Drag-Sail Deorbit Simulator

Drag-Sail Deorbit

Sail area 4.0 m²

Spacecraft mass 100 kg

Starting altitude 600 km

Solar activity (density) Moderate

Time warp ×1

Status

Altitude

–

Mission time

–

Area / mass

–

Orbital period

–

Est. deorbit time

–

25-year rule

–

Drag decays the orbit fastest near perigee-dense low altitude and high area-to-mass ratio. Deploying a bigger sail trades almost no extra mass for a much larger cross-section, cutting years off disposal time.

How it works

A satellite in low Earth orbit still grazes the outer atmosphere. Drag removes orbital energy every pass, shrinking the semi-major axis a bit at a time — slowly at 800 km, rapidly below 400 km, because density rises roughly exponentially as altitude falls. The rate depends on the area-to-mass ratio (A/m): a wide, light drag sail exposes far more area per kilogram than the bus alone, so it multiplies the decay rate without needing propellant.

rho(h) = rho0 · exp(−(h − h_ref)/H)
da/dt  = −Cd · (A/m) · rho(a) · v_circ(a)
v_circ = sqrt(GM / a)

Sail area — cross-section exposed to the residual atmosphere; doubling it roughly halves the time to reentry at a given altitude.
Spacecraft mass — a heavier bus needs more sail area to reach the same A/m and therefore the same decay rate.
Starting altitude — decay time grows very fast with altitude because density falls off exponentially with height.
Solar activity — solar EUV heating puffs up the thermosphere, raising density at a given altitude and speeding decay; low activity does the opposite.

Real-world relevance: international guidelines (the "25-year rule" and its tightened variants) require operators to remove a satellite from useful orbit within 25 years of end-of-mission — either by propulsive deorbit or, for satellites too small or too depleted to manoeuvre, by a passive drag device like this sail. This simulator lets you check, for a given spacecraft, whether a sail of a given size actually meets that deadline.

Satellite Drag sail Orbit track Sensible atmosphere

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.