org.jeospace.physics.orbit
Interface World

All Superinterfaces:

Identifiable, KineticBody, OrbitalBody

All Known Implementing Classes:

BaseWorld, Moon, SolarWorld

public interface World

extends OrbitalBody

Defines the requirements necessary to describe a world's physical characteristics and motions as they relate to being a part of an orbital system. Specifically:

• Uniquely identify a world
• Describe the characteristics of a world necessary to place worlds or satellites in it's orbit and descibe the orbits in relationship to the world
• Position a world in it's orbit about it's parent system
• Orient the world's rotational axis
• Rotate the world about it's axis

Version:

$Revision: 1.1.1.1 $

Author:

Rex Melton

See Also:

Spherical, Ellipsoid, AngleNorm

Method Summary

Ellipsoid	getEllipsoid() Return the reference ellipsoid of the world
double	getGravitationalConstant() Return the gravitational constant of the world.
AngleNorm	getLongitudeNormalization() Return the normalization option to be used to format longitude coordinates.
Spherical	getRotationalAxis(double timeValue) Return the position on the celestial sphere that is intersected by a vector along the rotational axis of the world - from it's origin, through the world's the North Pole.
double	getSiderealRotation(double timeValue) Return the sidereal rotation of the world about it's axis at the specified instant in time.

Methods inherited from interface org.jeospace.physics.orbit.OrbitalBody

getOrbitalElements

Methods inherited from interface org.jeospace.physics.KineticBody

getCoordinate, getCoordinate, getReferenceFrame

Methods inherited from interface org.jeospace.designation.Identifiable

getIdentification

Method Detail

getEllipsoid

public Ellipsoid getEllipsoid()

Return the reference ellipsoid of the world

Returns:

the ellipsoid

getGravitationalConstant

public double getGravitationalConstant()

Return the gravitational constant of the world. The gravitational constant is the product of the universal gravitational constant (G) and the mass of the world. The constant is in units of km^3 sec^2 and is used in the calculations of orbital elements of objects in orbit about the world.

Returns:

the gravitational constant

getRotationalAxis

public Spherical getRotationalAxis(double timeValue)

Return the position on the celestial sphere that is intersected by a vector along the rotational axis of the world - from it's origin, through the world's the North Pole.

Issues:

• Should there be a specification for the coordinate reference frame ?

Parameters:

timeValue - the time instant at which to calculate the rotational axis alignment

Returns:

the position on the celestial sphere that is intersected by the rotational axis of the world.

getSiderealRotation

public double getSiderealRotation(double timeValue)

Return the sidereal rotation of the world about it's axis at the specified instant in time.

Issues:

• Sidereal rotation, i.e. rotation as measured against the celestial reference frame
• This requires that the world's ellipsoid is reference-able to the celestial reference frame. Other than the Earth (and Moon?), that is not implemented
• Should the return be in an Angle object? Nothing else is returned in radians, though that is convenient for injecting into a VRML/X3D browser.

Parameters:

timeValue - the time instant at which to calculate the rotational axis

Returns:

the rotation in units of radians.

getLongitudeNormalization

public AngleNorm getLongitudeNormalization()

Return the normalization option to be used to format longitude coordinates. For worlds other than Earth and the Moon, this is also an indicator of the direction of rotation. (i.e. in the solar system, a world's 'north pole' is define to be in the hemisphere of positive declination. Longitudes are measured in the direction opposite of their rotation. Therefore, by the Jeospace convention of measuring angles (see AngleNorm) worlds that are rotating in a right-hand positive direction about their 'north-pole' are normalized as AngleNorm.FULL_REVOLUTION_NEGATIVE and worlds that are rotating in a right-hand negative direction about their 'north-pole' are normalized as AngleNorm.FULL_REVOLUTION_POSITIVE.

Returns:

the normalization option desired for the longitudes of this world.