Cascade

overview

When the 2026 Swift Student Challenge opened, I knew I wanted to make something about space. Reading about Kessler Syndrome gave me a subject I wanted to explore, with collisions creating debris that can cause further collisions. I wanted to see that process unfold and be able to change its starting conditions.

Cascade became an educational simulator for iPad, with arcade-style controls over a 3D scene in RealityKit. You can change the starting satellite count and the variation in their orbits, or set off a satellite yourself. Messing with a simulator is the part I like most. That freedom to try something and watch the result became the core of the app.

The learning material has its own place in Learn More, including a chart of the growth of cataloged objects in Earth orbit. Keeping it separate lets someone experiment first and read when a question comes up. The controls stay beside the scene, so changing a setting does not mean losing sight of what it affects.

I’m not a physicist, so I leaned on AI tools for the orbital-gravity math. Much of my own work went into keeping the simulation usable as debris accumulated. Fragments share a mesh, and collision checks use a spatial grid to narrow the search. The tetrahedral fragments have four vertices each. That shape began as a performance decision, and I liked the angular appearance enough to keep it.

Cascade was selected as a Swift Student Challenge winner. I was proud of the result after the research and rounds of optimization. There is a demo below, and the project is on GitHub.

demo

design

SF Pro Display sets the interface type.

Fixed-width digits keep the satellite and debris counts steady as they change.

credits