Initial State

The Initial State segment can be used to define the initial conditions of your MCS or of a subsequence within the MCS. You can specify the state at a given epoch in a variety of coordinate types and in any coordinate system. You can also configure the spacecraft’s physical values. The segment adds the defined state to the ephemeris, and then passes the state to the next segment.

Selecting a Coordinate System

The name of the currently selected coordinate system is displayed in a read-only field. To select a different coordinate system, click button to the right of this field and make the desired selection in the Select Reference window that appears. The name of that coordinate system will then appear in the Coordinate System field. For more information on coordinates systems, see STK Technical Notes.

Entering Orbit Elements

The initial state can be defined using Cartesian, Geodetic, or Spherical elements if the coordinate system is fixed, or by Cartesian, Spherical, and several other element sets if the coordinate system is inertial. Select the desired element set from the Coordinate Type drop-down menu and then define an orbit epoch and values for the elements of the selected set.

Initial State Tool

Click Initial State Tool... to change the initial state of the satellite by reading ephemeris from a file, or to move the epoch of the initial state using a vehicle's propagated ephemeris.

Spacecraft Parameters and Fuel Tank

The Spacecraft Parameters and Fuel Tank tabs can be used to manually define the Spacecraft Configuration.

User Variables

The User Variables tab can be used to set initial values for user variables that have been defined for the mission.