Track the ISS with Ansys STK
See exactly when and where the space station will fly over your town.
Last reviewed: March 2026Overview
The International Space Station completes roughly 16 orbits every day, racing across the sky at 28,000 km/h just 400 km above your head. Predicting exactly when and where it will appear requires real orbital mechanics—the same math used by NASA flight controllers and satellite operators around the world. Ansys STK (Systems Tool Kit) is the professional software they actually use, and a free educational version is available to students.
In this project you will create a new STK scenario, insert the ISS using live Two-Line Element (TLE) data from CelesTrak, and explore the orbit in 2D and 3D views. You will learn about inclination, altitude, period, and ground track—the core vocabulary of anyone who works with satellites.
The real payoff comes when you add your location as a ground station and generate an access report: a precise schedule of every moment when the ISS is above your horizon over the next week. On a clear night, you can step outside with a timer and watch it pass exactly when STK said it would—one of the most satisfying confirmations in aerospace education.
What You'll Learn
- ✓ Define orbital parameters (inclination, altitude, period, RAAN) and explain what each one means physically.
- ✓ Import a TLE file into STK and understand what the numbers in a TLE represent.
- ✓ Interpret a 2D ground track and identify where the satellite's orbit repeats.
- ✓ Generate an access report between a satellite and a ground station.
- ✓ Predict a naked-eye ISS pass and verify it against real observations.
Step-by-Step Guide
Download and install STK Free
Go to ansys.com/stk and register for a free student account to download STK. Install it on a Windows PC (a virtual machine works too). Launch the application and take a few minutes to explore the ribbon interface—the 2D Map and 3D Globe windows will be your main workspaces.
Create a new scenario and set the time window
Click New Scenario, name it "ISS Tracking", and set the analysis period to cover the next seven days starting from today. STK will automatically load Earth with realistic terrain and lighting. Practice zooming and rotating the 3D view to get comfortable with navigation before adding any objects.
Insert the ISS using TLE data
Download the current ISS TLE from CelesTrak (search for "ISS (ZARYA)"). In STK, go to Insert > New Object > Satellite, choose "From TLE File", and paste in the two-line element set. The ISS orbit will appear instantly on both the 2D and 3D views. Observe the ground track and note how it shifts westward with each orbit due to Earth's rotation.
Add your location as a ground facility
Insert a Facility object and enter your city's latitude and longitude (find them on Google Maps). Set the elevation mask to 10° to match typical sky-obstruction conditions. Your location will appear as a marker on the globe. Zoom in on the 3D view to see it sitting on the terrain.
Run an access analysis
Right-click your Facility, choose Access, and select the ISS as the target object. Click Compute. STK will calculate every moment during your seven-day window when the ISS is above your horizon. Open the Access Report to see a table of rise time, maximum elevation, and set time for each pass. Note the maximum elevation angle—passes above 40° are ideal for naked-eye viewing.
Predict and verify a pass
Pick the highest-elevation pass from your report and note the exact UTC time. Convert it to your local time zone. On a clear night, go outside two minutes before the predicted start time, face the azimuth direction shown in the report, and watch for the ISS moving steadily (no blinking) across the sky. Compare what you see to the STK animation playing in real time on your computer. Document the result with a photo or video and note any timing error.
Career Connection
See how this project connects to real aerospace careers.
Aerospace Engineer →
STK is used daily at NASA, SpaceX, and defense contractors for mission planning, conjunction analysis, and link budget calculations.
Space Operations →
Satellite operators use STK access reports to schedule ground-station contact windows for uploading commands and downloading telemetry.
Flight Dispatcher →
Understanding orbital timing and coverage builds intuition for scheduling that transfers to managing complex flight operations.
Air Traffic Control →
Low-Earth orbit satellites are increasingly part of the communication and surveillance infrastructure ATC relies on; understanding their orbits adds professional context.
Go Further
- Add a second satellite (e.g., Hubble Space Telescope) and compare their ground tracks—note the different inclinations and what that means for ground coverage.
- Simulate a communications link by adding an antenna to your facility and running a link budget report.
- Change the ISS orbit altitude in STK by editing the TLE and observe how the orbital period and ground track change.
- Use STK's Coverage tool to calculate what fraction of Earth's surface the ISS can see in a single day.