Payloads

The Payloads page enables you to define any number of payloads and related modes associated with the simulated spacecraft. You can enable and disable payload modes via the SET_POWER command, and you can use payloads to model the power and data generation rate for defined payload states. The Payloads page is also useful for the analysis of spacecraft power and data resources as well as ground target accessibility and planning.

UI details

Payloads list

The Payloads list contains all payloads that have been added to the spacecraft model. Clicking a particular payload in the list activates the modeling attributes for that payload. It also enables the buttons to add, copy, and delete a payload.

Modeling attributes

To the right of the Payloads list are the following payload Modeling attributes for the selected payload:

Parameter	Description
Payload Name	Specifies the name of payload. Changing this will update the Payloads List. Commands associated with user-defined modes always contain the Payload Name so that you can distinguish between multiple payloads when commanding the spacecraft, either through real-time commanding or using the sequence builder.
Standby Power	Specifies the power consumed (W) when payload is in "Standby".
Link to STK satellite object	You can associate the payload with a sensor object on the STK satellite. When linked, the object's field-of-view will pulse whenever one of the defined modes for the payload is enabled.
Boresight	At the bottom of the window is an area to define the boresight vector (a unit vector in the spacecraft body frame) for the payload, if applicable. When linking to an STK satellite object (i.e., a sensor object), you must set the STK pointing attributes for the object in the STK object’s Properties page, and these must be consistent with the boresight vector defined in SOLIS.

Modes Table

Use the Payloads Mode Table to define the modes associated with the selected payload. You may add, copy, and delete modes. Names will be autogenerated for you when adding a payload.

Payload Modes Glossary

Parameter	Description
Mode Mnemonic	String used by the command engine to enable/disable the mode
Mode Name	User-defined name for the mode
Mode Power	Power draw for the payload when the associated payload mode is enabled and the payload state is "On"
Data Type	A shortcut menu that defines how the payload generates data: Bulk Data or Data Rate
Data Output	Value that defines the quantity of data generated by the payload when the associated mode is selected and the payload state is "On"

Payload modeling

Power

You can model the Payload Power in SOLIS if you select Payloads on the Power/Thermal page. You must select the mode with the payload state set to "On" for the power (W) to be added to the spacecraft power load model.

Data

There are two options for payload data modeling in SOLIS:

• Bulk Data Generation: The payload generates the amount of data defined by the data output attribute each the time the payload mode is On.
• Data Rate: When the payload mode is On, the payload generates data at the rate specified by the data output attribute.

In both cases, the data from the payload is transferred to the spacecraft data recorder. Bulk Data Generation and Data Rates are expressed in multiples of bits and bits per second (bit/sec). For converting between these units, use the binary system, for example, 1 Gbit/sec translates to 2³⁰ bit/sec, 2²⁰ kbit/sec, and 2¹⁰ Mbit/sec.

Data recorder

The data recorder is modeled to show the status of data stored on the spacecraft. Data is collected by payloads and sent by transmitters.

Data Recorder Glossary

Parameter/Control	Description	Units
Recorder Size	Data capacity of the recorder	User-Defined
Initial State	Initial percentage state of the recorder	%
Saturate	If you select this check box, the data recorder will stop accumulating data when saturated. If not, the data recorder will keep accumulating data and show how much more than 100% was used.	N/A