•The Put command provides a mechanism to collect Spacecraft state data into an Ephemeris object.
oWhenever you want to add the Spacecraft's current state into the Ephemeris object, use the Put command.
oThis is often in a While loop, usually following Step and/or Maneuver commands.
oYou can also use the
oSee the Creating an Ephemeris File page for more information and examples.
•If you want to automatically add all the states a Spacecraft will have over the entire Mission Plan simulation, you may want to Put the Spacecraft to the Ephemeris using the "as Global" option, as shown above.
oNote that the "as Global" option is scoped to the control statement it was called in. That is to say, when the "as Global" option is used inside of an If block, While loop, or For loop, all steps inside of the control statement will automatically be added; any steps taken outside of the control statement will NOT be added.
oYou can also employ the "Global" option using the checkbox shown on the Ephemeris Object editor.
oWhen the Ephemeris object has been initialized with the Global checkbox turned on, the associated Spacecraft's state will be added to the Ephemeris object automatically whenever the Spacecraft is stepped or maneuvered; therefore, no Put command from Spacecraft object to Ephemeris object is required.
oThis is particularly useful if the Mission Sequence is complex (multiple loops, maneuvers, etc.) or if the "Step To" syntax is used.
•Once all of the Spacecraft states have been collected into the Ephemeris object, the Put command can be used to generate an external ephemeris file.
oThis is usually at the end of the Mission Sequence.
oSeveral formats are available for the creation of external ephemeris files, including FreeFlyer ephemerides (*.FFephem), STK ephemerides (*.e), SPICE ephemerides (*.bsp), CCSDS ephemerides, and Goddard Space Flight Center Code 500 ephemerides (requires NASA pack).
oYou can also use the Ephemeris.GenerateEphemeris() method instead of the Put command.
oSee Ephemerides and AHF for more information.
•With the FreeFlyer ephemeris format in version 2 or higher, FreeFlyer has the ability to add custom columns.
oWhen adding custom columns, you can specify whether the value for the column will be automatically retrieved from a mapped Spacecraft property when the Put command is called, or if the value for the column will be explicitly provided to the Put command.
oIf a custom column is not mapped to a Spacecraft property, the value for this column must be explicitly provided to the Put command, as shown in the example above.