Electrodynamic Tether Deorbit

Tether Control

Tether current I 2.0 A

Tether length L 2000 m

Time acceleration 20,000×

Satellite in a stable 400 km equatorial orbit. Current flowing — orbit will decay.

Orbit Telemetry

Altitude

400.0 km

Orbital speed

7.67 km/s

Lorentz force

0.00 N

Decay rate

0.0 km/day

Orbital period

92.6 min

Local B field

0.0 μT

How it works

A dead satellite trailing a bare conducting tether below it, oriented along the local vertical, sits in Earth's magnetic field B. Driving a current I through the tether's length L creates a Lorentz force on the whole assembly:

F = I · L × B          (Lorentz force on a current-carrying wire)
B(r) ≈ B₀ (Rₑ/r)³      (equatorial dipole falloff, B₀ ≈ 31.2 μT)
E = -GMₑm / (2r)       (orbital energy, circular orbit)
dr/dt = (F·v) / (dE/dr)

Because the tether is radial and Earth's field near the equator points along the spin axis, F lands almost exactly along the direction of travel. Point the current one way and F opposes velocity — the tether acts as electromagnetic drag with no propellant, bleeding orbital energy until the dead satellite re-enters. This is a real, flight-tested debris-mitigation technique (e.g. Terminator Tether-class deorbit devices) for retiring defunct satellites and upper stages before they become collision hazards. Reverse the current and the same hardware does the opposite: it pushes against the field to raise the orbit, using station electrical power instead of propellant — a genuine reboost mode, at the cost of fighting the tether's own natural motional EMF (ν×B·L) instead of harvesting it.

Current / Length sliders — larger I·L means a bigger force and a faster orbital energy change in either mode.
Mode toggle — flips the current direction, switching between braking (deorbit) and thrusting (reboost).
Time acceleration — real decay from a few amps of tether current is a few km/day; this speeds up only the altitude integration so the effect is visible, while force, speed and period readouts stay true instantaneous physics.

Satellite + tether Lorentz force Magnetic field (dipole)

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