This directory contains all of the metadata associated with this CD-ROM.
This information is divided into a series of separate template files. These
include the MISSION.CAT file that describes the Pioneer Venus mission,
INSTHOST.CAT that describes the Pioneer Venus Orbiter (PVO) and Multiprobe
spacecraft, the SEDR_DS.CAT file that describes the data set, and the
REF.CAT file that describes the references cited on this volume. The SEDR
is anclillary data and there is no associated instrument (no INST.CAT file).
These files are primarily for use in the PDS Data Set Catalog
(http://pds.jpl.nasa.gov/catalog.html) and some of the information
contained here may be found elsewhere on the CD-ROM.
The following table describes the contents of the catalog templates
contained in this directory.
file contents
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MISSION.CAT Mission template for the Pioneer Venus mission
INSTHOST.CAT Instrument Host (Spacecraft) template for PVO and Probes
SEDR_DS.CAT SEDR data set description
REF.CAT Reference catalog
SOFTWARE.CAT Software catalog
---------------------------------------------------------------------------
The PDS no longer catalogs coordinate system information. The following
text, found elsewhere on this disk, in a file called COORDSYS.TXT, was
extracted from the old PDS coordinate system catalog:
PVO Spinning Spacecraft coordinates (PVO_SSCC):
Spacecraft coordinates (Xs, Ys, Zs) are used to describe the
physical mounting locations of the Sun sensors, the star sensor,
and the experiment sensors. The spacecraft coordinate system is
centered at the spacecraft center of mass and rotates with the
spacecraft. The Xs-Ys plane is parallel to the plane of the
spacecraft equipment shelf. The positive Zs axis points out the
top of the spacecraft. The positive Ys axis coincides with the
split line of the equipment shelf. With no spacecraft wobble or
nutation, the spacecraft positive Zs axis will coincide with the
spin axis and the equipment shelf will thus be perpendicular
to the spin axis.
PVO Inertial Spacecraft Coordinates (PVO_ISCC):
The inertial spacecraft coordinate system for the PVO spacecraft
is same coordinate system as the spinning spacecraft coordinate
system (SSCC) except that it does not spin with the spacecraft.
Thus the Spin axis or positive Z axis direction is the same in
both systems and it points out the top (toward the BAFTA assembly)
of the spacecraft. The axes in the spin plane are defined as
follows: The X-Z plane is defined to contain the spacecraft-Sun
vector with the positive X direction being sunward,
and the coordinate system is defined to be right-handed. The
transformation from SSCC to ISCC is:
_ _
| cos(p) -sin(p) 0 |
| sin(p) cos(p) 0 |
| 0 0 1 |
_ _
where p is the spin phase angle measured in ISSC coordinates.
Venus Solar Orbital Coordinates (VSO):
The VSO coordinate system is a Cartesian coordinate
system centered on Venus. The components of this
coordinate system are as follows: The X axis direction points
from the center of Venus to the Sun, taken positive towards the
Sun, the Z axis is parallel to the northward pole of the Venus
orbital plane, the Y axis completes the right-handed set and
points towards dusk. Locations of bodies (spacecraft) given in
VSO coordinates are usually represented in units of
Venus radii where Rv = 6052 km.
Equatorial Inertial Spherical Coordinates (ISC_EQTR):
The Equatorial Inertial Spherical Coordinate system is defined by the
equatorial plane of the Earth for the reference epoch of 1950.0. The
principal direction vectors of this system are the Earth's Equatorial
Pole and the Vernal Equinox direction. The components of the coordinate
system are:
1) Radius: Distance from the reference body to the spacecraft.
2) Declination: The angle between the reference body-spacecraft
radius vector and the reference body equatorial plane, measured
positive north of the equatorial plane.
3) Right Ascension: The angle between the Vernal Equinox line and the
projection of the reference body-spacecraft radius vector onto the
Earth equatorial plane, measured eastward from the Vernal Equinox
line.
4) Inertial Speed (V): The magnitude of the inertial velocity of the
spacecraft.
5) Inertial Flight Path Angle (GAMMA): The angle between the spacecraft
inertial velocity vector and the plane perpendicular to the
reference-body-to-spacecraft (radius) vector; positive when measured
away from the reference body.
6) Inertial Azimuth Angle (SIGMA): The angle, measured in the plane
perpendicular to the reference-body-to-spacecraft (radius) vector,
from the projection of true north into that plane eastward to the
projection of the inertial velocity vector into that plane.
When the reference body is taken to be the Earth, this becomes the
coordinate system EME-50 (FK-4).
Inertial Spherical Coordinates - Ecliptic (ISC_ECLP):
The Ecliptic Inertial Spherical Coordinate system is defined by the
ecliptic plane of the Earth for the reference epoch of 1950.0. The
principal direction vectors of this system are the Earth's Ecliptic
Pole and the Vernal Equinox direction. The components of the coordinate
system are:
1) Radius: Distance from the reference body to the spacecraft.
2) Celestial Latitude: The angle between the reference body-spacecraft
radius vector and the reference body ecliptic plane, measured positive
north of the ecliptic plane.
3) Celestial Longitude: The angle between the Vernal Equinox line and the
projection of the reference body-spacecraft radius vector onto the
Earth ecliptic plane, measured eastward from the Vernal Equinox line.
4) Inertial Speed (V): The magnitude of the inertial velocity of the
spacecraft.
5) Inertial Flight Path Angle (GAMMA): The angle between the spacecraft
inertial velocity vector and the plane perpendicular to the
reference-body-to-spacecraft (radius) vector; positive when measured
away from the reference body.
6) Inertial Azimuth Angle (SIGMA): The angle, measured in the plane
perpendicular to the reference-body-to-spacecraft (radius) vector,
from the projection of true north into that plane eastward to the
projection of the inertial velocity vector into that plane.
When the reference body is taken to be the Earth, this becomes the
coordinate system ECL-50.
Earth-Sun Line Cartesian Coordinates (ESL-CART):
The Earth-Sun Line Cartesian coordinate system is defined to have
the X-Y plane be the instantaneous ecliptic plane with the positive
Z direction taken to be the Sun-centered, northward ecliptic normal.
The positive X direction is away from the Sun along the Sun-Earth line.
Y completes the right-handed set and is positive away from the Sun.
Note: This system rotates with the Earth about the Sun.
Inertial Cartesian Coordinate System - Equatorial (ICC_EQTL):
The Equatorial Inertial Cartesian Coordinate System is defined for
the reference epoch of 1950.0 The X-direction is positive
away from the reference body towards the Vernal Equinox which is determined
by the line of intersection between the mean Earth equatorial plane and
the ecliptic plane of reference. The Y direction is measured outward
from the center of the reference body, perpendicular to and east of the
the X-axis, and lying in the equatorial plane of reference. The Z direction
is positive toward the north equatorial pole of reference, from the center
of the reference body.
Inertial Cartesian Coordinate System - Ecliptic (ICC_ECLP):
The Equatorial Inertial Cartesian Coordinate System is defined for
the reference epoch of 1950.0 The X-direction lies in the Ecliptic Plane
and is positive away from the reference body towards the Vernal Equinox
which is determined by the line of intersection between the mean Earth
equatorial plane and the ecliptic plane of reference. The Y direction
is measured outward from the center of the reference body, perpendicular
to and east of the the X-axis, and lying in the ecliptic plane of
reference. The Z direction is positive toward the north ecliptic pole of
reference, from the center of the reference body.
Body-Fixed Spherical Coordinate System (BFS_CRDS):
The body-fixed spherical coordinate system is the familiar Geographic
coordinate system at Earth generalized to other planets. The system
consists of the components Radius, Latitude, Longitude. The definition
of the prime meridian varies for each planet as does the rotation
period. It is crucial to know the exact definition of these variables
when changing the reference body.
Note: This coordinate system rotates with the reference body.
Spacecraft Centered Ecliptic Coordinates (SCC_ECLP):
The Spacecraft Centered Ecliptic coordinates system (Xe, Ye, Ze) is
used to describe the locations of the roll reference celestial objects
(Sun or star) and the planet Venus. The coordinate system is centered
at the spacecraft center of mass. The Xe-Ye plane is parallel to the
Ecliptic Plane and the Ze axis points to the North Ecliptic Pole.
The Xe axis points towards the Vernal Equinox. Directions in this
coordinate system are described by Celestial Longitude and Celestial
Latitude.
Non-Rotating Spin Coordinates (NRSC):
The roll angle of the roll reference object will be calculated in this
coordinate system as well as the roll angles of the Fs, RIP, RAM, and
NADIR signals. The non-rotating coordinate system (Wx, Wy, Wz) is
centered at the spacecraft center of mass. The Wz-axis is parallel to the
spacecraft spin axis. The Wx-Wy plane is perpendicular to the spacecraft
spin axis. The Wx-Wz plane includes the Vernal Equinox of reference.
Thus the Wx-axis is at the intersection of the plane perpendicular to
the spacecraft spin axis and the plane containing the spin axis and the
Vernal Equinox. Roll angles in this coordinate system are measured in the
Wx-Wy plane from the roll reference direction.