LEO to GEO Space Surveillance with EOIR

STK Premium (Air), STK Premium (Space), or STK Enterprise
You can obtain the necessary licenses for this tutorial by contacting AGI Support at support@agi.com or 1-800-924-7244.

Required Capability Install: This lesson requires an additional capability installation for STK EOIR. The EOIR install is included in the STK Premium software download, but requires a separate install process. Read the Readme.htm found in the STK install folder for installation instructions. You can obtain the necessary install by visiting https://support.agi.com/downloads or calling AGI support.

This lesson requires STK 12.9 or newer to complete in its entirety. If you have an earlier version of STK, you can complete a legacy version of this lesson.

The results of the tutorial may vary depending on the user settings and data enabled (online operations, terrain server, dynamic Earth data, etc.). It is acceptable to have different results.

Capabilities covered

This lesson covers the following STK capabilities:

  • STK Pro
  • Electro-Optical Infrared Sensor Performance (EOIR)

Problem statement

Engineers and operators require a way to simulate the detection, tracking, and imaging performance of Electro-Optical Infrared (EOIR) sensors for earth science, space situational awareness, and missile defense applications. Results support concept design, engineering, test, and operations. You need to model an EOIR sensor on a low Earth orbiting (LEO) satellite to evaluate the total duration of tracking and surveying of a satellite in a geostationary orbit (GEO).

Solution

Use STK to propagate a satellite into a LEO orbit. Then, attach a sensor to it which you'll configure for its EOIR capabilities. Propagate a second satellite into a GEO orbit. Track the GEO satellite with the EOIR configured sensor to obtain signal to noise ratio data during your analysis period and to generate a visual sensor scene and associated data.

What you will learn

Upon completion of this tutorial, you will understand:

  • How to configure Sensor objects to use the EOIR type
  • How to create a custom EOIR SNR graph
  • How to create an EOIR sensor scene
  • How to view data in the EOIR Scene Visual Details dialog box

Video guidance

Watch the following video. Then follow the steps below, which incorporate the systems and missions you work on (sample inputs provided).

Creating a new scenario

Create a new scenario.

  1. Launch STK ().
  2. Click Create a Scenario in the Welcome to STK dialog box.
  3. Enter the following in the STK: New Scenario Wizard:
    4. Option Value
    Name LEO_GEO_EOIR
    Location Default
    Start Time Default
    Stop Time + 12 hrs
  4. Click OK when finished.
  5. Click Save () when the scenario loads. A folder with the same name as your scenario is created for you in the location specified above.
  6. Verify the scenario name and location and click Save.

    7. Save () often!

Verifying that EOIR is installed

Ensure that EOIR is installed on your computer.

  1. Select the View menu.
  2. Select Toolbars in the shortcut menu.
  3. Select EOIR in the next shortcut menu.

    4. If EOIR is not in the list of tools, you didn't install EOIR. Please read the Required Product Install note at the top of this lesson.

  4. Locate the EOIR () toolbar.

Inserting the first Satellite object

The main focus of this analysis will be to target and track a satellite in GEO orbit. We will use the Orbit Wizard in STK to model the satellite.

  1. Select Satellite () in the Insert STK Objects Tool.ct To Be Inserted: list.
  2. Select Orbit Wizard () as the method.
  3. Click Insert... .

Using the Orbit Wizard

The first satellite to create is the GEO satellite that will be surveyed.

  1. Select Geosynchronous for the Type in the Orbit Wizard.
  2. Type GEO in the Satellite Name: field.
  3. Keep the rest of the default settings.
  4. Click OK .

Inserting the second Satellite object

Create a satellite in LEO orbit to track the GEO satellite. You don't need any specific orbit; for this mission, the default LEO satellite will suffice.

  1. Insert a Satellite () object using the Orbit Wizard () method.
  2. Type LEO in the Satellite Name: field.
  3. Keep the rest of the default settings.
  4. Click OK .

Inserting a Sensor object

Before adding complexity of modeling to an EOIR sensor, make sure the sensor is able to track GEO () in the first place. The default Sensor () object allows for the field of view of a satellite to be constrained and customized. You will attach a Sensor () object to LEO () that will model the EOIR sensor focused on GEO ().

  1. Insert a Sensor () object using the Define Properties () method.
  2. Select LEO () in the Select Object dialog box.
  3. Click OK .
  4. Right click on Sensor1 () in the Object Browser.
  5. Select Rename.
  6. Rename Sensor1 () to LEO_Sensor.

Changing the sensor type

You will use a rectangular field of view.

  1. Select the Basic - Definition page.
  2. Select Rectangular for the Sensor Type.
  3. Set the following values in the Rectangular frame:
    4. Option Value
    Vertical Half Angle 1.5 deg
    Horizontal Half Angle 1.5 deg
  4. Click Apply to accept your changes and keep the Properties Browser open.

Targeting the sensor

After the field of view has been defined, it is time to point the sensor and track GEO (). The Targeted pointing type causes the sensor to point to other objects in the scenario.

  1. Select the Basic - Pointing page.
  2. Select Targeted for the Pointing Type.
  3. Move () GEO to the Assigned Target list.
  4. Click OK to accept your changes and close to the Properties Browser.

View LEO_Sensor's field of view

You can view LEO_Sensor's () field of view in the 3D Graphics window.

  1. Bring the 3D Graphics window to the front.
  2. Use your mouse to set your view so that you can see LEO_Sensor () targeting GEO ().

    3. LEO Sensor targeting geo

Opening the Access tool

Open the Access tool.

  1. Right click on LEO_Sensor () in the Object Browser.
  2. Select Access... ().

Computing an access report

A quick way to verify if LEO_Sensor () can see GEO () is to compute the access between them.

  1. Select GEO () in the Associated Objects list in the Access tool.
  2. Click .
  3. Click Access… in the Reports frame.
  4. Confirm that you have accesses between the LEO_Sensor () and GEO (). This report tells us how long GEO () is within the field of view of LEO_Sensor ().
  5. Note the total duration of the access intervals (e.g. ~25698 seconds).
  6. Close () the access report.
  7. Close () the Access Tool.

Setting the EOIR sensor type

Up until now, you have only modeled the system geometrically. Go a step further and set the EOIR parameters for LEO_Sensor ().

The EOIR sensor specifications in this lesson are notional.

  1. Open LEO_Sensor's () properties ().
  2. Select the Basic – Definition page.
  3. Select EOIR as the Sensor Type.

Defining Spatial settings

Set the EOIR spatial properties.

The EOIR sensor specifications in this lesson are notional.

  1. Select the Spatial tab.
  2. Set the following in the Field of View frame:
    3. Option Value
    Horizontal Half Angle 1.5 deg
    Vertical Half Angle 1.5 deg
  3. Click Apply .

Defining Spectral settings

Set the EOIR spectral properties.

  1. Select the Spectral tab.
  2. Note the options on the panel.
  3. Leave the values as default.

Defining Optical settings

The Optical Properties Input mode enables you to specify which two optical parameters are inputs and will calculate the third.

  1. Select the Optical tab.
  2. Select F-Number and Entrance Pupil Diameter for the Input.
  3. Set the following values:
    4. Option Value
    F/# 2.00
    Entrance Pupil Diameter 400 (cm)
  4. Keep the default settings for the rest of the Optical tab.
  5. Click Apply .

Defining Radiometric settings

For further refinement, adjust the radiometric settings. These properties define the radiant energy measurement properties.

  1. Select the Radiometric tab.
  2. Enter 1e-19 in the EquivalentValue cell in the Sensitivity frame.
  3. Leave all other parameters as the defaults.
  4. Click OK .

Setting GEO's EOIR shape

Next, set up the EOIR shape for GEO (). This will define what LEO_Sensor () will see when it targets GEO (). You will define the material and shape properties, starting off with a simple setup of a 5-meter spherical object out at GEO's () orbit.

  1. Open GEO’s () properties ().
  2. Select the Basic – EOIR Shape page.
  3. Set the following parameters:
    4. Option Value
    Radius 5 m
    Temperature 500 K
  4. Leave all other parameters as the defaults.
  5. Click OK .

Adding GEO to the EOIR target configuration

Open the EOIR Configuration to select an STK object to be included in the generated sensor scene and to make sensors available to generate radiometric results.

  1. Click EOIR Configuration... () in the EOIR toolbar.
  2. Double click on Satellite/GEO () in the Available STK Objects (Double click to select ) list in the EOIR Configuration dialog box. This moves it to the Selected Targets list.
  3. Click OK .

Plotting the signal to noise ratio (SNR) of GEO

Analyze if LEO_Sensor () can target and image the 5-meter object out at GEO's () orbit.

Creating a new graph

Create a new graph called EOIR SNR.

  1. Right click the LEO_Sensor () in the Object Browser.
  2. Select Report and Graph Manager... ().
  3. Select My Styles () in the Styles list.
  4. Click Create new graph style ().
  5. Type EOIR SNR as the graph's name.
  6. Click the Enter key on your keyboard.

    7. When you click the Enter key, the Content page launches with the available data providers and the name is set for your graph.

Choosing data providers

Select the data providers you require for your graph.

  1. Select the Content page.
  2. Expand () the EOIR Sensor To Target Metrics data provider in the Data Provider list.
  3. Move () Signal to noise ratio () to the Y Axis list.
  4. Enter 600 sec in the Step Size: field.

    5. EOIR can take a while to calculate, so it is a good idea to start with coarse settings and dial them in later.

  5. Click OK .

Generating the custom graph

  1. Select EOIR SNR () in My Styles () in the Report & Manager.
  2. Click Generate... .

Examine the signal noise data

Your custom graph is generated. View the results. You saw in the earlier access calculations all the intervals of access. Now you have data representing how well you can image the GEO satellite. There are several modifications you can make to the graph and 3D graphics window to visualize the geometry of the sensor collection during the peak of the first and last interval before analyzing the results using EOIR.

  1. Right click on the peak of the first interval.
  2. Select Set Animation Time.
  3. Bring the 3D Graphics window to the front.
  4. Rotate your 3D graphics window view so you can see LEO_Sensor () targeting GEO () with the Sun in view.

    5. Low Snr: 3D View of leo_sensor targeting geo and the snr graph

    Your graph compared to the above graph may vary based on analysis start time due to seasonal variations.

Opening the EOIR sensor scene

View the sensor output.

  1. Click EOIR Sensor Scene... () in the EOIR toolbar.

    2. This generates an image that represents the sensor output.

  2. Right click on the EOIR sensor scene.
  3. Select Details...

Performing EOIR sensor scene analysis

You can view the EOIR sensor scene details.

  1. Move the EOIR Scene Visual Details dialog box, so that it doesn't sit on top of the scene.
  2. Click on any points of light in the scene.

    3. This generates information about each point of light in the EOIR Scene Visual Details dialog box.

  3. Click on the gray dot near the middle of the image to find GEO ().

    4. GEO () is very dim compared to the background because the Sun is saturating the scene. GEO will display in the Object: field of the EOIR Scene Visual Details dialog box when you find it.

  4. Close () the EOIR Scene Visual Details dialog box.

Comparing the results with the behavior in the 3D Graphics window

The SNR is much higher now that the Sun is reflecting off of GEO () to LEO_Sensor () , as you can see in the 3D Graphics window.

  1. Bring the EOIR SNR graph back to the front.
  2. Right click on the peak of the last interval.
  3. Select Set Animation Time.
  4. Bring the 3D Graphics window back to the front.
  5. Rotate your 3D graphics window view so you can see LEO_Sensor () targeting GEO () with the Sun in view.

    6. high SNR: 3D View of leo_sensor targeting geo and the snr graph

Performing EOIR sensor scene analysis

You can view the EOIR sensor scene details.

  1. Bring the EOIR Sensor Scene back to the front.
  2. Right click on the EOIR sensor scene.
  3. Select Details...
  4. Using your mouse click in the scene to generate information about each point of light.
  5. Click on the very center of the image to select GEO ().

    6. The Sun is no longer saturating the EOIR Sensor Scene. GEO () is seen in the middle of the EOIR Sensor Scene as a dim point of light.

Cleaning up workspace

Clean up your workspace.

  1. Close () the EOIR Scene Visual Details dialog box.
  2. Close () the EOIR Sensor Scene dialog box.
  3. Close () the EOIR SNR graph.
  4. Close () the Report & Graph Manager.

    5. EOIR recalculates both graphs and sensor scenes automatically, so it’s important to close these when not using them.

Restricting access calculations using EOIR constraints

Reexamine the access computation. Add a new level of complexity by setting a S/N limit and then regenerate the access report.

  1. Open LEO_Sensor’s () properties ().
  2. Select the Constraints - Active page.
  3. Click Add new constraints () in the Active Constraints toolbar.
  4. Select SNR in the Constraint Name list in the Select Constraints to Add dialog box.
  5. Click Add.
  6. Click Close to close the Select Constraints to Add dialog box.
  7. Enter 50 in the Min: field in the SNR frame of the Constraint Properties section.
  8. Click OK .

    9. EOIR will automatically recalculate access intervals based on this new constraint, which may take a minute.

Viewing the access report

Create an Access report.

  1. Right-click the LEO_Sensor () in the Object Browser.
  2. Select Access... () in the shortcut menu.
  3. Select GEO () in the Associated Objects list in the Access tool.
  4. Click Access… in the Reports frame.

    5. You can see that there are fewer access intervals and less total access time when you consider the radiometric sensor properties in addition to the geometric properties.

Saving your work

  1. Close any open reports, properties and tools.
  2. Save () your work.

Summary

You used STK to place your LEO and GEO satellites into their respective orbits. You attached a Sensor object to the LEO satellite, targeting the GEO satellite. You created an access between the sensor and the GEO satellite to determine how many accesses were calculated. You reconfigured the Sensor object to use STK's EOIR capabilities, setting notional inputs to become familiar with the UI interface. You created and generated a custom SNR graph. You set your scenario to the time when the SNR was weakest and saw that the sensor was looking at the GEO satellite when the Sun was saturating the sensor. You created an EOIR sensor scene, opened the EOIR Scene Visual Details dialog box, and clicked on points of light and the GEO satellite to obtain data. You set your scene to when the SNR was strongest, viewed where the Sun was located and obtained more data about the scene. Finally, you created a sensor SNR constraint, recalculated access and saw that there were fewer accesses due to STK telling you when you could view the GEO satellite based on the SNR constraint.