LEO to GEO Space Surveillance with EOIR

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

The EOIR installation package is included with the STK Premium installation package. However, you must install EOIR on your computer separately from the STK application. See the EOIR capability help for more information.

The sensor specifications in this lesson are notional.

Capabilities covered

This lesson covers the following STK capabilities:

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

Overview

STK's EOIR capability models 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.

In this tutorial, we will model an EOIR sensor on a LEO satellite to evaluate the total duration of GEO surveillance. For this scenario, we will bring in the satellite objects, set up the EOIR sensor, create outputs, and generate a scene for the sensor.

Video guidance

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

Getting started

We'll begin by building a scenario and then inserting the objects for this mission, a LEO sat, GEO sat, and a tracking sensor. Once we've established these objects, we'll add a new level to our analysis with an EOIR sensor.

  1. Click the Create a Scenario () button.
  2. Enter the following in the New Scenario Wizard:
    3. Option Value
    Name LEO_GEO_EOIR
    Start Time Default Start Time
    Stop Time + 12 hrs
  3. Click OK .

Verifying that EOIR is installed

Ensure that EOIR is installed on your computer.

  1. If you do not see the EOIR toolbar (), extend the View menu.
  2. Select the Toolbars option.
  3. Select EOIR.

Inserting a GEO satellite

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

  1. Insert a Satellite () object using the Orbit Wizard () method.
  2. Set the Type to Geosynchronous.
  3. Set the Satellite Name to GEO.
  4. Accept the rest of the default settings and click OK .

Inserting a LEO satellite

Create a satellite in LEO orbit to track the GEO satellite. We 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. Set the Type to Circular.
  3. Set the Satellite Name to LEO.
  4. Accept the rest of the default settings and click OK .

Inserting a sensor

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

  1. Insert a Sensor () object using the Define Properties () method.
  2. When prompted, select LEO as the object to attach the sensor to.
  3. Click OK .
  4. Change the Sensor Type to Rectangular.
  5. Set the following values:
    6. Option Value
    Vertical Half Angle 1.5 deg
    Horizontal Half Angle 1.5 deg

Targeting the sensor

After the field of view has been defined, it is time to point the sensor and track the GEO satellite.

  1. Go to the Basic – Pointing page.
  2. Set the Pointing Type to Targeted.
  3. Move () GEO to the Assigned Target list.
  4. Click OK .

Computing access

A quick way to verify if the LEO satellite is properly observing the GEO satellite is to compute the access between them.

  1. Right-click the sensor () and select Access ().
  2. Ensure the Access For object is LEO- Sensor1.
  3. Set the Access To object to be GEO ().
  4. Under the Reports section, click Access… to generate an access report.

Confirm that you have access between the sensor and the satellite. This report tells us how long the GEO satellite is within the field of view of the LEO satellite. Note the total duration of the access intervals.

EOIR settings – spatial

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

  1. Open the sensor’s () properties ().
  2. Go to the Basic – Definition page.
  3. Set the Sensor Type to EOIR.
  4. On the Spatial tab, set the Field of View values:
    5. Option Value
    Horizontal Half Angle 1.5 deg
    Vertical Half Angle 1.5 deg
  5. Leave the Number of Pixels as the default.
  6. Click Apply .
  7. Go to the Spectral tab. Note the options on the panel, but leave the values as default.

EOIR settings - optical

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

  • F-# and Entrance pupil diameter
  • F-# and Focal length
  • Focal length and Entrance pupil diameter
  1. Go to the Optical tab.
  2. Set the Input to F-Number and Entrance Pupil Diameter.
  3. Set the F/# and the Entrance Pupil Diameter to the values below:
    4. Option Value
    F/# 1.20
    Entrance Pupil 400.00 cm
  4. Leave the Image Quality as Diffraction Limited.
  5. Leave the Optical Transmission and Diffraction Wavelength as the defaults.
  6. Click Apply .

EOIR settings – radiometric

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

  1. Go to the Radiometric tab.
  2. Set the Input to High Level.
  3. Set Sensitivity – Equivalent Value to 1 e-19.
  4. Leave all other parameters as the defaults.
  5. Click OK .

Satellite – EOIR shape

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

  1. Open GEO’s () properties ().
  2. Go to the Basic – EOIR Shape page.
  3. Set the following parameters:
    4. Option Value
    Shape Sphere
    Radius 5 m
    Body Temperature Static
    Temperature 500 K
  4. Click OK .

Adding the GEO satellite to the EOIR target configuration

Open the EOIR Target 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 the EOIR Target Configuration () icon on the EOIR toolbar.
  2. In the Available STK Objects panel, highlight Satellite/GEO from the list.
  3. Use the blue arrow button () to move the satellite to the Selected Targets list.
  4. Click OK .

Plotting the SNR of the target

Analyze if a satellite at LEO can target and image the 5-meter object out at GEO.

  1. Right-click the sensor () and select Report and Graph Manager ().
  2. In the Styles section, right-click the My Styles folder, and select New - Graph.
  3. Give the graph style a name of EOIR_SNR.

    4. When you click away, the graph style configuration page launches with the available data providers.

  4. Expand the EOIR Sensor To Target Metrics data provider.
  5. Double-click Signal to noise ratio to add this data to the Y Axis of the graph.
  6. Set the Step Size to 600 sec.

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

  7. Click OK .
  8. Double-click EOIR_SNR to generate the graph.

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 in the graph area and select Show Animation Time Line.
  2. Right-click the peak of the first interval and select Set Animation Time.
  3. Rotate your 3D graphics window so you can see the GEO target with the Sun in view.

Results may vary based on analysis start time due to seasonal variations.

Performing EOIR sensor scene analysis

View the sensor output.

  1. In the EOIR toolbar, click the EOIR Sensor Scene () icon to generate an image that represents the sensor output.
  2. Right-click the sensor scene and select Details....
  3. Using your mouse click in the scene to generate information about each point of light.
  4. Click on the bright spots in the image. Does the sun saturate the scene?
  5. Click in the middle of the image to find the GEO satellite and note that it is very dim compared to the background.
  6. Right-click the peak of the last interval and select Set Animation Time.
  7. Rotate your 3D graphics window so you can see the GEO target with the Sun.

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

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

  1. Right-click on the sensor scene and select Details....
  2. Using your mouse click in the scene to generate information about each point of light.
  3. Click on the very center of the image to select the GEO satellite.
  4. Close the window when done exploring.
  5. Close the graph when done exploring.

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 the sensor’s () properties ().
  2. Go to the Constraints - EOIR page.
  3. Select the Min check box and set it to 50.
  4. Click OK .

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

  5. Right-click the sensor () and select Access ().
  6. In the Access tool, ensure the Access For object is set to LEO- Sensor1.
  7. Select GEO () as the Access To object, then click Compute .
  8. In the Reports section, click Access… .

    9. 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.