PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "GCMS_TEAM, 2006-03-22" RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2006-06-20 NOTE = "HUYGENS GCMS ARCHIVE DATASET HP-SSA-GCMS-3-FCO/DESCENT-V1.0" END_OBJECT = TEXT END HUYGENS PROBE GAS CHROMATOGRAPH MASS SPECTROMETER ARCHIVE 1. Introduction This dataset contains Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) data products. The GCMS instrument also provides the analysis measurements for the Aerosol Collector Pyrolyzer (ACP) instrument and this dataset also contains ACP data products. The data products are included in subdirectories of the DATA directory located one level below the root. The subdirectories containing data from the operations of the GCMS instrument use the following name format: [yyyymmdd_abcdefg]: where yyyy indicates the year (when the GCMS produced the data), mm indicates the month, dd indicates the date and abcdefg indicates a 'descriptive' label. Documentation is included as part of the dataset to allow users to better understand the GCMS instrument's operation and its role in the Huygens Probe mission to Titan. This documentation is included in the DOCUMENT directory one level below the root. Additional information deemed useful to users of the dataset are included in the EXTRAS directory one level below the root. 2. Dataset (? Disk ?) Format Because these data and descriptive files are being submitted electronically, no special computer system is needed to access and use the files. All TABLE files are written in ASCII TEXT and use comma delimited fields. All file names conform to the PDS "27.3" requirements and use only capitol letters, numbers and the underscore (_) and period (.) symbols. 3. File Formats All tabular (data TABLE) files (DATA/yyyymmdd_abcdefg/GCMS_stuff_STGn.TAB) are formatted as ASCII TEXT files with COMMA DELIMITED fields (data columns.) All tabular files were created with embedded column labels as row 1 of the table. The column labels are character data and these are enclosed in double quotation marks ("). All tabular files are paired with a detached PDS LABEL file in the same directory or subdirectory that shares the same base file name: for example file information for GCMS_1US_STG2.TAB is in GCMS_1US_STG2.LBL. Every data record in all ASCII TEXT files is terminates using the ASCII character pair (carriage return - line feed) as the delimiter. The data files were extracted from a raw binary formatted data stream. The binary file available to us contained only the data for our GCMS instrument. The data is 'packaged' as it was delivered to the Huygens Probe telemetry system. An examination of the binary file reveals no particular ordering of the data: i.e., the 5 sources of GCMS mass scan data are seemingly and randomly mixed with at least 6 sources of GCMS instrument housekeeping data. Additionally, the sizes of the GCMS data records all vary and do not correspond to the size of the telemetry data packets. When the Huygens Mission was planned and as it was originally implemented, only systems such as a SUN workstation had the computational power and sophisticated software necessary to decode the binary data stream and convert it to something more useable. Near the end of the cruise phase of the mission the desktop PC computers became powerful enough and software became available so that we were able to develop alternate, backup, methods for data handling. This raw binary data is first processed to the 'Stage 1' level. Stage 1 data files contain 8-bit values ( 0 - 255). These Stage 1 values can then be processed to the level of 'Stage 2' data. Stage 2 files contain data that have been converted to meaningful values - counts per second, volts, amperes, bars, .... The final level of processing is to be 'Stage 3'. Stage 3 data has been fully processed, examined and scaled to correct for calibration effects, instrumental anomolies, etc.. At the time this document was created for the initial submission of the Stage 2 processed data (2006-March) no Stage 3 processing has yet been done. Document files (DOCUMENT/file_name.ASC) always exist in ASCII TEXT format and may also be present in other formats. As noted above, every record (line) is terminated using the character pair. No individual line of text in the TEXT document uses more than 80 characters. Again, every *.ASC file is paired with a detached PDS LABEL file (*.LBL) sharing the same base file name. Every flight instrument data directory contains one COMMA DELIMITED SPREADSHEET file named GCMS_TELEMETRY_STG1.CSV. These files are the data from the original telemetry binary packed files and are included for those users who wish to reprocess the data. The choice to use the SPREADSHEET format was made because this format yields a file about 1/4 the size of the 'standard' TABLE format file. Still, the SPREADSHEET file sizes vary from ~ 9 MB for the DESCENT data to ~22 MB for the Check-Out Scenario 1 tests to ~37 MB for the Check-Out Scenario 2 tests to a maximum size of ~93 MB for the pre-heating (Scenario 1) test. Again, a detached PDS LABEL file sharing the base file name exists containing additional information about the file. An EXTRAS directory is included with the dataset and contains subdirectories with files with information, textual and graphic, that may help the dataset users to better understand the GCMS instrument operation and the content of the processed data files. These files are in Portable Network Graphic (*.PNG) or Acrobat (*.PDF) format and detached label files using the same base file name are present in the same subdirectory. The 'system' for data (TABLE) files attempts to create a file name related to the data in the file. Stage 1 processed data files typically contain all of the data from a single source: i.e., an ion source or one type of housekeeping for one of the telemetry data channels. Stage 2 files can be these Stage 1 files processed to this next level of sophistication. Stage 2 files are also created such that they contain more limited subsets of the total data from a specific data source: i.e., the file will contain only that data obtained while the direct atmosphere sampling was done through Leak #1 or just the data obtained from the Rare Gas Sampling phase of the mission. File names will have one of the following forms: GCMS_%$&_STG#.TAB GCMS_%$&_stuff_STG2.TAB GCMS_HK_?_id_STG1.TAB GCMS_HK_id_STG2.TAB GCMS_ALL_?_STG1.TAB GCMS_SWEEPS_?_STG1.TAB GCMS_TOTALS_STG2.TAB GCMS_TELEMETRY_STG1.CSV where % identifies Ion Source Number (1 - 5) $ identifies Scan type (F = fractional, U = unitary) & identifies Ionizer energy (S = standard (70eV), A = alternate (25eV)) # identifies Stage of Data Processing (1 or 2 as of 2006-03-22) stuff identifies Additional information about the data in the file. ? identifies Telemetry Stream form which this data was extracted. id identifies Type of housekeeping data in the file. File Name Examples What Data is in the file. ------------------------------------------------------------------------------ GCMS_1FA_STG1.TAB Mass scan data from Ion Source 1, Fractional increment stepping, Alternate ion source energy processed to the Stage 1 level. GCMS_1US_STG2.TAB Mass scan data from Ion Source 1, Unitary increment stepping, Standard ion source energy and proc'd to the Stage 2 level. GCMS_1US_B3_STG2.TAB Mass scan data from Ion Source 1, Unitary stepping, Standard ionization energy, processed to the Stage 2 level and containing only the data from the time window when the GCMS was performing its 3rd residual background measurements. GCMS_1US_L3_RG_STG2.TAB Mass scan data from Ion Source 1, Unitary stepping, Standard ionization energy through Leak 3 path for the Rare Gas sample time window and proc'd to the Stage 2 level. GCMS_1US_L2_STG2.TAB Mass scan data from Ion Source 1, Unitary stepping, Standard ionization energy, proc'd to the Stage 2 level for the times when the GCMS was sampling through Leak #2. GCMS_2UA_STG2.TAB Mass scan data from Ion Source 2, Unitary stepping, Alternate ionization energy and processed to the Stage 2 level. GCMS_3US_S3_STG2.TAB Mass scan data from Ion Source 3 (GC Column #1), Unitary stepping, standard ionization energy for GC Sample #3 and processed to the Stage 2 level. GCMS_HK_A_IDLE_STG1.TAB Housekeeping Idle Packet data from only the 'A' telemetry stream processed to the Stage 1 level. GCMS_HK_B_TYPE2_STG1.TAB Housekeeping Type 2 data from only the 'B' telemetry stream processed to the Stage 1 level. GCMS_HK_TYPE2_STG2.TAB Housekeeping Type 2 data from both the 'A' and 'B' telemetry streams combined and time ordered and processed to the Stage 2 level. GCMS_ALL_A_STG1.TAB All 'A' telemetry data stream data processed to the Stage 1 level. GCMS_SWEEPS_B_STG1.TAB All 'B' telemetry data stream mass sweep data processed to the Stage 1 level. GCMS_TOTALS_STG2.TAB The 'total' ion counts data extracted from all of the mass scans, 'A' and 'B' stream, time ordered and processed to the Stage 2 level. GCMS_TELEMETRY_STG1.CSV The raw (binary) telemetry file for the GCMS instrument processed to the Stage 1 level and saved as a comma delimited SPREADSHEET file. 4. Archive Contents The files in this archive 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 | |- ERRATA.TXT Description of known anomalies and errors | present on this volume. | |- VOLDESC.CAT A description of the contents of this archive | volume in a format readable by both humans | and computers. | |- [CATALOG] A directory containing information about the | | Huygens GCMS Instrument dataset. | | | |- CATINFO.TXT PDS catalog objects. Mission, spacecraft and | | instrument descriptions. | | | |- DATASET.CAT PDS dataset catalog object. A description of | | the dataset, parameters, processing, data | | coverage and quality. | | | |- INSTRUMENT.CAT PDS dataset catalog object. A description of | | the GCMS instrument. | | | |- INSTRUMENT_HOST.CAT PDS dataset catalog object. A description of | | the Huygens Probe spacecraft. | | | |- MISSION.CAT PDS dataset catalog object. A description of | | the Huygens mission. | | | |- PERSONNEL.CAT PDS dataset catalog object. Information about | | those persons responsible for the GSFC | | GCMS instrument dataset. | | | |- REFERENCE.CAT PDS dataset catalog object. Information about | | available reference materials for the mission | | and the GCMS instrument. | | | |- SOFTWARE.CAT PDS dataset catalog object. A description of | | the software required to read/process this | | dataset. N/A! | | | |- TARGET.CAT PDS dataset catalog object. Information about | the target (Titan) of this mission. | | |- [DATA] A directory containing Huygens GCMS dataset | | files. | | | |- 19970506_DESCENT_BENCH Dataset from final instrument descent | | simulation operation on sealed (instrument | | residual background signal only) performed | | at GSFC 1997-05-06. | | | |- 19970802_MATED_CO1 Check-out test type 1 performed at KSC after | | the integration of the GCMS with the Huygens | | Probe spacecraft. | | | |- 19970805_MATED_CO2 Check-out test type 2 performed at KSC after | | the integration of the GCMS with the Huygens | | Probe spacecraft. | | | |- 19970910_PRECLOSE_CO1 Check-out test type 1 performed at KSC after | | the integration of the GCMS and before the | | Huygens Probe was closed for the final time. | | | |- 19970913_POSTCLOSE_CO2 Check-out test type 1 performed at KSC after | | the integration of the GCMS and after the | | Huygens Probe was closed for the final time. | | | |- 19970919_CONTINGENCY GCMS Contingency checkout procedure performed | | at KSC to evaluate this test just in case a | | problem occurred shortly after launch that | | necessitated the use of a pre-defined | | contingency sequence or sequences. | | | |- 19971023_F01 Dataset from 1st Huygens Probe test | | performed 1997-10-23 (Launch + 8 days.) | | This is a FCO2 (Flight Checkout Scenario 2) | | test. | | | |- 19980327_F02 Dataset from 2nd Huygens Probe test | | performed 1998-03-27 (Launch + 163 days.) | | This is a FCO1 (Flight Checkout Scenario 1) | | test. | | | |- 19981221_F03 Dataset from 3rd Huygens Probe test | | performed 1998-12-21 (Launch + 432 days.) | | This is a FCO2 test. | | | |- 19990915_F04 Dataset from 4th Huygens Probe test | | performed 1999-09-15 (Launch + 700 days.) | | This is a FCO1 test. | | | |- 20000202_F05 Dataset from 5th Huygens Probe test | | performed 2000-02-02 (Launch + 840 days.) | | This is a FCO2 test. | | | |- 20000728_F06 Dataset from 6th Huygens Probe test | | performed 2000-07-28 (Launch + 1017 days.) | | This is a FCO1 test. | | | |- 20010322_F07 Dataset from 7th Huygens Probe test | | performed 2001-03-22 (Launch + 1254 days.) | | This is a FCO2 test. | | | |- 20010919_F08 Dataset from 8th Huygens Probe test | | performed 2001-09-19 (Launch + 1435 days.) | | This is a FCO1 test. | | | |- 20020415_F09 Dataset from 9th Huygens Probe test | | performed 2002-04-15 (Launch + 1643 days.) | | This is a FCO2 test. | | | |- 20020916_F10 Dataset from 10th Huygens Probe test | | performed 2002-09-16 (Launch + 1797 days.) | | This is a FCO1 test. | | | |- 20030503_F11 Dataset from 11th Huygens Probe test | | performed 2003-05-03 (Launch + 2026 days.) | | This is a FCO2 test. | | | |- 20030918_F12 Dataset from 12th Huygens Probe test | | performed 2003-09-18 (Launch + 2164 days.) | | This is a FCO1 test. | | | |- 20031206_PATCHING Dataset from GCMS software patching work | | required to support the probe pre-heating | | mission scenario performed 2003-12-06. | | (Launch + 2243 days.) | | | |- 20031209_NO_PREHEATING Dataset from testing the no pre-heating | | scenario patch performed 2003-12-09. This | | is a type FCO1B test. (Launch + 2246 days.) | | | |- 20031213_PREHEATING Dataset from testing the pre-heating | | scenario patch performed 2003-12-13. This is | | a type FCO1B test and the dataset is large. | | (Launch + 2250 days.) | | | |- 20040320_F13 Dataset from 13th Huygens Probe test | | performed 2004-03-20 (Launch + 2348 days.) | | This is a FCO1B test. | | | |- 20040714_F14 Dataset from 14th Huygens Probe test | | performed 2004-07-14 (Launch + 2464 days.) | | This is a FCO2 test. | | | |- 20040914_F15 Dataset from 15th Huygens Probe test | | performed 2004-09-19 (Launch + 2526 days.) | | This is a FCO1B test. | | | |- 20040919_BAT_DEPSV1 Dataset from the first probe battery | | depassivation test. performed 2004-09-19 | | (Launch + 2531 days.) | | | |- 20041123_F16 Dataset from 16th Huygens Probe test | | performed 2004-11-23 (Launch + 2596 days.) | | This is a FCO1B test. | | | |- 20041205_BAT_DEPSV2 Dataset from the second probe battery | | depassivation test. performed 2004-12-05 | | (Launch + 2608 days.) | | | |- 20050114_DESCENT Dataset from the Huygens Probe DESCENT into | | the atmosphere of Saturn's moon Titan. | | performed 2005-01-14 (Launch + 2648 days.) | | | |- DTWG_MOLE_FRACTION Dataset created from the GCMS DESCENT data | and forwarded to the DTWG team for their use | while reconstructing the entry profile of | the Huygens Probe at Titan. | | | |- [DOCUMENT] A directory containing document files | | relating to this dataset. | | | |- DOCINFO.TXT Description of the files in the DOCUMENT | | directory. | | | |- HUYGENS_GCMS Directory containing the figures referred to | | in the text version of the GCMS papers in | | 'Space Science Reviews' (2002) and | | 'ESA SP-1177' (1997). | | HUYGENS_GCMS.ASC (SSR) | | HUYGENS_GCMS_SP1177.ASC (ESA SP-1177) | | | |- HUYGENS_GCMS_NATURE Directory containing the figures and table | | referred to in the text version of the | | 'Nature' report: HUYGENS_GCMS_NATURE.ASC | | | |- POSTLAUNCH_CALIBRATION Placeholder directory for reference | | information to be created during the post- | | entry GCMS Spare Unit characterization work | | to be completed in the labs at GSFC. | | | |- PRELAUNCH_CALIBRATION Directory with information from the pre- | launch GCMS instrument testing and | calibration work done at GSFC. | | |- [EXTRAS] A directory containing miscellaneous files | | providing optional additional information | | to dataset users. | | | |- EXTRAINFO.TXT Description of the files in the EXTRAS | | directory. | | | |- ANIMATED_GIF Directory containing animated GIF files | | depicting the valve and heater status and | | gas flow paths in the gas handling (inlet) | | system during the GCMS instrument's | | sampling sequence. | | | |- DATASET_RELATED Directory containing files showing samples | | of GCMS instrument data system counter | | overflow problem and of the structures of | | selected data TABLE files. | | | |- DOCUMENTS Directory with documents useful to users who | | desire to check (or understand) the | | tables of processed data. | | | |- FLIGHT_CHECKOUT Directory with the graphs of selected GCMS | instrument data created by the workstation | as it processed the telemetry and used after | each instrument operation to evaluate the | health status of the instrument. | | |- [INDEX] A directory containing index files relating | | to this dataset. | | | |- INDEXINFO.TXT 5. Recommended Hardware and Software Those wishing to use the data should check the NASA/PDS site, especially the Atmospheres Node of the NASA/PDS site, and the ESA/PSA site for the latest version(s) of the dataset file(s) of interest. NASA/PDS: http://pds.jpl.nasa.gov/ Atmospheres Node - NASA/PDS: http://atmos.nmsu.edu/atmos-home.html ESA/PSA: http://www.rssd.esa.int/index.php?project=PSA There are no known restrictions on the hardware and software necessary to read and manipulate the datasets in this archive. All of the data TABLE files use a comma delimiter between fields. Commercially available spreadsheet and scientific data plotting programs handle the data well. 6. Errata and Disclaimer 2006-06-13 - None documented at present. 7. Whom to Contact for Information For questions concerning the GCMS instrument: Dr. Hasso B. Niemann, PI Code 699 NASA/Goddard Space Flight Center Greenbelt, MD 20771 huygensgcms@listserv.gsfc.nasa.gov or Check the site: http://huygensgcms.gsfc.nasa.gov For questions concerning the use of the GCMS dataset: Dr. John Haberman, Code 699 NASA/Goddard Space Flight Center Greenbelt, MD 20771 huygensgcms@listserv.gsfc.nasa.gov Ms Jaime Demick-Montelara NASA/Goddard Space Flight Center Greenbelt, MD 20771 huygensgcms@listserv.gsfc.nasa.gov Mr. Eric Raaen NASA/Goddard Space Flight Center Greenbelt, MD 20771 huygensgcms@listserv.gsfc.nasa.gov or Check the site: http://huygensgcms.gsfc.nasa.gov For further information about the dataset and about the PDS please contact the Atmospheres Node of the Planetary Data System at the New Mexico State University in Las Cruces, NM. Lyle Huber lhuber@nmsu.edu For more information about the dataset and about the ESA Planetary Data Archive please contact the European Space Agency at the European Research and Technology Center (ESTEC), Noordwijk, The Netherlands. Olivier Witasse ESTEC/ESA owitasse@rssd.esa.int