Target Sequence

A Target Sequence is a structural element that can be used to define maneuvers and propagations in terms of the goals they are intended to achieve.

Setting up a Target Sequence

Target Sequences are defined in three steps:

Add segments to the Target Sequence.
Define Profiles
Configure the Target Sequence

A Target Sequence will run the segments nested within it, and apply profiles to the run according to its configuration. When applying a search profile, the Target Sequence will adjust the targeted values over multiple iterations in an attempt to converge at a solution within the defined tolerance. When applying segment configuration profiles, the Target Sequence will alter the properties of the targeted segments to affect the course of the MCS run. The results of a Target Sequence can then be applied to the MCS to produce a trajectory that meets the goals you need to achieve.

Adding Segments

Any MCS Segment can be nested within a Target Sequence, including another Target Sequence. The segments within a Target Sequence are defined in the same manner as they are in the MCS itself or in other sequences.

Defining Profiles

The actions that the Target Sequence will take are determined by the Profiles that are defined for it. There are two basic types of profiles - search and segment configuration. Search profiles define goals and modify variables to achieve them. Segment configuration profiles change segments within the target sequence.

It is possible for a segment configuration profile to make a change to the MCS that deactivates a parameter targeted by a search profile.

There are five types of search profile:

There are seven types of segment configuration profile:

Finally, there is one profile that can be designed to act as either of these basic types:

Scripting Tool

You can add, copy, delete, and perform other actions on profiles by right-clicking in the table that lists them or by using the following toolbar buttons:

Button	Name	Function
	Properties...	Opens the properties window of the currently selected profile. You can also double-click on a profile to open its properties window.
	New...	Opens the component selection window, which allows you to select a profile to assign to the segment.
	Cut	Removes the currently selected profile from the list and copies it to the clipboard.
	Copy	Makes a copy of the currently selected profile to the clipboard.
	Paste	Inserts a copy of the profile that is currently on the clipboard.
	Delete	Deletes the currently selected profile.
	Duplicate	Creates a copy of the currently selected profile and adds it to the list.

The Profiles table in the Target Sequence properties displays the following information for each profile that you have added to the Target Sequence:

Name -- The name given by the user to the profile or, if one was not given, the default name.
Reset -- Click to reset the controls of the profile to the segments' values.
Apply -- Click to apply the current values of the profile's controls, if it is a search profile, or to apply the change specified, if it is a segment configuration profile.
Mode -- The profile's mode of operation.
Status -- a profile-specific status indicator.
User Comment -- a description of the profile supplied by the user or, if one was not supplied, a default description.

The profiles are invoked in the order in which they appear in this table. You can click the

and

arrows to change the order of the profiles.

Configuring the Target Sequence

You can configure a Target Sequence to execute in many different ways depending on the solution you are trying to achieve. The parameters that define a Target Sequence are described in the following table.

Option	Description
Action	Select among: Run nominal sequence -- runs the mission control sequence. Run active profiles ONCE -- runs the profile with corrections applied to control parameters. Run active profiles -- runs the mission control sequence allowing the active profiles to operate.
When Profiles Converge	Select the action to be carried out if targeting has converged: Run to RETURN and continue -- Run to the first Return segment in the sequence, then pass control to the next segment after this target sequence. Often, the only Return is at the end of the target sequence. Run to RETURN and stop -- Run the target sequence to the first Return segment, and then stop running the MCS altogether. Stop -- Stop the MCS as soon as the target sequence has converged.
Continue if profiles don't converge	Select to have the target sequence continue if a profile fails to converge; otherwise, the MCS will stop upon the failure of a search profile.
Reset inner targeters before each run	Select to have the profiles of nested target sequences reset at the beginning of each run of the parent target sequence.
Apply Changes	Click to apply the current values of search profiles' controls and the changes specified by the segment configuration profiles to the segments within the target sequence.
Reset	Click to reset the controls of the search profiles to the segments' values.
Enable Logging	Select to allow the sequence to record run history information to a log file. Logging must be enabled in the MCS Options window before it can be enabled for individual target sequences.

Nesting Target Sequences

If you nest one target sequence into another, you can use the outer targeter to adjust the values of the inner targeter; the desired values of Equality Constraints that you set for the inner targeter are automatically available as Control Parameters for the outer targeter. However, for the outer targeter to be able to converge, the following conditions must be met:

The Action field of the inner targeter must be set to 'Run active profiles'.

The Mode for the inner target profile must be set to 'Iterate'.

The perturbation for the outer control must be greater than the tolerance of the inner constraint.

For example, suppose that you want to achieve lunar orbit and want to use B-plane parameters as Control Parameters, but would like to have those be the result of targeting from other parameters, such as launch time and coast duration. You can set up an inner target sequence to target the B-plane parameters and an outer one to target the lunar orbit parameters (e.g. radius of periapsis and inclination). If the above conditions on the setup of the inner targeter are met, the outer targeter will vary the Equality Constraints (the B-plane parameters) of the inner targeter to achieve the desired end result.

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