DATA_SET_DESCRIPTION |
Data Set Overview : This data set contains raw spectra from Total Luminance Photometer on the LCROSS spacecraft. The TLP was active only during the final 25 minutes of the mission, including the time of the centaur impact. It sampled an ~10 deg full angle, circular field of view at 1000 Hz. This dataset consists of a single ascii table holding raw values from the instrument and a second table holding housekeeping data. The only target was Cabeus crater on the moon. Related Data Sets : TLP_CAL_DS holds an intermediate calibration product, described in TLP_CAL_DS.CAT in this directory. Parameters : Science ------- No instrument parameters vary within this dataset. The sample rate is uniformly 1000 Hz. Housekeeping ------------ Instrument temperature is reported in the metadata tables in the SEM_TEMPERATURE and DEM_TEMPERATURE columns in degrees Centigrade. These are the two spacecraft telemetry points closest to the TLP Sensor Electronics Module (SEM) and (Digital Electronics Module (DEM) respectively. TLP_CAL_DS also contains the temperature of the detector. That temperature is not listed in this dataset. Processing : TLP sensor readings were transmitted to the spacecraft in 0.1 second groups (100 values). Each group was inserted into telemetry uncompressed and downlinked. The ground system extracted these groups in oder and appended them to a single .CSV file. The LCROSS Make Archive program read this file and wrote two PDS-formatted table (.TAB) files, one each for the PREIMPACT and IMPACT data collection periods. Corresponding to each of these two files is a table (.TAB) file containing metadata. Data : The files in this dataset are PDS-formatted, ascii, two-column tables with detached label files. The first column contains the time in UTC, and the second column contains the raw data value from the TLP. The rows are in time order and generally 1 msec apart. Metadata is contained in PDS-formatted, ascii, multi-column tables, also with detached labels. Coordinate System : The metadata tables contain the NSP1 boresight vector in J2000 Geocentric Inertial frame. This is the reference boresight vector for the LCROSS payload and is approximately at the center of the TLP field of view. Software : The GSEOS Version used to generate these spectra is GSEOS 5.2.407 (Feb 25, 2008), Python 2.2.3 (#37, Nov 28, 2003, 04:20:20), Project Version 6.1.064. The LCROSS.py Python script used with GSEOS is Version Jun 11, 2008. The LCROSS Report Generator used on GSEOS created CCSDS.dat files is version 114. The version of Satellite Toolkit used to prepare geometric information for the labels is 8.1.3. The LCROSS Make Archive program used to assemble the PDS-formatted submission is dated 03/14/2010.
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CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : The confidence level is unspecified. Review : This LCROSS data set was reviewed internally by the LCROSS science team before delivery to PDS. This data set has passed a PDS peer review. Data Coverage and Quality : LCROSS downlink was oversubscribed at times during the preimpact and impact data collection periods, which impacted TLP telemetry somewhat. Here is a summary of the percentage of data captured by the instrument that was recieved on the ground over several intervals of interest: 1. 91% of the data overall (over 23 min, 46.141 sec). 2. 98% between impact - 1 minute and impact + 1 minute 3. 100% between impact - 5 sec and impact + 5 sec That is, there were no telemetry dropouts during the 10 second interval bracketing the centaur impact. The TLP suffered an electrical failure in its Sensor Electronics Module (SEM) at approximately 11:33:00 UTC, roughly 100 seconds after the centaur impact. The behaviou after that time is consisent with a short observed during ground testing. Limitations : Other than the quality comments, no limitations are noted. Data Compression : No data compression was used in the datapath from the detector to the formatted files ready for submission to the PDS.
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