PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 80 SPACECRAFT_NAME = MAGELLAN TARGET_NAME = VENUS OBJECT = TEXT PUBLICATION_DATE = 2014-07-29 NOTE = "Overview of MAGELLAN Radio Tracking Data Archive" END_OBJECT = TEXT END ARCHIVE OF MAGELLAN RADIO TRACKING DATA 1. Introduction This archive contains Archival Tracking Data Files (ATDFs) and Orbit Data Files (ODFs) acquired by the National Aeronautics and Space Administration's (NASA) Deep Space Network (DSN) using the MAGELLAN spacecraft, which was orbiting Venus. ATDFs are original data; the ODFs were reconstructed from Magellan NAVIO files. The archive contains documentation which describes the data products. The ATDF products in this archive are the 247 files released by the MAGELLAN Project, less four files which were found to be unsuitable during the archiving process. The original collection was assembled by Jim Alexopoulos at the Planetary Data System (PDS) Geosciences (GEO) Node in 1997; the archive was completed in 2014 by Dick Simpson at Stanford University. Coverage is from May 1989 (as MAGELLAN began its Earth to Venus cruise) to October 1994 (after MAGELLAN burned up in the Venus atmosphere). Each ATDF contains raw Doppler counts, angle measurements, and residuals, edited and in time-ordered sequence. They are the most primitive level of data suitable for a planetary gravity investigation. ODFs in the archive were reconstructed from NAVIO files and cover the time interval mid-1992 until the end of the MAGELLAN mission in 1994. NAVIO is an in-house format used at the Jet Propulsion Laboratory (JPL). ODFs are provided at both 2- and 10-second integrations in separate files, each covering approximately a calendar year (1992, 1993, and 1994). The ODF contains similar data to the ATDF but in an edited and compressed format which many navigators and scientists prefer. Additional information about the Magellan gravity experiment, including the acquisition, processing, and quality of the data, can be found in A.S. Konopliv and W.L. Sjogren, Venus Gravity Handbook, Jet Propulsion Laboratory (JPL) Document 96-2, 1996, and in A.S. Konopliv, W.B. Banerdt, and W.L. Sjogren, Venus Gravity: 180th Degree and Order Model, Icarus, 139, 3-18, 1999. A 120x120 gravity model, based on these data, is posted at http://pds-geosciences.wustl.edu/geo/mgn-v-rss-5-gravity-l2-v1/ mg_5201/gravity. A 180x180 model (with an attached PDS label) is also available at the same URL. 2. Archive Contents There are 243 ATDFs in this archive, located in the TDF directory. They cover the period from 4 May 1989 (as MAGELLAN began its cruise toward Venus) to 12 October 1994 (the day after the MAGELLAN 'termination experiment'). There are six ODFs in the ODF directory; each file covers approximately one year at either 2- or 10-second integration. The individual files and their coverage are listed in INDEX/INDEX.TAB. Also in the archive are the files DOCUMENT/TRK_2_25.TXT, which describes the ATDF format and content, and TRK_2_18.TXT, which describes the ODF format and content. DOCUMENT/ARCH_SIS.TXT provides an overview of the archival volume. ATDF_TUT.TXT gives an example of how to read the binary contents of an ATDF. Ancillary data in the AMD, ION, TRO, and WEA directories may be used to calibrate (respectively) angular momentum desaturation events, effects of Earth's ionosphere, effects of Earth's troposphere, and effects of weather conditions near the DSN stations. Documentation on each of these can be found in Software Interface Specifications (SISs) in the DOCUMENT directory in files SFFDR.LBL, TRK_2_23.TXT, and TRK_2_24.TXT. The CATALOG directory contains text files describing the MAGELLAN mission, the spacecraft and ground radio system (and other relevant subsystems), and the data set. CATALOG also contains contact information for people involved with the gravity investigation and this archive and a list of references used in CATALOG files. The diagram below illustrates the structure of the archival volume. root | |- AAREADME.TXT |- ERRATA.TXT |- VOLDESC.CAT | |- CATALOG | | | |- CATINFO.TXT PDS catalog files for mission, | |- MISSION.CAT host, instrument, references, | |- INSTHOST.CAT personnel, and data set | |- INST.CAT | |- REF.CAT | |- PERSON.CAT | `- DATASET.CAT | |- DOCUMENT | | | |- DOCINFO.TXT Overview of directory | |- ARCH_SIS.TXT Overview of archival volume | |- SFFDR.LBL Label and documentation for | |- SFFDR.ASC Magellan small forces files | |- SFFDR.PDF in ASCII, PDF, and Word | |- SFFDR.DOC formats | |- TRK_2_23.TXT Media Calibration SIS | |- TRK_2_24.TXT Weather SIS | |- TRK_2_25.TXT Description of ATDF format | |- TRK_2_18.TXT Description of ODF format | `- ATDF_TUT.TXT Tutorial on 'decoding' the | ATDF format (with examples) | |- INDEX | | | |- INDXINFO.TXT Overview of directory | |- INDEX.LBL Label to INDEX.TAB | `- INDEX.TAB List of data files | |- AMD Data directory (5 AMDs and labels) |- ION Data directory (56 IONs and labels) |- ODF Data directory (6 ODFs and labels) |- TDF Data directory (243 ATDFs and labels) |- TRO Data directory (44 TROs and labels) `- WEA Data directory (15 WEAs and labels) One ATDF was lost before 1997. Two corrupted files were not included in the archive, and two files were omitted because they appeared to be duplicates of other files. Coverage (YYYY/DDD) Reason for Omission from Archive ------------------- ---------------------------------- 1990/166-1990/193 Lost before GEO collection in 1997 1991/084-1991/112 Corrupted 1992/034-1992/050 Duplicate 1993/313-1993/313 Duplicate 1994/162-1994/164 Corrupted 3. Whom to Contact for Information For questions concerning this archive: Ray Arvidson Planetary Data System, Geosciences Node Manager Washington University Dept. of Earth and Planetary Sciences 1 Brookings Drive Campus Box 1169 St. Louis, MO 63130 1-314-935-5609 E-mail address: arvidson@wunder.wustl.edu Dick Simpson Planetary Data System, Radio Science Advisor Stanford University Packard Building - Room 332 (MC 9515) 350 Serra Mall Stanford, CA 94305-4020 1-650-723-3525 E-mail: radiosci@att.net For questions concerning the generation of ATDF products and general ATDF information: Gene L. Goltz Jet Propulsion Laboratory (230-225E) California Institute of Technology 4800 Oak Grove Drive Pasadena, CA 91109 1-818-393-1142 E-mail address: gene.l.goltz@jpl.nasa.gov For questions about the gravity investigation, use of data products, and derivation of gravity models: Alexander S. Konopliv Jet Propulsion Laboratory (301-144) California Institute of Technology 4800 Oak Grove Drive Pasadena, CA 91109 1-818-354-6105 E-mail address: alexander.s.konopliv@jpl.nasa.gov