Understanding Classical, Sun Synchronous, Shuttle, and Molniya orbit type parameters

Use the Classical orbit type if you want to define the maximum allowable parameters of a body orbiting a predefined or user-defined celestial body.

The Sun Synchronous, Shuttle, and Molniya orbit types preset certain characteristics and let you define additional parameters.

Defining an orbit's shape

At least two different parameters are required to define the basic orbit shape.

In the Orbit dialog box, the parameters are available from Specify lists in the Orbit Parameters tab.

You can define the shape of an orbit according to its:

• Minimum or maximum radius (value must be greater than planet radius).

• Minimum or maximum altitude.

• Eccentricity (eccentricity of 0 corresponds to a circular orbit).

• Period.

Understanding orbit inclination

The orbit inclination is the angle that describes the tilt of the orbit plane with respect to the axis of the planet.

An orbit's angle inclination is measured between the following two vectors:

• The North vector which is the Z-axis of the inertial reference CS.

• The normal vector of the planet's orbit plane.

From the right hand rule, the orbit's plane normal points to the northern hemisphere for a counterclockwise satellite rotation, and points to the Southern hemisphere for a clockwise satellite rotation.

Inclination for counterclockwise rotation

	Normal to orbit plane
	Orbit plane
	Inclination
	North
	Satellite direction

Inclination for clockwise rotation

	Normal to orbit plane
	Orbit plane
	Inclination
	North
	Satellite direction

Understanding the ascending and descending nodes

The ascending node is the point on the equatorial plane where the satellite passes from the Southern hemisphere to the Northern hemisphere. The descending node is where the satellite passes from the Northern hemisphere to the Southern hemisphere.

Understanding the argument of periapsis

The perigee is the orbit point closest to the earth. The periapsis is the orbit point closest to an orbited celestial body.

The argument of periapsis is defined with reference to the ascending node.

The Argument of Periapsis option on the Orbit Parameters tab lets you specify the angle between the ascending node and the periapsis on the orbit plane. By convention, this angle is measured in the direction of satellite rotation.

Defining the satellite's position

You define a satellite's position with reference to the ascending node. Simcenter 3D Space Systems Thermal follows the convention of measuring the angle of the ascending node in the eastward direction from its reference. This angle is between 0° and 360°.

How do I

Set up an orbital heating simulation

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Orbit

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Using the Orbit Visualizer

Understanding Beta Angle orbit type parameters

Sun Planet Vectors orbit type parameters

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Understanding Classical, Sun Synchronous, Shuttle, and Molniya orbit type parameters, Simcenter 3D 2021.1 Series

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