CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL RECORD_TYPE = STREAM OBJECT = TEXT NOTE = "Comments on Viking Orbiter image CD-ROMs." PRODUCT_CREATION_TIME = 1993-10-25 END_OBJECT END COMMENTS ON VIKING ORBITER IMAGE CD-ROMS This document is a cumulative summary of comments and errors concerning the Viking Orbiter images published so far on CD-ROMs. The comments are divided into three sections: comments about Viking Orbiter 1 volumes; comments about Viking Orbiter 2 volumes; and comments that apply to all volumes. I. Viking Orbiter 1 Volumes 1. Comments on volume VO_1001, version 1 1.1 Format of two files in the software directory The files DCMPRS.MAR and MACDCOMP.HQX are stored on this CD-ROM in a variable length record format instead of a stream file format. This problem is fixed on later CD-ROMs. Copies of these two files should be obtained from CD-ROM volumes other than volume VO_1001. 2. Comments on volume VO_1003, version 1 2.1 Image files with wrong image data The top portions of two images (IMAGE_IDs 216S17 and 217S21) contain data from the wrong image frame. This problem exists on copies of these images from both the EDR (Experiment Data Record) tapes and the Planetary Image Archive tapes and was probably generated when the EDR images were created. Since most of the image data are correct in these two images, they have been included on this CD-ROM without modification. An attempt will be made to recover the correct image data from the Master Data Record tapes. If the correct data are recovered, new versions of these two images will be included on a later CD-ROM. Note: New versions of these two images are included on volume VO_1009. 3. Comments on volume VO_1004, version 1 3.1 PDS high-level catalog information The Planetary Data System high-level catalog information about the Viking Orbiter image data sets has been revised. The catalog information is contained in the file CATALOG.LBL located in the LABEL directory. The entities that have been revised are the data set, software, and data set processing entities. The revisions were based on comments from a peer review of the information. The order of entities in the file has also been changed. The current order is descriptions of the Viking Mission, the Viking Orbiter spacecraft, the Viking Orbiter cameras, the compressed and browse image data sets, the software used to generate the data sets, and data set processing. 4. Comments on volume VO_1005, version 1 4.1 Image file with wrong image data The middle portion of image 353S01 contains data from the wrong image frame. This problem exists on copies of the image from both the EDR (Experiment Data Record) tapes and the Planetary Image Archive tapes and was probably generated when the EDR image was created. Since most of the image data are correct, the image has been included on this CD-ROM without modification. An attempt will be made to recover the correct image data from the Master Data Record tapes. If the correct data is recovered, a new version of the image will be included on a later CD-ROM. Note: A new version of this image is included on volume VO_1009. 5. Comments on volume VO_1008, version 1 5.1 Image file with wrong image data The middle portion of image 448S21 contains data from the wrong image frame. This problem exists on copies of the image from both the EDR (Experiment Data Record) tapes and the Planetary Image Archive tapes and was probably generated when the EDR image was created. Since most of the image data are correct, the image has been included on this CD-ROM without modification. An attempt will be made to recover the correct image data from the Master Data Record tapes. If the correct data are recovered, a new version of the image will be included on a later CD-ROM. 6. Comments on Volumes VO_1001 to VO_1008 6.1 ENGSUM.FMT and LINHDR.FMT files in LABEL directory Some minor errors were identified in these files. The errors were corrected starting with volume VO_1009. The corrections should not affect software using these files. Specifically, the value of the DESCRIPTION keyword was changed for the TRACK_PRESENCE_MASK column in each file. In addition, the DATA_TYPE value for the LAST_ERT column in the ENGSUM.FMT file was changed from BIT_STRING to VAX_INTEGER to be consistent with other similar columns described in the file. 6.2 CUMINDEX.LBL, IMGINDEX.LBL, and LOSTIMAG.LBL files in the INDEX directory There is a missing quotation mark at the end of the DESCRIPTION keyword value for the IMAGE_ID column in each of these label files. This occurs on all volumes from VO_1001 to VO_1008. The effect of the missing quotation is that software reading these files will not be able to parse the PDS label information. The problem has been corrected starting with volume VO_1009. 7. Comments on volume VO_1009, version 1 7.1 Introduction Volume VO_1009 contains a mix of image data, which makes its content somewhat different from the other volumes. This volume contains the remaining Viking Orbiter 1 Survey Mission images (orbits 1468 through 1485, along with images recovered from the Master Data Record tapes). The volume also has images acquired by both Viking Orbiters 1 and 2 during their approach to Mars (sometimes referred to as approach images). These images are denoted by a value for MISSION_PHASE_NAME of PRE_ORBITAL_SCIENCE. In addition, there are several images showing the U.S. bicentennial emblem and several images for which the purpose is unknown. These images will be discussed further in the notes below. 7.2 IMAGE_ID for the pre_orbital_science images The pre_orbital_science images used a different coding scheme from the other orbiter images. The first three characters represent the day of year in which the image was acquired. The fourth character is C, D, E, or F, where C and E are images acquired by Viking Orbiter 1, and D and F are images acquired by Viking Orbiter 2. The last two characters represent a sequence number. 7.3 Bicentennial emblem images There are 8 files in the directory [BC7XXX] that contain images of the U.S. bicentennial emblem acquired with 4 separate color filters. It is thought that these images were recorded by the cameras on Earth and then transmitted back to Earth during the cruise to Mars. They are included in this Viking Orbiter EDR image archive for completeness. 7.4 Other pre_orbital_science images There are 4 images with IMAGE_IDs of A00X01, B00X02, C00X03, and D00X03 that were found on the Planetary Image Archive tapes. From their IMAGE_NUMBER and EARTH_RECEIVED_TIME, they appear to be images acquired during cruise to Mars. No other information is available as to their purpose. They are included in this Viking Orbiter EDR image archive for completeness. 7.5 Label information for pre_orbital_science images The label information for the pre_orbital_science images has not been validated in the same way as for the other images. This is because information about these images does not exist in available catalogs and photographic products are not available for all the images. The label information for the pre_orbital_science images was derived mainly from the information on the Planetary Image Archive tapes. There are likely to be errors in this data. For example, it was found after processing the image 040C10 that its IMAGE_NUMBER was out of sequence from the images acquired before and after it. In this case, the anomalous value was left in the image label and index files. In other such cases, the anomalous values were changed to UNKNOWN. 7.6 Images in the [F029TXX] and [F040TXX] directories There are 4 images in each of these directories that were found on the Planetary Image Archive tapes. Based on their IMAGE_NUMBER and EARTH_RECEIVED_TIME, these images appear to have been acquired by Viking Orbiter 1 between the end of the Extended Mission and the beginning of the Survey Mission. No other information is available as to their purpose. They are included in this Viking Orbiter EDR image archive for completeness. 7.7 Replacement versions for images 216S17, 217S21, and 353S01 Versions of these 3 images found on the Planetary Image Archive tapes appear on other volumes. In each case, the Planetary Image Archive version is flawed in that a portion of the file contains data from a different image. New versions of these 3 images derived from the Master Data Record (MDR) tapes are included on VO_1009. Because of the difficulty in recovering data from the MDR tapes, some of the data may be missing. Thus, the user can decide which version is better to use. The file CUMINDEX.TAB has been updated to point to the version on volume VO_1009. For reference, the original version of images 216S17 and 217S21 can be found on volume VO_1003, and the original version of image 353S01 can be found on volume VO_1005. 7.8 CUMINDEX.TAB file Since volume VO_1009 was made out of sequence, the CUMINDEX.TAB file contains a cumulative index of images on the first 14 Viking Orbiter EDR image CD-ROM volumes. 8. Comments on volume VO_1011, version 1 8.1 Image files with wrong image data The top portion of image 039A29 and the middle portion of image 057A52 contain data from the wrong image frames. This problem exists on copies of the images from both the EDR (Experiment Data Record) tapes and the Planetary Image Archive tapes and was probably generated when the EDR images were created. Since most of the image data are correct, the images have been included on this CD-ROM without modification. An attempt will be made to recover the correct image data from the Master Data Record tapes. If the correct data are recovered, new versions of the images will be included on a later CD-ROM. 9. Comments on volume VO_1019, version 1 9.1 Replacement versions for images 039A29 and 057A52 Versions of these 2 images found on the Planetary Image Archive tapes appear on another volume. In each case, the Planetary Image Archive version is flawed in that a portion of the file contains data from a different image. New versions of these 2 images derived from the Master Data Record (MDR) tapes are included on VO_1019. Because of the difficulty in recovering data from the MDR tapes, some of the data may be missing. Thus, the user can decide which version is better to use. The file CUMINDEX.TAB has been updated to point to the versions on volume VO_1019. For reference, the original versions of these 2 images can be found on volume VO_1011. II. Viking Orbiter 2 Volumes 1. Comments on volume VO_1051, version 1 1.1 Images 004Y01 through 004Y06 There are 6 images located in the directory [F004YXX]. Based on their IMAGE_TIME, these images appear to have been acquired during orbit 4 of Viking Orbiter 2 and preceded the other images from that orbit. As a result, these images were given a value of PRIMARY_MISSION for MISSION_PHASE_NAME and a value of 4 for ORBIT_NUMBER. These images appear to be views of deep space. No other information is available as to their purpose. They are included in this Viking Orbiter EDR image archive for completeness. III. General Comments for all Volumes 1. Comments on VDCOMP running on VAX/VMS systems The program VDCOMP.C in the SOFTWARE directory cannot be used on a VAX/VMS system to read compressed image data directly from a CD-ROM. The program will work if the data file is transferred to magnetic disk. The image data can be read directly from the CD-ROM by using VAX/VMS FORTRAN input/output routines with the DEC VFS prototype CD-ROM driver. For more information, refer to the SOFTINFO.TXT file in the SOFTWARE directory on this CD-ROM.