Target Planner

SOLIS enables you to define an attitude configuration when the satellite is between targets. Simply set the following parameters:

Consider the following example conditions

• The minimum dwell time is 30 seconds.
• The current time is 10 seconds.
• The time to slew to the Between Target is 50 seconds.
• The time to slew from the Between Target to the next target is 20 seconds.
• The next target is not available until 100 seconds.

In this case, the target planner would NOT schedule the between target, because there are only 100-20-50-10 = 20 seconds available to dwell at the between target. The target planner will then schedule a slower slew of 100-10 = 90 seconds directly from the previous target to the next target.

In this same example, if the minimum dwell time was set to any number less than 20 seconds, the target planner would schedule the between target and dwell on it for 20 seconds until moving on to the next target.

When you select this check box, the target planner summary CSV file is automatically saved to the "tp" directory of your spacecraft. Using Automation, you can override this filename and location.

From this area of the Target Planner tab, you can also set a target planner time that is separate from the SOLIS run time. Clear the Use SOLIS Times [Start, End] check box and then change times. The target plan will only be computed within this range of times.

The Target List shows all of the imported targets that have been recognized by SOLIS. Targets are either imported from STK Objects or from a file (for example, a TPC File).

Target Information and Customization

By selecting a specific target in the list, Targeting Information and Customization will be visible to the right of the Target List.

From this area, you can assign a target's Priority.

• Valid priority levels are integers from 1 to 255.
• A 1 represents the higher-priority targets.
• The planner algorithm ensures that higher-priority targets will not be missed as a result of scheduling a lower-priority target.

Below the Target List, the Targeting Configurations define how the Target Planner will treat each target. You can apply a targeting configuration to any number of targets. There is also an [Ignore Target] option.

Button	Description
	Add a new targeting configuration.
	Copy the selected targeting configuration.
	Delete the selected targeting configuration.

Add a new targeting configuration and then define its parameters to the right. You can set the following parameters for a targeting configuration:

Depending on the type of targeting desired, there are two sets of Type options:

Pointing Options

Scanning Options

Each scan has the potential to be scheduled in four different ways

• Start -> Stop
• Stop -> Start
• Start -> Stop w/ Reverse Clocking
• Stop -> Start w/ Reverse Clocking

These parameters define the default options of the scan for any target assigned to this targeting configuration. It is relatively common to override these defaults on a target-by-target basis, as it may not be desired that all scans have the same distance and bearing.

Overriding the Scan Defaults

When you select a Scan Target in the Target List, the End Options panel appears to the right. This panel enables you to define a target end point in four different ways.

Executing the Target Planner will generate a spacecraft command sequence to carry out the operations as configured within the interface. The first item in the sequence will be a comment containing a time-based summary of the plan, which appears in the Sequence Editor page or Raw Sequence Editor pages.

In addition to the time-based summary, there is a a target-based summary available. Columns are sortable for various types of analyses, and you can export the report to a CSV file.

The target planner algorithm selects target order based on minimizing the following cost function:

Cost(target) = EndTimeofAccess(target) - MinimumDwellTime(target) + SlewTime(target)

This technique gives preference to targets with shorter slew times and those with accesses nearing expiration. Targets with insufficient time remaining to slew to and achieve their minimum dwell time are not considered. Targets of lower priority can be scheduled prior to targets of higher priority, as long as their scheduling does not effect the ability to schedule higher priority targets in the future.

The target planner is generating command sequences to track targets on the central body's surface. Since these targets are moving relative to the spacecraft, the spacecraft configuration must have sufficient agility to track these targets. You can use the Actuator Wizard to rapidly configure the actuators to achieve a desired slew rate.

The chart below shows a worst-case rate of a target given an orbit altitude. The following assumptions are made to create the worst-case scenario:

• The orbit is circular.
• The target lies on the spacecraft ground track.
• The orbit is equatorial.