Satellite deorbit compliance & orbital lifetime calculator

King-Hele atmospheric decay integrated from the disposal orbit to reentry, checked against FCC 47 CFR 25.283 / ESA Zero Debris / legacy 25-year limits. First-order screening - confirm marginal verdicts with NASA DAS at the real disposal epoch.

This orbital lifetime calculator is free and runs in your browser - no sign-up, no install. It integrates King-Hele atmospheric decay from the disposal orbit in your post-mission disposal plan down to reentry, and checks the resulting post-mission lifetime against the regime you pick: the Federal Communications Commission (FCC) 5-year rule (47 CFR 25.283), the European Space Agency (ESA) Zero Debris standard, or the legacy 25-year guideline - the three regimes are compared side by side here. When an orbit fails, it sizes both remediations operators actually use - the deployable drag area, and the perigee-lowering disposal Δv, that bring the lifetime exactly to the limit. A first-order screen with a piecewise-exponential atmosphere at three solar-activity tiers; confirm marginal verdicts with NASA's Debris Assessment Software (DAS) at the real disposal epoch.

Every satellite operator now has to prove that whatever is left in orbit at end of mission comes back down promptly. The threshold tightened sharply: the FCC adopted a 5-year rule in 2022 (in force September 2024) for LEO satellites below 2,000 km - replacing the decades-old 25-year guideline - and ESA's Zero Debris standard matches it at under 5 years. Many disposal orbits that were fine under 25 years now fail. This tool tells you whether yours passes, and by how much.

The physics is atmospheric drag. A satellite with mass m, drag coefficient Cd, and cross-section A presents a ballistic coefficient BC = m/(Cd·A); the tool integrates the King-Hele simple-atmosphere decay equation da/dt = −(Cd·A/m)·ρ·√(μ·a) forward from the disposal orbit to the reentry altitude (100 km), using a piecewise-exponential atmospheric density table at three solar-activity tiers. For an elliptical disposal orbit, drag is concentrated at perigee - density is exponential in altitude - so the orbit first circularizes at perigee, then decays; that is why a low perigee is such a cheap way to shorten lifetime.

If the natural lifetime exceeds the limit, the tool solves the two remediation paths operators actually use. Required drag area - the deployable drag-sail area that would bring lifetime to exactly the limit (found by bisection, since lifetime falls monotonically with area). Disposal Δv - the perigee-lowering burn, applied at apogee, that drops the natural lifetime to the limit; from LEO this is usually only tens of m/s, and often cheaper than carrying a sail.

What this tool does not do: it is a first-order screening model, not a certified predictor. Future solar activity (the ~11-year cycle) swings thermospheric density several-fold, so real post-mission lifetime carries roughly 10-50% uncertainty - the same reason regulators accept a screening result but expect a full run of NASA DAS (Debris Assessment Software) at the actual disposal epoch for the filing. It also does not model attitude-driven area variation, geomagnetic-storm density transients, drag-sail deployment reliability, controlled-reentry targeting, or the casualty-risk / demise side of the standard (a separate assessment). A conservative compliance check uses the Low (solar-minimum) atmosphere, which gives the longest - worst-case - lifetime.