Orbital Sandbox - 80-second model-generated demonstration
No audio; on-screen captions provide the narration.

00-16 seconds | The question
Jupiter's moons sparked a question: how do orbits change over time? This sandbox turns questions into experiments.

16-32 seconds | Start with a circular orbit
400 km above Earth. Circular speed: 7.669 km/s. A fixed position and velocity determine the path.

32-48 seconds | Change velocity, keep position
At mission time zero, add 100 m/s in the direction of motion. Energy increases. The circular path becomes an ellipse.

48-64 seconds | Check the prediction
Apoapsis rises to 765.5 km. An independent vis-viva calculation agrees. The spacecraft slows as it climbs.

64-80 seconds | Test the model's limits
Earth is not a perfect sphere. In the 400 km comparison, adding J2 exceeds a 10 km separation threshold within 25 minutes.