Data Set Information
DATA_SET_NAME CLEM1-LUN/EAR/SKY-ASTAR/BSTAR/UVVIS/HRES/LWIR/NIR-2-EDR-V1.0
DATA_SET_ID CLEM1-L/E/Y-A/B/U/H/L/N-2-EDR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : The Clementine EDR (Engineering Data Record) Image Archive contains 88 CD-ROM volumes with more than 1.9 million images. Each volume contains approximately 3 lunar orbits but may vary in the number of orbits depending on the size of each orbit. The first volume in the set begins with orbit number 32--the start of the systematic lunar mapping phase of the mission. The image data products for the engineering checkout and operational rehearsal orbits (orbits 1-31), low Earth orbits, and earth phasing loop orbits are located on the last eight volumes at the end of the volume set. Table 1 shows the contents of the CD-ROM volume set. Table 1 - Volumes/Mission Phase ------------------------------- CL_0001 through CL_0036 - Lunar Mapping/Systematic Mapping Cycle 1 (orbits 32-164) CL_0037 through CL_0070 - Lunar Mapping/Systematic Mapping Cycle 2 (orbits 165-300) CL_0070 through CL_0081 - Lunar Mapping/Post-Systematic Mapping (orbits 301-348) CL_0081 through CL_0085 - Lunar Mapping/Engineering Checkout (orbits 1-30) CL_0085 - Low Earth Orbit CL_0086 through CL_0088 - Earth Phasing Loop A CL_0088 - Earth Phasing Loop B In addition to the image data, the CD-ROM volumes contain documentation, software, timeline data, and index files that support the collection. The 'aareadme.txt' file found in the root directory of each volume provides the user with overview information about the data volumes. The'document' directory contains detailed documentation about the CD-ROM contents, image file formats, software, and CD-ROM directory structure. The 'errata.txt' file found in the root directory of each volume provides the user with information about problems and anomalies encountered with the data set during the production of the CD-ROM volumes. Volume CL_0088, the last volume in the set, contains the most up-to-date software and documentation. The Clementine spacecraft imaged 100% of the lunar surface at resolutions that ranged from 100 meters/pixel at periselene (28 degrees south latitude for observations during the first month and 28 degrees north latitude for the second month) to 400 meters/pixel at the poles. Along the orbital track there is approximately 15% overlap in image coverage between adjacent images of the same spectral band. Across track overlap is approximately 10% at the equator and increases towards the poles. The primary scientific objective of the Clementine imaging observations was to provide data for lunar mineral mapping investigations. Imaging was acquired in 12 spectral bands from 415 to 8750 nm. Pole-to-Pole NAIDR observations with solar phase angles kept to less than 30 degrees at mid-latitudes were the predominant viewing conditions during the two month systematic mapping phase of the mission. Data : Each Clementine EDR data file consists of a single camera observation. The image data have been depacketized and reformatted with standard PDS labels but are otherwise raw. Raw data contain the geometric and radiometric characteristics of unprocessed and unrectified data. To make full use of the data, it is necessary to perform radiometric and geometric processing on the data products. The imaging sensors are framing cameras using charge couple device (CCD) technology. The Star tracker cameras (A-STAR and B-STAR) were principally used for spacecraft orientation. The UVVIS, HIRES, and NIR cameras have filter wheels that allow images to be acquired under six spectral filters. The LWIR camera has a single spectral filter. Table 2 shows the pixel dimensions of the images acquired by each camera and the center wavelength of each filter wheel position. Other than the image dimensions, the data products of each camera are identically formatted. Table 2 - Characteristics of each camera showing the dimension of an image in lines (rows) and samples (columns), the number of filter wheel positions, and the center wavelength of each filter. Camera/Lines/Samples/# of filt/filt.Wavelengths(Nanometers) ----------------------------------------------------------- UVVIS 288 384 6 415,750,900,950,1000,650(broadband) HIRES 288 384 6 415,560,650,750,650(broadband), opaque NIR 256 256 6 1100,1250,1500,2000,2600,2780 LWIR 128 128 1 8750 A-STAR 576 384 N/A (broad band, no filter wheel) B-STAR 576 384 N/A (broad band, no filter wheel) Data Compression ---------------- Data compression was done onboard using a compression chip provided by Centre National Etudes Spatiales (CNES). Onboard processing was performed on a completed image prior to storage on the solid state data recorder (SSDR) when the appropriate compression flag was set. The image data are stored on the CD-ROM volumes in the original compressed form as sent down by the spacecraft. In order to decompress an image, it is necessary to run the decompression software found on the CD-ROM volumes. The compression chip developed by MATRA under CNES specifications is used in two modes, which could be selected via a software uplink command. The first mode involved a discrete cosine transformation (DCT), (named Clem-JPEG-1), and optimized root mean square error for a nominal compression. The second (called Clem-JPEG-2) provided visual optimization at a fixed compression rate. In the first mode, blocks of 8x8 pixel 8-bit data are transformed to a best fit cosine series expansion in orthogonal row and column directions. This algorithm tends to preserve high frequency information with less data loss than does JPEG at the same compression ratio for the lunar data. Total signal from the 8x8 block is preserved exactly. The nominal amount of compression was set by limiting the scene error induced by compression to a fraction of the camera's temporal noises. Analysis of lunar images during the first part of the mission showed that the quantization matrix used by the chip was optimum for the imaging cameras. The HIRES camera was operated in a modified JPEG mode. The high frequency information in the HIRES scenes was spurious (it was caused by gain non-uniformity of the intensifier tube); eliminating high frequency content allowed higher compression without harming the information content of the scenes. The average compression rate for all images obtained during the mission was 5.5. Processing : Raw Clementine Images --------------------- The primary data archived is the collection of raw planetary images acquired by the Clementine mission. These data are pristine in the sense that they contain the artifacts and the radiometric and geometric characteristics of unprocessed and uncorrected data. The only processing performed on the data is to organize and format the data according to PDS standards. Requantization Matrices for Data Decompression ---------------------------------------------- The requantization matrix for the DCT compression algorithm is modified throughout the course of a mapping cycle as the viewing conditions and science requirements change. The requantization matrix used for an image is carried as part of the image object within a compressed image file. Browse Images ------------- A set of browse images is provided as part of the archive to facilitate rapid viewing of the image collection. Browse images can be used to visually search for areas of interest. If a browse image shows a potentially interesting scene, the image can be decompressed for more detailed inspection. Browse images are not in a compressed format, but they are reduced in size by averaging 8x8 pixel neighborhoods of the original image. The average is stored as a single pixel in the browse image. A browse image is stored in a secondary object in the image file. Histograms ---------- The histogram object is made up of a 256 element array with each element stored as a 32-bit unsigned integer. Each element in the histogram object contains the count of the number of pixels in the image array that corresponds to a specific density number (DN) value. The first element of the histogram is the number of pixels in the image array that have a DN value of 0. The second element contains the count of pixels with DN value 1, the sequence thus proceeding to the 256-th element which contains a count of the number of pixels with a DN value of 255. Inconsistencies may exist between the histogram statistics found in the image histogram object and the actual image that is decompressed on your computer platform. Subtle differences in the floating point hardware among computer platforms may cause the Density Number (DN) values of a resulting decompressed image to be occasionally different (within 1 DN) than the decompressed image used to generate the image histogram object. Ancillary Data and Information : Documentation ------------- Each volume contains detailed information about the organization and contents of the Clementine EDR CD-ROM volume set. The documentation for the collection is found in the 'document' directory. Although each volume contains a 'document' directory, use the documents found on the last volume (volume CL_0088) especially to obtain the most up-to-date version of the errata.txt file. Software -------- Each volume contains decompression software and simple image display programs for MAC, PCDOS or SUNOS platforms. Although each volume contains a 'software' directory, use the software found on the last volume (volume CL_0088) to obtain the most up-to-date version of the software. Image Index ----------- Each volume contains an image index file that describes the properties of each image found on the volume. The image index file is an ASCII formatted table where each row in the table corresponds to an image and each column corresponds to an image attribute. The attributes associated with an image include the center latitude and longitude, camera state at the time of the observation, spacecraft position, viewing angles, and photometric parameters. The image index file is located in the 'index' directory of each volume. For more information on the image index file, refer to the documentation found in this directory. An updated Image Index of the entire Clementine EDR volume set was generated by Clementine Mission Operations after completion of the volume set. The update contains refinements in the SPICE kernel data providing improvements in the viewing geometry information found in the table. Contact the PDS Imaging Node for the most up-to-date Image Index information. A CD-ROM volume may contain a table of missing images which lists planned image observations that are not available on the Clementine EDR volume set. An image is missing when (1) the planned observation was never acquired due to a spacecraft malfunction, (2) an interruption or error occurred during the telemetry transmission of data to Earth, or (3) data were lost due to problems in the ground processing system. Orbit Timeline -------------- Each volume contains a 'timeline' directory housing the timeline files for each orbit on the volume. The timeline data describes the planned and unplanned events that occurred during an orbit. The data, organized in chronological order, are formatted as Microsoft EXCEL (PC Version 5.0) spreadsheet files. Geometric Data -------------- The geometric data are an essential part of the archive; they contain the data and information to characterize the geometric properties of the imaging systems, and to fully describe the viewing geometry of a scene. These data are essential to geodetic, cartographic, and photometric applications. The geometric data are provided in NASA's SPICE kernel formats designed by the Navigational and Ancillary Information Facility (NAIF) at the Jet Propulsion Laboratory. SPICE is an acronym for Spacecraft, Planet, Instrument, C-matrix, and Event kernels. SPICE kernels evolve and improve as further analysis is done. Improvements could include correcting not-yet-discovered errors and filling in missing items. For the most up-to-date and accurate SPICE information available for the Clementine mission please contact the Planetary Data System NAIF Node. The geometric data found in the PDS data labels and image index files are based on the SPICE information available at the time of product creation. Although the geometric data found on the CD-ROM volumes are satisfactory for search and retrieval methods and locating images on the Lunar surface, they are not the most up-to-date data available and thus should not be used for precision data processing purposes. Data reviewers have reported confusion about several parameters that describe geometric information about the observations. The SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE, SPACECRAFT_ALTITUDE, and SUB_SPACECRAFT_AZIMUTH parameters, found in the image index file (IMGINDX.TAB) and the image file labels, are referenced with respect to the central body which the spacecraft is orbiting, not necessarily the target of the observation. During the lunar mapping phase of the mission, the central body is the Moon. Thus, if the target is the Earth, the above listed parameters are referenced with respect to the Moon and not Earth. Coordinate System ----------------- J2000 (also called EME2000) is the inertial reference system used to specify observational geometry. Latitude and longitude coordinates of target are planetocentric. For a complete description of the coordinate system used for the Clementine EDR data set, refer to [ACTON1996]. Media Format ------------ The disk has been formatted so that a variety of computer systems (e.g. IBM/PC compatible, Macintosh, Sun) may access the data. Specifically, it is formatted according to the ISO 9660 level 1 Interchange Standard. For further information, refer to the ISO 9660 Standard Document: Reference Number ISO 9660-1988, 15 April 1988. The extended attribute records (XAR) supported by the ISO are not used in this volume set. The lack of XARs on a file only affects the VAX/VMS user community. It will be necessary for VAX/VMS users to use the VMS CONVERT utility to convert document and text files before they can be satisfactorily accessed. VAX/VMS users can contact the PDS Imaging Node for support of the Clementine EDR archive.
DATA_SET_RELEASE_DATE 1995-01-01T00:00:00.000Z
START_TIME 1994-01-01T12:00:00.000Z
STOP_TIME 1994-01-01T12:00:00.000Z
MISSION_NAME DEEP SPACE PROGRAM SCIENCE EXPERIMENT
MISSION_START_DATE 1991-11-19T12:00:00.000Z
MISSION_STOP_DATE 1994-05-07T12:00:00.000Z
TARGET_NAME SKY
EARTH
MOON
TARGET_TYPE CALIBRATION
PLANET
SATELLITE
INSTRUMENT_HOST_ID CLEM1
INSTRUMENT_NAME A STAR TRACKER CAMERA
B STAR TRACKER CAMERA
LIDAR HIGH-RESOLUTION IMAGER
LONG WAVELENGTH INFRARED CAMERA
NEAR INFRARED CAMERA
ULTRAVIOLET/VISIBLE CAMERA
INSTRUMENT_ID A-STAR
B-STAR
HIRES
LWIR
NIR
UVVIS
INSTRUMENT_TYPE CAMERA
NODE_NAME Imaging
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Review/Validation Process ------------------------- Each CD-ROM volume went through a volume review and validation process. Although the volumes were carefully checked for errors and anomalies, problems with the data set not yet discovered may exist in the data collection. Please report any newly discovered problems to the PDS Imaging Node. Errors and anomalies found in the data collection are reported in the ERRATA.TXT file found in root directory of each volume. The ERRATA.TXT file found on the last volume (volume 88) contains a complete list of problems found in the volume set. Data Quality ------------ The DATA_QUALITY_NAME element provides a measure of the quality of an observation. For Clementine imaging data, DATA_QUALITY_NAME and DATA_QUALITY_ID are analogous. NOTE: The data quality indicators are only available through the on-line Clementine Navigator system and are not documented on the CD-ROM archive. The standard values for DATA_QUALITY_NAME are: NOMINAL IMAGE QUALITY (DATA_QUALITY_ID 1) The statistics of the image is sufficient for properly characterizing the brightness variations of a scene. Less than 5% of the image contains saturated values and the standard deviation of the density values of the image is greater than 4.0. UNDEREXPOSED OR DARK-SIDE IMAGE (DATA_QUALITY_ID 2) The integration time (exposure time) of the image is insufficient for properly characterizing the brightness variations of a scene or the image was acquired on the Dark Side of the Moon. The standard deviation of the density values of the image is less than 4.0. Images with data quality id 2 may not be suitable for proper characterization of the target. MODERATE IMAGE SATURATION (DATA_QUALITY_ID 3) The image contains a moderate amount of saturated data. The brightness variations within the brightest parts of an image can not be properly characterized. The image contains greater than 5% saturated data. The integration time (exposure time) of the image was too long for the brightest areas of the scene to be properly recorded. SEVERE IMAGE SATURATION (DATA_QUALITY_ID 4) The image contains greater than 25% saturated data. The integration time (exposure time) of the image was too long for the brightness of the scene. Additionally, it is possible that the operating mode of the camera was improperly set. EMPTY IMAGE (DATA_QUALITY_ID 5) The LIDAR HIRES camera was acquiring altimetry observations but no simultaneous image observation was made. The camera was intentionally programmed to not record imaging data. In order to operate the LIDAR ranging, the hardware of the HIRES camera needed to remain active even though no image data were acquired. Most of the LIDAR HIRES imaging data at the mid-latitudes have DATA_QUALITY_ID:5. The Clementine engineers were concerned that continued operation of the HIRES camera would cause deteriorating performance. With the intent of preserving the HIRES camera for the Geographos asteroid encounter, the imaging was 'turned off' for most of the mid-latitude lunar observations. The empty images are stored in the archive for the sake of preserving all data from the mission. Perhaps the only useful information in an 'empty' image is the measure of the camera dark current drift.
CITATION_DESCRIPTION Citation TBD
ABSTRACT_TEXT The Clementine EDR (Engineering Data Record) Image Archive contains 88 CD-ROM volumes with more than 1.9 million images. Each volume contains approximately 3 lunar orbits but may vary in the number of orbits depending on the size of each orbit. The first volume in the set begins with orbit number 32--the start of the systematic lunar mapping phase of the mission. The image data products for the engineering checkout and operational rehearsal orbits (orbits 1-31), low Earth orbits, and earth phasing loop orbits are located on the last eight volumes at the end of the volume set.
PRODUCER_FULL_NAME NAVAL RESEARCH LABORATORY
SEARCH/ACCESS DATA
  • Lunar Orbital Data Explorer
  • Imaging Planetary Image Atlas
  • Imaging Online Data Volumes
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