This volume contains part of the original data from the MESSENGER Energetic
Particle and Plasma Spectrometer (EPPS) calibrated data volume set.
Note that the EPPS is made up of two instrument subsystems, the Fast Imaging
Plasma Spectrometer (FIPS), and the Energetic Particle Spectrometer (EPS).
This volume includes only the Fast Imaging Plasma Spectrometer (FIPS)
instrument data. Two data sets were delivered within the original data
volume, the FIPS and the EPS.
This volume is intended for the use of scientists and students in the
study of the of the planet Mercury. The data may be used for research
Known Issues In Data
Some of the EPS Data Types have unusual or unexpected values users
should be aware of:
- The Time of Flight segment of the instrument is no longer operational.
Early observations (2006) were made in a mode such that rates and fluxes
for all ION and Electron channels are all zero in the early files.
Only FAST and SHAPED rates are nonzero.
-The "Delta" values in SCAN mode data are often negative due to
low count rate statistics.
-Certain PHA events are excluded by default in standard instrument team
analysis as they are of indeterminate analytical value:
* Events for which the multi-hit flag is set.
* Events with a negative RAW Energy.
* Events with Maximum (= 4095) RAW Energy.
Users are advised to discard these events as well unless they have
strong reasons to do otherwise.
See the EPPS CDR SIS document for a more detailed explanation of these
The volume is organized into a hierarchical directory structure. It is
transferred from the MESSENGER SOC to the Planetary Plasma Interactions
Node via the TCP/IP File Transfer Protocol (FTP) and thus the physical
characteristics of the final storage media are unknown to the SOC.
All science data are located under the DATA directory. The INDEX
directory contains a listing of all of the data products included on
this volume. The CATALOG directory contains PDS
documentation describing the instrument and data set. These include:
MESS_EPPS_INST.CAT EPPS instrument description
MESS_EPPSFIPS_CDR_DS.CAT EPPS FIPS calibrated data set description
Additional information on volume organization is given in the CDR SIS
in the DOCUMENT directory.
The data files on this volume are provided in ASCII text format
(extension .TAB). Each data file is also accompanied by a detached PDS
label file (extension .LBL), an ASCII file containing information
describing the data file and data record format.
Catalog files (extension .CAT) are provided in ASCII format.
Document files describing the volume and the data are included in the
Text files and detached label files contain 80-byte fixed-length ASCII
records, with a carriage-return character (ASCII 13) in the 79th byte
and a line-feed character (ASCII 10) in the 80th byte. This format
allows the files to be read by MacOS, DOS, UNIX and VMS operating
systems. Note that while both label and catalog files are ASCII, some
operating systems will not recognize the .LBL and .CAT extensions as
ASCII types. It may be necessary to either remap these extensions as
ASCII in the system or text browser, or else to open the files from
within the text browser.
Directory Structure and Contents for EPPS CDR Data Archive Volume
The following illustration shows the directory structure overview for
the EPPS CDR Data Archive Volume. This volume contains the EPPS FIPS CDR data
products and any additional files required for the volume to be
compliant with PDS standards. The content of
the volume is expected to be updated with periodic releases according to
the schedule found in the MESSENGER Data Management and Archiving Plan
(DMAP). Revised CDRs (if needed) will also be delivered according to the
same schedule. Revised CDRs will have an incremented version number in
the PDS label.