Spacecraft.CloseApproachRange(Variable, GroundStation, TimeSpanArray, Array, Array) Method

Description

Returns a sequential listing of events related to the proximity of the calling Spacecraft and the argument rangingStation using ANCAS 1 interpolation method. This method uses the position and velocity states from three data points to create a quintic polynomial approximating the range between the two objects over time.

For more information on the ANCAS algorithms, please refer to: Alfano, Salvatore. Determining Satellite Close Approaches, Part II. Journal of the Astronautical Sciences 42.2. Apr-Jun 1994, 143-152.

Timing Precision Mode

This page describes functionality in nanosecond timing precision mode.

Click here to see the documentation for this object in millisecond timing precision mode.

Note: This is an interval method. See the Interval Methods page for more information.

Note: This method has a state. See the Methods and Properties with State page for more information.

Method Signature

Spacecraft.CloseApproachRange(	Variable rangeLimit,
	GroundStation rangingStation,
	TimeSpanArray EventTime,
	Array EventType,
	Array EventRange)

Arguments

rangeLimit
Description:	Range that specifies the distance inside of which the closest approach detection is desired and outside of which the greatest separation detection is desired.
Units:	km

rangingStation
Description:	GroundStation object with respect to which range is computed.

EventTime

Description:

The time that the event occurred.

The FF_Preferences.IntervalEventReportingBehavior property controls whether the start of propagation is reported as an event. By default, if the close approach starts before the beginning of the propagation span, FreeFlyer will label the start of the propagation as the start of the close approach.

EventType

Description:

The type of the event that occurred.

Event Type == 1 is Range Limit Entry Detected.

Event Type == 2 is Range Limit Exit Detected.

Event Type == 3 is Minimum Range Detected.

Event Type == 4 is Maximum Range Detected.

EventRange
Description:	The range between the two Objects' centers at the epoch when the event occurred.

Return Value

Type:

number

Returns the number of elements filled into EventType and EventTime arrays.

Syntax

myVariable1 = mySpacecraft1.CloseApproachRange(myVariable2, myGroundStation1, myTimeSpanArray1, myArray1, myArray2);