PDS_VERSION_ID = PDS3
LABEL_REVISION_NOTE = "
2014;
2017-03-02, D. Kazden (PPI), removed ARCHIVE_STATUS keyword;
2021-05-03, D. Kazden (PPI), updated START/STOP_TIME;"
RECORD_TYPE = STREAM
OBJECT = DATA_SET
DATA_SET_ID = "MR9-M-RSS-5-ELEDENPROFILES-V1.0"
OBJECT = DATA_SET_INFORMATION
DATA_SET_NAME = "
MARINER 9 RSS DERIVED IONSPHERIC ELECTRON DENSITY PROFILES"
DATA_SET_COLLECTION_MEMBER_FLG = "N"
DATA_OBJECT_TYPE = TABLE
START_TIME = "1971-11-14"
STOP_TIME = "1972-06-25"
DATA_SET_RELEASE_DATE = 2015-10-15
PRODUCER_FULL_NAME = "PAUL WITHERS"
DETAILED_CATALOG_FLAG = "N"
DATA_SET_TERSE_DESC = "
Mariner 9 Radio Occultation Ionospheric Electron Density
Profiles, Version 1.0"
CITATION_DESC = "
P. Withers, S. Joy,
MARINER 9 RSS DERIVED IONSPHERIC ELECTRON DENSITY PROFILES,
MR9-M-RSS-5-ELEDENPROFILES-V1.0, NASA Planetary Data System,
2014."
ABSTRACT_DESC = "
This dataset contains 114 ionospheric electron density profiles
(EDS files) derived from Mariner 9 radio occultation data."
DATA_SET_DESC = "
Data Set Overview
==================
The Mariner 9 electron density profiles have been
published graphically in [KLIORE1972A], [KLIORE1972B],
[KLIOREETAL1973], [ZHANGETAL1990], and [KLIOREETAL1992].
They were archived as microfilmed data tables and images
at the National Space Science Data Center (NSSDC) as dataset
PSPA-00141, and this archive is described further at
http://nssdc.gsfc.nasa.gov/nmc/datasetDisplay.do?id=PSPA-00141.
We requested data tables and plots of ionospheric
properties as functions of radial distance for all
occultations for which ionospheric peak properties were
reported in [KLIOREETAL1972B] and [KLIOREETAL1973].
We assumed that the absence of reported peak properties
for a given occultation meant that no useful ionospheric
profile was delivered to the archive. This approach
primarily selected ingress occultations with solar zenith
angles less than 90 degrees, although a handful of the
selected occultations have solar zenith angles between
90 and 100 degrees. Neutral properties, although present
in the archive and available to other interested
researchers, were not deemed useful for our purposes.
We provided a list of selected orbits to the NSSDC and
subsequently received approximately 768 TIFF images of
microfilmed information. The information in these images
of data tables were processed using optical character
recognition software, incorrectly recognized digits (which
were legion) were manually corrected, and results were
stored as ASCII tables. Quality control for each occultation
was ensured by reproducing the accompanying electron
density-radial distance plot and any similar plots in prior
publications. This process generated an electron
density-radius profile labeled by its orbit number for each
available ingress occultation.
For productive scientific analysis, additional supporting
information is required. Tables in [KLIOREETAL1972B] and
[KLIOREETAL1973] report latitude, longitude, solar zenith
angle, peak electron density, peak radial distance, and
peak altitude for each occultation. We verified that the
peak electron densities and peak radial distances reported
by [KLIOREETAL1972B] and [KLIOREETAL1973] are consistent
with the recovered electron density profiles.
Martian geodesy has evolved significantly since the Mariner
era, so the published latitudes, longitudes, and peak
altitudes need careful consideration. Generally speaking,
pre-Mars Global Surveyor work tended to use areographic
latitudes and post-Mars Global Surveyor work has tended to
spherical planet, which leads to areocentric latitudes.
Since the difference between latitudes defined with these
two conventions is in any case always less than 1 degree,
we have interpreted the reported latitudes as modern-era
areocentric values [SMITHETAL2001]. Longitudes in
[KLIOREETAL1972B] and [KLIOREETAL1973] are west longitudes,
which were converted into east longitudes by subtracting
them from 360 degrees. Tracking the many different reference
areoids used over the past four decades to convert radial
distance to altitude is a major undertaking, which we
sidestepped by converting each occultation's list of
of radial distances into altitudes using the radius of the
MOLA areoid at the appropriate latitude and longitude
[SMITHETAL2001].
The end product is a set of 114 electron density profiles
as functions of radial distance and altitude, each
accompanied by orbit number, date, latitude, longitude,
solar zenith angle, radius of areoid, radial distance
to maximum electron density, altitude of maximum altitude
density, and maximum electron density. Electron density
uncertainties were neither archived nor discussed
extensively in publications from the Mariner 9 era, but
they can be estimated for each profile as the smallest
value in that profile.
78 profiles were acquired during the primary mission on
orbits 1-79 and 36 profiles were acquired during the
extended mission on orbits 352-450. In the primary mission,
profiles typically spanned 80 to 300 km with a vertical
resolution of 2 km and a lowest reported density
of 700 cm^-3. In the extended mission, profiles typically
spanned 80 to 240 km with a vertical resolution of 1 km
and a lowest reported density of 1200 cm^-3. Point-to-point
fluctuations in electron density are noticeably greater
in the profiles from the extended mission than in those of
the primary mission. The high gain antenna was not pointed
at Earth during extended mission occultations, which
reduced the signal-to-noise ratio of the experiments
[KLIOREETAL1973].
Parameters
==========
Each .TAB file in the ANC/ directory contains the following items.
Orbit number ORBIT NUMBER
Date of occultation, UTC DATE
Latitude of occultation, degrees north LATITUDE
Longitude of occultation, degrees east EAST_LONGITUDE
Solar zenith angle of occultation, deg SOLAR_ZENITH_ANGLE
Radius of areoid at LATITUDE and
EAST_LONGITUDE, km RADIUS_OF_AREOID
Radial distance to maximum electron
density, km R_NMAX
Altitude of maximum electron density, km Z_NMAX
Maximum electron density, number per
cubic centimeter NMAX
Each .TAB file in the EDS/ directory contains
the following items:
Radial distance, km RADIAL DISTANCE
Altitude, km ALTITUDE
Electron density, number per CC ELECTRON_DENSITY
The altitude is defined relative to an areoid produced by
the Mars Orbiter Laser Altimeter instrument on Mars Global
Surveyor [SMITHETAL2001].
Uncertainties in these parameters are not specified
precisely. Uncertainties in electron density can be
estimated for each profile as the smallest value
in that profile. In the primary mission, the typical
lowest reported density was 700 cm^-3, and in the
extended mission, the typical lowest reported
density was 1200 cm^-3.
Timing
======
Precise timing information is not readily available for
these profiles, although it could perhaps be provided by
a diligent investigation of the relevant SPICE kernels
(http://naif.jpl.nasa.gov/pub/naif/M9/kernels/).
We assigned dates to each occultation based on day of
year information written on the microfilmed tables.
Data Processing
===============
Data processing is described in the documents listed in
the REF.CAT file and references therein.
"
CONFIDENCE_LEVEL_NOTE = "
Data Coverage and Quality
=========================
Given the small number of available occultations, data
coverage is limited. No gaps have been identified in
individual profiles. Uncertainties in the ionospheric
electron densities are not known precisely, as discussed
above.
Limitations and Caveats
=======================
These data products come a spacecraft whose operations
ended over 40 years ago. Therefore the documentation and
other aspects of the dataset are not as complete as would
be expected for a current NASA mission. Nevertheless,
it is felt that archiving the dataset in its current state,
thereby preserving it for posterity, is better than risking
that it be lostirrevocably.
"
END_OBJECT = DATA_SET_INFORMATION
OBJECT = DATA_SET_TARGET
TARGET_NAME = MARS
END_OBJECT = DATA_SET_TARGET
OBJECT = DATA_SET_HOST
INSTRUMENT_HOST_ID = "MR9"
INSTRUMENT_ID = RSS
END_OBJECT = DATA_SET_HOST
OBJECT = DATA_SET_MISSION
MISSION_NAME = "MARINER 9"
END_OBJECT = DATA_SET_MISSION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "KLIOREETAL1972A"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "KLIOREETAL1972B"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "KLIOREETAL1973"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "KLIORE1992"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "ZHANGETAL1990"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
OBJECT = DATA_SET_REFERENCE_INFORMATION
REFERENCE_KEY_ID = "SMITHTAL2001"
END_OBJECT = DATA_SET_REFERENCE_INFORMATION
END_OBJECT = DATA_SET
END
|