=================================================== A BEGINNER'S GUIDE TO THE MARIE PDS ARCHIVE VOLUMES =================================================== This document provides information on how to use the MARIE archive volumes. Although this document is intended mainly for first-time users, it may be useful to more experienced data users as well. ============== WHERE TO BEGIN ============== To begin exploring the disk, insert the disk in a drive capable of reading a DVD. Most DVD drives should be able to read this disk. There are two main ways to start exploring the disk: 1. Open the file AAREADME.TXT. This file is in the root directory of the disk. AAREADME.TXT is an ASCII text file and can be opened with many different computer programs, including common word processors, text editors, and Web browsers. This file gives information on the nature, contents and structure of the disk, and on where things are located on the disk. 2. View the file AAREADME.HTM in a web browser. This file is in the root directory of the disk. It is an HTML file, and can be viewed in a web browser like a web page and used to browse the disk as if the disk were a website. If you do not know how to use a browser to open a file on a local disk, consult your browser's Help information. The AAREADME.HTM has the same information as AAREADME.TXT, along with links to other parts of the disk. ======================================== TWO NOTES ON THE TEXT FILES ON THIS DISK ======================================== 1. If you open an ASCII text file from this disk with a text editor, you may see a column of stray characters on one edge of the page. Usually the characters will look like ^M or ^J. These characters are just a side effect of the way that different computers and software programs handle line endings in ASCII files. Not all computers show them. 2. Each subdirectory on this disk contains a text file named INFO.TXT or some variant of INFO.TXT (such as DATAINFO.TXT). This is an ASCII text file which provides information about the contents of the directory. ======================================== WHAT'S IN THE ROOT DIRECTORY OF THE DVD? ======================================== Along with the files AAREADME.TXT and AAREADME.HTM, the root directory of this disk contains a text file named ERRATA.TXT. This describes known errors and irregularities in the data and the disk; you should read it before doing anything important with the data. The root directory of the DVD also contains the following directories: CATALOG - Contains high-level documents about the data set, instrument, spacecraft, mission, relevant literature, and relevant personnel. This directory does not contain catalogs of anything; the word "catalog" is just a PDS technical term. DATA - Contains the data, organized into subdirectories. DOCUMENT - Contains documents about the data set and the disk. EXTRAS - Contains files that are not indispensable for the use of the data, but that may be helpful to the user. GEOMETRY - Contains ephemeris and trajectory information about the spacecraft. INDEX - Contains listings of files on the disk. Used mostly by the PDS. The root directory also contains files VOLDESC.CAT and AAREADME.LBL, which are PDS files of little use to the beginning user. =================== WHERE ARE THE DATA? =================== The data files are under the top-level directory named DATA. You can find these files by exploring the contents of DATA, or by following the data links in AAREADME.HTM, which will take you to pages with links to the data. When you open the DATA directory, you will find three subdirectories named ANCIL, RAW_DATA, and REDUCED. The RAW_DATA directory houses the raw data files. The REDUCED directory houses the reduced (calibrated) data files. The ANCIL directory houses the ancillary (spacecraft engineering and housekeeping) data. These data come in four kinds: board temperatures, board powers, board voltages, and detector temperatures. ================================= WHAT'S IN THE RAW_DATA DIRECTORY? ================================= The RAW_DATA directory contains several subdirectories with names of the form yy_mmMMM, where yy is the two-digit year, mm is the two-digit month, and MMM is the month abbreviation. (Example: 01_04APR for April 2001 data. The month is named with both numbers and letters to make the data more searchable.) Each of these subdirectories contains files of the following kinds: Files with extension .DAT - These are the raw data files. They are in binary format, and hence cannot be read directly with text editors or browsers. There are two kinds of raw data files: event data (file names beginning with EVN), and count data (file names beginning with CNT). These file varieties are explained in the INFO.TXT file directly under RAW_DATA. Files with extension .LBL - These are PDS label files. They are ASCII text files that describe the data files in a form that is both human-readable and machine-readable. They have the same names as the raw data files, but with a different extension; hence there is one label file for each data file. The label files can be read with a text editor, or even with a web browser if the browser is set up to recognize files with extension LBL as text files. Format files (extension .FMT) - These are PDS format files. They are extensions of the label files, and contain label information that applies to many different data files. They are in ASCII format. Here is the naming convention for raw data files: EVN01117_02.DAT means: EVN = event file (would be CNT for a count file) 01 = year 2001 117 = day 117 of the year (where day 1 = Jan. 1) 02 = second file from that day DAT = binary data file Note that the "day of year" in the filename, and the month in the directory name, are NOT the day and month of the data in the file. They are the day and month at which the instrument team downloaded the file. (This is different from the time system used for reduced data files; see below.) ================================ WHAT'S IN THE REDUCED DIRECTORY? ================================ The REDUCED directory contains several subdirectories with names similar to the ones in the RAW_DATA directory. Each of these subdirectories contains files of the following kinds: Files with extension .TAB - These are the reduced data files. They are in ASCII text format, and hence can be read with text editors. They also can be read with a web browser, if the browser is set up to recognize files with extension TAB as text files. The .TAB files are explained in the INFO.TXT file directly under REDUCED. Files with extension .LBL - These are PDS label files. They are ASCII text files that describe the data files in a form that is both human-readable and machine-readable. They have the same names as the reduced data files, but with a different extension; hence there is one label file for each data file. The label files can be read with a text editor, or even with a web browser if the browser is set up to recognize files with extension LBL as text files. Format files (extension .FMT) - These are PDS format files. They are extensions of the label files, and contain label information that applies to many different data files. They are in ASCII format. Here is the naming convention for raw data files: EVN01117_0219.DAT means: EVN = event file (the only kind of reduced data file) 01 = year 2001 117 = day 117 of the year (where day 1 = Jan. 1) 02 = time 0219 (02 hr 19 min) in that day TAB = binary data file Note that the "day of year" in the filename, and the month in the directory name, are the day and month at which the file's data records begin. (This is different from the time designations used for raw data files; see above.) ============================== WHAT'S IN THE ANCIL DIRECTORY? ============================== The ANCIL directory contains four subdirectories, which house the four types of ancillary data: board temperatures, board powers, board voltages, and detector temperatures. The names of these four subdirectories are self-explanatory. Within each of the four top subdirectories, there are several further subdirectories, with names similar to those of the subdirectories of RAW_DATA and REDUCED. Each of these subdirectories contains files of the following kinds: Files with extension .TAB - These are the ancillary data files. They are in ASCII text format, and hence can be read with text editors. They also can be read with a web browser, if the browser is set up to recognize files with extension TAB as text files. The meaning of the .TAB files is explained in the INFO.TXT file directly under ANCIL. Files with extension .LBL - These are PDS label files. They are ASCII text files that describe the data files in a form that is both human-readable and machine-readable. They have the same names as the data files, but with a different extension; hence there is one label file for each data file. The label files can be read with a text editor, or even with a web browser if the browser is set up to recognize files with extension LBL as text files. Format files (extension .FMT) - These are PDS format files. They are extensions of the label files, and contain label information that applies to many different data files. They are in ASCII format. Here is the naming convention for raw data files: BRD01117_02.TAB means: BRD = board temperatures file (the four possibilities are: BRD - board temperatures, PWR - board powers, EXT - board voltages, DET - detector temperatures) 01 = year 2001 117 = day 117 of the year (where day 1 = Jan. 1) 02 = second data file from that day TAB = ASCII data file Note that the "day of year" in the filename, and the month in the directory name, are the day and month at which the data records in the file begin. (This is different from the time designations used for raw data files; see above.) =========================== WHERE IS THE DOCUMENTATION? =========================== The documentation on this disk (besides AAREADME.TXT and ERRATA.TXT) is mainly in two places: 1. The top-level directory CATALOG 2. The top-level directory DOCUMENT The files in the CATALOG directory are not catalogs of anything. They are documents, and can be very useful for understanding the data. Some documents under DOCUMENT exist in more than one format. Multiple versions of the same document have the same filename with different extensions. Files which contain the same document should be identical in content, except for features which cannot be represented in all of the formats. In each directory, the INFO.TXT file and the PDS label and format files (discussed elsewhere in this document) also provide some documentation for the disk contents. ================================ WHAT'S IN THE CATALOG DIRECTORY? ================================ When you open the CATALOG directory, you will find a file CATINFO.TXT, which describes the directory contents. All the other files in CATALOG have extension .CAT. These CAT files are ASCII documents that give high-level descriptions of the following things: The data sets (RAW_DATASET.CAT and CALIBRATED_DATASET.CAT) The MARIE instrument (INST.CAT) The Mars Odyssey mission (MISSION.CAT) The Mars Odyssey spacecraft (INSTHOST.CAT) MARIE-related personnel (PERSON.CAT) Relevant literature citations (REF.CAT) WARNING: Although you can read these .CAT files with a text editor, you may have problems if you double-click on them. Some computers use the file extension .CAT for other purposes having nothing to do with PDS data. If you can't open a .CAT file in your editor by double-clicking, then open your text editor first and use it to open the .CAT file. ================================= WHAT'S IN THE DOCUMENT DIRECTORY? ================================= When you open the DOCUMENT directory, you will find a file DOCINFO.TXT, which describes the directory contents. All the other files are documents about the data sets and the disk. Each document exists in several formats. Files with the same name but different extensions (for example: VOLSIS.DOC and VOLSIS.PDF) are the same document in different formats, and are identical in content, except that the pure ASCII version (.ASC) lacks illustrations and some other features. This redundancy is deliberate; it insures that users with a variety of different software programs can use the documents. File extensions used are: DOC (Word format), PDF (PDF format), HTM (HTML format), and ASC (pure ASCII format). There may also be files with extensions JPG, GIF or PNG. These are not independent files, but are illustrations that show up when the HTML documents are opened. Some users have found the document named VOLSIS to be particularly useful for understanding the disk. The VOLSIS document contains extensive information about the volume structure and contents. Except for VOLSIS (which is explained by the document's title page), the file names in the DOCUMENT directory should be self-explanatory. ================================= WHAT'S IN THE GEOMETRY DIRECTORY? ================================= The GEOMETRY directory contains information about the spacecraft trajectory, the MARIE instrument, and the physical properties of the planet Mars. Except for the trajectory, this information is in the form of SPICE kernel files, which are usable with the SPICE system of software maintained by the PDS Navigation and Ancillary Information Facility (NAIF). The file GEOMINFO.TXT in GEOMETRY explains this directory further. =============================== WHAT'S IN THE EXTRAS DIRECTORY? =============================== The EXTRAS directory contains materials that aren't strictly necessary for the use of the data, but that can be helpful. In addition to the document you are now reading, the EXTRAS directory contains most of the files that make up the HTML interface for the disk. EXTRAS also contains a version of the software used to convert raw to calibrated data. ============== ANY QUESTIONS? ============== For further information, please consult the documentation files discussed in this document. If you need to contact PDS for further information, or to report an error or make a comment on the disk, please follow the procedures in the "Errata" and "Contacts" sections of AAREADME.TXT.