Satellite: Astrogator Maneuver Ephemeris Block Initial: Relative Motion
Calc Objects for relative ephemeris.
The relative ephemeris
is computed with respect to two rotating frames, the RIC (Radial, In-Track, Cross-Track)
frame and the NTC (Normal, Tangential, and Cross-Track) frames, that are defined using the
primary's ephemeris. Cross-track refers to the direction perpendicular to the
position and inertial velocity; in-track refers to the direction perpendicular to both
the radial and cross-track (positive in the direction of motion); tangential refers to the
direction along the velocity vector; and normal refers to the direction perpendicular
to the velocity and cross-track directions (positive outward along radial).
Each
Calc Object allows a choice of a central body. The default is Earth.
See Also Formation
Name |
Dimension |
Type |
Description |
Time |
DateFormat |
Real Number |
Time. |
CrossTrack |
DistanceUnit |
Real Number |
The cross-track component of the relative position vector. |
CrossTrackRate |
Rate |
Real Number |
The cross-track component of the relative velocity vector as observed in the RIC rotating frame.
|
InTrack |
DistanceUnit |
Real Number |
The in-track component of the relative position vector. |
InTrackRate |
Rate |
Real Number |
The in-track component of the relative velocity vector as observed in the RIC rotating frame. |
Normal |
DistanceUnit |
Real Number |
The normal component of the relative position vector. |
NormalRate |
Rate |
Real Number |
The normal component of the relative velocity vector as observed in the NTC rotating frame.
|
RICAzimuth |
AngleUnit |
Real Number |
The angle measured in the plane formed by the in-track and cross-track directions, positive
from the In-Track direction toward the Cross-Track direction |
RICAzimuthRate |
AngleRateUnit |
Real Number |
The rate of change of the RIC azimuth |
RICElevation |
AngleUnit |
Real Number |
The angle measured perpendicular to the plane formed by the in-track and cross-track directions,
positive toward the Radial direction |
RICElevationRate |
AngleRateUnit |
Real Number |
The rate of change of the RIC elevation |
Radial |
DistanceUnit |
Real Number |
The radial component of the relative position vector. |
RadialRate |
Rate |
Real Number |
The radial component of the relative velocity vector as observed in the RIC rotating frame. |
Range |
DistanceUnit |
Real Number |
The range (i.e., distance between the primary and secondary object)
at the given time. |
RangeRate |
Rate |
Real Number |
The rate of change of the magnitude of the relative position vector. |
Tangential |
DistanceUnit |
Real Number |
The tangential component of the relative position vector. |
TangentialRate |
Rate |
Real Number |
The tangential component of the relative velocity vector as observed in the NTC rotating frame.
|
TimeDifference |
TimeUnit |
Real Number |
Alternative measure for in-track position difference, computed as as duration. The duration is computed
by dividing the in-track component of the relative position vector by the inertial velocity of the primary
object.
|