NSSDCA ID: PSFP-00394
Availability: Archived at NSSDC, accessible from elsewhere
This description was generated automatically using input from the Planetary Data System.
Data Set Overview ================= The data set consists of uncalibrated observations, also known as EDRs. For all the EDR products there is a detached PDS label file that describes the contents of one data file. Each label file will have the same base name as the data file it is describing, with the extension .LBL to denote a label file. The label file defines the start time and end of the observation, product creation time, and the structure of the binary (or ASCII) tables. Each data product is identified within the PDS label by a STANDARD_DATA_PRODUCT_ID value, shown in parentheses in the table below. The EPS portion of the data archive currently consists of five EDR data products. The EPS instrument creates all of its different science data packets during one observation, but the packets are telemetered to the ground at different times. The different formats of these data packets do not lend themselves to standardization into one EDR file format. Therefore, different EDR formats have been developed, each of which captures one specific data grouping such as spectra or PHA data. A given EDR data file will contain all the observations obtained on same earth day. The following table shows the different EPS data products. Following is a description of each of the current EPS EDRs. A more complete description of each may be found in the EPPS EDR SIS document, located in the DOCUMENT directory of the document volume. Current EPS Data Products: EPS Pulse Height (EPS_PULSE_HEIGHT) Contains Pulse Height Analysis data in binary table format. The PHA EDR format was changed by FSW6 on 8/18/2008 There is no longer a priority level associated with the PHA EDRs since the PHA data product is generated from PHA data packets and the high, medium, and low priority packets were retired. EPS_High Resolution Spectra (EPS_HIRES_SPECTRA) High resolution (energy channels) ion and electron energy spectra. New FS W6 EDR introduced on 8/18/2008, replaces EPS_HI_SPECTRA. EPS_Low Resolution Spectra (EPS_LORES_SPECTRA) Low resolution (energy channel) ion and electron energy spectra and rate counters. New FSW6 EDR introduced on 8/18/2008, replaces EPS_MED_SPECTRA. EPS Summary Spectra (EPS_SUMMARY_SPECTRA) Contains a subset of rate counters and low resolution energy spectra. New FSW6 EDR introduced on 8/18/2008 EPS Scan (EPS_SCAN_RATES) Contains the integrated hardware counters over four energy thresholds. Each threshold setting and integration lasts 1/4 second. New FSW6 EDR introduced on 8/18/2008 In addition to the science data, associated instrument parameters are included. EPPS Engineering and Status Data Product The EPPS_LONG_STATUS EDR data product contains the engineering and status information for the EPPS instrument. This data product consists of an external PDS label file and its pointer to an ASCII table file. The data product is in ASCII to facilitate the browsing of instrument status parameters with commonly available text readers during mission operations. New FSW5 EDR introduced on 9/6/2007 Previous Data Set Overview ========================== On 9/6/2007, version 5 of the EPPS flight software (FSW5) was uploaded to the MESSENGER spacecraft. FSW5 implemented several changes to the FIPS science telemetry. One significant change was the removal of FIPS housekeeping data stored in the FIPS High Priority Science Packet and its inclusion in the EPPS engineering and status data. Due to this change the EPPS_STATUS EDR has been replaced by the EPPS_LONG_STATUS as noted below. On 8/18/2008, version 6 of the EPPS flight software (FSW6) was uploaded to the MESSENGER spacecraft and installed on the EPPS instrument on 8/19/2008. FSW6 changed the packet formatting such that two EPS EDRs had to be retired and replaced by two new EDRs. Two additional EDRs had to be created to store data from two new instrument packets. Finally, the format for the EPS PHA EDR has been updated to support slight changes in the PHA data. Prior to these changes, the EPS portion of the data archive consisted of four EDR data products, which correspond to the different types of science data packets generated by the instrument at high priority, medium priority, and low priority. The EPS instrument created all of its different science data packets during one observation, but the packets were telemetered to the ground at different times based on priority. The different formats of the data packets did not lend themselves to standardization into one EDR file format. For example, the high priority science data packet contained the EPS high priority spectra, housekeeping information, and Pulse Height Analysis (PHA) data. Therefore, different EDR formats were developed, each of which captured one specific data grouping spectra, housekeeping information, or PHA data. Due to these changes the following EDR types have been retired in this version of the data set and will no longer be included in future archives: EPS_HI_SPECTRA, High Priority EPS Spectra (FSW6, 8/18/2008) EPS_HI_HOUSEKEEPING, High Priority Housekeeping (FSW6, 8/18/2008 EPS_MED_SPECTRA, Medium Priority EPS Spectra (FSW6, 8/18/2008) EPPS_STATUS, EPPS Engineering and Status () The following EDR types have changed in this version of the data set: EPS_PULSE_HEIGHT, EPS Pulse Height (FSW6, 8/18/2008) The following EDR types are new in this version of the data set: EPS_HIRES_SPECTRA, EPS High Resolution Spectra (FSW6, 8/18/2008) EPS_LORES_SPECTRA, EPS Low Resolution Spectra (FSW6, 8/18/2008) EPS_SUMMARY_SPECTRA, EPS Summary Spectra (FSW6, 8/18/2008) EPS_SCAN_RATES, EPS Scan (FSW6, 8/18/2008) EPPS_LONG_STATUS, EPPS Engineering and Status (FSW5, 9/6/2007) These changes are described in detail in the EPPS EDR SIS Document, Version 3A, contained in the DOCUMENT directory of the DOC_VOL. Instrument Overview =================== The EPS sensor consists of a 60-mm diameter, tuna-can-like cylinder, in which a start foil and stop foil, wrapped around opposite curved sides of the cylinder, constitute the TOF chamber. The detectors are arranged so that each detector senses the events within a given range of incidence angles. Each of the 6 detector modules is composed of 4 pixels: large and small ion and large and small electron. The FIPS consists of an electrostatic analyzer (ESA), located at the entrance to the sensor, a post-acceleration chamber between the output of the ESA and the carbon foil, and a time-of-flight telescope. The ESA at the entrance to the FIPS acts as a wide-angle lens for ions. It only allows ions with a specific energy/charge band to enter through its output plane. See the EPPSINST.CAT file for more information and [ANDREWSETAL2007] for full details. Calibration Overview ==================== This data set is NOT calibrated; it only provides the uncalibrated sensor measurements. Parameters ========== The principal parameters during normal science operations when observing with the EPPS are as follows: * EPS Medium-Priority Integration Interval (N2): This parameter sets the integration interval for medium-priority data (commonly 30 s). * EPS High-Priority Integration Interval (N1): This parameter sets the integration interval for high-priority data (commonly 300 s). N1 is an integer-multiple of N2. * EPS Detector Selection: EPS possesses 24 detectors: 12 for ions and 12 for electrons. Half are large-pixel, and half are small-pixel. Only 12 detectors can be used simultaneously, so the operational detectors can be set by command. * FIPS Mode Selection: This command allows selection of the mode of operation: normal, burst, and pick-up ion. The EPPS also includes modes for testing the instrument and maintenance activities. Data ==== The EPS EDR data set products are described as follows (the STANDARD_ DATA_PRODUCT_ID value is given in parentheses). The notes provided in brackets give the current status of the data product in version 2 of the data set. [RETIRED] The High Priority EPS Spectra EDR (EPS_HI_SPECTRA) contains spectral data, hardware and software rate counters in binary table format. Data and counter values are taken from the High Priority Science Packet. [RETIRED, FSW6, 8/18/2008] [RETIRED] The High Priority Housekeeping EDR (EPS_HI_HOUSEKEEPING) is an ASCII table file that contains 33 fields of housekeeping data. [RETIRED, FSW6, 8/18/2008] [RETIRED] The Medium Priority EPS Spectra EDR (EPS_MED_SPECTRA) contains contains spectral data, hardware and software rate counters in binary table format. Data and counter values are taken from the Medium Priority Science Packet. [RETIRED, FSW6, 8/18/2008] [NEW] The EPS High Resolution Spectra (EPS_HIRES_SPECTRA) contains high resolution (energy channels) ion and electron energy spectra. [NEW, FSW6, 8/18/2008] [NEW] EPS Low Resolution Spectra (EPS_LORES_SPECTRA) contains Low resolution (energy channel) ion and electron energy spectra and rate counters. [NEW, FSW6, 8/18/2008] [NEW] EPS Summary Spectra (EPS_SUMMARY_SPECTRA) contains a subset of rate counters and low resolution energy spectra. [NEW, FSW6, 8/18/2008] [NEW] EPS Scan (EPS_SCAN_RATES) contains the integrated hardware counters over four energy thresholds. Each threshold setting and integration lasts 1/4 second. [NEW, FSW6, 8/18/2008] [CHANGED] The EPS Pulse Height EDR (EPS_PULSE_HEIGHT) contains Pulse Height Analysis data in binary table format. The PHA data product is generated from the high, medium, or low priority science packet. The priority level will be identified within the PDS label. [CHANGED, FSW6, 8/18/2008) [CHANGED] The High Priority FIPS Spectra EDR (FIPS_HI_SPECTRA) contains spectral and velocity distribution, hardware and software rate counters in binary table format. Data and counter values are taken from the High Priority Science Packet. [CHANGED, FSW5, 9/6/2007] [RETIRED] The EPPS Status EDR contains engineering and status information for the EPPS instrument. The data product is in ASCII to facilitate the browsing of instrument status parameters with commonly available text readers during mission operations. [RETIRED, FSW5, 9/6/2007] [NEW] The EPPS Engineering and Status EDR (EPPS_LONG_STATUS), contains engineering and status information for the EPPS instrument. The data product is in ASCII to facilitate the browsing of instrument status parameters with commonly available text readers during mission operations. [NEW, FSW5, 9/6/2007]
These data are available on-line from the Planetary Data System (PDS) at:
http://www.igpp.ucla.edu/public/pds/NSSDC/MESS-E_V_H_SW-EPPS-2-EPS-RAWDATA-V1.0/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. George Ho | General Contact | Applied Physics Laboratory | george.ho@jhuapl.edu |