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Learn orbital mechanics

Last updated: 10 lessons, all free

Delta-V Academy is a 10-lesson interactive curriculum covering orbital mechanics from the six orbital elements through space domain awareness. Every lesson runs in the browser, uses real Keplerian physics with J2 perturbations, and offers four difficulty levels (kids, novice, intermediate, advanced). Every lesson is free with an email signup; Lesson 1 and kids mode require no account at all.

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The curriculum

  1. Lesson 1
    Drag the sliders, watch what happens. Real Keplerian physics in your browser.
  2. Lesson 2
    Higher orbits move slower. Drag the altitude slider and watch why.
  3. Lesson 3
    Same orbit, different speeds. Drag eccentricity, watch the satellite race through perigee and crawl through apogee.
  4. Lesson 4
    Watch the path a satellite traces on Earth's surface. Inclination changes everything.
  5. Lesson 5
    Earth isn't a sphere. That tiny squish moves every satellite a little bit, every day.
  6. Lesson 6
    A satellite's view shrinks as it climbs and stretches as it tilts. The geometry sets what's possible.
  7. Lesson 7
    Four altitude bands. Four totally different design philosophies.
  8. Lesson 8
    Real notation, real constellations. Why GPS uses 6 planes and Starlink uses 72.
  9. Lesson 9
    Where the sensor looks defines what the satellite can do.
  10. Lesson 10
    Radars, telescopes, and tracking algorithms. The architecture that keeps orbital traffic safe.

Three levels, real depth

Every lesson is written at three difficulty levels (plus a fourth kids-friendly mode):

  • Kids uses cartoon-illustrated graphics, plain-English labels, and fun-fact callouts. Designed for ages 6-14.
  • Novice uses plain English and real-world analogies. No equations. Defines every technical term on first use.
  • Intermediate introduces equations with each variable explained. Uses real numbers and concrete examples.
  • Advanced assumes the reader can follow Kepler-style derivations and uses exact mission parameters (GPS at 20,200 km, Iridium NEXT at 86.4°, etc.). Trusts the reader.

What makes this different

  • Real physics. Two-body Kepler propagation with J2 secular drift, real Walker constellation parameters, real sensor archetype math.
  • Real constellations. 1,584 Starlink satellites, 66 Iridium NEXT satellites, 24 GPS Block IIIA, the actual GEO belt, real Molniya orbits. Not toy approximations.
  • Free forever. No content paywall. Email signup for Lessons 2-10 (used for cross-device progress sync). Optional AI Pro subscription only matters if you want to use the AI Mission Architect more than 3 times per day.
  • Browser-only. No install, no Java, no plugin. Three.js + WebGL. Works on phones.

Open the simulator

The fastest path to understanding orbital mechanics is to play with one. Launch the simulator and try Lesson 1 right now. Or, dig into a specific topic via the lesson pages above.

See also: frequently asked questions · support the project