Data Set Information
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| DATA_SET_NAME |
CH1-ORB MOON M3 4 L1B RADIANCE NEAR-IR SPECTRAL IMAGES V3.0
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| DATA_SET_ID |
CH1-ORB-L-M3-4-L1B-RADIANCE-V3.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : This volume contains the Level 1B (L1B) Archive, a collection of radiometrically-calibrated and pixel-located data products acquired during from November 2008 through August 2009 by the Moon Mineralogy Mapper (M3) instrument during the Chandrayaan-1 mission to the Moon.The data were acquired while the instrument was operated in global or targeted mode. The documentation in the DOCUMENT directory provides detailed information about the data files and their format and content. A M3 Level 1B Data Product consists of pixel-located, resampled, calibrated data in units of spectral radiance that make up one observation tagged by a unique file name. The data in one Level 1B Product represent a consistent instrument configuration (frame rate, pixel binning). There is a single multiple-band image (BIN; suffix *_RDN.IMG) stored in one file with a detached PDS label (ASCII; suffix *_L1B.LBL), and a detatched header file (ASCII; suffix *_RDN.HDR), plus several files containing data related to pixel location (BIN; suffix *_LOC.IMG), observation geometry (BIN; suffix *_OBS.IMG), and UTC timing for each image line (ASCII; suffix *_TIM.TAB). As of Septemer 2011, we have developed a detector-temperature-driven empirical gain adjustment to the M3 Level 1B data. We refer to this correction as the SSC_ADJ correction and it is based on a family of spectral gain curves that are applied to each Level 1B radiance cube after its nominal radiometric calibration. Based on the detector temperature for each scene, a single curve is chosen from the family of temperature-based curves and each spectrum in the radiance cube is multiplied by this correction factor. This update should replace versions 1.0 and 2.0 of the M3 Level 1B data products. Processing : Level 1B processing involves the following operations: - converts the decompressed, uncalibrated image cube data into resampled, scaled, calibrated spectral radiance image cubes - calculates the surface location of all pixel centers - calculates the observation geometry and illumination on a pixel-by-pixel basis - calculates the UTC time for the middle of the integration period for each frame of the image data Data : Under the Data directory there is a separate subdirectory based on the start and end times of a 13-week imaging period. Each imaging period subdirectory is further divided into subdirectories for each month of an Optical Period (OP). Each OP month subdirectory is further divided based on the type of data product (e.g. Level 0 or Level 1B). YYYYMMDD_YYYYMMDD/YYYYMM/L1B directory: ---------------------------------- This directory contains the following files: *RDN.IMG -------- The L1B multiple-band spectral radiance image cube has dimensions of sample, line, and wavelength. The size and format of the M3 spectral radiance image cube depend on the observation mode (global/target). M3 calibration data such as wavelength centers, full-width half-max values and radiometric gain factors can be found in the CALIB directory of the archive volume. In target mode, the spectral radiance image cube has the following characteristics: 32-bit floating point Little endian 256 spectral channels 608 spatial samples N image lines Band interleaved by line In global mode, the spectral radiance image cube has the following characteristics: 32-bit floating point Little endian 85 spectral channels 304 spatial samples N image lines Band interleaved by line During the transmission and encoding/decoding of the data, some data elements may be lost. Data lost to poor compression or complete packet loss are noted in the *.LOG files located in the EXTRAS directory. All M3 L1B spectral radiance image cubes are standardized to remove the different effects of the four possible orbit limb and flight yaw mode combinations: descending/forward; descending/reverse; ascending/forward and ascending/reverse. In ascending limb data the lines/times are reversed, so all L1B spectral radiance image cubes have the northernmost image line first. In descending/reverse and ascending/forward modes the samples are reversed, so the first sample is on the west side of the image and do not appear left-right mirrored. In descending/forward no changes in lines or samples are performed; this is the only case that matches the Level 0 data. Refer to the ORBIT_LIMB_DIRECTION and SPACECRAFT_YAW_DIRECTION keywords in the PDS label (*_L1B_LBL) to reconcile a specific Level 1B spectral radiance image cube with the associated Level 0 data. Due to the successive loss of the two star trackers the data become progressively more difficult to model. Hence our models increase in complexity and parameterization. For M3 we have been forced into development of three different spacecraft attitude models that describe the orientation of the Chandrayaan-1 spacecraft during an orbit. These models were developed sequentially as we processed data collected during the mission. A detailed description of each model and the keywords associated with each model are provided in the M3 Data Product SIS. *RDN.IMG.HDR ------------ Each L1B spectral radiance image cube file will be accompanied by a detached ASCII header file. A detached header provides compatibility with ENVI software. *L1B.LBL -------- A spectral radiance image cube label (*_L1B.LBL) is detached and points to the following L1B data products: - the single multi-band image (*_RDN.IMG) and its respective detached header file (*_RDN.HDR), - the pixel location data (*_LOC.IMG) and its respective detached header file (*_LOC.HDR), - the observation geometry data (*_obs.img) and its respective detached header file (*_OBS.HDR), - the UTC timing data (*_TIM.TAB) *LOC.IMG -------- The pixel location data for each image are stored in a three-band, band- interleaved-by-line, binary file of double precision 8-byte values, in little-endian byte order. The three bands of the file, in order, are as follows: 1) longitude (reported in decimal degrees) 2) planetocentric latitude (reported in decimal degrees) 3) radius (reported in meters from the Moon center) There are no embedded headers or other data in the file. Each location file will be accompanied by a detached header file. A detached header provides compatibility with ENVI software. The location file is, in essence, a three-band set of 'detached backplanes' that match the sample and line spatial extent of the spectral radiance image cube data. No map correction or resampling is applied to the radiance image cube; the file only reports the surface locations of the unadjusted pixel centers. *LOC.HDR -------- Each location data file will be accompanied by a detached ASCII header file. A detached header provides compatibility with ENVI software. *OBS.IMG -------- The observation geometry data for each image are provided in a ten-band, band-interleaved-by-line, binary file of single precision 4-byte values, in little-endian byte order. The ten bands of the file, in order, are as follows: 1) to-sun azimuth angle (decimal degrees, clockwise from local north) 2) to-sun zenith angle (decimal degrees, zero at zenith) 3) to-sensor azimuth angle (decimal degrees, clockwise from local north) 4) to-sensor zenith angle (decimal degrees, zero at zenith) 5) observation phase angle (decimal degrees, in plane of to-sun and to-sensor rays) 6) to-sun path length (decimal au with scene mean subtracted and noted in PDS label) 7) to-sensor path length (decimal meters) 8) surface slope from DEM (decimal degrees, zero at horizontal) 9) surface aspect from DEM (decimal degrees, clockwise from local north) 10) local cosine i (unitless, cosine of angle between to-sun and local DEM facet normal vectors) Similar to the location data, these files are, in essence, ten-band set of 'detached backplanes' that match the sample and line spatial extent of the spectral radiance image cube data. No map correction or resampling is applied to the radiance image cube; the file only reports the observation parameters of the unadjusted pixel centers. *OBS.HDR -------- Each observation geometry data file will be accompanied by a detached header file. A detached header provides compatibility with ENVI software. *TIM.TAB -------- The timing file (*TIM.TAB) is an ASCII file with four columns of data. The first column lists the line number of the multiple-band spectral radiance image cube (*RDN.IMG). The second column lists the corresponding UTC time for the middle of the integration period for each spectral radiance image cube line or major frame of the data and is expressed as: YYYY-MM-DDTHH:MM:SS.SSSSSS. The third column lists Year reference of Decimal Day of Year (DDOY) as extracted from the earliest time of each spectral radiance image cube line expressed as: YYYY. The fourth column lists DDOY which represents the number of days elapsed since 00:00 UTC of January 1 of the year associated with the time stamp of the first image line. The DDOY format is as follows: DDD.dddddddddddd where DDD represents the integer number of days and dddddddddddd represent the fractional part of the day of year value. Note that the M3 Level 0 data products have two representations of image frame times captured in the 1280-byte image frame header: 1) a copy of the raw bytes of CH-1 and M3 binary clock tick data and 2) a nominal conversion of those raw clock ticks to a UTC time in an ASCII format. This nominal conversion is built on the assumed operation of the clocks in a wholly stable manner with fixed tick rates and no drift or unexpected rate issues. To achieve optimized timing for subsequent processing, the Level 1B code develops individual clock conversion models for each image of sufficient length. This per-image modeling accommodates any clock drift or rate changes and provides the best possible frame times for the Level 1B data products. As such, the ASCII UTC times in the Level 0 data products may differ from those in the Level 1B data products. The Level 0 data product times should be considered deprecated and are only approximate UTC frame times. The per-image optimized conversion used in the Level 1B processing yields the most accurate image frame times and these are the times reported in the timing file. File Naming Convention : The file naming convention for L1B data products is as follows. M3GYYYYMMDDTHHMMSS_VNN_PT.EXT Or M3TYYYYMMDDTHHMMSS_VNN_PT.EXT M3: The instrument. G or T: The imaging mode; G for global mode and T for target mode. YYYY: The year of the time stamp from the first image frame of the image cube. MM: The month of the time stamp from the first image frame of the image cube. DD: The day of the time stamp from the first frame of the image cube. T: A single character string that precedes the UTC time of the time stamp from the first frame of the image cube. HH: The hour in UTC of the time stamp from the first frame of the image cube. MM: The minute within the hour in UTC of the time stamp from the first frame of the image cube. SS: The second within the minute in UTC of the time stamp from the first frame of the image cube. VNN: The version number of the product. PT: The type of data product: L0 : Level 0 L1B : Level 1B RDN : Spectral Radiance data LOC : Pixel Location data OBS : Observation geometry data TIM : Observation timing data EXT: The file name extension: IMG : Image object HDR : Detached header file LBL : Detached label file TAB : ASCII text file All fields must occupy the allotted number of characters. Thus, if fewer digits are required to express a number than are allotted, the convention fills the unneeded spaces with leading zeroes. Coordinate Systems : The coordinate system used is the new 'Standardized Lunar Coordinate System for the Lunar Reconnaissance Orbiter' (LRO Working Group, 2007). This new lunar coordinate system is being adopted as an international standard and will greatly facilitate the direct integration of data from multiple missions and among international partners. The coordinate system is based on planetocentric coordinates in the Mean Earth/Polar Axis (ME) reference frame. The z-axis is the mean axis of rotation with the positive direction pointing north. The x-axis is the intersection of the Equator and Prime Meridian, as defined by the mean Earth direction. The y-axis completes the frame in a right-handed sense and points in the direction of +90 degrees longitude. Latitude ranges from +90 to -90 form the North Pole to the South Pole. Longitude will be reported as 0 to 360 degrees increasing to the East. Software : The M3 team uses the commercial software packages ENVI and IDL to display and analyze M3 data products. ENVI and IDL are distributed by ITT Visual Information Solutions and are available at http://www.ittvis.com/. In addition, PDS' NASAView Image Display Software can also be used for basic image viewing of M3 L1B data products: http://pds.nasa.gov/tools/nasa-view.shtml. Nevertheless, the data are in no way in any proprietary format. Instead they are arranged as simply and as openly as possible. The provision of both ENVI and PDS labels will guarantee the data will be readily accessible to the widest possible audience. Media/Format : The M3 archive will be made available online via Web and FTP servers. This will be the primary means of distribution. Therefore the archive will be organized as a set of virtual volumes, with each data set stored online as a single volume. As new data products are released they will be added to the volume's data directory, and the volume's index table will be updated accordingly. The size of the volume will not be limited by the capacity of the physical media on which it is stored; hence the term virtual volume. When it is necessary to transfer all or part of a data set to other media such as DVD for distribution or for offline storage, the virtual volume's contents will be written to the other media according to PDS policy, possibly dividing the contents among several physical volumes.
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| DATA_SET_RELEASE_DATE |
2011-10-21T00:00:00.000Z
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| START_TIME |
2008-11-18T10:26:04.000Z
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| STOP_TIME |
2009-08-16T04:58:33.000Z
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| MISSION_NAME |
CHANDRAYAAN-1
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| MISSION_START_DATE |
2008-10-22T12:00:00.000Z
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| MISSION_STOP_DATE |
2009-08-28T12:00:00.000Z
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| TARGET_NAME |
MOON
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| TARGET_TYPE |
SATELLITE
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| INSTRUMENT_HOST_ID |
CH1-ORB
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| INSTRUMENT_NAME |
MOON MINERALOGY MAPPER
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| INSTRUMENT_ID |
M3
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| INSTRUMENT_TYPE |
IMAGING SPECTROMETER
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| NODE_NAME |
Imaging
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : Confidence level information will be provided after more thorough analysis of the data. Review : Prior to creation of the final version of this archival data set, its keys elements including samples of data products, PDS labels and catalog files, and the Software Interface Specifications, were examined during a peer review held by PDS Imaging Node in January 2010. Data Coverage and Quality : The M3 image acquisition time will be divided into peak periods or Optical Periods (OP) when lighting is optimal for observation. The Optical Periods occur twice a year and are understood to have two central months of optimal illumination (solar beta angles -30 deg to +30 deg) with two optional two-week wing periods (solar beta angles +/-30 deg to +/-45 deg) on either side of the optimal 2 months (thus, one Optical Period equals 13 weeks). Each 13 week optical period is followed by a 13-week hiatus. The original instrument operations plan included the acquisition of the entire surface of the Moon in low-resolution Global Mode during the first Optical Period (OP1) while OP2, OP3, OP4 were reserved for high resolution Target Mode data acquisition. However, the mission was cut short, just before the halfway point, in August, 2009 when the spacecraft ceased operations. Despite the abbreviated mission and numerous technical and scientific challenges during the flight, M3 was able to cover more than 95% of the Moon in Global Mode. Only minimal high-resolution Target Mode images were acquired, as these were to be the focus of the second half of the mission. The technical challenges encountered during the mission have complicated the data processing and calibration. These challenges include thermal issues, loss of the spacecraft star trackers and a raising of the orbit from 100 km to 200 km on May 19, 2009. Details of these challenges are currently being documented and will be referenced and/or included in the delivery of the M3 PDS Archive Volume. Nonetheless, the data products released in the M3 PDS Archive Volume will contain optimal calibration and characterization. (NOTE: If these docs are included in the archive, put them in DOCUMENT directory, not EXTRAS.) M3 operations were sustained for two Optical Periods. (For more detailed information regarding the spacecraft operation schedule, please see the MISSION.CAT.) Please see the M3 Data Product SIS for more detail/information. Limitations : None.
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| CITATION_DESCRIPTION |
Lundeen, S., Chandrayaan-1 Moon Mineralogy Mapper Calibration Data Record, CH1-ORB-L-M3-4-L1B-RADIANCE-V3.0, NASA Planetary Data System, 2011.
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| ABSTRACT_TEXT |
This dataset contains pixel located, radiometrically-calibrated data collected by M3 instrument on Chandrayaan-1.
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| PRODUCER_FULL_NAME |
SARAH R. LUNDEEN
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| SEARCH/ACCESS DATA |
Imaging Node Online Volumes
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