA_SET_ID = "MGN-V-RSS-1-ROCC-V2.0" VOLUME_SET_ID = USA_NASA_PDS_MG_22xx VOLUME_ID = {MG_2201, ... , MG_2214} The radio occultation and bistatic radar data were acquired using essentially the same radio system. ============================================================================== ACKNOWLEDGMENTS ============================================================================== These data were collected under auspices of the Magellan Project during its extended mission. Among those deserving special thanks are Doug Griffith, David Okerson, Rob Lock, Dan Lyons, and Julie Webster of the Magellan Project; Gina Gonzalez, Sami Asmar, and Sal Abbate of the JPL Radio Science Support Team; and Jim Cavender and Bill Adams of Martin Marietta. Gordon Pettengill of the Massachusetts Institute of Technology was Principal Investigator for the experiment; G. Leonard Tyler of Stanford University and Donald B. Campbell of Cornell University advised. The archiving was supported by the Geosciences Node of the Planetary Data System. Assistance was provided by Ed Guinness of Washington University, Peter Ford of M.I.T., and Ron Joyner of the Jet Propulsion Laboratory. The overall design was based on an archival data set of Magellan radio occultation raw data. ============================================================================== DISCLAIMER ============================================================================== Although considerable care has gone into making this volume set, errors are both possible and likely. Users of the data are advised to exercise the same caution as they would when dealing with any other unknown data set. Reports of errors or difficulties would be appreciated. Please contact one of the persons listed below. ============================================================================== COGNIZANT PERSONNEL ============================================================================== The person most directly responsible for construction and release of this volume set is Dick Simpson, Experiment Engineer for the Mars Global Surveyor Radio Science Team and Radio Science Advisor to the Planetary Data System. Although many people contributed to the volume set, any faults in the product are his alone. The Team Leader for the Mars Global Surveyor Radio Science Team and Principal Investigator for this archiving activity is G. Leonard Tyler. The persons most directly involved with analysis of the data were Gordon Pettengill, Peter Ford, and Dick Simpson. Peter G. Ford Room 37-601 Massachusetts Institute of Technology Cambridge, MA 02139 Tel: 617-253-6485 FAX: 617-253-0861 pgf@space.mit.edu Gordon H. Pettengill Room 37-641 Massachusetts Institute of Technology Cambridge, MA 02139 Tel: 617-253-4281 FAX: 617-253-0861 ghp@space.mit.edu Richard A. Simpson Center for Radar Astronomy Durand Bldg - Room 232 Stanford University Stanford, CA 94305-9515 Tel: 415-723-3525 FAX: 415-723-9251 rsimpson@magellan.stanford.edu G. Leonard Tyler Center for Radar Astronomy Durand Bldg - Room 232 Stanford University Stanford, CA 94305-9515 Tel: 415-723-3535 FAX: 415-723-9251 len@nova.stanford.edu