NSSDCA ID: PSPG-00830
Availability: Archived at NSSDC, accessible from elsewhere
This description was generated automatically using input from the Planetary Data System.
Data Set Overview ================= This data set is used to study the mineralogic composition of iron-bearing phases in Martian rocks and soils. For a Moessbauer experiment on any target, MIMOS II stores in memory for return to the Earth the following information: (1) a PHA spectrum for each of the 5 detectors; (2) five Moessbauer spectra (one reference and four sample spectra) for each of the 13 temperature intervals for a total of 65 spectra; (3) reference and sample temperatures; and (4) engineering data (e.g., the error signal for the velocity transducer). The Moessbauer spectra are in counts per channel for 512 channels. In (2), the four sample Moessbauer spectra in each temperature interval can selected in a number of ways. For example, they can be the 14.4 keV spectrum from each of the four detectors or the sum of the 14.4 and 6.4 keV spectra for each of the four detectors. Alternatively, the four spectra can be 14.4 and 6.4 keV spectra, each summed over two detectors. The spectra can be analyzed individually or combined to produce higher quality spectra. Combining spectra from different temperature intervals will depend on how strongly the spectra depend on temperature. Processing ========== This SIS uses the Committee On Data Management And Computation (CODMAC) data level numbering system to describe the processing level of EDR data products. MB EDR data products are considered CODMAC Level 2 or Edited Data (equivalent to NASA level 0) products. The EDR data files are generated from Level 1 or Raw Data, which are the telemetry packets within the project specific Standard Formatted Data Unit (SFDU) record. The MB EDR data products will be generated by the MIPL (Multimission Image Processing Laboratory) at JPL under the OPGS using the telemetry processing software, mertelemproc. The EDR data products will be raw uncalibrated data reconstructed from telemetry data products generated by the SSW team and formatted according to this EDR SIS. Meta-data acquired from the telemetry data headers will be used to populate the PDS label. There will not be multiple versions of an MB EDR. If telemetry data is missing partial data sets will be created and the missing data will be filled with zeroes. The data will be reprocessed after all data are received and the original version will be overwritten. Data ==== A MB EDR data product consists of five contiguous blocks of binary data or a single block and a detached ASCII PDS label. Each data block is 32 Kbytes long for a total size of 160 Kbytes or 32 Kbytes. The five data blocks are a copy of the instrument's memory buffer. The EDR file contains Moessbauer spectra for a given target measured in thirteen temperature windows, along with temperature data, an energy spectrum, a drive error signal spectrum, copies of the instrument parameter block and logbook. In addition, the file contains ten compressed Moessbauer spectra stored in the EEPROM as backup in case the instrument loses power. The backup spectra are updated during data acquisition, approximately every 6 minutes. Data from the instrument's SRAM occupy the first four blocks in the Moessbauer EDR data product. It contains three copies of the instrument parameter block, a drive error signal, temperature data, an energy spectrum, and Moessbauer spectra from 13 temperature windows. Each copy of the instrument parameter block in the SRAM is 512 bytes long. The SRAM has three copies of the parameter block for a total of 1536 bytes. The drive error signal, which monitors the operation of the MB drive unit, has 512 channels with two bytes per channel. The drive error signal values are stored in LSB first order. The MB EDR file contains temperature data recorded by three sensors: one on the electronics board, one on the sensor head, and one on the reference sensor. Each temperature value is scaled and stored as a two byte integer in MSB first order. The file contains 256 temperature records. Within each record, the order of values is board sensor, sample sensor, and reference sensor. The following equations contain the conversion of the scaled temperatures into Kelvin: Board sensor = 273.2 + 25 + (scaled value * 1.638*2500/4096+608)/2 Sample sensor = (scaled value)/10 Reference sensor = (scaled value)/10 The energy spectrum, which monitors the operation of the detectors, contains 256 channels of data for each of 5 detectors. Each value is a three byte integer stored in LSB first order. The data are aggregated so that data for the first detector are followed by data for the second detector and so on. Moessbauer data collected during a measurement are divided into temperature windows defined by a selectable lookup table. Each Moessbauer temperature window consists of five spectra (one for each detector). One spectrum contains 512 channels with three bytes per channel stored in LSB first order. The first channel of each spectrum gives the measurement lifetime, where lifetime is the number of cycles that the MB drive unit has executed during the measurement. The collection of MB spectra can be described as a three-dimensional array with axes of temperature window, detector, and channel, with the channel axis varying the fastest. The fifth data block of the MB EDR data file contains a copy of the instrument FRAM and EEPROM memory, along with copies of one Moessbauer temperature window, the drive error signal, instrument parameter block, and temperature data. The FRAM consists of three copies of the instrument parameter block and the instrument logbook. The logbook has 256 records with eight bytes in each record. The structure of the logbook is described in the Moessbauer Spectrometer Information Interface Control Document. The EEPROM contains ten compressed MB spectra. The data are compressed by combining data from several temperature windows or from several detectors. Each compressed MB spectrum has 512 channels with three bytes per channel stored in LSB first order. Software ======== A reader program, called mb2asc, will be available for a variety of computer platforms to convert the MB EDR binary format data into ASCII format. This reader will be archived with the EDR data products. The ASCII format data can be imported into spread sheet and plotting programs. Media/Format ============ The data set will initially be delivered and kept online. Upon Mission completion, the Moessbauer EDRs will be delivered to PDS on DVD as part of the complete MER EDR data set.
These data are available on-line from the Planetary Data System (PDS) at:
http://pds-geosciences.wustl.edu/mer/mer2-m-mb-2-edr-ops-v1/mer2mb_0xxx/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation |
---|